This document summarizes key concepts related to plant water relations and mineral nutrition. It discusses water potential and its components, including osmotic potential, pressure potential, and matric potential. It also describes absorption and translocation of water, as well as stomatal regulation. Additionally, it outlines the essential mineral elements for plants, including macronutrients, micronutrients, and their roles. Mechanisms of mineral transport such as passive and active transport are also summarized.
1. • Water relations (water potential, osmotic
potential, pressure potential, matric
potential). Absorption and translocation of
water. Stomatal regulation.
2. Water potential
• Water potential is the potential energy of
water per unit volume in a solution relative to
pure water in reference conditions.
• Water potential quantifies the tendency of
water to move from one area to another due
to osmosis, gravity, mechanical pressure, or
matrix effects such as capillary action
3. • It is measured in kilopascals (kPa) and is
represented by the Greek letter Psi (Ψ).
• Water potential is never positive but has a
maximum value of zero, which is that of
pure water at atmospheric pressure.
4. Osmotic potential
• The potential of water molecules to move
from a hypotonic solution (more water,
less solutes) to a hypertonic
solution (less water, more solutes) across a
semi permeable membrane.
• It is also defined as the measure of the
tendency of a solution to take in pure solvent
by osmosis.
5. • A measure of the potential of water to move
between regions of
differing concentrations across a water-
permeable membrane
by using this formula:
ψπ = − C R T,
where ψπ is the osmotic potential, C is
the concentration of solutes, R is
the universal gas constant (i.e. 8.314472 J K−1
mol−1), and T is the absolute temperature.
6. Pressure potential
• The pressure of water exerted upon the cell
wall in a turgid cell called pressure potential or
turgor pressure.
• It is represented by ψp.
7. Matric potential
• Matric potential Symbol ψ m.
• A component of water potential due to the
adhesion of water molecules to non dissolved
structures of the system, i.e. the matrix, such as
plasma membranes or soil particles.
• Matric potential is a consequence of the binding
of water to materials such as soil particles,
cellulose, and proteins, and the enclosure
of water in capillaries or other fine pores.
17. Soil as a source of minerals
• Sixteen chemical elements are known to be
important to a plant's growth and survival.
The sixteen chemical elements are divided
into two main groups:
• Non-mineral and Mineral.
18. Non-mineral
• The Non-Mineral Nutrients are Hydrogen (H),
Oxygen (O), & carbon (C).
• These nutrients are found in the air and
water.
19. Mineral elements
• The 13 mineral nutrients, which come from
the soil, are dissolved in water and absorbed
through a plant's roots.
• There are not always enough of these
nutrients in the soil for a plant to grow
healthy.
• This is why many farmers and gardeners use
fertilizers to add the nutrients to the soil.
• The mineral nutrients are divided into two
groups: macronutrients and micronutrients.
20. Macronutrients
• Macronutrients can be broken into two more
groups: i) primary and ii) secondary
nutrients.
• i) The primary
nutrients are nitrogen (N), phosphorus (P),
and potassium (K).
• These major nutrients usually are lacking from
the soil first because plants use large amounts
for their growth and survival.
21. ii) Secondary nutrients:
The Secondary
nutrients are calcium (Ca), magnesium (Mg),
and sulfur (S).
• There are usually enough of these nutrients in
the soil so fertilization is not always needed.
• Also, large amounts of Calcium and Magnesium
are added when lime is applied to acidic soils.
• Sulfur is usually found in sufficient amounts from
the slow decomposition of soil organic matter, an
important reason for not throwing out grass
clippings and leaves.
22. Micronutrients
• Micronutrients are those elements essential for
plant growth which are needed in only very small
(micro) quantities .
• These elements are sometimes called minor
elements or trace elements.
• The micronutrients
are Boron (B), Copper (Cu), Iron (Fe), Chloride (Cl
), Manganese (Mn), Molybdenum (Mo) and Zinc
(Zn). Recycling organic matter such as grass
clippings and tree leaves is an excellent way of
providing micronutrients (as well as
macronutrients) to growing plants.
23. Nitrogen
• Specific role:
1. It is an important constituents of Proteins,
Nucleic acid, alkaloids, some vitamins,
coenzymes.
