Enzymes are globular proteins that catalyse the thousands of metabolic reactions taking place within cells and organism.

(i) Phosphorylation - Hexokinase, Phospho fructokinase and glyceraldehyde - 3 phosphate dehydrogenase
(ii) De-Phosphorylation - Phospho glycerate Kinase and Pyruvate Kinase

(i) Mineral deficiency of plant A is due to Molybdenum
(ii) Mineral deficiency of plant B is due to Zinc

This is due to the immobile nature of minerals, Eg: Calcium.

(i) Yes. Nitrogen cannot be directly absorbed by plants but they are essential for normal growth and functioning of a plant. Hence they are fixed by bacteria and some fungi.
(ii) It can be utilised only in the form of nitrates (NO₃^-) and nitrites (NO₂^-).

(1) Water potential \(\left(\Psi_{\mathrm{W}}\right)\) can be determined by,
(i) Solute concentration or Solute Potential \(\left(\Psi_{\mathrm{S}}\right)\)
(ii) Pressure potential \(\left(\Psi_{\mathrm{P}}\right)\)
(2) By correlating two factors, water potential is written as,
(3) Water potential = Solute potential + Pressure potential
(4) \(\Psi_{W}=\Psi_{S}+\Psi_{P}\)

Roots, buds, matured stem, flowers and fruits.

1. Genetic stability - Daughter cells are genetically identical to parent cells.
2. Growth - As multicellular organisms grow, the number of cells making up their tissue increases. The new cells must be identical to the existing ones.
3. Repair of tissues - Damaged cells must be replaced by identical new cells by mitosis.

Properties of Water
(i) Adhesion and cohesion property
(ii) High latent heat of vapori sation
(iii) High melting and boiling point
(iv) Universal solvent
(v) Specific heat capacity

Physiological effect:
1) Cytokinin promotes cell division in the presence of auxin (IAA).
2) Induces cell enlargement associated with IAA and gibberellins
3) Cytokinin can break the dormancy of certain light-sensitive seeds like tobacco and induces seed germination.
4) Cytokinin promotes the growth of lateral bud in the presence of apical bud.
5) Application of cytokinin delays the process of aging by nutrient mobilization.
6) It is known as Richmond Lang effect.
7) Cytokinin
(i) increases rate protein synthesis
(ii) induces the formation of inter-fascicular cambium
(iii) overcomes apical dominance
(iv) induces formation of new leaves, chloroplast and lateral shoots.
8) Plants accumulate solutes very actively with the help of cytokinins.

Because carbohydrates are partially oxidised to organic acid, particularly malic acid without corresponding release of CO₂ but O₂ is consumed. Hence the RQ value will be zero.
\(\underset { Glucose }{ 2{ C }_{ 6 }{ H }_{ 12 }{ O }_{ 6 }+3{ O }_{ 2 }\rightarrow } \underset { malic\quad acid }{ 3{ C }_{ 4 }{ H }_{ 6 }{ O }_{ 5 }+3{ H }_{ 2 }O+Energy } \)
RQ of glucose in succulents = \(\frac { Zero \ molecule \ of \ { CO }_{ 2 } }{ 3 \ molecules \ of \ { CO }_{ 2 } } \) = 0 (Zero)

(i) Nitrogen fixation process requires Nitrogenase enzyme complex, Minerals (Mo, Fe and S), anaerobic condition, ATP, electron and glucose 6 phosphate as H⁺ donor.
(ii) Nitrogenase enzyme is active only in anaerobic condition.
(iii) To create this anaerobic condition a pigment known as leghaemoglobin is synthesized in the nodules which acts as oxygen scavenger and removes the oxygen.

1. The discovery of enzyme phosphorylase in guard cells by Hanes (1940) greatly supports the starch-sugar interconversion theory.
2. The enzyme phosphorylase hydrolyses starch into sugar and high pH followed by endosmosis and the opening of stomata during light. The vice versa takes place during the night.

Ribonucleic acid (RNA): Ribonucleic acid (RNA) is a polymeric molecule essential in various biological roles in coding, decoding, regulation and expression of genes. RNA is single stranded and is unstable when compared to DNA.

Types of RNA:
1. mRNA (messenger RNA) - Single stranded, carries a copy of instructions for assembling amino acids into proteins. It is very unstable and comprises 5% of total RNA polymer. Prokaryotic mRNA (Polycistronic) carry coding sequences for many polypeptides. Eukaryotic mRNA (Monocistronic) contains information for only one polypeptide.
2. tRNA (transfer RNA) - Translates the code from mRNA and transfers amino acids to the ribosome to build proteins. It is highly folded into an elaborate 3D structure and comprises about 15% of total RNA. It is also called as soluble RNA.
3. rRNA (ribosomal RNA) - Single stranded, metabolically stable, make up the two subunits of ribosomes. It constitutes 80% of the total RNA. It is a polymer with varied length from 120 - 3000 nucleotides and gives ribosomes their shape. Genes for rRNA are highly conserved and employed for phylogenetic studies.

