sach

2. J 3 ^
PHANKHACNGHE•
(Giao vien Trudng TUPT chuyen Ha Tinh)
P H U O N G P H A P
GIAI TOAN
c su
SINH HOCBoi dif^ig hoc sinh gioi va on thi Dai hoc
THLT VIEN TINH BiNN THUA?4
iHa NQi
NHA XUAT BAN BAI HOC QUOC GIA HA NOI

4. Cuon sach "Phirang phdp gidi todn xdc sudt sink hoc" dugc viet bam
sat churong trinh thi tuy8n sinh Dai hoc va thi Hoc sinh gioi cap tinh, cap
Quoc gia. Trong cuon sach nay chiing toi da phan loai cac dang bai tap xac
suat, dua ra quy trinh giai ngan gon va de hieu.
Noi dung eua cuon sach dugc trinh bay thanh 5 chuyen de, moi chuyen
de deu CO 3 muc: Lwu y li thuyet, Cdc dang bdi tap (gom cdc bdi tap mdu
vd phucmg phdp gidi); Bdi tap van dung (bdi tap tie ludn, bdi tap trdc nghiem
vd dap an chi tiet). Moi bai tap mau la mot dang toan xac suat dugc trinh
bay ngan ggn, de hieu, de su dung. He thong cac bai tap van dung dugc
soan bam sat ngi dung chuong trinh thi Dai hoc va thi chon hgc sinh gioi
cac cap.
Chung toi tin tuong rang, cuon sach "Phuffng phdp gidi todn xdc sudt
sinh hoc" nay cung voi cuon sach "Phirffng phap giai nhanh cac dang
bai tap sinh hoc" cua thay Phan Khac Nghe la hai cuon tai lieu cung cap
day du phuong phap giai cac dang toan sinh hgc, la nhung cuon tai lieu
tham khao hOru ich giup hgc sinh tu hgc va giao vien tham khao su dung
trong cong tac boi duong hgc sinh gioi.
Du rat tarn huyet va danh nhieu thai gian de bien soan, song do nhiing
han che khach quan va chu quan nen cu6n sach khong tranh khoi con c6
thieu sot nhat dinh, tac gia rat mong nhan dugc cac y kien gop y de trong
Ian tai ban sau cuon sach dugc hoan thien han.
Mgi gop y xin gui ve dia chi: phankhacnghe@yahoo.com.vn
TAC GIA
3

6. Chuyen de
1.
XAC SUAT TRONGDI TRUYEN PHAN TUf
VA BI ENDI
I. XACSUAT TRONGDI TRUYEN PHANTUT
5 . LliU Y LI THUYET
- Theo li thuyet ngau nhien, sir xuat hien cua cac bo ba tren mARN tuan theo
quy luat toan hoc. Van dung li thuydt nay c6 th§ dir doan dugc tren mot phan tu
mARN CO the c6 bao nhieu Ian xuat hien 1 loai bo ba nao do.
- O di truyen phan tu, enzym cat gioi han la loai enzym cat phan tu ADN a
nhung vi tri dac hieu. Vi tri dac hieu thuomg la mot doan trinh t nucleotit. Moi
loai enzym cat giai han nhan biet doan trinh tu nucleotit va cat a vi tri dac hieu.
Theo li thuyet ngau nhien thi dira vao doan trinh tu nucleotit dac hieu ma enzym
nhan biet cat de du doan dugc do dai cua doan ADN dugc cat ra.
B. MOT SO DANG BAI TAP THUCING GAP
C) di truyen phan tu, xac suat dugc su dung khi tinh cac bg ba xudt hien tren
mARN theo li thuyet ngau nhien hoac xac suat de cat cac phan tu ADN bang cac
enzym cat han che.
Khi giai bai toan dang nay thi nen tien hanh theo 2 birdc sau day:
Buac 1: Tim ti le cua cac loai nucleotit lien quan den bo ba can tinh xac suat.
Buac 2: Sur dung toan to hop tinh xac suat.
Bai 1: Trong mot ong nghiem, c6 ti le 4 loai nucleotit A, U, G, X Ian lugt la 10%;
20%; 30%; 40%. Tu 4 loai nucleotit nay nguoi ta da tong hgp nen mot phan tu
ARN nhan tao. Theo li thuyet, tren phan tu mARN nhan tao nay, xac suat xuat
hien bo ba AAA la bao nhieu?
Hir&ng dan giai:
Buac 1: Tim ti le cua cac loai nucleotit lien quan den bp ba can tinh xac suat
Ti le cua nucleotit loai A la = 10% = 0,1.
Bu&c 2: Su dung toan to hgp de tinh xac suit
Xac suat xuk hien bg ba AAA = (0,1)^ = 0,001 = lO'l
Bai 2: Trong mot ong nghiem, c6 4 loai nucleotit A, U, G, X voi ti le an lugt la
A : U : G : X = 2 : 2 : 1 :2. Tu4 loai nucleotit nay nguoi ta da t6ng hgp nen
mot phan tu ARN nhan tao.
a. Theo li thuyet, tren phan tu mARN nhan tao nay, xac suit xuit hien bg ba
AUG la bao nhieu?
b. N6u phan tu mARN nay c6 3000 nucleotit thi se c6 bao nhieu bg ba AAG?
5

7. Hu&ngdangiai:
Buac1:Timtilecuacacloainucleotitlienquandenbobacantinhxacsuat
22
-TilecuanucleotitloaiAla=
-TilecuanucleotitloaiUla=
-TilecuanucleotitloaiGla=
2+2+1+27
2^2
2+2+1+27
11
2+2+1+27
Buac2:Svrdungtoant6hopdetinhxacsuat
a.Theolithuyet,trenphantumARNnhantaonay,xacsuatxuathienboba
2214
AUGla=-X-X
777343
b.SobobaAAGtrenphantumARNnay:
-Theolithuylt,trenphantiimARNnhantaonay,xacsuatxuathienboba
2,,14
AAGla=(-rX-=
77343
-PhantumARNnhantaoc63000nucleotitthitheolithuyetngaunhiensec6
4
sobobaAAG=—x3000~34,985.
Nhuvay,theolithuyStngaunhienthitrenmARNnhantaonaysec6khoang
34d6n35'bobaAAG.
Bai3:Trongmot6ngnghiem,c6tile4loainucleotitA,U,G,XvoitileIanluot
laA:U:G:X=2:1:3:2.Tir4loainucleotitnaynguoitadatonghopnen
motphantuARNnhantao.Theolithuylt,trenphantuARNnhantaonay,xac
suatxuithienbobaketthiiclabaonhieu?
Hu&ngdangidi:
Buac1:Timtilecuacacloainucleotitlienquandenbobacantinhxacsuat
TrenmARNc63bobakkthiiclaUAA,UAG,UGA.Vivaycanphaitinhti
lecua3loainucleotitA,U,Gc6trongcacbobanay.
221
-TilecuanucleotitloaiAla=
-TilecuanucleotitloaiUla=
-TileciianucleotitloaiGla=
2+1+3+284
11
2+1+3+28
33
2+1+3+28
Buac2:Sudimgtoantohopdetinhxacsuat
6

8. 1.2 1 1
- Xac suat xuat hien bo ba UAA = (-f x - =
• • 4 8 128
1 1 3 3
- Xac suat xuat hien bo ba UAG = - x - x - =4 8 8 256
- Xac suat xuit hien bo ba UGA = - x - x ^
4 8 8 256
Xac suat xuat hien bo ba ket thuc = —^ + — ^ + ^ ^
128 256 256 256 32
Nhu vay, tren phan tu ARN nhan tao nay, trung binh cu 32 bo ba thi c6 1 bo ba
kk thiic.
Bai 4: Neu cac nucleotit duoc xep ngau nhien tren mot phan tu ARN c6 10^
nucleotit, chiia 30%A, 20%X, 10%U, 40%G. So kn trinh tu 5'-GXXA-3' duoc
trong doi xuit hien la bao nhieu?
Hu&ng dan giai:
Buac 1: Tim ti le cua cac loai nucleotit lien quan den bo ba can tinh xac suat
- Ti le cua nucleotit loai G = 40% = 0,4.
- Ti le cua nucleotit loai X = 20% = 0,2.
- Ti le cua nucleotit loai A = 30% = 0,3.
Buac 2: Su dung toan to hgrp de tinh xac suat
Xac suat xuk hien trinh tu 5'-GXXA-3' = 0,4 x (0,2)^ x 0,3 = 0,0048 = ^
625
- Theo li thuyet ngau nhien thi tren mot phan tu ARN c6 lO'' nucleotit, chua
30%A, 20%X, 10%U, 40%G. S6 l§n trinh tu 5'-GXXA-3' duoc trong doi xuat
hien la = — x i o^ = 4,8 ~ 5 (lugt).
625
- Nhu vay tren phan tu ARN nay, theo li thuyet thi se c6 tir khoang 4 dSn 5 lugt
trinh tu 5'-GXXA-3' dugc xuk hien.
Bai 5: Co mot enzym cSt gioi han cSt cac doan ADN mach kep a doan trinh tu
nucleotit AGGXT. Khi su dung enzym nay dk dt mot phan tu ADN c6 t6ng s6
3.10^ cap nucleotit (bp) thi theo li thuyet phan tu ADN nay se bi cat thanh bao
nhieu doan ADN?
Hu&ng dan giai:
Buac 1: Tim ti le cua cac loai nucleotit lien quan den bo ba can tinh xac suat
Theo li thuyet thi a trong tu nhien, ti le cua 4 loai nucleotit a tren ADN la
tuong duong nhau, moi loai chifim ti le = —
4
Buac 2: Su dung toan to hgp de tinh xac suat

9. -DoantrinhtuAGGXTc65nucleotitnenc6xacsuat=(—f=—r.
-ComotenzymcatgiaihancStcacdoanADNmachkepadoantrinhtu
nucleotitAGGXT.KhisudungenzymnaydecStmotphantuADNc6t6ngs6
3.10'capnucleotit(bp)thitheolithuyetphantuADNnaysec6s6vitribicStla
=3.10^=29296,875~29296(vitricSt).
4
-Vai29296vitricatthisec6s6doanADNla29296+1=29297doan.
C.BAITAPVANDUNG
1.Baitaptyluan
Bai1.Trongmotongnghiem,c64loainucleotitA,U,G,XvaitileIanluatla
A:X:U:G=1:2:1:2.Tir4loainucleotitnaynguaitadatonghopnen
motphantuARNnhantao.NeuphantumARNnayc62500nucleotitthisec6
baonhieubobaUXA?
Bai2.Trongmotongnghiem,c6tile4loainucleotitA,U,G,Xhnluatla20%;
30%;25%);25%).Tu4loainucleotitnaynguaitadatonghapnenmotphantu
ARNnhantao.Theolithuyet,trenphantumARNnhantaonay,xacsukxuk
hienbobaUUGlabaonhieu?
Bai3.ComotenzymcatgiaihancStcacdoanADNmachkep6doantrinhtu
nucleotit5'AGTTX3'.KhisiidungenzymnaydlcitmotphantuADNc6
tongso5.10^capnucleotit(bp)thitheolithuyetphantuADNnaysebic4t
thanhbaonhieudoanADN?
Bai4.NeucacnucleotitduacxepngaunhientrenmotphantuADNc610^cap
A+T2''
nucleotit,c6tile=-.SoIantrinhtu5'-XGXA-3'dugrctrongdaixuSt
G+X3
hienlabaonhieu?
Bai5.Trongmot6ngnghiem,c64loainucleotitA,U,G,Xvaiti16bangnhau.
Tu4loainucleotitnaynguaitadatonghapnenmotphantuARNnhantao.
Theolithuyet,trenphantuARNnhantaonay,xacsudtxudthi§nbpbaket
thiiclabaonhieu?
.2.Baitaptracnghiem
Cau1.Trongmotongnghiem,c64loainucleotitA,U,G,Xvaiti1?Ianlugrtla
A:U:X:G=2:1:2:3.Tu4loainucleotitnaynguaitadatonghapnen
motphantuARNnhantao.N6uphantuARNnayc61500nucleotitthisec6
baonhieubobaUAG?
A.24.B.18.C.31.D.42.
8

10. Cau 2. Neu cac nucleotit duac xep ngau nhien tren mot phan ttr ADN c6 lO' cap
A + T 1 ' >
nucleotit, c6 ti le = - . So Ian trinh t 5'-GGXA-3' dugc trong dgi xnk
G + X 3
hien la
A. 21143. B. 65917. C. 123456. D. 23461.
Cau 3. Trong mot ong nghiem, c6 ti le 3 loai nucleotit A, U, G voi ti le Ian lucrt la
A : U : G = 1 : 1 :2. Tir3 loai nucleotit nay nguai ta da t6ng hop nen mot phan
tu ARN nhan tao. Theo li thuyet, tren phan tir ARN nhan tao nay, xac suit xuSt
hien bo ba ket thiic la bao nhieu?
A.—. B. — . C. —. D. '
64 192 32 64
Cau 4. Trong mot ong nghiem, c6 3 loai nucleotit A, U, X voi ti le Ian lucrt la A :
U : X = 2 : 1 :2. Tu3 loai nucleotit nay nguoi ta da tong hop nen mot phan tu
ARN nhan tao. Theo li thuyet, tren phan tu ARN nhan tao nay, xac suat xuSt
hien bo ba ket thiic la bao nhieu?
A. A . B . J - . c . i l . D. '
125 125 125 125
Cau 5. Co mot enzym cat gioi han cat cac doan ADN mach kep a doan trinh tu
nucleotit 5'AGTTXG3'. Khi su dung enzym nay dk cSt mot phan tu ADN c6
tong so 2.10^ cap nucleotit (bp) thi theo li thuy6t phan tu ADN nay se bi cat
thanh bao nhieu doan ADN?
A. 579. B. 977. C. 403. D. 489.
Cau 6. Trong mot 6ng nghiem, c6 ti le 3 loai nucleotit A, U, G voi ti le Idn lucrt la
A : U : G = 2 : 1 :2. Tu3 loai nucleotit nay nguai ta da tong hgrp nen mot phan
tu ARN nhan tao. Theo li thuyet, tren phan tu ARN nhan tao nay, xac sudt xuk
hien bo ba AUG la bao nhieu?
A . J - . B . A . C. A . D. 2
125 125 125 100
Cau 7. Trong mot ong nghiem, c6 2 loai nucleotit A, U voi ti 1? Ian lugt la A : U = 2 : 3.
Tu 2 loai nucleotit nay nguoi ta da t6ng hgp nen mot phan tu ARN nhan tao.
Neu phan tu ARN nay c6 2500 nucleotit thi se c6 bao nhieu bo ba UAA?
A. 240. B. 180. C. 152. D.412.
Cau 8. Trong mot 6ng nghiem, c6 ti le 3 loai nucleotit A, U, G voi ti le kn lugt la
A : U : G = 2 : 2 : l . T i r 3 loai nucleotit nay nguai ta da t6ng hgrp nen mot phan
tir ARN nhan tao. Theo li thuyet, tren phan tu ARN nhan tao nay, xac suit xuit
hi?n bo ba kk thuc la bao nhieu?
A . i i . B . J - . C . i l . D. '
125 125 125 125
9

11. Cau9.ComotenzymcatgioihancatcacdoanADNmachkepadoantrinhtu
nucleotit5'ATXG3'.KhisudungenzymnaydecatmotphantuADNc6tong
so10"*capnucleotit(bp)thitheolithuyetphantiiADNnaysebicatthanhbao
nhieudoanADN?
A.38.B.3.C.157.D.40.
Cau10.NSucacnucleotitduacxgpnglunhientrenmotphantuADNc63.10^
A+T1'-
capnucleotit,c6tile=—.SoIantrinhtu5'-GAXA-3'duactrongdai
xukhienla
A.143.B.480.C.126.D.461.
3.Dapan:
a.Cacbaitu*luan:
Bail.
Buac1:Timtilecuacacloainucleotitlienquandenbobacantinhxacsuat
11
-TilecuanucleotitloaiUla=
-TilecuanucleotitloaiXla=
-TilecuanucleotitloaiAla=
1+2+1+26
221
1+2+1+26
11
1+2+1+26
Buac2:Sudungtoantohopdetinhxacsuat
-TheoHthuyet,trenphantumARNnhantaonay,xacsuatxuathienboba
TTVAr1111
UXAla=-x-x-=
636108
-PhantumARNnhantaoc62500nucleotitthitheolithuyetngaunhiensec6
s6bobaUXA=-^x2500=^-23.
Nhuvay,theolithuyetngaunhienthitrenmARNnhantaonaysec6khoang
23bobaUXA.
Bai2.
Buac1:TimtilecuacacloainucleotitlienquandSnbobacantinhxacsuat
-TilecuanucleotitloaiUla=30%=0,3.
-TilecuanucleotitloaiGla=25%=0,25.
Buac2:Sudungtoantohopdetinhxacsuat
XacsudtxuithienbobaUUG=(0,3)^x0,25=0,0225=.
400
10

12. Bai 3.
Buac 1: Tim ti le cua cac loai nucleotit lien quan den bo ba can tinh xac suit
Theo li thuySt thi a trong tu nhien, ti le cua 4 loai nucleotit a tren ADN la
tuong duong nhau, moi loai chiem ti le = —
4
Buac 2: Su dung toan t6 hop dS tinh xac suSt
- Doan trinh tu 5'-AGTTX-3' c6 5 nucleotit nen c6 xac sudt = ( — )^ = -K .
4'
- Co mot enzym cat giai han cat cac doan ADN mach kep a doan trinh tu
nucleotit 5'-AGTTX-3'. Khi su dung enzym nay d8 cat mot phan tu ADN c6 t6ng
so 5.10^ cap nucleotit (bp) thi theo li thuyet phan tu ADN nay se c6 so vi tri bi cat
la = ^ X 5.10^ =488281,25 -488281 (vi tri cat).
4
- Vai 488281 vi tri cat thi se c6 s6 doan ADN la 488281 + 1 = 488282 (doan).
Bai 4.
Buac 1: Tim ti le cua cac loai nucleotit lien quan den bo ba can tinh xac suat
Phan tu ADN nay CO tile = - . ^ A = T = 20%, G = X = 30%.
• G + X 3
- Ti le cua nucleotit loai A = T = 20% = 0,2.
- Ti le cua nucleotit loai G = X = 30% = 0,3.
Buac 2: Su dung toan t6 hop dk tinh xac suit
Xac suat xuat hien trinh tu 5'-XGXA-3'
= 0,3 X 0,3 X 0,3 X 0,2 = 0,0054 = .
5000
- Theo li thuyet ngau nhien thi tren mot phan tu ADN c6 10* nucleotit, c6 ti le
A + T ^ 2
G + X 3'
S6 lan trinh tu 5'-XGXA-3' duac trong doi xuat hien la = x 10* = 5400.
^ • • 5000
- Nhu vay tren phan tu ADN nay, theo li thuyet thi se co 5400 luat trinh tu
5' -XGXA-3' dugc xuat hien.
Bai 5.
Buac 1: Tim ti le cvia cac loai nucleotit lien quan den bo ba can tinh xac suat
- Tren mARN c6 3 bo ba kit thuc la UAA, UAG, UGA. V i vay chn phai tinh ti
le cua 3 loai nucleotit A, U, G c6 trong cac bo ba nay.
1
- Bon loai nucleotit A, U, G, X c6 ti le bang nhau nen moi loai chiem ti le = —.
4
11