2. Porphyrins are important part of chlorophylls
and cytochromes.
24. • Deficiency symptoms:
1. Nitrogen deficiency causes yellowing i.e.
chlorosis of leaves.
2. Plant growth is stunted (because protein
contents, cell division and cell enlargement
are decreased).
3. In many plants e.g. tomato, the stem, petiole
and the leaf veins become colored due to
formation of anthocyanin pigments.
26. • Deficiency symptoms:
1. Phosphorus deficiency may cause premature
leaf fall.
2. Dead necrotic areas may be developed on
leaves or fruits.
3. Leaves may turn dark to blue green.
27. Sulphur
• Specific role:
• It is important constituent of some amino
acids (cysteine and methionine) which with
other amino acid form the protein.
• Disulphide linkages help to stabilize the
protein structure.
• It is also constituent of vitamin biotin,
thiamine and coenzyme-A.
28. • Sulfhydryl groups are necessary for the activity
of many enzymes.
• Deficiency symptoms:
• Sulphur deficiency causes yellowing of the
leaves.
• The tips and margins of the leaf roll inwards.
• Stem become hard due to the development of
sclerenchyma.
29. Calcium
• Specific Role:
1. It is important constituent of the middle
lamella in cell wall.
2. It is essential in the formation of cell
membranes.
3. It acts as a second messenger in metabolic
regulation.
4. It helps to stabilize the structure of
chromosomes.
5. It may be an enzyme activator.
30. • Deficiency symptoms:
1. Calcium deficiency causes disintegration of
growing meristematic regions of the root,
stem and leaves.
2. Chlorosis occurs along the margins of the
younger leaves.
3. Malformation of younger leaves also takes
place.
31. Magnesium
• Specific role:
1. It is very important constituent of
chlorophylls.
2. It acts as activator for many enzymes in
phosphate transfer reactions particularly in
carbohydrate metabolism and nucleic acid
synthesis.
3. It plays important role in building ribosomal
particles during protein synthesis.
32. • Deficiency symptoms:
1. Magnesium deficiency causes inter veinal
chlorosis of the leaf. Older leaves are affected
first.
2. Dead necrotic patches appear on the leaves.
33. Potassium
• Specific role:
1. Although potassium is not a constituent of
important organic compound in the cells, it is
essential for the process of respiration and
photosynthesis.
2. It is major contributor to osmotic potential of
plant cells.
3. It probably acts as an activator of many enzymes
involved in carbohydrate metabolism and
protein synthesis.
34. 4. It serves to balance the charge of both
diffusible and non diffusible ions.
5. Plays important role in stomatal opening.
Deficiency symptoms:
1. Mottled chlorosis of the leaves occurs.
2. Necrotic areas develop at the tip and margins
of the leaf.
3. Plant growth remains stunted with marked
shortening of internodes.
36. 1. Passive transport
a. Facilitated diffusion
b. Donnan effect and equilibrium
c. Ion exchange
d. Mass flow of ions
37. 2. Active transport
• Pumps (primary active transport)
1. Electrogenic pump (proton-atpases (H+-
ATPases), proton-pyrophosphatases (H+-
ppases), calcium pumping atpases (Ca2+-
ATPases), atp-binding casette transporters)
2. Electroneutral pump
• Secondary active transport (symport and
antiport)
38.
39.
40.
41.
42. • Photosynthesis: Introduction, Oxygenic and
non-oxygenic photosynthesis Mechanism:
light reactions (electron transport and
photophosphorylation) and dark reactions
(Calvin cycle). Differences between C3 and C4
plants. Factors affecting this process, Products
of photosynthesis.
43. Photosynthesis
• The oxidation-reduction reaction by
which green plants prepare
carbohydrates from carbon dioxide and
water in the presence of sunlight and
chlorophyll.
• Over all reaction of photosynthesis is:
• CO2 + H2O → C6H12O6 + O2
44. Role of sunlight in Photosynthesis
• Light is electromagnetic waves which
consists of different wavelengths.
• Light shows dual nature i.e. both wave
and particle [photon].
• Energy of photon is inversely
proportional to the wavelength. i.e.
large wavelength has low energy.
45. • Light consists of different wavelengths.
• Only visible part of the light [390 nm-
760 nm] is used in photosynthesis.