(i) Some cells exit G₁ and enters a quiescent stage called G₀, where the cell remains metabolically active without proliferation.
(ii) Cells can exist for long periods in G₀ phase. In G₀ cells cease growth with reduced rate of RNA and protein synthesis.
(iii) The G₀ phase is not permanent. Mature neuron and skeletal muscle cell remain permanently in G₀.
(iv) Many cells in animals remains in G₀ unless called on to proliferate by appropriate growth factors or other extracellular signals. G₀ cells are not dormant.

Difference between Mitosis and Meiosis:

S.No	Mitosis	Meiosis
1.	One division	Two divisions
2.	Number of Chromosomes remains the same	Number of Chromosomes is halved
3.	Homologous Chromosomes line up separately on the metaphase plate	Homologous Chromosomes line up in pairs at the metaphase plate
4.	Homologous Chromosome do not pair up	Homologous Chromosome pair up to form bivalent
5.	Chiasmata do not form and crossing over never occurs	Chiasmata form and crossing over occurs
6.	Daughter cells are genetically identical	Daughter cells are genetically different from the parent  cells
7.	Two daughter cells are formed	Four daughter cells are formed

(i) Watson and Crick shared the Nobel Prize in 1962 for their discovery, along with Maurice Wilkins, who had produced the crystallographic data supporting the model. Rosalind Franklin (1920-1958) had earlier produced the first clear crystallographic evidence for a helical structure.
(ii) James Watson and Francis Crick of Cavendish laboratory in Cambridge built a scale model of double helical structure of DNA which is the most prevalent form of DNA, the B-DNA. This is the secondary structure of DNA.
(iii) As proposed by James Watson and Francis Crick, DNA consists of right handed double helix with 2 helical polynucleotide chains that are coiled around a common axis to form right handed B form of DNA.
(iv) The coils are held together by hydrogen bonds which occur between complementary pairs of nitrogenous bases.
(v) The sugar is called 2'-deoxyribose because there is no hydroxyl at position 2'.
(vi) Adenine and thiamine base pairs has two hydrogen bonds while guanine and cytosine base pairs have three hydrogen bonds.
(vii) As published by Erwin Chargaff in 1949, a purine pairs with pyrimidine and vice versa. Adenine (A) always pairs with Thymine (T) by double bond and Guanine (G) always pairs with Cytosine (C) by triple bond.

(i) Senescence is controlled by plants own genetic programme and death of the plant or plant part consequent to senescence is called Programmed Cell Death.
(ii) In short senescence of an individual cell is called PCD.
(iii) The proteolytic enzymes involving PCD in plants are phytaspases and in animals are caspases.
(iv) The nutrients and other substrates from senescing cells and tissues are remobilized and reallocated to other parts of the plant that survives.
(v) The protoplasts of developing xylem vessels and tracheids die and disappear at maturity to make them functionally efficient to conduct water for transport.
(vi) In aquatic plants, aerenchyma is normally formed in different parts of the plant such as roots and stems which encloses large air spaces that are created through PCD.
(vii) In the development of unisexual flowers, male and female flowers are present in earlier stages, but only one of these two completes its development while other aborts through PCD.

Plants which are growing in nitrogen deficient areas develop insectivorous habit to resolve nitrogen deficiency.
a. Nepenthes (Pitcher plant): Pitcher is a modified leaf and contains digestive enzymes. Rim of the pitcher is provided with nectar glands and acts as an attractive lid. When insect is trapped, proteolytic enzymes will digest the insect.
b. Drosera (Sundew): It consists of long club shaped leaves with tentacles which secrete sticky digestive fluid which looks like a sundew and attracts insects.
c. Utricularia (Bladder wort): Submerged plant in which leaf is modified into a bladder to collect insect in water.
d. Dionaea (Venus fly trap): Leaf of this plant modified into a colourful trap. Two folds of lamina consist of sensitive trigger hairs and when insects touch the hairs it will close and traps the insects.

S.No. Characters Dicot Stem Monocot Stem 1.  Hypodermis  Collenchymatous  Sclerenchymatous 2.  Ground tissue Differentiated into cortex, endodermis and pericycle and pith Not differentiated, but it is a continuous mass of parenchyma 3.  Starch Sheath  Present  Absent 4.  Medullary rays  Present  Absent 5. Vascular bundles  (a) Collateral and open  (a) Collateral and closed  (b) Arranged in a ring  (b) Scattered in ground tissue  (c) Secondary growth occurs  (c) Secondary growth usually does not occur.