13. Buac2:Sudungtoantohapdetinhxacsuat
-XacsudtxudthienbobaUAA=-x(-)'=—.
••4464
-XacsuatxuathienbobaUAG=—x—x—=—.
44464
-XacsuitxuithienbobaUGA=—x-x—=—.
••44464
Xacsuatxuathienbobaketthuc=—+—+—=
1
6464646421
Nhuvay,trenphantuARNnhantaonay,trungbinhcu21bobathic61boba
ketthuc.
b.Cacbaitr^cnghiem
12345678910
BBADDCACDB
II.XACSUATKHICOBIENDl
.LUUYLITHUYET
-Khigiamphan,tebaokhongdotbi^nsesinhragiaotukhongdotbien.Hop
tukhongdotbiendugcsinhradosirkethapgiuagiaotuduekhongdotbi6nvai
giaotucaikhongdotbien.
-Khipheplaic6nhieucapgenthinenphantichtheotungcapgendktinhti1$,
saudomaitinhxacsuat.
B.MQTSODANGBAITAPTHadNGGAP
1.Baitapvegiaotudptbien.
Buac1:Xacdjnhtilecualoaigiaotvtcantinhxacsuat
Suae2:Sitdungtoant6hypdetinhxacsuat.
Bai1:Motcathec6kieugenAaBbDd.Neutrongquatrinhgiamphan,c612%
sotebaodabiroiloanphanliciiacapNSTmangcapgenBbagiamphanI,
giamphanIIdienrabinhthuan^,cac^capNSTkhacphanlibinhthuang.
Trongcacgiaotuduocsinhra,layngaunhien1giaotuthixacsuitdkthu
dugcgiaotumanggenABbDlabaonhieu?
Hie&ngdangidi:
Buac1:Xacdinhti1?cualoaigiaotuABbD.
-CapgenAagiamphanbinhthuangsesinhra2loadgiaotCrlaAva^^.
-CapgenDdgiamphanbinhthuangsesinhra2loaigiaoti>laDvad,trongdoD=^
12

14. - Cap gen Bb giam phan khon g bin h th uon g, Bb khon g phan l i tron g giam phan
I se sinh ra 2 loai giao t u la Bb va O, trong do Bb = ^ • Co 12% s6 t6 bao giam
phan bi dot bien nen giao t u dot biSn Bb c6 t i le = 6 %.
-> Va y loai giao t ii ABb D c6 t i le = ^ x 1 x 6% = 1,5%.
Buac 2: Su dung toan to hop de tin h xac suat
Lay ngau nhien 1 giao t u t h i xac suk dk th u dugc giao t u ABb D la 1,5%.
Bai 2: Mot ca thS c6 k i l u gen AaBbDd . NSu tron g qua trin h giam phan, c6 20%
so te bao da b i r oi loan phan l i cua cap N ST mang cap gen Bb a giam phan I ,
giam phan I I dien ra bin h thuon g, cac cap N ST khac phan l i bin h thuon g.
Trong cac giao t u dugc sinh ra, iy ngau nhien 2 giao t u t h i xac sudt de t h u
dugc 2 giao t u mang gen Ab D la bao nhieu?
Hu&ng d a n giai:
Buac 1: Xac din h t i le cua loai giao t u Ab D.
- gen Aagjam p h &ibiiih thuong se sinh ra 2 lorn giao t u la A va a, tro ^ .
- Cap gen Dd giam phan binh Ihuong se sinh ra 2 loai giao t u la D va d, trong do D = ^
- Co 20% so te bao da b i r oi loan phan l i cua cap N ST m ang cap gen Bb o giam
phan I , giam phan I I d i ln ra bin h thuon g c6 80% s6 t l bao m ang cap gen Bb
giam phan bin h th uon g se sinh ra 2 loai giao t u la B va b , tron g do giao t u m ang
gen b = 80% x l - 4 0 % .
Vay loai giao t u Ab D c6 t i le = ^ x 1 x 40% = 10% = 0,1.
Cac loai giao t u con lai c6 t i le = 1 - 0,1 = 0,9.
Buac 2: Su dung toan to hop dk tin h xac suk
Lay ngau nhien 2 giao t u t h i xac suat de th u dugc 1 giao tix m ang gen Ab D la
= C^x0,lx0,9 = 0,18.
- Khi lay ngau nhien 2 giao tvt ma chi yeu cau 1 giao tir mang gen AbD thi
giao tir con lai khong phai la AbD.
- Trong 2 giao tir chi can 1 giao tur mang gen AbD nen phai la C2 = 2.
2. Bai tap ve hgp tir dQt bien
Buac 1: XAc dinh ti If cua loai hop tu* can tinh xac suat
Buac 2: Su- dung toan to hrjp de tinh xac suat.
13

15. Bai1:Giasuc6motthedotbi^nlechboivanc6khanangsinhsanhuutinhbinh
thuangvacacloaigiaotudugctaoradkuc6khanangthutinhvaixacsuitnhunhau
thikhichothebakep(2n+1+1)tuthuphansinhradoiF].Layngaunhien1cathe
adoiFi,xacsudtdlthudugccathic6bgNST2n+1labaonhieu?
Hu-&ngdangidi:
Buac1:Xacdinhtilecualoaihgptu2n+1
-The3kep(2n+1+1)giamphansetaora4loaigiaotu:n,n+1,n+1,n+2.
~121
Vaitylecuamoiloai:Giaotu(n)=—,Giaotu(n+1)=—,Giaotu(n+2)=—
444
-HgptuCObgNST(2n+1)dugctaoranhasukkhgpcuagiaotudue(n)vai
giaotucai(n+1)hoacgiaotudue(n+1)vaigiaotucai(n).Nhuvaytylecua
loaihgptu(2n+1)bangtichtylecuacacloaigiaotu
g(n).(^(n+1)+$(n+1)•Sjn)=2.(n).(n+1).
^Haptu(2n+1)COtile=2x-X-=-.
^•424
Buac2:Sudungtoantohgpdetinhxacsuat
Layngaunhien1catheadoiFi,xacsukdkthudugccathec6bgNST2n+l
la-=25%.
4
Bai2:Chobiettrongquatrinhgiamphancuacathedueeo16%sotebaoc6cap
NSTmangcapgenAakhongphanlitronggiamphan1,giamphanIIdienra
binhthuang,cactebaokhacgiamphanbinhthuang,cathecaigiamphan
binhthuang.C)pheplai(3^AaBbxjAaBBsinhraFi.Ldyngaunhien1cathi
aFi,xacsuatdethudugccatheeokieugenaaBblabaonhieu?
Hu&ngdangidi:
Buac1:XacdinhtilecualoaihgptuaaBb.
c^AaBbXOAaBB=(c^'Aax$Aa)(c?Bbx$BB)
KieugenaaBblahgptukhongdotbien,nodugcsinhradosuthutinhgiuagiaotu
duekhongdotbien(ab)vaigiaotucaikhongdotbiln(aB).
-Catheduec616%sotebaoc6dotbienacapAanensec684%tlbaokhongdot
biln^(jAax$Aasesinhraaavaitile=-x0,84=0,21.
4
-C5capgenBbkhongc6dotbiennencJBbx$BBsesinhraBbvaitile=^.
-VaytrongcacloaihgptuthihgptuaaBbchilmtile=^x0,21=0,105.
Buac2:Sudungtoantohgpdetinhxacsuat
Layngaunhien1catheaFi,xacsuatdethudugceatheeokieugenaaBbla0,105.
14

16. Bai 3: Cho biet trong qua trinh giam phan cua ca the cai c6 12% so te bao c6 cap
NST mang cap gen Bb khong phan li trong giam phan I, giam phan II dien ra
binh thuang, cac te bao kliac giam phan binh thuang, ca the due giam phan
binh thuang. 6 phep lai d^AaBB x 2AaBb sinh ra Fj. Lay ngau nhien 2 ca the
a Fi, xac suat de thu dugc 1 ca the c6 kieu gen AaBBb la bao nhieu?
Hir&ng dan giai:
Buac 1: Xac dinh ti le cua loai hop tu AaBBb.
d'AaBB X $AaBb = (c^Aa x ^AaX^^BB x 9Bb)
Kieu gen AaBBb la hop tu dot bien, no dugc sinh ra do sir thu tinh giua giao tu
due khong dot bien voi giao tu cai dot bien.
- Co M cai CO 12% s61% bao c6 dot biln a cap Bb ^ (SBB X $Bb se sinh ra BBb
vaitile= - x 0,12 = 0,06.
• 2
- d cap gen Aa khong c6 dot bien nen <SAa. x $Aa se sinh ra Aa voi ti le = —.
• 4
- Vay trong cac loai hop tu thi hop tu AaBBb chilm ti le = - x 0,06 = 0,015.
4
Cac hop tu con lai c6 ti le = 1 - 0,015 = 0,985.
Buac 2: Su dung toan to hop dk tinh xac suit
Lay ngau nhien 2 ca the a Fi, xac suk dS thu dugc 1 ca hk c6 kilu gen AaBBb la
= C^x0,015x0,985 - 0 , 0 3 . '
C. BAI TAP VAN DUNG
1. Bai tap tu luan
Bai 1. Cho biet trong qua trinh giam phan cua ca the due c6 20% so te bao c6 cap
NST mang cap gen Aa khong phan li trong giam phan I, giam phan II dien ra
binh thuang, cac te bao Ichac giam phan binh thuang, ca the cai giam phan
binh thuong. O phep lai (5*AaBb x ^aaBb sinh ra Fi. Lay ngau nhien 1 ca the a
Fi, xac suat de thu dugc ca the c6 kieu gen aabb la bao nhieu?
Bai 2. Mot loai thuc vat c6 bg NST 2n = 24. Mot thI dot biSn bi mit 1 doan a
NST s6 1, dao 1 doan a NST s6 3, lap 1 doan a NST s6 4. Gia su qua trinh
giam phan diln ra binh thuang thi trong cac giao tu dugc sinh ra, l4y ngau
nhien 1 giao tu. Xac suat de thu dugc giao tu khong bi dot bien la bao nhieu?
Bai 3. Cho biet trong qua trinh giam phan cua ca the cai c6 10% so te bao c6 cap
NST mang cap gen Bb khong phan li trong giam phan I, giam phan II dien ra
binh thuang, cac te bao khac giam phan binh thuang, ca the due giam phan
binh thuang. Ci phep lai c^AaBb x $AaBb sinh ra Fi. Lay ngau nhien 2 ca the
a Fi, xac suat de thu dugc 1 ca the c6 kieu gen AaBb la bao nhieu?
15

17. Bai4.Motcatheamotloaidongvatc6bonhiemsicihk(NST)2n=12.Khi
quansatquatrinhgiamphancua2000tebaosinhtinh,nguodtathiy40bao
COcapnhiemsactheso1khongphanlitronggiamphanI,cacsvrkienkhac
tronggiamphandienrabinhthuong;cact6baoconlaigiamphanbinh
thuomg.Laynglunhien2giaotir,xacsuitd^thudugrc1giaotuc66NSTla
baonhieu?
Bai5.Giasuc6motthedotbienlechboivanc6khanangsinhsanhixutinhbinh
thuomgvacacloaigiaotudugctaoradeuc6khanangthutinhvoixacsuAtnhu
nhauthikhichothemot(2n-1)tuthuphansinhradoiFi.lAyngaunhien2ca
theadoiFi,xacsuatdkthudugc1cathIc6boNST2n-1labaonhieu?
2.Baitaptracnghiem
Cau1.Cadocdugcc62n=24.Comotthkdotbi^n,trongdoacapNSTs61c6
1chiecbimatdoan,amotchieccuaNSTs65bidao1doan,aNSTs63dugc
lap1doan.KhigiamphanneucaccapNSTphanlibinhthuongthitrongs6
cacloaigiaotudugctaora,khilayngaunhien1giaotu,xacsukthudugc
giaotudotbi%nla
A.87,5%.B.12,5%.C.75%.D.25%.
Cau2.Motcathiamotloaidongvatc6bonhiemsicthk(NST)2n=12.Khi
quansatquatrinhgiamphancua2000t6baosinhtinh,nguoitathdy20tSbao
COcapnhiemsactheso1khongphanlitronggiamphan1,cacsirkienkhac
tronggiamphandienrabinhthuong;cactSbaoconlaigiamphanbinh
thuomg.Layngaunhien1giaotu,xacsuatdethudugcgiaotuc65NSTla
A.1%.B.0,05%.C.0,5%.D.10%.
Cau3.Chobiettrongquatrinhgiamphancuacotheduec636%soikbaoc6cap
NSTmangcapgenBbkhongphanlitronggiamphanI,giamphanIIdienra
binhthuong,cactebaokhacgiamphanbinhthuomg,cathScaigiamphan
binhthuong.6pheplaic^AaBbx$AaBbthudugcFi.hkyngaunhien1ca
theFi,xacsuatdethudugccathic6kilugenaaBBla
A.8%.B.2%.C.4%.D.6%.
Cau4.CJpheplai(5*AaBbDdEex$AabbddEe.Trongquatrinhgiamphancuaco
thedue,capNSTmangcapgenAad10%s6tlbaokhongphanlitronggiam
phanI,giamphanIIdienrabinhthuong,caccapNSTkhacphanlibinh
thuong.Trongquatrinhgiamphancuacothecai,capNSTmangcSpgenEeo
2%sotebaokhongphanlitronggiamphanI,giamphanIIdienrabinh
thuong,caccSpNSTkhacphanlibinhthuong.Ldyngaunhien1cathiodoi
con,xacsuatdethudugccathedgtbienla
A.11,8%.B.2%.C.0,2%.D.88,2%.
16

18. Cau 5. Mot ca th^ d mot loai dong vat c6 bo nhiem sic thk (NST) 2n = 12. Khi
quan sat qua trinh giam phan cua 1000 tk bao sinh tinh, nguoi ta thiy 50 tS bao
CO cap nhiem sic thk so 1 khong phan l i trong giam phan I, cac sir kien khac
trong giam phan dien ra binh thuong; cac tk bao con lai giam phan binh
thuong. Trong cac giao t u dugfc sinh ra, idy ngau nhien 1 giao tu, xac sudt dk
thu dugrc loai giao t u c6 5 nhiem s4c thk la
A. 2,5%. B. 1%. C. 5%. D. 0,5%.
Cau 6. Gia su c6 mot thk dot bien lech boi van c6 kha nang sinh san hiJu tinh binh
thuong va cac loai giao t u duac tao ra ddu c6 kha nang thu tinh vai xac suit
nhu nhau thi khi cho thk ba kep (2n+l) thu phin vai thk luang boi (2n) sinh ra
dai F|. Lay ngau nhien 1 ca thk F, xac suit dk thu duac loai hap tu c6 bp NST
2n + 1 la
A. 50%. B. 12,5%. C. 25%. D. 75%.
Cau 7. CJ phep lai c5^AaBbDdEe x $AaBbddEe. Trong qua trinh giam phan cua
ca the due, cap NST mang cap gen Aa a 25% s6 t6 bao khong phan l i trong
giam phan 1, giam phan II dien ra binh thuong, cac cap NST khac phan l i binh
thuong; Trong qua trinh giam phan cua ca the cai, cap NST mang cap gen Ee a
8% s6 te bao khong phan l i trong giam phan I, giam phan II dien ra binh
thuong, cac cap NST khac phan l i binh thuong. Ldy ngau nhien 1 ca thk a dai
con, xac suat de thu duac ca the khong dot bi6n la
A. 2%. B . 3 1 % . C. 69%. D.62%.
Cau 8. Mot ca th6 a mot loai dong vat c6 bo nhiem sic t h I (NST) 2n = 20. Khi
quan sat qua trinh giam phan cua 1000 tS bao sinh tinh, nguoi ta thiy 40 tS bao
CO cap nhiem sac the so 8 khong phan l i trong giam phan I, cac su kien khac
trong giam phan dien ra binh thuong; cac tk bao con lai giam phan binh thuong.
Lay ngau nhien 1 giao tu, xac suat de thu duoc loai giao tu c6 11 NST la
A. 49%. B.2%. C. 98%. D. 4%.
Cau 9. Cho biet trong qua trinh giam phan cua ca t h I due c6 16% s6 tk bao c6 cap
NST mang cap gen Aa khong phan l i trong giam phan I, giam phan II dien ra
binh thuong, cac te bao khac giam phan binh thuong, co thk cai giam phan
binh thuong. CJ phep lai 6^Aabb x ^AaBB thu dugrc Fi. L i y ngau nhien 1 ca
the o Fi, xac suit dk thu dugc ca thk dot bi^n dang th6 ba la
A. 16%. B. 8%. C. 32%. D. 4%.
Cau 10. Cho biet trong qua trinh giam phan cua co thS due c6 8% s6 tk bao c6 cap
NST mang cap gen Bb khong phan l i trong giam phan I, giam phan II dien ra
binh thuong, cac te bao khac §iam phan binh thuong. Trong qua trinh giam
phan cua co thk cai, co 12% so t l bao co cap NST mang cap gen Dd khong
phan l i trong giam phan II, cac cap NST khac phan l i binh thuong. CJ phep lai
d'AaBbDd x $AabbDd thu dugc Fi. L i y ngau nhien 1 ca t h I 6 Fi, xac suat dk
thu dugc ca the dot hikn la
A. 80,96%. . B. 19,04%. C._2S)%. 45: 9 , 6 % T- ~ - »
THLT VIEN TJNHBiNHTHUAN