• Chlorophyll absorbs blue [390-430 nm]
and red [670-700 nm] wavelengths.
• Carotenoids absorb wavelengths
ranging between 500 nm to 600 nm.
46.
47. Photosynthetic pigments
• Three common pigment types are used in
Photosynthesis.
1.Chlorophyll
2.Carotenoids and
3.Phycobillins.
• Chlorophyll is of various types as Chlorophyll a,
b, c, d, e, f and bacteriochlorophyll [a, b, c, d, e,
f and g].
48. • Chlorophyll a and b are found in most of the
plants. Chlorophyll c, d, e and f are found in
algae.
• Chlorophyll molecule is composed of two
parts one head and other tail.
• The head contains central Magnesium atom
surrounded by four Nitrogen containing rings
called pyrrole rings.
• The four pyrrole rings are called porphyrin.
• The head is hydrophilic and is present at the
surface of thylakoid membrane.
49. • Long hydrocarbon chain called phytol side
chain is attached to one of the four pyrrole
rings.
• This is hydrophobic and is present
embedded in the thylakoid membrane.
• Chlorophyll a and b differ from each other in
one functional group.
• Chlorophyll ‘a’ has methyl group while
chlorophyll ‘b’ has aldehyde group.
• Empirical formula of chlorophyll a is:
• C55H72O5N4Mg
• Empirical formula of chlorophyll b is:
• C55H70O6N4Mg
53. Carotenoids
• They are of two types,
• Carotenes and Xanthophyll.
• They are orange, brown, yellow or
red colored pigments.
• They are called accessory pigments.
• They protect chlorophyll from
intense light and from oxidation.
58. Absorption spectrum
• Different pigments absorb particular
wavelengths from visible part of light
spectrum, this is known as its
absorption spectrum. E.g.
• Chlorophyll absorbs wavelengths
ranging from 400-460 nm and 630-700
nm.
• Carotenoids absorb wavelengths
ranging from 500-600 nm.
59.
60. Action spectrum
• Action spectrum is the measure of
effectiveness of different wavelengths of light
on the rate of a physiological process (e.g.
photosynthesis).
61.
62. • Role of CO2 as one of the raw materials of
Photosynthesis
• Carbon dioxide is fixed in organic compounds
in photosynthesis.
• Carbon is the back bone of all organic
compounds.
• Carbon dioxide is the source compound of
carbon for all organic compounds.
63. Role of water in Photosynthesis
• Water is one of the raw material for
Photosynthesis.
• Water is the source compound for Hydrogen.
• Hydrogen is the main component of organic
compounds.
• It was thought previously that oxygen evolved
in Photosynthesis come from Carbon dioxide.
• But latter it was suggest by Neil that Oxygen
evolved in Photosynthesis come from water.
64. • Hill’s confirmed Neil’s study.
• Hill reported that when light is provided to
isolated chlorophyll pigment in complete
absence of carbon dioxide and in the presence
of water and some hydrogen acceptor, Oxygen
is still evolved.
• Other scientists used isotope [O16 and O18] of
oxygen to confirm Neil’s study.
• Group I CO2+ H2O18 → C6H12O6+ O2
18
• Group I CO2
18+ H2O16 → C6H12O6
18+ O2
16
65. Mechanism of Photosynthesis
• Photosynthesis occurs in two steps;
i] Light Reaction/ Hill’s Reaction/ Z-scheme
ii] Dark Reaction/ Calvin cycle
82. Internal factors
1. Chlorophyll contents
2. Protoplasmic factors
3. Accumulation of the end products of
photosynthesis
4. Anatomy of leaf
5. Microstructure of chloroplasts
95. Stable isotopes
• Stable isotopes are non-radioactive forms of
atoms.
• Although they do not emit radiation, their
unique properties enable them to be used in a
broad variety of applications, including water
and soil management, environmental studies,
nutrition assessment studies and forensics.
100. Photoperiodism
• The relative length of day and night to which a plant
is exposed is called photoperiod.
• The response of plant (in the form of flowering) to
photoperiod is called Photo periodism.
Types of plants based on Photoperiod
1) Short day plants: e.g. Tobacco, Dahlia, soyabean,
Crysenthemum etc
2) Long day plants e.g. Hibiscus, beet, spinach, potato
etc.
