2. • Cells that require the most energy contain the most
energy generating mitochondria
• The cells of the brain, liver, kidney tubule, skeletal
muscle and heart muscle have thousands of
mitochondria in each cell while cells of the skin,
which do not require much energy, have only a few
hundred mitochondria.
• The egg cell has around 1000 mitochondria
• The sperm cell has large numbers of mitochondria
in its middle piece

3. • In flowering plants, the chloroplast are
specially dense in palisade mesophyll cells. Each
cell has up to 100 chloroplast
• Pancreatic cells which synthesise and secrete
enzyme and hormones contain a high density of
rough endoplasmic reticulum

5. • Organism can be categorised as
a) Unicellular
b) Multicellular
• Unicellular organism are organism with just one
cell
• For example Amoeba and Paramecium
• Multicellular organism are made up of more than
one cell

7. • Unicellular organism are small and simple
organism
• The survival of a unicellular organism
depends largely on its cellular component
which include the organelles, as it does not
have any organs or system

9. • Is irregular in shape. It has an oval nucleus
surrounded by cytoplasm and the whole organism
is bounded by a plasma membrane
• The cytoplasm is divided into 2 layers
a) outer layer (ectoplasm)
b) inner layer (endoplasm)

10. LOCOMOTION OF AMOEBA SP
• It moves by extending temporary pseudopodia
or ‘false feet’ and anchoring the tips on the
ground
• Movement by means of pseudopodia is known
as amoeboid movement
• This is followed by the flow of cytoplasm into
the projected pseudopodia
• The shape of the Amoeba sp change as it moves

11. FEEDING OF AMOEBA SP
• The Amoeba sp feeds on bacteria and algae much
smaller than itself
• When the Amoeba sp comes in contact with it food,
it puts its pseudopodia all around the food to enclose
it in a drop of water, forming a food vacuole
• Amoeba sp engulf food by phagocytosis
• The food vacuole fuses with a lysosome and the
food is digested by a hydrolytic enzyme called
lysozyme

13. • The resulting nutrient are absorbed into the
cytoplasm
• The exchange of gases, nutrients and waste
substance occur through the plasma diffusion
• As Amoeba sp live in fresh water, water diffuse into
the cell by osmosis and fill the contractile vacuole
• Contractile vacuole are involved in osmoregulation
• When the vacuole is filled to a maximum size, it
contract to expel it contents from time to time

14. REPRODUCTION OF AMOEBA SP
• The Amoeba sp reproduces mainly by binary
fission
• Binary fission is a method of asexual reproduction
which does not involved the fusion gametes
• When food is abundant, the Amoeba sp reproduced
by binary fission
• When the Amoeba sp reaches a maximum size, the
nucleus divides into two and the cytoplasm
constricts, forming two new Amoeba sp
• The Amoeba sp does not reproduce sexually

16. • Being multicellular not only enable organism to
be larger, it also enables their cells to become
specialised
•Within a multicellular organism, there are different
type of cells. Each type of cell specialises in
performing a particular function
• Example
a) The red blood cell in animal transport oxygen
b) The xylem vessel in plant transport water and
mineral salts

17. • The division of labour permits greater
efficiency and enable multicellular organism to
exploit environments that are denied to
unicellular organism
• Example : only multicellular organism can
adapt to life in terestrial environment
• Multicellular organisms have a great potential
for specialisation, leading to the development of
tissues and organs.