19. Cau11.Motcathkamotloaidongvatc6bonhilmsicthk(NST)2n=20.Khi
quansatquatrinhgiamphancua2000tebaosinhtinh,nguodtathay80tebao
COcapnhiemsicthkso8khongphanHtronggiamphanI,cacsirkienkhac
tronggiamphandienrabinhthuong;cact6baoconlaigiamphanbinh
thuong.Loaigiaotuc69NSTchi6mtile
A.98%.B.4%.C.49%.D.2%.
Cau12.C)pheplaic5^AaBbDdx$Aabbdd.Tronpquatrinhgiamphancuacothe
due,capNSTmangcapgenAao20%s6tebaokhongphanlitronggiam
phanI,giamphanIIdienrabinhthuong,caccapNSTkhacphanlibinh
thuong;Trongquatrinhgiamphancuacothecai,capNSTmangcapgenbbd
10%sotebaokhongphanlitronggiamphanI,giamphanIIdienrabinh
thuong,caccapNSTkhacphanlibinhthuong.Layngaunhien1cathe6doi
con,xacsuitdethudugccathec6kieugenaabbddla
A.4,5%.B.72%.C.9%.D.2,25%.
Cau13.CJpheplai(5*AaBbDdx$AaBbdd.Trongquatrinhgiamphancuacothi
due,capNSTmangcapgenAao15%sotebaokhongphanlitronggiam
phanI,giamphanIIdienrabinhthuong,caccapNSTkhacphanlibinh
thuong;Trongquatrinhgiamphancuacothecai,capNSTmangcapgenbbd
20%s6ikbaokhongphanlitronggiamphanI,giamphanIIdienrabinh
thuong,caccapNSTkhacphanlibinhthuong.Layngaunhien1catheodoi
con,xacsuatdethudugccathec6kieugenAabbddla
A.4,5%.B.4,25%.C.8,5%.D.2,125%.
3.Dapan
a.Cacbaiturluan:
Bai1.
Buac1:Xacdinhtilecualoaihgptuaabb.
(?AaBbX$aaBb=((?Aax$aa)((?Bbx$Bb)
Kieugenaabblahgptukhongdotbien,nodugcsinhradosirthutinhgiuragiaotu
duekhongdotbien(ab)voigiaotucaikhongdotbien(ab).
-CothedueCO20%sotebaocodotbienocapAanenseco80%tebaokhongdot
bidn^(5'Aax^aasesinhraaavoitile=^x0,8=0,4.
-6capgenBbkhongc6dotbidnnen^Bhx^Bbsesinhrabbvoitile=-.
4
-Vaytrongcacloaihgptuthihgptuaabbchilmtile=—x0,4=0,1.
4
Buac2:Sudimgtoantohgpdetinhxacsuat
lAyngaunhien1catheoFi,xacsuatdethudugccathecokieugenaabbla0,1.
18

20. Bai 2.
Buac 1: Xac dinh ti le cua loai giao tu khong dot biSn
Trong qua trinh giam phan binh thuang, cac cap NST phan li d6ng dhu h cac
giao tu.
- Do vay a cap so 1 c6 1 NST bi dot bidn thi khi phan li se cho 1/2 giao
tu binh thuang.
- C) cap so 3 CO 1 NST bi dot bien thi khi phan li se cho 1/2 giao tu binh thuang.
- O cap so 4 CO 1 NST bi dot bien thi khi phan li se cho 1/2 giao tir binh thuang.
- Cac cap NST khac deu khong bi dot bien nen deu cho giao tu binh thuang.
Vay giao tu khong bi dot bien ve tat ca cac cap NST c6 ti le = — x — x — = —
' 2 2 2 8
Buac 2: Su dung toan to hop de tinh xac sudt
Lay ngau nhien 1 giao tu. Xac suat de thu dugc giao tu khong bi dot bien la -
8
Bai 3.
Buac 1: Xac dinh ti le ciia loai hop tu AaBb.
c^AaBb X 5AaBb = {SAa x 9Aa)(c5'Bb x $Bb)
Kieu gen AaBb la hop tu khong dot bien, no dugc sinh ra do su thu tinh giua giao tu
due khong dot bien voi giao tu cai dot bien.
- Ca thi cai c6 10% so t l bao c6 dot biSn a cap Bb thi se c6 90% tS bao khong dot
hikn ^ SBh x $Bb se sinh ra Bb voi ti le = - x 0,9 = 0,225.
4
- CJ cap gen Aa khong c6 dot bien nen SAa. x $Aa se sinh ra Aa voi ti le = —.
4
- Vay trong cac loai hop tii thi hop tu AaBb chilm ti le = — x 0,225 = 0,05625.
4
Cac hop tu con lai c6 ti le = 1 - 0,05625 = 0,94375.
Buac 2: Su dung toan to hop dk tinh xac suit
lAy ngau nhien 2 ca the a Fi, xac suit dl thu dugc 1 ca the c6 kidu gen AaBb la
= C^x0,05625x0,94375 -0,106.
Bai 4.
Buac 1: Xac dinh ti le cua loai giao tu c6 6 NST.
- Loai nay c6 bo NST 2n = 12 thi khi giam phan binh thuang (cac cap NST
phan li dong dku vk hai cue te bao) thi s6 NST cua giao tu la n = 6 NST.
-> Giao tu CO 6 NST la giao tu khong dot bi&n.
- Giao tu binh thuang chi dugc tao ra tu cac te bao giam phan binh thuang.
- S6 t l bao giam phan binh thuang la 2000 - 40 = 1960 {tk bao).
19

21. -Loaigiaotuc66NSTchiemtile==o,98.
•^•2000
Loaigiaotuconlaic6tile=1-0,98=0,02.
Buac2:Sudungtoantohopdetinhxacsuat
Ldyngaunhien2giaotu,xacsuatdethudugc1giaotuc66NSTla
=C'2x0,98x0,02=0,0392.
Bai5.
Buac1:Xacdinhtilecualoaihoptu2n-1
-Themot(2n-1)giamphansetaora2loaigiaotu:nvan-1.
Voitylecuamoiloai:Giaotu(n)=^,Giaotu(n-1)=^
-HoptuCOboNST(2n-1)duoctaoranhasukethopcuagiaotiidue(n)voi
giaotucai(n-1)hoacgiaotudue(n-1)voigiaotucai(n).Nhuvaytylecua
loaihoptu(2n-1)bangtichtylecuacacloaigiaotu
$(n).c?(n-1)+$(n-1).S(n)=2.(n).(n-1)
->Hoptu(2n-l)c6tile=2x—X—=—.
•222
Buac2:Sudungtoantohopdetinhxacsuat
Liyngaunhien2cathi,xacsuitdlthuduoc1cathec6boNST2n-1la
'22z
b.Cacbaitracnghi^m
0,5.
12345678910111213
ACCAAACBBBDAB
Chuyende
2.
XACSUATTRONGQUYLUATDiTRUYEN
I.DITRUYENMENDEN
A.KIENTHLfCLITHUYETLIENQUANDENTINHXACSUAT
-Tronggiamphan,suphanlicuacapNSTlacochedantoisuphanlicuacap
alen.Banchatcuaquyluatphanlilasuphanlicuacacalentrongcapalen,moi
alendimotgiaotu.
-QuyluatphanlicuaMendenlaquyluatditruySncabancuamoiquyluat
khac.Tuclaacacquyluatditruyenkhac,caccapgenciingphanlitheoquyluat
cuaMenden(trirquyluatditruySntheodongme,gennamatebaochat).
20

22. - Cac cap NST phan li doc lap voi nhau nen cac cap gen nSm tren cac* cSp NST
cung phan li doc lap. Cac cap gen phan li doc lap voi nhau thi ti le phan li kiku
gen, ti le kilu hinh a doi con tuan theo quy luat xac suat cua toan hoc. Tuc la ti le
phan li kieu hinh bang tich ti le cua cac cap tinh trang, ti le phan li kieu gen bang
tich ti le cua cac cap gen.
- Khi gen di truySn theo quy luat phan li doc lap thi chiing ta su dung quy luat
to hop tir do de tinh su to hop cua cac cap alen.
- Cac cap gen phan li doc lap voi nhau thi a doi con c6:
+ Ti le kilu gen bang tich ti le phan li kiSu gen cua timg cap gen;
+ Ti le phan li kieu hinh bang tich ti le phan li cua cac cap tinh trang;
+-S6 loai kilu gen bang tich so loai kieu gen cua cac cap tinh trang;
+ So loai kieu hinh bang tich so loai kieu hinh cua cac cap tinh trang;
+ Ti le cua m6i loai kilu hinh bang tich ti le cua cac tinh trang c6 trong kieu
hinh do.
- Hai cap tinh trang di truyen phan li doc lap voi nhau khi ti le phan li kieu hinh
cua phep lai bang tich ti le cua cac cap tinh trang.
- Trong truong hop tinh trang do mot gen quy dinh, nSu a doi con xuat hien kieu
hinh chua c6 a b6 me thi kieu hinh do do gen Ian quy dinh, neu kieu hinh da c6 a bo
hoac me ma khong bieu hien a doi con thi do la kieu hinh Ian.
- Xac suat xuat hien mot kieu hinh nao do chinh la ti le cua loai kieu hinh do trong
t6ng s6 ca th^ ma ta xet.
- d phep lai ma t6ng s6 cap gen di hop a b6 va me la n cap gen thi a doi con,
C*
loai ca the c6 a so alen troi chiem ti le = ~ . Neu cu c6 mot cap gen dong hgrp
trgi thi a phai bat di 1.
Vi du: d phep lai AaBbdd x AabbDd, loai ca thk c6 2 alen troi a dai con chiem
C^ 3
ti le = —f = - . (vi ca bo va me c6 4 cap gen di hop)
2 8
O phep lai AaBbDD x AAbbDd, loai ca the c6 5 alen trpi a doi con chiem ti le
1 ,
= ^ = - . (vi ca bo va me c6 3 cap gen di hop va trong do c6 2 cap gen dong hop
2 8
troi nen ca the c6 5 alen troi thi khi ap dung gidng nhu chi c6 3 alen troi).
- Khi xet rieng timg cap gen, alen troi la troi hoan toan thi ta dua vao bang sau
de tim ti le cua loai kieu hinh c6 lien quan den tinh xac suat.
Kieu gen Kieu hinh o doi con Ti le cua Ti le cua
cuaP So loai Ti le Kieu hinh troi (A-) Kiku hinh lan (aa)
AA X Aa 1 100% A- CO ti le= 100% aa CO ti le = 0
Aa X Aa 2 3 : 1
A- CO ti le = —
4
aa CO ti le =
4
21

23. AaXaa21:1
A-COtile=—
•2
,1
aaCOtile=-
•2
aaXaa1100%A-COtil?=0A-COtile=100%
B.CACDANGBAITAP
1.Baitaptinhxacsuatvekieuhinh
Cdchgidi:Khibaitoanyeucautinhxacsuatvemotkieuhinhnaodothican
phaitienhanhtheo2buoc.
Budc1:Xacdinhkieugencuabomevavietsod6laidktimtileciialoaikilu
hinhcantinhxacsuat.
Buac2:Surdungtoantohopdetinhxacsuat
Bai1:ChobietAquydinhthancaotroihoantoansovoiaquydinhthanthdp,B
quydinhhoadotroihoantoansovoibquydinhhoatrang.Haicapgennay
namtren2capNSTkhacnhau.Caythancao,hoadothuanchunggiaophan
voicaythanthap,hoatrangducrcFi,FigiaophantirdodugcF2.Layngau
nhien5cayaF2,xacsuatdetrong5caynaychic62caythancao,hoado.
Hw&ngdangidi:
Buac1:Xacdinhkieugencuabomevavietsodolai
-Caythancao,hoadothuanchungc6kieugenAABB
Caythanthap,hoatrangc6kieugenaabb.
-SadSlai:AABBxaabb
F,:AaBb
•FiXF|AaBbxAaBb.
-VietgiaotuvalapbangtasethudugcdaiF2c6tilekiSuhinh9thancao,
hoado;3thancao,hoatrang;3thanthap,hoado;1thanthap,hoatrang.
9
->Caythancao,hoadoc6tile=—.
16
Buac2:Sudungtoantohopdetinhxacsuat
-Lay5cay,canc62caythancao,hoadothiphailatohapchap2cua5phan
-OF2,caythancao,hoadochiemtile=—;Cayc6kieuhinhkhongphai
16
thancao,hoadoc6tile=1-
1616
-Lay5cayaF2,xacsuatdetrong5caynaychic62caythancao,hoadola:
,^,39690
'16^^6^1048576
Luythua2laviphaic62caythancao,hoado;Luythira3viphaic63cayc6
kieuhinhkhongphaithancao,hoado.
22

24. - Khi bai toan yeu cau trong 5 cay chi c6 2 cay than cao, hoa do thi 3 cay
con lai phai c6 kieu hinh khac.
- Cac kieu hinh khac c6 ti 1^ = 1 - ti 1^ ciia kieu hinh can tinh xac suat
Bai 2: Cho hik A quy dinh than cao troi hoan toan so voi a quy dinh than thdp, B
quy dinh hoa do troi hoan toan so voi b quy dinh hoa trang. Hai cap gen nay
nam tren 2 cap NST khac nhau. Cho cay di hop v§ 2 cap gen lai phan tich dugc
Fb. Liy ngSu nhien 3 cay Fb- Xac suat de trong 3 cay nay chi c6 1 cay than
thap, hoa trang la bao nhieu?
Hir&ng dan giai:
Buac 1: Xac dinh kiku gen cua b6 me va vi^t so d6 lai
- Cay di hop 2 cap gen c6 kiSu gen la AaBb
Lai phan tich la lai voi cay dong hop Ian. Cay dong hop Ian c6 kieu gen aabb.
- So d6 lai: AaBb x aabb
Fb: lAaBb, lAabb, laaBb, laabb
- Ti le kieu hinh a dai Fb la 1 than cao, hoa do; 1 than cao, hoa trang; 1 than
thap, hoa do; 1 than thap, hoa trang.
Cay than thap, hoa trang c6 ti le = — .
4
Buac 2: Six dung toan to hop de tinh xac suat
- Lay 3 cay, can c6 1 cay than thap, hoa trang thi phai la to hop chap 1 cua 3
phan tir = Q^^
- CJ Fb, cay than thap, hoa trfing chiSm ti le = —; Cay c6 kieu hinh khong phai
4
than thap, hoa tring chiem ti le = 1 - - = -
4 4
- Lay 3 cay Fb. Xac suat de trong 3 cay nay chi c6 1 cay than thap hoa trang la
„ i 1 , 3 , 2 27
4 64
Bai 3: Cho biet gen A quy dinh than cao troi hoan toan so voi alen a quy dinh
than thap. Cay than cao tir thu ph4n, thu dugc dai Fi c6 ti le 75% cay cao : 25%
cay thap.
a. Lky ngau nhien 1 cay Fi. Xac sudt dS dugc cay than cao la bao nhieu?
b. Ldy ngau nhien 1 cay than cao Fi. Xac suat de dugc cay thuan chung la bao nhieu?
c. Ldy ngau nhien 3 cay than cao Fi. Xac suit dk thu dugc 1 cay thuan chung la
bao nhieu?
Hu&ng dan giai:
a. Lay ngau nhien 1 cay Fi. Xac suat de dugc cay than cao la bao nhieu?
23

25. Buac1:TimtilecaythancaodF.
BaitoanchobietdoiFic6tile75%caycao:25%caythap->CJFi,caythan
caochiemtile=0,75.
Buac2;Tinhxacsuat
Layngaunhien1cay,xacsuitdkthudugrccaythancaola0,75.
b.Layngaunhien1caythancaoFi.Xacsuatdedugccaythuanchunglabaonhieu?
Buac1:Timtilecaythu^chungtrongs6caccaythancaoaF.
BaitoanchobietdaiFic6tile75%caycao:25%)caythSpTilekikugena
doiFilalAA:2Aa:laa.
CaythancaoaFic62loaikiSugenvoitilelalAAva2Aa->caythuan
chungchi6mtile=y
Bu6c2:Xacsudt
Layngaunhien1caythancaoFi,xacsuatdedugrccayihuknchungla=y.
c.Layngaunhien3caythancaoFi.Xacsuatdethudugrc1caythuSnchungla
baonhieu?
Buac1:Caythancaotuthuphdn,daiconthudugrc75%cao:25%thipchung
tocaythancaodemtuthuphanc6ki^ugenAavadaiconc6tilekikugenla
lAA:2Aa:laa.->TrongsocaccaythancaoaFi(1AAva2Aa),caythu4n
chungchiSmtile=^
Buac2:
-Chgn3caythancaoFi.XacsuAtdithudugrc1caythuSnchungla
2.Baitaptinhxacsuatvekieugen
1(2^_3.1.44
33.99
Cdchgidi:Canphaitienhanhtheo2buac
Buac1:Timtilecuakieugencantinhxacsuit
Buac2:Sicdungtoantohgrpdltinhxacsuit.
Bai1:6pheplaiAaBbxAabbthudugrcdoiFi.Ldyngaunhien3cathkFi,xac
suatdethudugrc3cathedeuc6kieugenAaBblabaonhieu?
Hir&ngdangidi:
Buac1:Timtilecuakieugencantinhxacsuat
-Sod6lai:AaBbxAabb=(AaxAa)(Bbxbb)
-CaplaiAaxAasesinhradaiconc6kieugenAavoitile=^
24

26. - Cap lai Bb x bb se sinh ra doi con c6 kieu gen Bb voi ti le = ^
-> Phep lai AaBb x Aabb se sinh ra doi con c6 kieu gen AaBb vai ti le = —
4
Buac 2: Su dung toan t6 hop de tinh xac suit
Lay ngau nhien 3 ca the a Fi, xac suat de ca 3 ca thk dSu c6 kiSu gen AaBb la
1
(T) -
4 64
Bai 2: Xet phep lai Aa x Aa dugc F|. CJ doi Fi, lay ngau nhien 2 ca the, xac suat
de thu dugrc 2 ca the thuan chung la bao nhieu?
Hu&ng dan giai:
Buac 1: Xac dinh ti le cua ca the thuan chung a doi Fi.
- CJ phep lai Aa x Aa doi Fi c6 ti le ki^u gen la 1 A A : 2Aa : laa.
- Doi Fi CO ti le kieu gen 1 A A : 2Aa : laa nen ca the thuan chung chiem ti le
4 4
Buac 2: Tinh xac suk:
Ti le thuan chung cua moi ca the = 0,5 Lay ngau nhien 2 ca the thi xac suit
de ca 2 ca the dku thuan chung = (0,5)^ = 0,25.
Bai 3: Xet phep lai Aa x aa thu dugfc Fi. CJ doi Fi, lay ngau nhien 3 ca the, xac
suat de thu dugrc 2 ca the khong thuan chung la bao nhieu?
Hu&ng dan gidi:
Buac 1: Xac dinh ti le cua ca the khong thuSn chung a doi Fi.
- (3 phep lai Aa x aa doi Fi c6 ti le kieu gen la 1 Aa : laa.
- Dai Fi CO ti le kieu gen l A a : laa nen ca thS khong thuin chung chigm ti le
=^ = 0,5. Ca thd thu4n chung chi^m ti le = 1 - 0,5 = 0,5.
Buac 2: Tinh xac suk:
Lay ngau nhien 3 ca the, xac suat de 2 ca the deu khong thuan chung
= C^ x(0,5)2 x(0,5)- 0,375.
Bai 4: Cho biet moi cap gen quy dinh mot cap tinh trang, alen troi la troi hoan
toan. Xet phep lai AaBbDdEe x AaBBDdEE duac Fi.
a. Lay ngau nhien 1 ca thk, xac su^t de thu duoc ca ihk thu&i chung la bao nhieu?
b. Trong so cac ca the c6 kieu hinh 4 tinh trang troi, idy ngau nhien 3 ca t h i ,
xac suat de thu dugrc 3 ca the thuan chung la bao nhieu?
Hu&ng dan gidi:
Phep lai AaBbDdEe x AabbDdEE = (Aa x Aa)(Bb x BB)(Dd x Dd)(Ee x EE)
25