3) Day neutral plants e.g. maize, tomato, sunflower,
cucumber etc.
Phytochrome Pfr (730 nm) and Pr (660 nm)
Flowering Hormone (Florigen)
M.H. Chailakhain (1936)
109. Role of Auxins
1. Cell elongation
2. Tropism
3. Apical Dominance
4. Formation of Lateral Roots
5. Leaf Abscission
6. Fruit development
7. Application of auxins
111. Role of Gibberellins
1. Stem elongation of dwarf plants.
2. Promotion of growth of dormant buds and
germination of dormant seeds.
3. Bolting and flowering in long day plants.
4. Modification of juvenility.
5. Induction of maleness in flowers.
6. Fruit setting and growth.
7. Mobilization of food and minerals in seed
storage cells.
113. • Regulation of cell cycle
• Regulation of Morphogenesis
• Delay of senescence and mobilization of
nutrients
• Promotion of lateral bud development in
dicots
• Promotion of chloroplast maturation
• Stimulation of cell enlargement
115. • Abscisic acid
• First isolated from cotton and Bitula
pubescence
• Cause of bud and seed dormancy
• It promotes abscision.
• It inhibit flower formation in plants.
• It is also called stress hormone.
• It has role in closing stomata.
116. Ethylene
• It is growth inhibitory hormone.
• It inhibits root growth and development of
axillary buds.
• It stimulates ripening of fruits.
• It also induces senescence.
118. • BRs have been shown to be involved in numerous plant
processes:
• Promotion of cell expansion and cell elongation; works
with auxin to do so.
• It has an unclear role in cell division and cell wall
regeneration.
• Promotion of vascular differentiation; BR signal
transduction has been studied during vascular
differentiation.[8]
• Is necessary for pollen elongation for pollen
tube formation.[9]
• Acceleration of senescence in dying tissue cultured cells;
delayed senescence in BR mutants supports that this action
may be biologically relevant.[5]
• Can provide some protection to plants during chilling and
drought stress.[5]
119. Carbohydrates
• These are poly hydroxy aldehydes or
ketones.
• Carbohydrates contain either
aldehyde or ketones.
• They also contain many hydroxyl (-
OH) groups. E.g. glucose, sucrose,
starch, cellulose etc.
120. Types of carbohydrates: There are 3
types of carbohydrates.
• 1. Monosaccharides
• 2. Oligo saccharides
• 3. Poly saccharides
121. Monosaccharides
• They are simple sugars.
• They are non hydrolysable.
• They are soluble in water.
• They are sweet in taste.
• They contain either aldehyde or ketone.
• They are white crystalline powder.
• They contain carbon atoms ranging
from 3 to 7.
122. • Monosaccharides which contain 3
carbon atoms are called tri-oses e.g.
Glyceraldehyde.
• Monosaccharides which contain 4
carbon atoms are called tetr-oses.
E.g. eythrose
• Monosaccharides which contain 5
carbon atoms are called pent-oses.
E.g. Ribose
• Ribose contains aldehyde group,
ribulose is its ketonic form.
123. • Monosaccharides with 6 carbon
atoms are called hexoses e.g.
glucose, fructose, galactose.
• Glucose contains aldehyde group while
fructose contains ketonic group.
• Glucose, fructose, galactose all three
have the same molecular formula
(C6H1206) but different structural
formula, hence are isomers of each
others.
• They are interconvertible.
124. • Ribose and glucose form ring
shaped structures when put in
water.
131. 2. Oligosaccharides
• They are hydrolysable yielding 2
to 10 monosaccharides units.
• Monosccharides are bonded to each
other by glycosidic bond.
• Oligosaccharide which yields 2
monosaccharides on hydrolysis is
called disaccharide.
132. • Oligosaccharide which yields 3
monosaccharides on hydrolysis is
called trisaccharide and so on.
• Common disaccharides are sucrose,
lactose and maltose.
• Sucrose is present in sugar cane and
hydrolyzed into glucose and
fructose.
• Lactose is present in milk and it
yields glucose and galactose upon
hydrolysis.
133. Maltose is present in fruits and it
yields 2 glucose molecules upon
hydrolysis.
