Animal And Plant Breeding

Step 1: Understanding seed germination in cereals.
In cereal grains such as barley and wheat, the stored food material is present in the endosperm mainly in the form of starch. During germination, this starch must be converted into simpler sugars to nourish the growing embryo.

Step 2: Role of phytohormones.
Gibberellins are plant growth hormones that stimulate the aleurone layer of the endosperm to synthesize hydrolytic enzymes, especially amylase. Amylase breaks down starch into maltose and glucose.

Step 3: Elimination of other options.
Abscisic acid inhibits germination and induces dormancy.
Auxin mainly promotes cell elongation.
Cytokinin promotes cell division but does not induce amylase synthesis.

Step 4: Conclusion.
Therefore, gibberellin is the phytohormone responsible for promoting seed germination by synthesizing amylase enzyme.

Step 1: Understanding bacteriophage lambda.
Lambda phage is a bacterial virus that infects {Escherichia coli} and is widely used as a cloning vector.

Step 2: Role in gene transfer.
It introduces foreign DNA into bacterial cells during infection, making it useful in recombinant DNA technology.

Step 3: Eliminating incorrect options.
Lambda phage does not infect plant, yeast, or insect cells.

Step 4: Conclusion.
Therefore, lambda phage is used for gene transfer in bacteria.

Step 1: Understanding the purpose of Pusa Shubhra.
Pusa Shubhra is a cauliflower variety developed for its resistance to diseases, particularly black rot, a common bacterial infection in cruciferous plants.
Step 2: Analyzing the options.
(A) black rot: Correct. Pusa Shubhra is specifically developed to prevent black rot, a bacterial disease affecting cauliflower.
(B) leaf curl: Incorrect. Leaf curl is not the primary concern addressed by Pusa Shubhra.
(C) stripe rust: Incorrect. Stripe rust affects wheat, not cauliflower, and is not the target of Pusa Shubhra's resistance.
(D) Hill bunt: Incorrect. Hill bunt affects wheat, not cauliflower.
Step 3: Conclusion.
The correct answer is (A) black rot, as Pusa Shubhra is developed to resist this bacterial disease.

Step 1: Understanding pollutants and their sources.
Different pollutants originate from specific natural or human-made activities. Identifying their correct sources helps in understanding environmental pollution.
Step 2: Correct matching.
High levels of sulphur dioxide are mainly released from electric power plants due to burning of fossil fuels.
Endosulfan is a pesticide widely used in agricultural practices.
Pollen is a naturally occurring pollutant released from plants.
Gaseous and particulate lead mainly originates from automobile exhaust.
Step 3: Verification of option.
Only option (2) correctly matches all pollutants with their respective sources.
Step 4: Conclusion.
Hence, option (2) is the correct answer.

Step 1: Understanding pioneer species.
Pioneer species are organisms that first colonize barren and harsh environments such as bare rocks. These environments lack soil, nutrients, and moisture, making survival difficult for most plants.
Step 2: Role of lichens.
Lichens are a symbiotic association of algae and fungi. They can grow directly on bare rocks and release organic acids that slowly break down rocks into soil, initiating the process of ecological succession.
Step 3: Analysis of options.
(A) Pteridophytes: Require soil and sufficient moisture, so they cannot grow on bare rocks.
(B) Bryophytes: Need a thin layer of soil, which develops only after lichens colonize the rocks.
(C) Gymnosperms: Advanced plants that require well-developed soil.
(D) Lichens: Correct, as they are capable of surviving on bare rocks and initiate soil formation.
Step 4: Conclusion.
Lichens are the pioneers of vegetation on rocks because they initiate soil formation and ecological succession.

Step 1: Understanding chlorophyll pigments.
Chlorophyll pigments are responsible for absorption of light energy during photosynthesis and occur in different forms such as chlorophyll-a and chlorophyll-b.
Step 2: Colour of chlorophyll-a.
Chlorophyll-a absorbs light mainly in the blue-violet and red regions and reflects blue-green light, giving it a blue-green colour.
Step 3: Analysis of options.
(A) Yellow: Incorrect — associated with carotenoids.
(B) Blue green: Correct — characteristic colour of chlorophyll-a.
(C) Orange: Incorrect — carotene pigments.
(D) Yellow green: Incorrect — this describes chlorophyll-b.
Step 4: Conclusion.
Chlorophyll-a is blue green in colour.

Step 1: Understanding grafting.
Grafting is a vegetative propagation method that requires vascular cambium for the fusion of stock and scion.

Step 2: Analyzing monocots.
Monocot plants lack vascular cambium because their vascular bundles are scattered and closed.

Step 3: Option analysis.
(A) Branches may or may not be present.
(B) Buds are present in monocots.
(C) Apical meristem is present.
(D) Cambium is absent, hence grafting is not possible.

Step 4: Conclusion.
The correct answer is (D) cambium.