27. a.Xacsuatdethuduaccathethuanchung:
Buac1:TinhtilecathethuSnchxingadaiFi:
-Chungtaxettilethuanchungadoiconciiatimgcapgenbom?.
($AaX$Aataoradaiconc6tilethuanchung=^.
SBhX$BBtaoradoiconc6tilethuanchung=^.
(5^DdX$Ddtaoradoiconc6tilethuanchung=^.
c5*EeX$EEtaoradaiconc6tilethuanchung=^.
->Loaicathithuanchungveca4capgenchiemtile=lxi-xlxl=J-
^^222216
Buac2:
Tilethuanchungla—nenkhilayngaunhien1cathethixacsuatdethu
16
dugccathethuanchung=—=0,0625.
16
b.Xacsuatde3cathedeuthuanchung.
Buac1:Trongcaccathec6kieuhinhtroi,tilecathethuanchungla:
-Chiingtaxettilethuanchungadaiconcuatumgcapgenbome.
c^AaX5Aataoradaiconc6kieuhinhtroigom2kieugenla1AAva2Aa.
->Tilethuanchiing=^.
i5*BbX9BBtaoradoiconc6kieuhinhtroig6m2kikugenlaIBBvaIBb.
Tilethudnchiing=^.
cTDdX$Ddtaoradoiconc6kieuhinhtroigom2kieugenlaIDDva2Dd.
->Tilethuanchiing=^.
SEeX$EEtaoradaiconc6kieuhinhtroigom2kieugenlalEEvalEe.
->Tilethuanchiing=^.
->Loaicathethuanchungveca4tinhtrangchiemtile=Ixi-xlx—=—
323236
26

28. Buac 2:
1 , » , , ,
Ti le thuan chiing la — nen khi lay ngau nhien 3 ca the thi xac suat de thu
36
dugc 3 ca the thuan chung ( ^
Bai 5: Cho biet moi cap gen quy dinh mot cap tinh trang, alen troi la troi hoan
toan. Tidn hanh phep lai AaBbDd x AaBbDD thu dugc Fi. Ldy ngau nhien 2 ca
the, xac suat de thu dugc 2 ca the c6 kieu hinh mang 2 tinh troi va 1 tinh trang
Ian la bao nhieu?
Hie&ng dan gidi:
Buac 1: Ti le ca the c6 kieu hinh mang 3 tinh troi va 1 tinh trang Ian:
AaBbDd x AaBbDD = (Aa x Aa)(Bb x Bb)(Dd x DD)
Aa XAa sinh ra dai con c6 cac kieu hinh chiem ti le — A-, — aa
4 4
Bb XBb sinh ra doi con c6 cac kieu hinh chiem ti le — B-, — bb
• 4 4
Dd XDD sinh ra dai con c6 kieu hinh troi chiem ti le 100% D-
Loai ca the c6 kieu hinh mang 2 tinh troi va 1 tinh trang Ian la nhirng kieu hinh dugc
kihieulaA-bbD- vaaaB-D-.
3 1 3
- Kieu hinh A-bbD- chiem tile= — x — x l =
4 4 16
1 3 ^
- Kieu hinh aaB-D- chiem tile= — x — x l =
4 4 16
Loai ca the c6 kieu hinh mang 2 tinh troi va 1 tinh trang Ian chiem ti le
3 ^ 3 6 3
16 16 16 8
Buac 2: Tinh xac suat
Xac suk de thu dugc 2 ca thI c6 kilu hinh mang 2 tinh troi va 1 tinh trang Ian la
3_
. 8 64
Bai 6: Cho biet moi cap gen quy dinh mot cap tinh trang, alen troi la troi hoan toan.
Tiln hanh phep lai AABbDd x AabbDD thu dugc Fi. hiy ngau nhien 2 ca th§ a
Fi, xac suit d8 trong 2 ca th6 nay c6 it vhk 1 ca thI thu^ chung la bao nhieu?
Hu&ng dan gidi:
Buac 1: Ti le ca the thuan chung:
AABbDd XAabbDD = (AA x Aa)(Bb x bb)(Dd x DD)
27

29. AAXAasinhradoiconc6cackieugenlAA,lAa.Trongdokieugend6ng
hopchiSmtile=^.
BbXbbsinhradoiconc6cackieugenIBb,Ibb.Trongdokieugendonghgtp
chiemtile=.
DdXDDsinhradoiconc6cackieugenIDD,IDd.Trongdokieugendong
hopchiemtile=^.
LoaicathSc6kilugend6nghopvhca3capgenc6tile=^x^x^=^
LoaicathethuanchungchiSmtile=-;Loaicaihkkhongthu^chung
8
chiemtile=1-—=—.
88
Buac2:Tinhxacsuat
-Trong2cathd,xacsuitd^khongc6cathInaothu^nchung=(—)^=^^
88'64
-Xacsuatdec6itnhat1cathethu&ichung=1-xacsuitdkkhongc6cathInao
thuanchung=1——=—ss0,9.
^6464
3.Baitaptinhxacsuattimsoalen
Bai1:6pheplaiAaBbDdxAaBbDdthudugrcFi.hiyngSunhien2catheFi.
Xacsuatdethuduac2cathemamoicathedeuc63alenIanva3alentroila
baonhieu?
Hir&ngdangidi:
Buac1:Tilecathemang3alenIanva3alentroi.
CJpheplaiAaBbDdxAaBbDd,doibomec6tongso6capgendihap.
Khidoibomec66capgendihapthiadoicon,loaicathec63alentrpiva
20S
3aleniSnchiemtile==—-—
•2'6416
Buac2:Tinhxacsuit
525
Xacsuatdeca2cathedeuc63alenIanva3alentroila=(—f'=~0,1.
M6256
Bai2:6pheplaiAaBbddEExAaBbDdeethudugcFi.Liyngaunhien3cathe
Fi.Xacsuatdethudugc3cathimamoicathkdhuc63alenIanva5alentrpi
labaonhieu?
28

30. Hu&ng dan gidi:
Buac 1: Ti le ca the mang 3 alen Ian va 5 alen troi.
C5 phep lai AaBbddEE x AaBbDdee, dai b6 me c6 t6ng s6 5 cap gen di hap.
CJ cap gen EE x ee thi dai con luon c6 kieu gen Ee (1 alen troi va 1 alen Ian). Nhu
vay, a dai con nghiem nhien c6 1 alen troi va 1 alen Ian nen bai toan tra thanh a phep
lai AaBbdd x AaBbDd, can tim ti le cua loai ca the c6 alen troi a dai con.
-> Khi dai bo me c6 5 cap gen di hop thi a dai con, loai ca the c6 4 alen troi va
C 5
3 alen Ian chiem ti le ^ ' =
2' 32
BUffc 2: Tinh xac suAt
5 , 3 _ 125
Xacsuatdeca3 cathedeuc6 3 alenlanva4alentr6ila = (-—) = — — -0,0038.
32 32768
Bai 3: 6 phep lai AaBBddEE x AaBbDdEE thu dugc Fi. Lay ngau nhien 3 ca thi Fi.
Xac suat dk trong 3 ca thi da lay chi c6 dung 1 ca thi c6 5 alen troi la bao nhieu?
Hu&ng dan gidi:
Buac 1: Ti le ca the mang 3 alen Ian va 5 alen troi.
CJ phep lai AaBBddEE x AaBbDdEE, dai bo me c6 tong so 4 cap gen di hop.
O cap gen EE x EE thi dai con luon c6 kieu gen EE (2 alen troi).
C5 cap gen BB x Bb thi dai con luon c6 it nhk 1 alen troi
Nhu vay, a dai con nghiem nhien c6 3 alen troi nen bai toan tra thanh a phep
lai AaBBddEE x AaBbDdEE, can tim ti le cua loai ca the c6 5 alen troi a dai con.
Tuang duang voi loai ca the c6 2 alen troi a dai con.
Khi dai bo me c6 4 cap gen di hop thi a dai con, loai ca the c6 2 alen troi
_ _ 6 _ 3
chiem ti le =
2* 16 8
3 5
Loai ca the khong c6 5 alen troi chiem ti le = 1 - - = -
8 8
Buac 2: Tinh xac suat
Xac suat de trong 3 ca the, chi c6 1 ca the mang 5 alen troi la
= c; K(i)><(5,^ = i ±i l i i l = ^=o.44.
' 8 8 8x8x8 512
4. Bai tap xac suat lien quan den chon giong
Bai 1: O mot loai vat nuoi, gen A nam tren NST thuong quy dinh long dai troi
hoan toan so voi a quy dinh long ngan. O mot trai nhan giong, nguai ta nhap ve
25 con due long dai va 100 con cai long ngin. Cho cac ca thi nay giao ph6i tu
do voi nhau sinh ra Fi c6 36% ca thi long ngin. Cac ca thi Fi giao phoi tu do
duoc F2. Biet rang khong xay ra dot biln. hiy ngau nhien 2 ca the a F2, xac
suat de thu dugc 2 ca the di hap la bao nhieu?
29

31. Hir&ngdangidi:
Buac1:TimtilecathidihopaF2:
-VilongnganlatinhtrangIannen100concailongngandeuc6kieugenaa
-Cho25conduegiaophoitudovoicacconcaiaasinhraFic636%cathe
longngan.->TilekieugenaFila=0,64Aa:0,36aa(viconcaic6kieugenaa
nendoiconluonc6gena)
^TilegiaotuAla0,32;tilegiaotuala0,68
Caccaihk¥oph6itudoduacF2
0,32A0,68a
0,32A0,1024AA0,2176Aa
0,68a0,2176Aa0,4624aa
-CJF2cathedihopchiSmtile:0,2176+0,2176=0,4352.
Buac2:Timxacsuit.
Layngaunhien2cathe,xacsuatdethudugc2cathedihgrp=(0,4352)^=0,1894
Bai2:C5motloaidongvat,genAnamtrenNSTthuongquydinhnhieunactroi
hoantoansovaiaquydinhitnac.Omottrainhangiong,nguaitanhapve10
conduenhieunacva30concaiitnac.Chocaccathenaygiaophoitirdovai
nhausinhraFic6tilekieuhinh9connhiSunac:1conitnac.Caccath^Fi
giaophoitudoduacF2.Bietrangkhongxayradotbien.hiyngaunhien3ca
thenhieunacaF2,xacsuatdethudugc2cathethuanchunglabaonhieu?
Hir&ngdangidi:
Buac1:TimtilecathedihopaF2:
-ViitnaclatinhtrangIannen30concaiitnacdSuc6kiSugenaa
-Cho10condugcgiaophoitudovaicacconcaiaasinhraFic6tilecathkit
nac(aa)=——=0,1.TilekilugenaFila=0,9Aa:0,1aa(viconcaic6
1+9
kieugenaanendoiconluonc6gena)
^TilegiaotuA=0,1+^=0,55;tilegiaotua=1-0,55=0,45
CaccatheFigiaophoitudodugcF2
0,55A0,45a
0,55A0,3025AA0,2475Aa
0,45a0,2475Aa0,2025aa
-CathknhiSunacaF2g6mc60,3025AAva0,495Aa'-^—AA:—Aa
30

32. - C5 F2, trong so cac ca the nhieu nac thi ca the thuin chung chiSm ti le =
29
Ca the khong thuan chung chiem ti le =
29
Buac 2: Tim xac suat.
Lay ngau nhien 3 ca the, xac suit de thu dugc 2 ca thd thuan chung
= Clxi—fx — = 0,2976 ~ 0,3
3 ^29 29
Bai 3: Cho biet A quy dinh than cao troi hoan toan so voi a quy dinh than thap. C)
phep lai Aa x aa dugc Fi. Can phai lay it nhat bao nhieu hat Fi de trong so cac
hat da lay xac suat c6 it nhat 1 hat mang kieu gen aa Ion hon 90%?
Hir&ng dan giai:
Buac 1: Tim ti le cua kieu gen Aa va kieu gen aa a dai con.
- 0 phep lai Aa x aa dugc Fi c6 ti le kieu gen 1 Aa va 1 aa
-> d Fi, ti le kieu gen aa = ^ , kieu gen Aa = ^ .
- Goi n la so hat it nhat can phai lay.
Xac suat de tat ca cac hat deu c6 kieu gen Aa la = )" =
Buac 2: Tim xac su4t.
- Xac suat de c6 it nhat 1 hat mang kieu gen aa = 1 - xac suat de khong c6 hat
1
nao mang kieu gen aa = 1 -
2"
- Theo bai ra ta c6 1 -
j _
r
>0,9.
2"
<0,1 ^ n > 4 .
Vay phai lay it nhat 4 hat thi moi thoa man dieu kien bai toan.
C. BAI TAP VAN DUNG
1. Bai tap tu luan
Bai 1: Cho biet A quy dinh than cao troi hoan toan so voi a quy dinh than thap, B
quy dinh hoa do troi hoan toan so voi b quy dinh hoa trang. Hai cap gen nay
nam tren 2 cap NST khac nhau. Cay than cao hoa do, thuan chung giao phan
voi cay than thap hoa trang dugc Fi, Fi giao phan tu do dugc F2. Lay 3 cay a
F2, xac suat de trong 3 cay nay chi c6 1 cay than cao, hoa do la bao nhieu?
31

33. Bai2:ChobietAquydinhthancaotroihoantoansovdiaquydinhthanthdp.
Chocaythancaodihgptuthuphdnadoiconc675%caythancaova25%
caythanthap.TrongsocaccayFilay2caythancao,xacsuatdeca2caynay
deuCOki^ugend6nghop?
Bai3:ChohikAquydinhthancaotroihoantoansovoiaquydinhthanthdp.
Chocaythancaodihoptuthuphanadaiconc675%caythancaova25%
caythanthap.
a.TrongsocaccayFilay2caythancao,xacsuatdeca2caynaydeuc6kieu
gend6nghop?
b.Trongs6caccayFiidy4caythancao,xacsukdkchic61caymangkilu
gendonghop?
Bai4:Chobietmoicapgenquydinhmotcaptinhtrang,alentroilatroihoan
toan.TienhanhpheplaiAaBBDdxAaBbddthudugcFi.Layngaunhien2ca
the,xacsuatdethuduac2cathec6kieuhinhmang2tinhtroiva1tinhtrang
Ianlabaonhieu?
Bai5:Chobietmoicapgenquydinhmotcaptinhtrang,alentroilatroihoan
toan.TienhanhpheplaiAABbDdxAaBbDdthuduacFi.hiyngaunhien3
catheCOkieuhinhtroidFi,xacsuatdetrong3cathenayc62cathethuSn
chunglabaonhieu?
Bai6:ChobietAquydinhthancaotroihoantoansovoiaquydinhthanthap.(3
pheplaiAaxAaduacFi.Canphail,aybaonhieuhatFidetrongsocachatda
layxacsuatc6itnhat1hatmangkieugenaaIanhan80%?
Bai7:OpheplaiAaBbDdxAaBbDdthudugcFi.Layngaunhien2catheF].
Xacsuatdethudugc2cathemamoicathedhuc65alenIanlabaonhieu?
Bai8:CJpheplaiAaBBddEExAaBbDdeethudugcFi.Layngaunhien3cathS
Fi.Xacsuatd8thudugc3cathemamoicaihkdkic66alentroilabaonhieu?
Bai9:OpheplaiAabbddEExAaBbDdEethudugcFi.Layngaunhien3cathe
Fi.Xacsuatdetrong3cathedalayc62cathic63alentroilabaonhieu?
Bai10:OpheplaiAabbDdEexAaBbDdeethudugcFi.Layngaunhien3catheFi.
Xacsuatdetrong3cathidaliychic6dung1cathec64alentroilabaonhieu?
Bai11.CJmotloaithucvat,Aquydinhhoadotroihoantoansovaiaquydinh
hoatrang,Bquydinhthancaotroihoantoansovaibquydinhthanthdp.Hai
capgennaynamtren2capNSTkhacnhau.Chocaythancao,hoadodihgp
ve2capgennoitrengiaophanvainhaudugcFi.C)daiFi,chichgncaccay
COkieuhinhthancao,hoadodemtrongvachogiaophanngaunhienthudugc
F2.Lay1cayc6thancao,hoadoaF2,xacsuatdethudugccaythuanchung
veca2capgennoitrenlabaonhieu?
Bai12.CJmotloaithucvat,Aquydinhhoadotroihoantoansovaiaquydinh
hoatrang,Bquydinhthancaotroihoantoansovaibquydinhthanthdp.Hai
capgennaynamtren2capNSTkhacnhau.Chocaythancao,hoadodihgp
32

34. ve 2 cap gen noi tren giao phdn voi nhau duac Fi. CJ doi Fi, chi chon cac cay
CO kieu hinh than cao, hoa do dem trong va cho giao phan ngau nhien thu dugc
F 2 . Lay ngau nhien 1 cay a F 2 , xac suat de thu dugrc cay than cao, hoa trang la
bao nhieu?
2. Bai tap tr^c nghi^m
Cau 1. Cho biet A quy dinh than cao troi hoan toan so voi a quy dinh than thap.
Cho cay than cao di hop tu thu phan thu dugc Fi c6 75% cay than cao va 25%
cay than thap. Trong so cac cay Fi lay 4 cay than cao, xac suat de trong 4 cay
nay chi c6 1 cay mang kieu gen dong hop la
A. 1. B . I . C . ^ . D . i .
81 81 81 3
Cau 2. Cho biet moi cap tinh trang do mot cap gen quy dinh. Cho cay than cao
hoa mau do giao phan voi cay than thap hoa mau trang duac Fi gom 100% cay
than cao hoa mau do. Cho Fi tu thu phSn doi F T C6 ti le 56,25% cay than cao,
hoa do : 18,75% cay than cao, hoa trSng : 18,75% cay than thdp, hoa do :
6,25% cay than thap, hoa trSn^. Lky ngau nhien 2 cay than cao, hoa do a F 2 .
Xac suat de thu duac 2 cay thuan chung la bao nhieu?
A . l . B . ± . C . i . D. '
9 36 81 16
Cau 3. Cho biet A quy dinh than cao troi hoan toan so voi a quy dinh than thip.
Cho cay than cao di hop tu thu phin a doi con c6 75% cay than cao va 25%
cay than thap. Trong so cac cay Fi lay 2 cay than cao, xac suat de ca 2 cay nay
deu CO kieu gen dong hop la
A . i B . l . C . l D . I .
9 3 9 4
Cau 4. Cho cay hoa do tu thu phan thu duac Fi c6 2 loai kieu hinh, trong do cay
hoa do chiem ti le 56,25%. Lay ngau nhien 1 cay hoa do a Fi, xac suat de thu
dugc cay thuan chung la bao nhieu?
A. A. B . I . C . i D . i .
16 7 9 4
Cau 5. Cho biet moi cap tinh trang do mot cap gen quy dinh. Cho cay than cao,
hoa do giao phan voi cay than thap, hoa trang dugc Fi gom 100% cay than cao,
hoa do. Cho Fi tu thu phan doi F 2 c6 ti le 56,25% cay than cao, hoa do :
18,75% cay than cao, hoa tring : 18,75% cay than thkp, hoa do : 6,25% cay
than thap, hoa trang. Lay ngau nhien 2 cay than cao, hoa trdng a F 2 . Xac suit
de thu dugc 1 cay thuan chung la bao nhieu?
A.1 B.I. C . i D . ±
3 9 9 16
33