134.
135.
136. Trisaccharid
e
Unit 1 Bond Unit 2 Bond Unit 3
Nigerotriose glucose α(1→3) glucose α(1→3) glucose
Maltotriose glucose α(1→4) glucose α(1→4) glucose
Melezitose glucose α(1→2) fructose α(1→3) glucose
Maltotriulos
e
glucose α(1→4) glucose α(1→4) fructose
Raffinose galactose α(1→6) glucose β(1→2) fructose
Kestose glucose α(1↔2) fructose β(1←2) fructose
137. Polysaccharides
• These are polymers of monosaccharides.
• They yields more than 10 monosaccharide
upon hydrolysis.
• They are tasteless and insoluble in water.
• Plants synthesis glucose which is converted
into starch and again into glucose when plants
need them.
138. • Glycogen is a polysaccharide found
in animals.
• Cellulose is another polysaccharide.
• Plant body is composed of cellulose.
• Human digestive system cannot digest
cellulose.
• Cotton fiber is another type of cellulose.
• Chitin is a polysaccharide.
• It is polymer of glucose which also
contain amino group (-NH2).
139. • They are found in the exoskeleton
of arthropods such as crabs and
insects.
• They are also non digestable.
Function of carbohydrates
1. Source of energy.
2. Storage molecules
3. Structural building materials
140. Lipids
• Organic compounds.
• These are soluble in organic solvents
[alcohol, petrol, ether, ethane, acetone
etc.]
• Insoluble in inorganic solvent [water].
• They are non polar.
• They contain less oxygen than
carbohydrates.
142. Acylglycerol
• They are composed of glycerol and
fatty acids.
• Glycerol are three carbon atoms, to
each atom hydroxyl group is
attached.
• Fatty acids are long carbon chain
compounds containing carboxylic
group.
143.
144. Phospholipids
• It is composed of one glycerol
molecule, two fatty acid molecules
and one phosphoric acid usually
attached with nitrogen group.
• Phospholipid has two parts, a
phosphate head, it is polar and two
fatty acid tails which are non polar
and are therefore hydrophobic.
146. Waxes
• They are formed of long chain fatty acid molecule
bonded to long chain alcohol.
• Glycerol is absent.
• They are solid at room temperature.
• They have high melting point.
• They are hydrophobic.
• Very stable compound, show resistance to
degradation.
• They are present in insect’s exoskeleton, leaves and
fruits of plants and body covering of sheep etc.
148. Steroids
• These are lipids which do not
contain fatty acids.
• They contain phenanthrene ring
which is composed of four fused
rings containing seventeen
carbons.
150. • Cholestrol is an example of steroid
lipids
• It is present in animal cell membranes.
• It is precursor of all steroid hormones
e.g. aldosterone, sex hormones and
vitamin D.
• Aldosterone regulate blood sodium
level.
• Sex hormones help to maintain male
female characteristics.
155. Terpenoids
• These are class of lipids which do not contain fatty acids.
• They are formed of iso-prene units.
• Iso prene is 2-methyl 1,3-buta-diene molecule.
• Examples of terpenoids are terpenes, rubber and carotenoids.
• Carotenoids are pigments of red, brown or orange color.
• The most common carotenoids are carotene [red/orange
color] and xanthophyll [yellow color].
• Beta carotene is the most common carotene found in carrots.
• Human body makes vitamin A from beta carotene molecule.
158. Functions of Lipids
• Energy molecule.
• Building material
• Some lipids are hormones.
• Plant hormones are auxins,
gibberellins and cytokinin.
• Animal hormones are aldosterone,
testosterone.
159. Protein
• Organic compounds and Polymer of
amino acids.
• It contains carbon, hydrogen, oxygen
and nitrogen. Some protein contains
Sulphur.
• There are twenty types of amino acids,
which combine in different ways
forming thousands of proteins
molecules.
162. • Non-polar, aliphatic R group. E.g.
Glycine, Alanine, valine, Leucine,
Methionine, Isoleucine
• Polar, uncharged R group.e.g.
serine, threonine, cysteine,
proline, asparagin, glutamine etc.
• Aromatic R group e.g.
phenylalanine,
tyrosine,tryptophan etc.