35. Cau6.ChobietAquydinhthancaotroihoantoansovoiaquydinhthanthap,B
quydinhhoadotroihoantoansovoibquydinhhoatring.Haicapgennayn^m
tren2capNSTkhacnhau.Chocaydihopve2capgenlaiphantichdugcFb.
Lay4cayFb,xacsuatdetrong4caynaychic62caythanthap,hoatrSngla
91327
A.B.—.C.-.D.^'
256168128
Cau7.ChobietAquydinhthancaotroihoantoansovoiaquydinhthanth^p,B
quydinhhoadotroihoantoansovoibquydinhhoatrang.Haicapgennay
namtren2capNSTkhacnhau.Chocaydihopve2capgenlaivoinhaudugcFi.
Layngaunhien2caythancaohoadooFicholaivoinhau.Xacsuatxuathien
cayCOkiSuhinhthanthap,hoatrangadoiF2la:
KXB.1CXD.l
998116
CSu8.Tinhtrangchieucaothandomotcapgenquydinh.Chocaythancaolai
vaicaythancao,Fidugc75%caycao,25%caythap.Lay2caythancaoFi,
xacsuatdedugc2caythuanchungla
491
A.100%.B.-.C—.D.-.
9169
Cau9.ChobietAquydinhthancaotrgihoantoansovoiaquydinhthanthapva
khongCOdotbienxayra.Chocaythancaolaivoicaythanthapthudugcdoi
FiCOhailoaikieuhinhlacaythancaovacaythanthap.Chocaythancaoa
doiFituthuphanthudugcF2c6hailoaikieuhinhlacaythancaovacaythan
thap.Lay2caythancaoddoiF2,theolithuyet,xacsuatdetronghaicaynay
CO1caythuanchungla
A.i.B.1C.i.D.?.
9939
Cau10,Chocayc6nhieuquatuthuphanthudugcFic63loaikieuhinh,trong
docaynhieuquachiemtile56,25%.TrongsonhiSngcaynhieuquaaFi,loai
caydihgpmotcapgenchiemtile
A.^.''B.1'C.i.D.i.
9994
Cau11.Tinhtrangchieucaothandomotcapgenquydinh.Chocaccaythancao
tuthuphan,Fidugc93,75%caycao,6,25%caythdp.LSy2caythancaoFi,
xacsuatdedugc2caythuanchungla
1994
A.i.B.—.C.—.D.
9162525
Cau12,ChobietAquydinhthancaotroihoantoansovoiaquydinhthanthdp.
ChocayAatuthuphandugcFi.TrongsocaccayFi,chgnngaunhien4cay
thancao,xacsuatdetrongso4caychic63caythuanchung.
34

36. A. A. B . i . C . 1 D.
81 9 9 81
Cau 13. Cho hik A quy dinh than cao troi hoan toan so vai a quy dinh than thdp
va khong c6 dpt bien xay ra. Cho cay than cao lai voi cay than thSp thu dugc
doi Fi CO hai loai kieu hinh la cay than cao va cay than thdp. Cho cay than cao
a doi Fi tu thu phan thu duac F2 c6 hai loai kiSu hinh la cay than cao va cay
than thap. hiy 2 cay than cao a doi F2, theo l i thuylt, xac suit dk ca hai cay nay
deu thuan chung la
A. 1. B . 2 . c . l . D . l .
9 9 9 3
Cau 14. CJ phep lai AabbddEE x AaBbDdEe thu duac Fi. Lay ngau nhien 1 ca
the Fi. Xac suat de duac ca the c6 4 alen troi la bao nhieu?
A . ± . B . A. C.'A. D . ' '
64 32 1 6 64
Cau 15. CJ phep lai AabbDdEe x AaBbDdEe thu duac Fi. L i y ngau nhien 1 ca
the Fi. Xac suat de thu dugc ca the c6 2 alen troi la bao nhieu?
A. A. B . I ^ . C . ^ ' . D. '
64 64 128 32
Cau 16. O mot loai thuc vat, gen A quy dinh than cao troi hoan toan so vai aquy-
dinh than thap; gen B quy dinh qua do troi hoan toan so voi b quy dinh qua
vang. Cho cay than cao, qua do (P) tu thu phan, trong t6ng so cac cay thu dugc
a FO kieu hinh than thap, qua vang chi^m ti le 6,25%. hiy 1 cay than cao,
qua do a doi con, xac suat de duac cay thuan chung la
A . i . B.A. • c.i. a '
66 27 9 51
Cau 11. p mot loai thuc vat, A quy dinh hoa do troi hoan toan so voi a quy dinh
hoa trang, B quy dinh than cao troi hoan toan so voi b quy dinh than thip. Hai
c^p gen nay nam tren 2 cap NST khac nhau. Cho cay than cao, hoa do di hgp
ve 2 cap gen noi tren giao phan vai nhau dugc Fi. O dai Fi, chi chgn cac cay
CO kieu hinh than cao, hoa do dem trong va cho giao phan nglu nhien thu dugc
F2. Chon mot cay c6 than cao, hoa do a F2, xac sudt de thu dugc mot cay thuSn
chung ve ca 2 cap gen noi tren la
A . l i . B.-L. C . ^ . D . l .
81 16 9 4
Cau 18. Cho biet moi cap gen quy dinh mot cap tinh trang, alen troi la troi hoan toan.
Tien hanh phep lai AaBBDD x AaBbdd thu dugc Fi. Lay ngau nhien 2 ca the, xac
suat de thu dugc 2 ca the c6 kieu hinh troi v^ ca 3 tinh trang la bao nhieu?
A . l « . B . ^ . C . ^ . D . l .
81 16 81 4
35

37. Cau19.Chobikm6icapgenquydinhmotcaptinhtrang,alentrpilatrpihoan
toan.TiSnhanhpheplaiAABbxAabbthudugcFi.Layngaunhien3cathka
Fi,xacsuatdetrong3caXhknayc6itnhk1cathethuanchunglabaonhieu?
A.^.B.i.C.^.D."
64646464
Cau20.CJmotloaivatnuoi,genAnSmtrenNSTthuongc^uydinhlongdaitroi
hoantoansovaiaquydinhlongngan.Omottrainhangiong,nguoitanhapve
15conduelongdaiva50concailongngin.Chocaccathknaygiaophoitu
dovainhausinhraFic650%cathelongngdn.CaccatheFigiaophoitirdo
dugcF2.Bietrangkhongxayradotbien.Layngaunhien2catheaF2,xac
sudtdkthudugcitnhdt1cathkdihgplabaonhieu?
6486464
Cau21.dpheplaiAaBbDdxAaBbDdthudugcFi.Layngaunhien3catheFi.
Xacsuatdethudugc3cathemamoicathedeuc63alenIanlabaonhieu?
A.0,3B.0,4.C.0,097.D.0,31.
Cau22.CJpheplaiAabbddeexAaBbDdeethudugcFi.Layngaunhien2catheFi.
Xacsuitdkthudugc2cathemam6icaihkdSuc62alentroilabaonhieu?
Q393
A.—.B.—.C.—.D.-.
1616648
Cau23.Chobietmoicaptinhtrangdomotcapgenquydinh.Chocaythancao
hoamaudogiaophanvaicaythanthaphoamautrangdugcFigom100%cay
thancaohoamaudo.ChoFitirthuphandaiF2c6tile56,25%caythancao,
hoado:18,75%caythancao,hoatrang:18,75%caythanthap,hoado:
6,25%caythanthap,hoatrang.Layngaunhien1caythancaohoamaudoa
F2.Xacsu^tdethudugccaythudnchungla
A.37,5%.B.25%.C.12,5%.D.6,25%.
Cau24.TinhtrangchiSucaothandomotcapgenquydinh.Chocaythancao
laivaicaythancao,thudugcFic675%caycao,25%caythdp.Layngaunhien1
caythancaoFichotuthuphansinhradaiF2.Xacsuatdecaydugclayc6dai
contoancaythancaola
A.1B.^.C.lD.^
99316
Cau25.Choh'lkAquydinhthancaotroihoantoansovaiaquydinhthanthap.
ChocaythancaodihoptuthuphdnthudugcFic675%caythancaova25%
caythanthdp.Trongs6caccayFilay4caythancao,xacsuatdetrong4cay
naychic61caymangkieugendihgpla
A.1.B.1?.C.^.D.l.
3818181
36

38. Cau 26. Cho biet moi cSp gen quy dinh mot cap tinh trang, alen trpi la trpi hoan
toan. d dai con cua phep lai AaBbDd x AabbDD, iy ngau nhien 2 ca thS, xac
suk dk thu duoc 2 ca the c6 kieu hinh A-bbD- la
A . ± . B.A. C.1L. D. '
16 64 256 64
Cau 27. Cho biet moi cap gen quy dinh mot cap tinh trang, alen troi la troi hoan
toan. C5 dod con cua phep lai AaBbDdEe x aabbDDEe, liy ngau nhien 1 ca thS,
xac suat de thu duoc ca thl c6 kiSu hinh A-bbD- la
A. 25%. B. 37,5%. C. 56,25%. D. 18,75%.
Cau 28. Cho biet moi tinh trang do mot gen cjuy dinh va troi hoan toan. CJ doi con
cua phep lai c^AaBbddEe x $AabbDdEE, lay ngau nhien 2 ca thg, xac suk thu
duoc 1 ca the c6 kieu hinh mang 3 tinh trang trpi va 1 tinh trang Ian la
A . i . B . I i . C . ^ . D. l .
4 32 128 8
Cau 29. Cho biet moi tinh trang do mot gen c^uy dinh va troi hoan toan. CJ doi con
cua phep lai AaBbDdEe x 9AaBbDdEe, lay ngau nhien 1 ca the, xac suk dk thu
duac ca the c6 kieu hinh c6 dung 2 tinh trang troi va 2 tinh trang Ian la
9 9 27 27
A . — . B . — C. — D.
256 128 128 256
Cau 30. Trong dieu kien moi cap gen quy dinh mot cap tinh trang va trgi Ian hoan
toan. d phep lai AaBbDd x aaBbdd thu duoc Fi. hiy ngau nhien 1 ca thd Fi,
xac suat de thu dugc ca the chi c6 mot tinh trang troi la
A. 37,5%. B. 31,25%. C. 18,75%. D. 50%.
Cau 31. CI phep lai AaBbDd x aaBbdd thu dugc Fi. L i y ngau nhien 2 ca thd Fi,
xac suat de thu duac 1 ca the thudn chung la
A. ^ . B . i . C . ^ . D . l .
64 . 8 32 81
Cau 32. Cho hik moi cap tinh trang do mot cap gen guy dinh. Cho cay than cao
hoa mau do giao phan voi cay than thap hoa mau trang dugc Fi g6m 100% cay
than cao hoa mau do. Cho Fi tu thu phan doi F2 c6 ti le 56,25% cay than cao,
hoa do : 18,75% cay than cao, hoa trSng : 18,75% cay than thip, hoa do :
6,25% cay than thap, hoa trkig. N6u cho cac ca thk Fi lai phan tich thu dugc
Fb. Lay ngau nhien 1 cay a Fb, xac suat de thu dugc cay cao, hoa do la
A. 37,5%. B. 25%. C. 12,5%. D. 50%.
Cau 33. Cho biet moi cap tinh tran^ do mot cap gen quy dinh. Cho cay than cao,
hoa do giao phan voi cay than thap, hoa trfing dugc Fi g6m 100% cay than cao,
hoa do. Cho Fi tu thu phSn doi F2 c6 ti le 56,25% cay than cao, hoa do :
18,75% cay than cao, hoa tring : 18,75% cay than thdp, hoa do : 6,25% cay
than thap, hoa trSng. CJ F2, liy ngau nhien 1 cay than cao, hoa do, xac suat dk
thu dugc cay thuin chung la
37

39. A.
1
B.
32
C.
1
D.
8
1681981
Cau34.Tinhtrangmausichatdaudomotcapgenquydinh.Chocayhatvang
laivaicayduacmoctuhatxanh,dugcFigom75%hatvang,25%hatxanh.
ChocaccayFituthuphanthudugchatF2,
d6thudugccayc6100%hatvangla
1
Layngaunhien1cayFi,xacsuat
A.i
9
B.
3
D.
]_
16
Cau35.Chohikmoicaptinhtrangdomotcapgenquydinh.Chocaythancao
hoamaudogiaophanvoicaythanthaphoamautrangdugcFigom100%cay
thancaohoamaudo.ChoFituthuph4ndoiF2c6tile56,25%caythancao,
hoado:18,75%caythancao,hoatring:18,75%caythanthdp,hoado:
6,25%caythanthip,hoatring.Ldyngaunhien2caythancao,hoamaudoa
¥2,xacsuitdethudugc1caythuanchungla:
B.
8
C.
16
D.i.
9 8181
Cau36.Chobietmoicaptinhtrangdomotcapgenquydinh.Chocaythancao,
hoamaudogiaophanvoicaythanthap,hoamautrangdugcFigom100%cay
thancao,hoamaudo.ChoFituthuphandoiF2c6tile56,25%icaythancao,
hoado:18,75%caythancao,hoatrSng:18,75%caythanthap,hoado:
6,25%caythanthap,hoatrSng.0F2,layngaunhien3caythancao,hoado,
xacsuatdethudugc1caythuanchungla
A.i.
9
B.
32
81
C.
64
243
D.
64
729
3.Dapan:
a.Cacbaityluan
Bail.
Buac1:¥ihgp2capgenthiF2c69loaikilugenva4loaikieuhinh,trong
9
doloaikieuhinhthancaohoadochiemti1?—.Loaicayc6kieuhinhkhac
16
chiemtile=1-
1616
Buac2:Lay3cayF2,xacsuatdechic61caythancao,hoadola
c;.(-).(-)'=
1323
4096
~0,32.
38

40. Bai 2.
Buac 1: Ti le kilu gen a Fi la — AA ; — Aa : — aa. Vay trong s6 cac cay Fi,
4 2 4
cay than cao gom c6 2 loai kieu gen la AA va Aa, trong do cay d6ng hop chilm ti
1 ' 2
le - , cay di hop chiem ti le —. •
3 3
Buac 2: Lay 2 cay than cao, xac suat d l ca 2 cay dku d6ng hop la ( ^ )^ = ^
Bai 3.
I l l
a. Ti le kieu gen d Fi la — AA ; — Aa : — aa. Vay trong so cac cay Fi, cay
4 2 4 "
than cao gom c6 2 loai kieu gen la AA va Aa, trong do cay d6ng hop chigm ti le
1 ' 2
—, cay di hop chiem ti le —.
3 3
Lay 2 cay than cao, xac suat de ca 2 cay dhu d6ng hop la )^ = ^
b. Trong so 4 cay, c6 1 cay mang kieu gen ddng hop thi 3 cay con lai phai
1 2 1 8 32
mang kihu gen di hop. Vay xac suit la C l . ( - ) . ( — )^ = 4. - . — = —
' ^ 3 3 3 27 81
Bai 4.
Buac 1: Ti le ca the c6 kieu hinh mang 3 tinh troi va 1 tinh trang iSn:
AaBBDd x AaBbdd = (Aa x Aa)(BB x Bb)(Dd x dd)
Aa X Aa sinh ra doi con c6 cac kieu hinh chiem ti le — A-, — aa
4 4
BB X Bb sinh ra doi con c6 kilu hinh troi (B-)vai ti le 100%.
Dd X dd sinh ra doi con c6 cac kiku hinh chidm ti le - D-, — dd
• 2 2
Loai ca the c6 kieu hinh mang 2 tinh troi va 1 tinh trang l§n la nhung ki^u hinh
dugc ki hieu la A-B-dd va aaB-D-.
3 1 3
- Kieu hinh A-B-dd chiem ti le = — X 1 X — = —
4 2 8
- KiSuhmhaaB-D-chilm ti le = - x l x - = —
• 4 2 8
-> Loai ca the CO kieu hinh mang 2 tinh troi va 1 tinh trang iSn chilm ti 1$
8 8 8
39

41. Buac2:TinhxacsAt
Xacsuatdethuduac2cathec6kieuhinhmang2tinhtroiva1tinhtrangiSnla
=(0,5)^=0,25.
Bai5.
Buac1:Tilecathec6kieuhinhmang3tinhtroiva1tinhtrangIan:
AABbDdXAaBbDd=(AAxAa)(BbxBb)(DdxDd)
AAXAasinhradoiconc6kieuhinhtroigom2kieugenlaAAvaAa,trong
doki^ugenAAchi^mtile=^.
BbXBbsinhradoiconc6kieuhinhtroigom2kieugenlaBBvaBb,trong
dokikugenBBchilmtile=^.
DdXDdsinhradoiconc6kieuhinhtroigom2kieugenlaDDvaDd,trong
dokieugenDDchiemtile=^.
Cathethuanchunglanhirngcathec6kieugendonghopvet^tcacaccapgen.CJ
doiFicuapheplaitren,loaicathethuanchungchiemtile=—x-xl=^
23318
Catliekhongthuanchungchiemtile=1-—=—
^1818
Buac2:Tinhxacsuit
Lay3cathe,xacsuatdethudugc2cathethuanchungla
=C3^X(J-)2XIZ==0,0087.
^181818x18x18
Bai6.
Buac1:Timti1$cuakieugenAavakieugenaaadoicon.
-(3pheplaiAaxAadugcFic6tilekieugen1AA,2Aava1aa
->(3Fi,tilekieugenc6tileaa=—.
4
-Goinlasohatitnhatcanphailay.
Xacsuitdkkhongc6hatnaomangkilugenaala=(—)"=^
4'4"
Buac2:Timxacsuat.
-Xacsuatdec6itnhat1hatmangkieugenaa=1-xacsuatdekhongc6hat
1
naomangkieugenaa=1-
4"
.40

42. - Theo bai ra ta c6 1 - ^ > 0, 8 - > - ^ < 0, 2 ^ n > 2.
Vay phai lay it nhat 2 hat thi mod thoa man dieu kien bai toan.
Bai 7.
Buac 1: Ti le ca the mang 5 alen Ian.
C) phep lai AaBbDd x AaBbDd, dai bo me c6 t6ng s6 6 cap gen di hap.
-> Khi dai bo me c6 6 cap gen di hap thi a dai con, loai ca the c6 5 alen Ian
6 3
chiem ti le = — f = — = —
• 2' 64 32
Buac 2: Tinh xac suat
3 . 2 _ 9
Xac suat de ca 2 ca the deu c6 5 alen Ian la = (—) =
32 1024
Ba i 8 .
Buac 1: Ti le ca the mang 6 alen troi.
CJ phep lai AaBBddEE x AaBbDdee, dai bo me c6 tong so 4 cap gen di hap.
d cap gen BB x Bb thi dai con luon c6 it nhit a alen troi B.
O cap gen EE x ee thi dai con luon c6 kieu gen Ee (1 alen troi va 1 alen Ian).
Nhu vay, a dai con nghiem nhien c6 2 alen troi nen bai toan tra thanh d phep
lai AaBBddEE x AaBbDdee, can tim ti le cua loai ca the c6 4 alen troi a dai con.
-> Khi dai bo me c6 4 cap gen di hop thi a dai con, loai ca thk c6 4 alen trpi va
C' 1
3 alen Ian chiem ti le = = —
• 2' 16
Buac 2: Tinh xac suat
' ' ' ' 1 1 1
Xac suat de ca 3 ca the deu c6 6 alen troi la = (—) = .
16 4096
B a i 9.
Buac 1: Ti le ca the mang 3 alen troi.
CJ phep lai AabbddEE x AaBbDdEe, dai b6 me c6 t6ng s6 5 cap gen di hgfp.
CJ cap gen EE x Ee thi dai con luon c6 it nhSt 1 alen troi.
Vi vay bai toan tra thanh can tim ca the c6 2 alen troi.
-> Khi dai bo me c6 5 cap gen di hgrp thi a dai con, loai ca thi c6 2 alen troi
10
chiem tile= =2' 32 16'
5 11
Loai ca the khong c6 3 alen troi chiem ti le = 1 -
16 16
41

43. Buac2:Tinhxacsuat
Xacsuitdktrong3caihkdaidyc62caihkc63alentroila
3x5x5x11825
4096
0,2.
161616x16x16
Bai10.
Buac1:Tilecathemang4alentroi.
CJpheplaiAabbDdEexAaBbDdee,dodbomec6tongso6capgendihop.
^Khidaib6mec66capgendihopthiadoicon,loaicathic64alentroi
C15
chiemtile=—f=—.
•2'64
Loaicathekhongc64alentroichiemtile=1-^^
49
6464
Buac2:Tinhxacsuit
Xacsuatdetrong3cathedalaychic6diing1cathec64alentroila
108045 ^,15,49,23x15x49x49
=C;X—x(—)=-0,41.
646464x64x64262144
Bai11.
Buac1:Timtilecathdthuanchungtrongs6caccaythancao,hoadoa¥2.
Daylamotcauhoivephankienthucchongiongbangnguonbienditohop.
-CaydihopAaBbgiaophanvoinhauthidoiFic6caycao,hoadogom
lAABB,2AaBB,2AABb,4AaBb.Caccaynaygiaophanngaunhienthic616so
dolai,dodochiingtaxacdinhcacloaigiaotu,saudoxacdinhtilecuacaythan
cao,hoado.
-CaccathelAABB,2AABb,2AaBB,4AaBbsec6tilecacloaigiaotula
-AABB,-AABb,-AaBB,-AaBb.
9999
Kilugen'-AABB
9
-AABb
9
-AaBB
9
-AaBb
9
IAB
9
IAB,IAB,IAB,
Giaotu
4
iAb
9
laB
9
lAb,
lab
9
42

44. - Vay tat ca cac cay hoa do F2 noi tren se cho 4 loai giao tu vai ti le la
- AB, - Ab, - aB, - a b ~ 4AB, 2Ab, 2aB, lab.
9 9 9 9
Neu chi tinh theo tung cap gen thi:
2 1
.0 cap Aa, A = ' ^ ^ ^•
2 1
O cap gen Bb, B = —, b = —.
- Ca the than cao, hoa do c6 ki hieu kieu gen A-B-
= (1 - aa)(l - bb) = (1 - - ) x ( l - - ) = — .
4 4 16
- Cay than cao, hoa do thuan chung A A B B c6 ti le = — x — = —
^ ^ • 9 9 81
- Trong so cac cay than cao, hoa do thi cay thuan chung chiem ti le = — : — = —.
• 81 81 4
Buac 2: Sic dung toan to hop de tinh xac suat
Vay khi chon mot cay c6 than cao, hoa do a F2 , xac suat de thu dugfc mot cay
thuan chung ve ca 2 cap gen noi tren la —.
4
Bai 12.
Buac 1: Tim ti le kieu hinh a F2 .
Cay di hop AaBb giao phan vai nhau thi dai Fi c6 cay cao, hoa do gom
lAABB, 2AaBB, 2AABb, 4AaBb
Neu chi tinh theo tung cap gen thi:
1 2 2 1
O cap gen Aa, c6 - A A + — Aa =1 , A = - ,a = - .
3 3 3 3
C J c a p g e n B b , c 6 - B B +- B b = l , B = - , b = - .
3 3 3 3
1 1 1 8
Cay than cao, hoa trSng (aaB-) c6 ti 1? = aa x B- = - x - x ( l - - ) =
3 3 9 81
Buac 2: Su dung toan to hap dk tinh xac suit
8
Lay ngau nhien 1 cay a F2 , xac suat de thu duac cay than cao, hoa XxSmg la 81
43

45. b,Cacb^itracnghiem
123456789101112
cCACBDCDBACA
131415161718192021222324
CCCCDBDCACDC
252627282930313233343536
CBDCCBCBCBCC
il.DITRUYENTirOfNGTACGENVAGENDAHIEU
A.TOMTATLITHUYET
-Moitinhtrangc6thedomotgenquydinh(tinhtrangdongen)hoacdonhieu
genquydinh(tinhtrangdagenhaycongoilatuomgtacgen).Trongtunhien,hau
hetcactinhtrangdeudonhieuloaiphantuproteintuongtacvoinhauquydinh
nentuongtacgenlaphobien.Mottinhtrangc6thidordtnhi^ucapgencimg
namtrenmotNSThoacnamtrencaccapNSTkhacnhauquydinh.Trongchuong
trinhsinhhocphothongchidecaptoicackieutuongtacdo2hoac3capgendi
truyenphanlidoclapvatuongtacvoinhau,c63kilutuomgtaclab6sung,cong
gopvaatche.Tuongtacgentaoranhilukiluhinhmoilamxuathiennhi^uhikn
ditohop.
-Dexacdinhkieutuongtacthiphaiduavaotilephanlikiluhinhcuapheplai
Kilu
tuong
tac
KHa
doicon
KHapheplai
phantich
Quyuocgen
Bosung
9:71:3
A-B-choki§uhinh(KH)loai9
A-bb,aaB-,aabbchoKHloai7
Bosung
9:6:11:2:1
A-B-choKHloai9
A-bb,aaB-choKHloai6
aabbchoKHloai1
Bosung
9:3:3:11:1:1:1
A-B-choKHloai9;A-bbchoKHloai3
aaB-choKHloai3;aabbchoKHloai1
Atche
13:33:1
Aat,aakhongat.BquydinhKH3
bquydinhKH13 Atche
12:3:12:1:1
Aat,aakhongat.BquydinhKH3
BquydinhKH1
*Riengtilekiiuhinh9:3:4cdtheduffcgidithicktheoquyluattuomgtacbo
sunghoactirffngtacatche.
-Dexacdinhquyluatditruyencuamoitinhtrangthiphaitinhtilekiluhinha
doicon,ungvoimoiquyluatsec6mottilekieuhinhdactrungchoquylu^td6.
44

46. Viduneudoi conc6tilekieuhinh9cao:7thapthi kh3ngdinhtinhtrangdi
truyentheoquyluattuongtacb6sung.Neuchocayhoatranglaiphantichdvcgcdoi
conCOtile3trang:1dothitinhtrangditruyentheoquyluattuongtacatche,...
-Khitinhtilekiluhinhphai iy kiguhinhcuacathedemlai lamchuan.
Vi duchocayhoadolaiphantichthudugc doiconc675%cayhoatrSng,25%cayhoadothitilekieuhinhla|d6:tr§ng=1:3|chijrkhongphaila|trang:do=3:1
Neuxacdinhsaitilekieuhinhthikhongthexacdinhdungquyluatditruyencua
tinhtrang.
-Cancurvaodieukienbai toanvatilephanlikiluhinhcuapheplai dlkhSng
dinhquyluatditruyencuatinhtrang.Diravaotilekieuhinhadoiconvaquyluatdi
truyencuatinlitrangsesuyradugckieugencuabdme.Hoacdiravaosokieutohgp
vakieuhmhIan(nduc6)adoicon.
-NIUtilephanlikiluhinhla2:1thic6hientugnggengaychktatrangthai
donghgphoacc6motloaigiaotunaodokhongc6khanangthutinh.
-Khibaitoanc6nhi^upheplaicuacungmot tinhtrangthi phai diravaophep
laiCOtilekieuhinhdactnmgnhatdesuyraquyluatditruyencuatinhtrangdo.
-Trongtnxomghgptuongtaccongggp,vaitrociiacacalentroi langangnhau
dodosirbieuhienkieuhinhtuythugcvaosolugnggentrgic6trongmoikieugen.
-Khidcfibomec6nhieukieugenkhacnhauthitienhanhtimgiaotudothehe
b6medosinhra,saudolapbangdltimtilekiluhinh.
B. CAGDANG BAI TAP VEXACSUATTRONGTUdNGTACGEN
1.Cacbaitaptinhxacsuatvekieuhinh
Cdchgiai: Khi baitoanyeucautinhxacsuatvemot kieuhinhnaodothi can
phaitienhanhtheo2buoc.
Buac 1:Xacdinhkieugencuab6 mevak sod6laidetimtilecualoai kieu
hinhcantinhxacsuk.
Buac2:Sicdungtoant6hgpdStinhxacsudt
Bai1:dmotloaithircvat,tinhtrangmauhoado2capgenAavaBbnamtren2cap
NSTkhacnhauquydinh. Khitrongkieugenc6caAvaBthi quydinhhoado;
cactruonghgpconlaic6hoatrang.C)pheplaiAaBbxAaBbdugcFj. Layngau
nhien1catheFi,xacsuatdethudugccathec6kieuhinhhoadolabaonhieu?
Hu&ngdan giai:
Buac 1:XacdinhtileciialoaikieuhinhhoadoaFi.
-Tinhtrangmauhoaditruyentheoquyluattuongtacbosungloaic6tile:
9do:7trang.
-Saddlai: AaBb xAaBb=(AaxAa)(BbxBb)
AaX Aa->doiconc6 3A-; laa.
BbX Bb doiconc6 3B-;Ibb.
45

47. DaiFiCOtile9A-B-;3A-bb;3aaB-;laabb.
DokhiCOcaAvaBthic6hoado,cactnronghgrpconlaic6hoatrSngchonen
doiconCOtilekieuhinhla>
9cayhoad6(9A-B-)
7cayhoatrang(3A-bb,3aaB-,laabb).
9
->CJdoiF],cayc6kieuhinhhoadochiemtile=—.
•16
Buac2:Sudungtoantohopdetinhxacsuat
9 Layngaunhien1cayaFithixacsuatthuduoccayhoadochinhla
16
Bai2:CJmotloaithircvat,genBquydinhhoadotroihoantoansovaibquy
dinhhoah6ng.GenAkimhamsirbieuhiencuagenBvabnenhoac6mau
trang,genakhongc6boattinhnay,haicapgennamtren2capNSTkhac
nhau.Chocaydihapve2capgennoitrentirthuphanduacFi.Layngau
nhien1cathiFi,xacsuitdkthudugccathic6kieuhinhhoadolabaonhieu?
Hu&ngdangiai:
Buac1:XacdinhtilecualoaikiluhinhhoadoaFi.
-Tinhtrangmauhoaditruyentheoquyluattuangtacatchl,gentroiatgen
khongalenvaino.
-Caydihop2capgenc6kieugenlaAaBb.
Sad6lai:AaBbxAaBb=(AaxAa)(BbxBb)
AaXAa->daiconc63A-;laa.
BbXBb->daiconc63B-;Ibb.
DeriFiCOtile9A-B-;3A-bb;3aaB-;laabb.
DoAatchesubieuhiencuagenBvabchonencackieugenA-B-,A-bbdSu
chokieuhinhhoatrang.
Daiconc6tilekieuhinh12hoatr^g(9A-B-va3A-bb),
3hoado(3aaB-),
1hoahong(laabb).
3
OdoiFi,cayc6kieuhinhhoadochiemtile=—.
16
Buac2:Sudungtoantohapdetinhxacsuat
3 Layngaunhien1cayaFitMxacsuatthudugccayhoadochinhla
16
Bai3:Omotloaithircvat,tinhtrangchieucaothando2capgenAavaBbnam
tren2capNSTkhacnhauquydinh.Khitrongkieugenc6caAvaBthiquy
dinhcaythancao;cactruanghopconlaiquydinhthanthip.Clpheplai
AaBbXAaBbdugcFi.Liyngaunhien2cathiFi,xacsuitdltrong2cathi
naychic61cathec6kieuhinhthancaolabaonhieu?
46

48. Huang dan giai:
Buac 1: Xac dinh ti le cua loai kieu hinh cay than cao va cay than thap a Fi.
- Tinh trang chieu cao cay di truyen theo quy luat tuong tac bo sung loai c6 ti
le 9 cao : 7 thap.
-Saddlai: AaBb x AaBb = (Aa x Aa)(Bb x Bb)
Aa X Aa -> doi con c6 3A-; laa.
Bb X Bb ^ doi con c6 3B-; Ibb.
Doi F, CO ti le 9A-B-; 3A-bb; 3aaB-; laabb.
Do khi CO ca A va B thi c6 cay cao, cac tnromg hop con lai c6 cay thip cho nen
doi con CO ti .le kieu hinh la
9 cay than cao (9A-B-)
7 cay than thdp (3A-bb, 3aaB-, laabb).
9 ' ' 7
^ O doi Fi, cay than cao chiem ti le = — , cay than thap chiem ti le
16 " "16
Buac 2: Su dung toan to hop de tinh xac suk
Lay ngau nhien 2 cay d Fi thi xac suat thu duac 1 cay than cao la
^ , 9 7 2x9x7 126 ^
' 16 16 16x16 256
Bai 4: CJ ngo, tinh trang chieu cao do 2 cap gen Aa va Bb nSm tren 2 cap NST
khac nhau tuong tac theo kieu cong gop, trong do cu c6 moi gen troi lam cho
cay cao them 20 cm. Lay hat phan cua cay cao nhat (c6 chieu cao 210 cm) thu
phan cho cay thap nhat dugc Fi, cho Fi tir thu phan duac F2. Lay ngau nhien 1
cay a F2, xac suat de thu dugc cay c6 dp cao 190cm la bao nhieu?
Huang dan giai
Buac 1: Xac dinh ti le cua loai kieu hinh cay than cao 190 cm a F2.
- Cay cao nhat c6 kieu gen AABB cao 210 cm.
- Cay thap nhat c6 kieu gen aabb c6 do cao = 210 c m - 4 x 20 = 130 cm.
So d6 lai: AABB x aabb
FI: AaBb
F| x Fi AaBb x AaBb.
- Loai cay cao 190 cm la loai cay c6 3 alen troi va 1 alen Ian.
4 1
- Loai ca the c6 3 alen troi c6 ti le = -7- = — = —.
• 2' 16 4
- Loai cay cao 190 cm c6 ti le = - .
4
Buac 2: Sii dung toan to hop de tinh xac suat
47

49. Layngaunhien1cayaF2,xacsuatdethuduaccayc6docao190cmla=—.
4
Bai5:Omotloaithucvat,tinhtrangkhoilugmgquado4capgenditruyentheo
kieutucmgtacconggop,trongdocuc6them1alentroiselamchoquanang
them20g,cayd6nghopgenIanaabbddeec6quanang150g.hiyhatphdncua
cayCOquanangnhatthuphanchocayc6quanhenhatduacFi,choFigiao
phanngaunhienduacF2.Layngaunhien5cayaF2,xacsudtdkthudugc3
cayCOkhoiluongqua21Oglabaonhieu?Bietrangcaccapgenditruyenphan
lidoclapvainhau.
Huangdangidi
Buac1:Xacdinhtilecualoaicayc6quanang210gaF2.
Sad6lai:AABBDDEExaabbddee
Fi:AaBbDdEe
FiXFiAaBbDdEexAaBbDdEe.
-Loaicayc6quanang210glaloaicayc63alentroiva5alenIan.
Cl_567
-Loaicathec63alentroic6tile=
2'25632
7_
32
7
->Loaicayc6quanSng210gc6ti1?=—;Loaicaykhongc6quanang210g
,,725
COtile=1=—
3232
Buac2:Sudungtoantohgpdetinhxacsuat
Layngaunhien5cayaF2,xacsuatdethudugc3cayc6quanang210gla
=CSK^)'K^)'='""^^'f==0,027.
'323232'33554432
Bai6:CJmotloaithucvat,detaothanhmaudociiahoac6sirtacdongcuahai
genAvaBtheosad6:GenAGenB
enzimAenzimB
Chattrang1.—•Chattrang2.—•Chatdo.
Genavabkhongc6boattinh,haicapgennamtrenhaicapNSTkhacnhau.
ChocayhoatranglaivoicayhoatrangdugcFidongloathoado.ChoFitirthu
phandugcF2.Layngaunhien2cayaF2.Xacsuitdetrong2caychic61cayhoa
dolabaonhieu?
Huangdangidi:
Buac1:Xacdinhtilecualoaikieuhinhhoado,hoatringaF2.
48

50. - Nhin vao so do ta suy ra ducrc tinh trang di truyen theo quy luat tuong tac b6
sung. Khi trong kieu gen c6 A va B thi c6 hoa do
Khi thieu gen A hoac thieu B hoac thieu ca hai gen thi c6 hoa trSng.
- Khi cho cay hoa trdng lai voi cay hoa trSng dugc Fi d6ng loat hoa do
-> Bo me thuan chung va Fi c6 kikn gen di hop ve ca 2 cap gen
-> Kieu gen cua Fi la AaBb
Fi tir thu ph4n, ta c6: AaBb x AaBb
Dai F2 CO ti le kilu hinh 9A-B- 9 Hoa do
3A-bb ^
3aaB- r 7 Hoa trang
laabb
Ti le kieu hinh a F2 la 9 cay hoa do : 7cay hoa tring.
9 ' ' 7
-> O F2, cay hoa do chiem ti le = — , cay hoa trang chiem ti le = —
16 16
Buac 2: Tinh xac suat
Lay ngau nhien 2 cay a F2. Xac suat de trong 2 cay chi c6 1 cay hoa do la
9 7 2x9x7 126 63 ^
C ' x — X — = = = ==0,49.
16 16 16x16 256 128
Bai 7: Cho ca the hoa do lai voi ca t h i hoa trSng, Fi dong loat hoa trSng. Cho Fi
tir thu phan thi doi F2 c6 t i le: 75% hoa tring, 18,75 hoa do, 6,25% hoa vang.
Cho cay Fi lai phan tich, thu dugc doi Fb. Lky ngau nhien 3 ca the a doi Fb.
Xac suat de trong 3 ca the nay chi c6 1 cay hoa trang la bao nhieu?
Hu&ng dan gidi:
Buac 1: Tim ti le cua cay hoa trang o doi Fb.
- Doi F2 CO ti le 75% hoa trSng : 18,75 hoa do : 6,25%) hoa vang = 1 2 : 3 : 1
Tinh trang mau hoa di truydn theo quy luat tuomg tac at chd.
- Quy uac : A-B- 1 quy dinh hoa trSng
A-b b .
aaB- } quy dinh hoa do
aabb } quy dinh hoa vang
Sod Slai: P. AAbb x aaBB
F,: AaBb
Fi lai phan tich : AaBb x aabb
Doi con CO lAaBb, lAabb, laaBb, laabb.
Ti le kieu hinh doi con la 2 cay hoa trang : 1 cay hoa do : 1 cay hoa vang.
-> CJ doi con cua phep lai phan tich, cay hoa tring chiSm ti 1?= — =0,5.
4
49