163. • Positively charged R group e.g.
lysine, arginine, Histidine etc.
• Negatively charged R group e.g.
aspartate, glutamine.
• The bond which bindes two amino
acids together is called peptide
bond.
• This bond forms by condensation
reaction.
164. A protein molecule containing two
peptides bonds and 3 amino acids is
called dipeptide chain.
• A protein molecule containing 3
peptide bonds and 4 amino acids
is called tripeptide chain.
• A protein molecule containing
many peptide bonds is called
polypeptide chain.
165. • Most protein molecules are
usually formed of 2 or many
polypeptide chains. E.g
Haemoglobin and insulin.
• Haemoglobin consists of four
polypeptide chains.
• Insulin is composed of 2
polypeptide chains.
166. Shapes of protein
• Fibrous proteins:
• It consists of one or more polypeptide
chains which are linearly arranged in
the form of fibers.
• They are water insoluble. e.g. keratin
found in nails, hairs, fur, outer skin,
myosin, collagen which is found in skin,
ligaments, tendons, bones and in the
cornea of the eye.
167. Globular proteins
• They are globular or spherical in
shape due to foldings.
• They are water soluble.
• Examples are, haemoglobin,
albumen of egg, enzymes,
antibodies and proteins of cell
membranes.
168. Level of organization of protein
Primary structure
• A polypeptide chain having a linear sequence
of amino acids.
Secondary structure
• when the polypeptide chain become spirally
coiled.
Tertiary structure
• When the secondary protein further coils
adapting three dimensional structure.
169. Quaternary structure
• When two or more than two
polypeptide chains are arranged
in to a large sized molecule. E.g.
haemoglobin
170. Function of proteins
• Building material of animals.
• Component of cell membranes.
• Enzymes are protein in nature.
• Some hormones are protein in nature e.g.
Insulin.
• Myosin and actin are movements proteins.
• Haemoglobin is oxygen/carbon dioxide
carrying protein.
• Bean, pulses, pea contain proteins.
171. Enzymes
• Enzymes are biological catalyst.
• It speeds up biological chemical
reactions.
• Mostly they are proteinaceous in
nature.
• Ribozymes are enzymes which
are not protein.
172. Physical properties
i] Enzymes are molecules of high molecular weight.
E.g. peroxidase is one of the smallest enzymes and
has molecular weight of 40000. catalase is one of
the largest of enzymes and has molecular weight of
250000.
ii] Enzymes are colloidal substances
iii] Enzymes are amphoteric substances
iv] Enzymes are active in small amount
v] Enzymes are unchanged at the end of reaction
vi] Enzymes speed up chemical reactions
173. • Enzymes lower the activation energy of
reacting molecules.
• Enzymes are highly specific.
• Enzymes can be denatured.
174. Chemical properties
Co-factors: There are certain enzymes which require
co-factors for action.
• If Co-factors are organic molecules, then it is
called co-enzymes. E.g. vitamins, NAD, FAD.
• If co-factor is inorganic substance, then it is
called prosthetic group. E.g. Mg, Cu, Zn, Co
etc.
• Holoezymes
• Enzymes plus cofactor is called holoenzymes.
• Protein part of the enzyme is called apo
enzyme.
175. Mode of Action there are two theories
regarding mode of action of enzymes.
1. Lock and key Hypothesis
2. Induce fit hypothesis
Reaction Mechanism
• Active sites of enzymes bind with the
substrates forming enzyme substrate
complex.
• Enzyme substrate complex is converted
into free enzyme and products.
181. Enzyme nomenclature
• Names of most of the enzymes end
in the suffix –ase.
Classes of enzymes
1. Oxido reductases
2. Transferases
182. • These enzymes transfer group of atoms
from one compound to another [e.g.
amino group, carboxyl group, methyl and
carbonyl group.]
• Hydrolases: These enzymes catalyze
hydrolysis reactions. E.g. esterases,
phosphatases and peptidases.
183. Lyases
• These enzymes catalyze reactions in
which group of atoms [water, carbon
dioxide and ammonia] are removed
to form double bond or added to
remove double bond.
184. Isomerases
• These enzymes convert one isomer
to another e.g. epimerases and
mutases.
Ligases: Ligases bind two substrate
molecules together.