51. CayCOhoakhongtrangchiemtile=1-0,5=0,5.
Buac2:Sudungtoantohapdetinhxacsuat.
hiyngaunhien3cathkadoiFb.Xacsuitdetrong3cathlnaychic61cay
hoatringla=C^x0,5x(0,5)'=0,375.
2.Cacbaitaptinhxacsuatvekieukieugen
Cdchgidi:CanphaitiSnhanhtheo2buac
Buac1:Timtilecuakikugencantinhxacsuit
Buac2:Sudungtoantohopdetinhxacsuat.
Bai1:Chocayhoadotuthuphan,thuduacdoiFic6tilekieuhinh9cayhoado:
7cayhoatrang.Liyngaunhien2cayhoadoaFi.Xacsuitdkthudugrc2cay
thuanchunglabaonhieu?
Huangdangidi
Buac1:Timtilethuanchungtrongsocaccayhoado
-DoiFiCOtilekiSuhinh9:7chungtotinhtrangditruySntheoquyluat
tucmgtacbosung.
-Quyuac:A-B-quydinhhoado
A-bbl
aaB->•quydinhhoatrang
aabb_
-DaiFiCOtile9:7chungtocayhoadoFic6cackieugenvoltilela
lAABB,2AaBB,2AABb,4AaBb.Trongdochic6kikugenAABBlakikugen
thuanchung.
CJcayhoadoFi,caythuinchungchiSmtile=^
Buac2:Sudungtoantohopdetinhxacsuit.
Layngaunhien2cayhoadoaFi,xacsuatdethuduac2caythuinchungla
981
Bai2:Chocaythancaolaiphantich,thudugcdaiconc6tilekikuhinh1cay
thancao:3caythanthap.Layngaunhien3caythanthipadoicon.Xacsuit
detrong3caynaychic61caythuinchunglabaonhieu?
Huangdangidi
Buac1:Timtilethuanchungtrongs6caccaythanthip
-Laiphantichmadoiconc6tilekikuhinh1:3chungtotinhtrangditruySn
theoquyu§Xtuongtacbosung.
-Quyuac:A-B-quydinhthancao
A-bb^
aaB-^quydinhthanthap
aabb
50

52. - Cay than thap a dai con (cua phep lai phan tich) c6 cac kilu gen vod ti le la
lAabb, laaBb, laabb. Trong do chi c6 kilu gen aabb la kilu gen thuan chung.
-> d cay than thSp cua dai con, cay thuSn chung chiSm ti le = ^ ; Cay khong
1 2
thuan chung chiem ti le = 1 - - = —.
Buac 2: Su dung toan to hap de tinh xac suat.
Lay ngau nhien 3 cay than thap a dai con, xac suit dk trong 3 cay nay chi c6 1
cay thu&i chung la = Cx-><(-f = l ! ^ = 1 ^^0,44.
' 3 3 3x9 9
Khi bai toan yeu cau trong 3 cay chi c6 1 cay thuan chung thi c6 nghia la 2
cay con lai phai khong thuan chung.
Bai 3: Cho cay c6 hoa mau vang lai voi cay hoa mau vang, dai Fi c6 ti le kieu
hinh 56,25% cay hoa vang; 43,75% cay hoa trdng. Liy ngau nhien 2 cay hoa
trang a Fi. Xac suat de thu dugc it nhSt 1 cay thuAn chung la bao nhieu?
Huang dan giai:
Bum 1: Tim ti le cua cay thuan chung trong so cac cay hoa tring a Fi.
- Dai con c6 ti le 56,25%) cay cho hoa vang; 43,75%) cay hoa trSng = 9 : 7
-> Tinh trang di truyen theo quy luat tuang tac bo sung.
- Quy uac : A-B- quy dinh hoa vang
A-bb-|
aaB- Y quy dinh hoa t r ^ g
aabb ^
Kieu gen ciia bo me la AaBb x AaBb.
- Cay hoa trang a Fi gom c6 lAAbb, 2Aabb, laaBB, 2aaBb, laabb. Trong do
cay thuan chung gom c6 3 cay la 1 AAbb, laaBB, laabb.
-> C5 dai F], trong so cac cay hoa trang, cay thuSn chung chilm ti le = y ; cay
3 4
khong thuan chung chiem ti le = 1 - y = - .
Buac 2: Six dung toaii to hap dl tinh xac suSt.
- Lay ngau nhien 2 cay hoa trSng, xac suat dk ca 2 cay dhu khong thuan chung la
7 49
Xac suat de c6 it nhat 1 cay thuin chung = 1 - xac sudt dk ca 2 cay khong
16 33
thuan chung = 1 = — ~ 0,67.
^ 49 49
51

53. Khibomedeuc6kieugendihppthio"dMcon,cathemangkieugendong
hopCOheso1,cathemangkieugendihop1capgenh^so2,dihgp2cap
genthiheso4,dihop3capgenthihgso8.
Bai4:C5motloaithucvat,tinhtrangchiducaocaydo4capgenditruySntheo
kilutuomgtacconggop,trongdociic6themmotalentroiselamchocaycao
them20cm,cayd6nghopgenIanaabbddeec6docao120cm.Liyhatphan
cuacaycaonhatthuphanchocaythapnhatdugcFi,choFigiaophanngau
nhiendugcF2.LSynglunhien2cayc6docao160cmaF2,xacsuatdetrong2
caynaychic61caythuanchunglabaonhieu?Bietrangcaccapgenditruyen
phanlidoclapvoinhau.
Huongdangiai
Bu&c1:XacdinhtilecuacaythuSnchungtrongs6caccaycao160cmaF2.
Sod6lai:AABBDDEExaabbddee
Fi:AaBbDdEe
FiXFiAaBbDdEexAaBbDdEe.
-Loaicaycao160cmlaloaicayc62alentroiva5alenIan.
-Loaicathec62alentroic6sotohop=Cg=28.
-Loaicathic62alentroivathuAnchunggomc64kieugenlalAAbbddee,
laaBBddee,laabbDDee,laabbddEE.
41
-Trongsocaccathec6docao160cm,caythuanchungc6tile=—=-.
,287
Caykhongthuanchungchiemtile=1-^=^.
Buac2:Sudungtoant6hopdltinhxacsuit
Liyngaunhien2cayc6docao160cmaF2,xacsuatdetrong2caynaychic61
^,162x1x612
caythuanchungla=C'x-x-==—-0,24.
^^'777x749
Bai5:CJmotloaithircvat,genBnSmtrenNSTs61quydinhhoadotrgihoan
toansovoibquydinhhoah6ng.GenAnSmtrenNSTso3kimhamsirbieu
hiencuagenBvabnenhoac6mautring.genakhongc6boattinhnay.Cho
caydihgpvk2capgentirthuphdndugcFi.Layngaunhien3cayhoatranga
Fi,xacsuitdkthudugc1caythudnchunglabaonhieu?
Huangdangiai:
Buac1:TimtilecuacaythuSnchiingtrongs6caccayhoatrangaFi.
-Tinhtrangdo2capgenquydinhvaditruygntheoquyluattuomgtacatche.
-Quyuac:A-B--|quydinhhoatrang
A-bb
52

54. aaB- } quy dinh hoa do
aabb } quy dinh hoa hong
Cho cay di hop h 2 cap gen tu thy phan dugc Fi
AaBb X AaBb
doi con CO 3 loai kiki hinh, trong do kiku hinh hoa tr^ng g6m c6 cac kieu gen la:
1 AABB + 2AABb + 2AaBB + 4AaBb + lAAbb + 2Aabb = 12
Cay hoa tring thuSn chung gom c6 1 AABB + 1 AAbb.
2 1
Trong so cac cay hoa trang 6 doi Fi, cay thuan chung c6 ti le = — = —
12 6
Cay khong thuan chung chiem ti le = 1 - — = —
6 6
Buac 2: Su dung toan t6 hop de tinh xac suit.
Lay ngau nhien 3 cay hoa trang a Fi, xac suat de thu dugc 1 cay thuan chung la
' 6 6 6x6' 216
Bai 6: CJ mot loai thuc vat, tinh trang kh6i luang qua do 3 cap gen nam tren 3 cap
NST khac nhau tuong tac cong gop, trong do cii c6 moi gen troi thi qua nang
them 10 gam. Qua c6 khoi lugng nhe nhat la 80 gam. Cho cay c6 qua nang nhat lai
voi cay c6 qua nhe nhat dugc Fi, cho Fi tu thu phin thu dugc F2. Lay ngau nhien 3
cay a F2, xac su^t dl thu dugc 1 cay c6 qua nang 130 gam la bao nhieu?
Huang dan giai:
2' 64
3. Cac bai tap xac suat khi bo me c6 nhieu kieu gen khac nhau
d ¥2, cay CO qua 130g chiSm ti le = = — = 9,375%.
Cdch gidi: Khi bai toan yeu cau tinh xac suat ve mot kieu hinh nao do thi can
phai tien hanh theo 3 buac.
Buac 1: Xac dinh kilu gen ciia cac ca the b6 me va vi^t sa d6 lai.
Buac 2: Xac dinh kieu gen cua bo me va viet sa do lai de tim ti le cua loai kieu
hinh can tinh xac suit.
Buac 3: Su dung toan to hgp de tinh xac suat
Bai 1: CJ mot loai thuc vat, tinh trang chieu cao cay do 2 cap gen Aa va Bb nam tren 2
cap NST khac nhau quy dinh. Khi trong kieu gen c6 ca A va B thi quy dinh than
cao; cac truong hgp con lai quy dinh than thap. O phep lai AaBb x AaBb dugc Fi.
Cho tat ca cac cay than cao a Fi giao phan ngau nhien thu dugc F2. Lay ngau
nhien 1 cay a F2, xac suat de thu dugc cay than cao la bao nhieu?
Huang dan gidi:
Buac 1: Xac dinh ti le cua loai kieu hinh than cao 0 F2.
53

55. -Tinhtrangchieucaothanditruyentheoquyluattuooigtacbosungloaic6ti
1?9cao:7thap.
-Sod6lai:AaBbxAaBb=(AaxAa)(BbxBb)
AaXAa->doiconc63A-;laa.
BbXBb^doiconc63B-;Ibb.
DoiFiCOtile9A-B-;3A-bb;3aaB-;laabb.
-DokhiCOcaAvaBthic6thancao,cactruonghopconlaic6thanthipcho
nendaiconc6ti1?kiluhinhla
9caythancao(9A-B-)
7caythanthdp(3A-bb,3aaB-,laabb).
-CaythancaoadoiFig6mcackikugenvoitilelalAABB,2AaBB,2AABb,
4AaBb=-AABB,-AaBB,-AABb,-AaBb.
9999
-KhichotdtcacaccaythancaoaFigiaophanngaunhienthisec6rdtnhiguphep
lai,vivayneuvietcacpheplaithisematratnhieuthaigianvadesaisot.Dovay,each
totnhatlavietgiaotucuatitcacaccathe,saudolapmotsad6laichung(vibanchit
cuagiaophoiladocacgiaotirk^thopvoinhau).
-CacloaigiaotudocaccaythancaoFisinhrala
Kieugen-AABB
9
-AABb
9
-AaBB
9
-AaBb
9
Giaotu
IAB
9
lAb
9
iaB
9
iAb,
lab
9
VaytatcacaccaythancaoaFinoitrensecho4loaigiaotuvoitiISla
-AB,-Ab,-aB,-ab~4AB,2Ab,2aB,lab.
9999
-Lapbangdexacdinhcacloait6hopkieugenddoicon
~^~—4AB2Ab2aBlab
4AB16AABB8AABbSAaBB4AaBb
2Ab8AABb4Aabb4AaBb2Aabb
2aB8AaBB4AaBb4aaBB2aaBb
lab4AaBb2Aabb2aaBblaabb
54

56. Kiku hinh a doi F2: 64 cay than cao (16 + 8 + 8 + 8 + 8 + 8 + 4 + 4 +4)
17 cay than thap
64
^ O dcri F2, cay than cao c6 ti le = — .
81
BtC&c 2: Su dung toan to hgrp de tinh xac suat
64
Lay ngau nhien 1 cay 0 F2thi xac suat thu dugc cay than cao la —
81
Bai 2: CJ mot loai thirc vat, tinh trang chi6u cao than do 2 cap gen Aa va Bb nam
tren 2 cap NST khac nhau quy dinh. Khi trong kieu gen c6 ca A va B thi quy
dinh cay qua do; cac truong hop con lai quy dinh cay qua vang. Cho cay di hop
ve 2 cap gen lai voi nhau dugc Fi. Cho t^t ca cac cay qua vang a Fi giao phin
ngau nhien dugc F2. Lay ngau nhien 1 ca the F2, xac suat de thu dugc ca the c6
kieu hinh qua do la bao nhieu?
Huong dan giai:
Buac 1: Xac dinh ti le cua loai kilu hinh qua do va qua vang 0 F2.
- Tinh trang mau sac qua di truyen theo quy luat tuong tac b6 sung loai c6 ti le
9 do: 7 vang.
d dai Fi, cay qua vang c6 cac kieu gen voi ti le la lAabb, 2Aabb, laaBB,
2aaBb, laabb = - AAbb, - Aabb, - aaBB, - aaBb, - aabb.
7 7 7 7 7
- Cac loai giao tu do cac cay qua vang F| sinh ra la
Kieu gen
-Aabb
7
-Aabb
7
laaRB
7
-aaBb
7
laabb
7
Giao tu
i A b
7
^ A b ,
l a b
7
i a B
7
i a B ,
l a b
7
l a b
7
Vay tat ca cac cay qua vang a Fi noi tren se cho 3 loai giao tu voi ti le la
- Ab, - aB, -ab~ 2Ab, 2aB, Sab.
7 7 7
- Lap bang de xac dinh cac loai t6 hgp kilu gen a doi con
2Ab 2aB Sab
2Ab 4Aabb 4AaBb 6Aabb
2aB 4AaBb 4aaBB 6aaBb
3ab 6Aabb 6aaBb 9aabb
55

57. KieuhinhadoiF2:
8cayquado;41cayquavang.
8
->doiF2,cayquadoc6tile=49
Buac2:Sicdungtoant6hopdktinhxacsudt
8
Layngaunhien1cayaF2thixacsuatthudugccayquadola
49
Bai3:Omotloaithucvat,detaothanhmaudocuahoac6sutacdongcuahai
genAvaBtheosod6:
GenAGenB
ii
enzimAenzimB
Chattrang1•Chattring2•Chdtdo^Hoamaudo.
Genavabkhongc6hoattinh,haicapgennamtrenhaicapNSTkhacnhau.Cho
pheplaiAaBbxAabbdugcFi.Layngaunhien1cayhoadoFidemlaiphantich
dugcFb.Layngaunhien1cayaFb.Xacsuatdedugccayhoadolabaonhieu?
Huangdangidi:
Buac1:Xacdinhtilecualoaikiluhinhhoado,hoatrSngaFb.
-Nhinvaosodotasuyradugctinhtrangditruyentheoquyluattuomgtacb6
sungkieu9do:7trang.
-Saddlai:AaBbxAabb=(AaxAa)(Bbxbb)
DaiF2COtilekieuhinh3A-B-3hoado
3A-bb1
laaB->•5hoatrang
laabb
TilekieuhinhaFila3cayhoado:5cayhoatrSng.
12
-cayhoadoFigomc6cackieugenla1AABb,2AaBb=-AABb,-AaBb.
-Layngaunhien1cayhoadoFithisedugccayAABBhoacdugccayAaBb
12
voitilexacsuat=-AABbhoac—AaBb.
3•3
-Chocayhoadodugclaylaiphantichthitac62truonghgp.
12
-AABbXaabbhoac—AaBbxaabb.
3•3
Dedongian,chiingtaxemxetchunggiongnhuchotdtcacaccayhoadoaFjlai
12
phantich.CaccayhoadoFic6-AABbhoac-AaBbnengiaotula
33
56

58. Kieu gen
- A A B b
3
-AaBb
3
IAB. 7AB,
0
Giao tu
i A b
6
7Ab,
6
i a b
6
•
i A b
6
7Ab,
6
i a b
6
Vay tat ca cac cay hoa do a F i noi tren se cho 4 loai giao tu voi ti le la
- A B , - A b , - a B , -ab~2AB,2Ab, laB, lab.
6 6 6 6
- Lap bang de xac dinh cac loai to hop kieu gen a doi con
2AB 2Ab laB lab
lab 2AaBb 2Aabb laaBb laabb
1
Ti le kieu hinh a doi Fb la
2 cay hoa do, 4 cay hoa tring = 1 cay hoa do, 2 cay hoa tring
-> d Fb, cay hoa do chiem ti le =
Budfc 2: Tinh xac suat
Lay ngau nhien 1 cay 0 Fb. Xac suat de dugc cay hoa do la
d doi Fi, neu lay ngau nhien 1 ca the hoa do dem lai thi ket qua tuong tu-
nhtr trircmg hop cho tat ca cac cay hoa do Fi dem lai.
Bai 4: CJ mot loai dong vat, cho ca the long trang lai voi ca the long do dugc F j
dong loat long trang. Cho F i giao phoi ngau nhien thi doi F2 c6 ti le: 13 ca the
long trang, 3 ca the long do. Lay ngau nhien 2 ca the long do F2 cho giao phoi
voi nhau, thu dugc doi F3. Lay ngau nhien 1 ca the a doi F3, xac suat de thu
dugc ca the long trang la bao nhieu?
Huang dan giai:
Buac 1: Tim ti le kieu hinh a doi F3.
- Doi F2 CO ti le 13 : 3 -> Tinh trang di truyen theo quy luat tuomg tac at che.
-Quyuoc: A-B-'
A-bb quy dinh long trang
aabb ^
aaB-} quy dinh long do
57

59. -Sad6lai:P.AAbbxaaBB
Fi:AaBb
-Figiaoph6ingaunhien:AaBbxAaBb
DaiF2COtile13conlongtrang:3conlongdo.
12
-ConlongdoF2gomcackieugenlaaBB,2aaBb=-aaBBhoac—aaBb.
-Layngaunhien2conlongdoF2chogiaophoingaunhienthisec6ketquadoiF3
giongnhutruomghopchotdtcacaccathllongdoF2giaoph6ingaunhien.
12
-Giaoturcua-aaBB,—aaBbla
33
Kieugen
-aaRB
3
-aaBb
3
Giaotu
iaB
3
iae.
lab
3
-CaccathklongdoF2cho2loaigiaotula—aB,-ab=2aB,1ab.
-Lay2cathelongdoF2chogiaophoingaunhien,taduacbangsau:
2aBlab
2aB4aaBB2aaBb
lab2aaBblaabb
DoiF3COtilekiluhinh8do:1trSng.
->Cathelongtrangc6tile=^
HSCOthekhonglapbangmalamtitblingeachcathelongtrgng(aabb)
.1.1.1
COtile=-abX—ab=—
•339
Buac2:Sudungtoant6hopdktinhxacsuit.
Layngaunhien1catheadoiF3,xacsuitdkthuduaccathklongtring1^=~
Bai5:CJmotloaithircvat,khichocaythancaotuthuphinthuduacFic6tile
kieuhinhgom56,25%caythancao,43,75%caythanthip.Chotitcacaccay
thanthapFigiaophoingaunhiendugcF2.Liyngaunhien1cathkthanthipa
F2,xacsuatdethudugccaythuinchiinglabaonhieu?
58

60. Huong dan gidi:
Buac 1: Xac dinh ti le ca the thuan chung trong so cac cay than thap d F2.
- Dai Fi CO ti le 56,25% cay than cao : 43,75% cay than thSp = 9 : 7 ^ Tinh
trang di truyen theo quy luat tuang tac bo sung.
- Quy uac: A-B- quy dinh than cao
A-bb-
aaB-
aabb
quy dinh than thap
- Cay than thap a dai Fi gom cac kieu gen vai ti le la lAAbb, 2Aabb, laaBB,
1 2 1 2 1
2aaBb, laabb = — AAbb, — Aabb, — aaBB, - aaBb, — aabb.
7 7 7 7 7
- Khi cho tk ca cac cay than thap Fi giao phan ngau nhien thi se c6 rdt nhiSu phep
lai, vi vay neu viet cac phep lai thi se mk rk nhi^u thai gian va de sai sot. Do vay, each
tot nhat la viet giao tu cua tat ca cac ca the, sau do lap mot sa d6 lai chung (vi ban chk
cua giao phoi la do cac giao tu kk hop vai nhau).
- Cac loai giao tu do cac cay than thdp Fi sinh ra la
Kieu gen
-Aabb
7
-Aabb
7
-aaBB
7
-aaBb
7
— aabb
7
Giao tu
i A b
7
l a b
7
i a B
7
i a B ,
i a b
7
i a b
7
Vay tat ca cac cay than thap a Fi noi tren se cho 3 loai giao tu vai ti le la
I Ab, I aB, ^ ab = 2Ab, 2aB, 3ab.
- Lap bang de xac dinh cac loai to hop kilu gen a doi con
2Ab 2aB 3ab
2Ab 4AAbb 4AaBb 6Aabb
2aB 4AaBb 4aaBB 6aaBb
3ab 6Aabb 6aaBb 9aabb
Kiku hinh a doi F2: 8 cay than cao; 41 cay than thip.
- Cay than thkp a F2 gom c6 cac kieu gen vai ti le la 4AAbb, 12Aabb, 4aaBB,
12aaBb, 9aabb = — AAbb, — Aabb, — aaBB, — aaBb, — aabb
49 49 49 49 49
59

61. TrongsocaccaythanthSpadoiF2,caythuinchungla—AAbb,—aaBBva
4949
944917
—aabbc6tile=—+—+—=—;
49•49494949
Buac2:Sudungtoant6hopd^tinhxacsudt
hiyngaunhien1cathethanthapaF2,xacsuatdethudugccaythudnchung
Bai6:CJmotloaithucvat,tinhtrangchieucaothando2capgenAavaBbnam
tren2capNSTkhacnhauquydinh.Khitrongkieugenc6caAvaBthiquy
dinhcaythancao;cactruonghgpconlaiquydinhthanthap.Chocaydihgp
ve2capgenlaivoinhaudugcFi.ChotatcacaccaythancaoaFilaiphan
tichdugcFb.Layngaunhien1catheFb,xacsuatdetrongFbthudugccathI
thuanchunglabaonhieu?
Huangdangiai:
Buac1:XacdinhtilecaythudnchungtrongsocaccaycayaFb.
-Tinhtrangchieucaocayditruyentheoquyluattuongtacbosungloaic6ti
le9cao:7thap.
C)doiFi,caythancao
-Caythancao0doiFig6mcackieugenvoitilelalAABB,2AaBB,2AABb,
4AaBb=-AABB,-AaBB,-AABb,-AaBb.
9999
-CacloaigiaotudocaccaythancaoFisinhrala
Kieugen
-AABB
9
-AABb
9
-AaBB
9
4
-AaBb
9
IAB
9
Giaotu
lAb
9
laB
9
iAb,
lab
9
VaytatcacaccaythancaoaFinoitrensecho4loaigiaotuvoitilela
4221
-AB,-Ab,-aB,-ab~4AB,2Ab,2aB,lab.
9999
60

62. - Cho tk ca cac cay than cao Fi lai phan tich, lap bang dl xac dinh cac loai t6 hgp
kilu gen a doi con
4AB 2Ab 2aB lab
lab 4AaBb 2Aabb 2aaBb laabb
Kieu hinh a doi F2:4 cay than cao; 5 cay than thap.
Cay thu^ chung a Fb g6m c6 1 cay aabb -> Ti le cay thuan chiiiig 0 Fb la ^
Btcac 2: Six dung toan t6 hop tinh xac suat
hiy ngau nhien 1 ca thi Fb, xac suit de thu duac ca the thuan chung la ^
Bai 7: d mot loai dong vat, dk tao thanh mau long do c6 sir tac dong cua hai gen
A va B theo so do:
Gen A Gen B
i i
enzim A enzim B
Chat trSng 1 Chat trang 2 •> Chat do -> long mau do.
Gen a va b khong c6 hoat tinh, hai cap gen nam tren hai cap NST khac nhau.
Cho ca thk long do di hop 2 cap gen giao ph6i vai nhau ducrc Fi. Liy ngau nhien 2
ca thk long do Fi cho giao ph6i vai nhau duac F2. hiy ngau nhien 1 ca the a F2.
Xac suit dk dugc ca the long do thuan chung la bao nhieu?
Hu&ng dan gidi:
Bttac 1: Xac dinh ti le cua ca the long do thuan chung 0 F2.
- Nhin vao so d6 ta suy ra dugc tinh trang di truyen theo quy luat tuang tac bo
sung kieu 9 do : 7 trang.
-Saddlai: AaBb x AaBb = (Aa x Aa)(Bb x Bb)
Dai F2 CO ti le kilu hinh 9A-B- 9 long do
3A-bb -|
3aaB- > 1 long trang
laabb -
- Ca the long do Fi gom c6 cac kieu gen la
1AABB, 2AaBB, 2AABb, 4AaBb = ^ AABB, | AaBB, | AABb, ^ AaBb.
- Lay ngau nhien 2 ca th^ long do Fi cho giao ph6i ngau nhien thi gidng nhu
trucmg hgp cho tat ca cac ca the long do Fi giao phoi ngau nhien
- Cac loai giao tu do cac ca the long do Fi sinh ra la
61

63. Ki^ugen
-AABB
9
-AABb
9
-AaBB
9
4
-AaBb
9
IAB
9>^-AB,
9
Giaotu
lAb
9
laB
9
iAb,
^- iab
9
VaytatcacaccathelongdoaFinoitrensecho4loaigiaotuvoitilela
-AB,-Ab,-aB,-ab~4AB,2Ab,2aB,lab.
9999
-Lapbangdexacdinhcacloait6hopkieugenadoicon
4AB2Ab2aBlab
4AB16AABB8AABb8AaBB4AaBb
2Ab8AABb4Aabb4AaBb2Aabb
2aB8AaBB4AaBb4aaBB2aaBb
lab4AaBb2Aabb2aaBblaabb
TilekieuhinhadoiF2la64cathSlongdo;17cathelongtrSng
-CJF2,Cayhoadothuanchungc6kieugen16AABBchigmtile=
16
81
Buac2:Tinhxacsuat
Liyngaunhien1cathkaF2.XacsuStdkduaccathIlongdothuSnchungla
=1^.0,2.
81
Bai8:CJmotloaidongvat,khichocathklongdolaiphantichthidoiFbc6tile
kieuhinhla1cathelongdo:3cathklongtrSng.L^yngaunhien2cathklong
trangadoiFbchogiaophoingaunhiendugcdaiFi.hiyngaunhien1cathSa
Fi,xacsu§tdkthudugc1cathklongtringlabaonhieu?
Huangdangiai:
Buac1:Timtileki6uhinhadaiFi.
-DaiFbCOtile1:3^Tinhtrangditruygntheoquyluattuangtacb6sung.
-Quyuac:A-B-}quydinhlongdo
62

64. A-bb
aaB-
aabb
quy dinh long trang
1
- O doi Fb, cd the long trang gom c6 lAabb, laaBb, laabb vol ti le = - Aabb,
^aaBb, ^aabb.
- Lay ngau nhien 2 ca the long trang a doi Fb cho giao phoi ngau nhien thi
giong nhir truong hop cho cac ca the long tr§ng a dai Fb giao ph6i ngau nhien.
- Giao tu cua - Aabb, - aaBb, - aabb la
3 3 3
Kieu gen
-Aabb
3
-aaBb
3
-aabb
3
Giao tu
^ A b ,
6 ^-l a b l a b l a b
6 6 3 •
- Cac ca the long trang a Fb cho 3 loai giao tu la
- Ah, 1 aB, - ab = 1 Ab, laB, 4ab.
6 6 3
- Lay 2 ca the long trang a Fb cho giao ph6i ngau nhien, ta duac bang sau:
— lAb laB 4ab
lAb lAAbb lAaBb 4Aabb
laB lAaBb laaBB 4aaBb
4ab 4Aabb 4aaBb 16aabb
Doi Fi CO ti le kieu hinh 2 long do : 34 long trang.
34 17
-> Ca the long trang chiem ti le
36 18
HS CO the khong lap bang ma lam tat bang each ca the long do (A-B-) c6 ti
le = ^Ab X l a B + l a B X 1 Ab = — . Sau do suy ra ti le ciia ca thi long
6 6 6 6 18
1 17
trang = 1 - ti le cua ca thi long do = 1 = — .
^ 18 18
BiCac 2: Su dung toan to hop de tinh xac suat.
Lay ngau nhien 1 ca the a Fi, xac suat de thu dugrc 1 ca the long trang la
, 17
18
63

65. Bai12.C)motloaidpngvat,genAnamtrenNSTthuongquydinhlongdotroi
hoantoansovcriaquydinhlongtrang.KieugenAAlamchohoptuhicheta
giaidoanphoi.ChocaccathelongdogiaophoitudovoinhauduacFi.Cho
FigiaophoingaunhienvoinhauthuduacF2.Layngaunhien1cathea¥2,
xacsuatdethudupecathelongdolabaonhieu?
Huangdangiai:
Buac1:TimtilekieuhinhadaiF2.
-CatheAAvacatheAad^uc6longdonhungviAAbich^tagiaidoanphoi
nencathelongdochic6duynhat1loaikieugenlaAa.
-Soddlai:P:AaxAa
TilekieugenciiahoptuFi:1AA:2Aa:laa.
21
AAbichetagiaidoanphoinentilekieugenadoiFila2Aa:laa=—Aa:-aa
->GiaotircuaFigomc6—A,—a.
.^33
ChoFingauphoitadupeF2
1,2
-A—a
33
399
22,4
—a-Aa—aa
399
144
TilekieugencuahoptuF2la-AA:-Aa:-aa.
ViAAchetagiaidoanphoinenF2conlaiAavaaa=^•^
1
-Cathelongdochiemtile=—=0,5
Buac2:Sudungtoant6hopdetinhxacsuit.
Layngaunhien1catheaF2,xacsuatdethudupecathelongdola0,5=50%
C.BAITAPVANDUNG
1.Baitaptyluan:
Bai1.6motloaithucvat,tinhtrangchieucaothando2capgenAavaBbnSmtren
2capNSTkhacnhauquydinh.Khitrongkieugenc6caAvaBthiquydinhcay
thancao;cactruonghopconlaiquydinhthanthap.C)pheplaiAaBbxAaBb
dupeF].Layngaunhien3catheFi,xacsuatdetrong3cathenaychic61cathe
COkieuhinhthanthaplabaonhieu?
64

66. Bai 2. C5 ngo, tinh trang chieu cao do 2 cap gen Aa va Bb n i m tren 2 cap NST
khac nhau tuong tac theo kieu cong gop, trong do cur c6 m6i gen trpi lam cho
cay cao them 20 cm. Lay hat phan cua cay cao nhat (c6 chieu cao 210 cm) thu
phan cho cay thap nhat dugc Fi, cho Fi tir thu phan duac F2. hky ngau nhien 2
cay a Yj, xac suat de thu duac 1 cay c6 do cao 190 cm la bao nhieu?
Bai 3. Cho ca the hoa do lai vai ca th6 hoa trSng, Fi dong loat hoa trSng. Cho Fi
tu thu phan thi doi F2 c6 ti le: 13 cay hoa tring, 3 cay hoa do, 1 cay hoa vang.
Cho cay Fj lai phan tich, thu dugc doi Fb. Lay ngau nhien 2 ca the a doi Fb.
Xac suat de trong 2 ca the nay chi c6 1 cay hoa do la bao nhieu?
Bai 4. Cho cay c6 hoa mau vang lai voi cay hoa mau vang, doi Fi c6 ti le kiku
hinh 9 cay hoa vang; 7 cay hoa trang. Lay nglu nhien 3 cay hoa vang a Fi. Xac
suat de thu dugc ft nhat 1 cay thuan chung la bao nhieu?
Bai 5 . 0 mot loai thuc vat, tinh trang chieu cao cay do 2 cap gen Aa va Bb nam tren 2
cap NST khac nhau quy dinh. Khi trong kieu gen c6 ca A va B thi quy dinh than
cao; cac truang hgp con lai quy dinh than thap. 6 phep lai AaBb x AaBb dugc Fi.
Cho xk ca cac cay than cao a Fi giao phan ngau nhien thu dugc F2. hiy ngau
nhien 1 cay a F2, xac suat de thu dugc cay than thap la bao nhieu?
Bai 6. CJ mot loai dong vat, cho ca the long tring lai vai ca thS long do dugc Fj
dong loat long trang. Cho Fi giao phoi ngau nhien thi doi F2 c6 ti le: 13 ca the
long trang, 3 ca the long do. Lay ngau nhien 2 ca the long do F2 cho giao ph6i
vai nhau, thu dugc dai F3. Lay ngau nhien 1 ca the a doi F3, xac sudt dk thu
dugc ca the long do la bao nhieu?
Bai 7. CJ mot loai thuc vat, khi cho cay than cao tu thu phdn thu dugc Fi c6 ti le
kieu hinh gom 56,25% cay than cao, 43,75% cay than thip. Cho tat ca cac cay
than thap Fi giao phan ngau nhien dugc F2. Lay ngau nhien 1 ca the than cao a
F2, xac suat de thu dugc cay thuan chung la bao nhieu?
Bai 8. CJ mot loai thuc vat, tinh trang chieu cao than do 2 cap gen Aa va Bb nSm
tren 2 cap NST khac nhau quy dinh. Khi trong kieu gen c6 ca A va B thi quy
dinh cay than cao; cac truang hgp con lai quy dinh than thap. Cho cay di hgp
ve 2 cap gen lai vai nhau dugc Fi. Cho t i t ca cac cay than cao a Fi lai phan
tich dugc Fb. Lay ngau nhien 1 ca th^ Fb, xac suat dk thu dugc ca the khong
thuan chung la bao nhieu?
Bai 9. CJ mot loai dong vat, khi cho ca the long do lai phan tich thi doi Fb c6 t i le
kieu hinh la 25% ca the long do : 75% ca the long trang. Lay ngau nhien 2 ca
the long trang a dai Fb cho giao phoi ngau nhien dugc doi Fi. Lay ngau nhien 1
ca the a F], xac suat de thu dugc ca the long do la bao nhieu?
Bai 10. CJ mot loai dong vat, gen A nSm tren NST thuang quy dinh long do trgi
hoan toan so vai a quy dinh long trSng. Ki8u gen A A lam cho hgp t u bi chk a
giai doan phoi. Cho cac ca the long do giao ph6i tu do voi nhau dugc Fi. Cho
Fi giao phoi ngau nhien vai nhau thu dugc F2 Lay ngau nhien 1 ca the a F2,
xac suat de thu dugc ca the long trSng la bao nhieu?
65

67. Bai11.Chocayhoadotirthuphan,daiFic6tile9cayhoado:3cayhoahong:
3cayhoavang:1cayhoatrang.Neulaytatcacaccayhoah6ngaFichogiao
phanngaunhienthudugcF2.Layngaunhien1cayaF2,xacsuatdethudugc
cayhoatringlabaonhieu?
Bai12.ChocayhoadoPtirthuphan,daiconFic6tile9cayhoado:3cayhoa
h6ng:3cayhoavang:1cayhoatring.ChocaccayhoadoFilaiphantich
thudugcFb.Layngaunhien1cayadaiFb,xacsuatdethudugccayhoavang
labaonhieu?
Bai13.CJmotloaithucvat,khitrongkiSugenc6cagenAvagenBthihoac6mau
do.Neutrongkieugenchic6Ahoacchic6Bthihoac6mauvang.Neukhongc6
genAvaBthihoac6mautrang.CJpheplaiAaBbxAabbthudugcFi.Layngau
nhien3cayaFi,xacsuatdethudugc1cayhoatranglabaonhieu?
Bai14.C)motloaithucvat,khitrongkieugenc6cagenAvagenBthihoac6
maudo.Neutrongkieugenchic6Ahoacchic6Bthihoac6mauvang.Neu
khongCOgenAvaBthihoac6mautrang.HaicapgenAavaBbnSmtren2
capNSTkhacnhau.Chocaydihgpve2capgennoitrentuthuphandugcFi.
Layngaunhien2cayhoadoaFi,xacsuatdethudugc1cayc6kieugendi
hgpAaBblabaonhieu?
2.Baitaptracnghiem:
Cau1.Ongotinhtrangvemauhatdo2genkhongalenquydinh.Chongohat
tranggiaophanvaingohattrangthudugcFIc6962hattrang:241hatvang:
80hatdo.Layngaunhien1cayatheheF],xacsuatdethudugccayc6kieu
gendonghgptrgiveca2capgenla
A.i.B.^.C.i.D.i.
16794
Cau2.ChomotcaytuthuphanthudugcFic6tilekieuhinh43,75%caycao;
56,25%caythap.Layngaunhien1caythancaoa¥,xacsuatdedugccay
thuanchungla
A.A.B.l.C.i.D.I.
16794
Cau3.ChocayhoadotuthuphanthudugcFic62loaikieuhinh,trongdocay
hoadochiemtile56,25%.Layngaunhien2cayhoadoaFi,xacsuatdethu
duac2caykhongthuanchungla
A.A.B.^.c.^.a'
16498181
Cau4.dmotloaithucvat,khitrongkieugenc6cagenAvagenBthihoac6
maudo.Neutrongkieugenchic6Ahoacchic6Bthihoac6mauvang.Neu
khongCOgenAvaBthihoac6mautrang.HaicapgenAavaBbnamtren2
capNSTkhacnhau.
66