Plant Physiology

Analysis of Deficiency Symptoms and Corresponding Elements:

A: Fe, Mn, Zn → Chlorosis ✅ 🔹 Deficiency of Iron (Fe), Manganese (Mn), and Zinc (Zn) leads to chlorosis (yellowing of leaves due to lack of chlorophyll), especially in younger leaves.

B: Cu, Ca → Necrosis ✅ 🔹 A deficiency of Copper (Cu) and Calcium (Ca) results in necrosis (localized death of plant tissue), often causing dark spots or tissue decay in leaves.

C: N, K → Inhibition of Cell Division ✅ 🔹 A deficiency in Nitrogen (N) and Potassium (K) leads to inhibition of cell division, resulting in stunted growth and underdeveloped plant tissues.

✅ Correct Answer: (2) A: Chlorosis, B: Necrosis, C: Inhibition of Cell Division.

Analysis of Assertion and Reason

Assertion (A): "Root pressure does not play a major role in water movement in tall trees." ✅ This statement is correct. Root pressure is important in smaller plants and under certain conditions (such as at night), but in tall trees, transpiration pull is the dominant mechanism for water transport.

Reason (R): "Root pressure is responsible for pushing up water to small heights in the stem." ✅ This statement is also correct. Root pressure helps in pushing water upwards but is only effective for short distances. In tall trees, its role is minimal compared to transpiration pull.

🔹 However, the reason (R) does not fully explain the assertion (A). While root pressure plays a minor role in water movement at shorter heights, it is not the primary driver in tall trees.

Thus, the correct answer is: (2) A and R are correct, but R is not the correct explanation of A.

Analysis of the Combinations

Let's analyze the combinations:

• I. Carbon from atmospheric CO₂: This is correct for Methanogens, which are a type of archaea that obtain carbon from atmospheric CO₂ and use it for energy.
  Therefore, I corresponds to Methanogens.
• II. Energy from oxidation of inorganic substances: This statement correctly describes the behavior of Chlorobium, a type of bacteria that uses the oxidation of inorganic substances as a source of energy, usually for photosynthesis.
• III. Only carbon from organic sources: This statement is true for Rhodopseudomonas, which is a bacterium that uses only organic carbon sources for its energy needs.
  Therefore, III corresponds to Rhodopseudomonas.
• IV. Carbon from dead organic sources: This is correct for Bacillus, which is a genus of bacteria that uses organic matter from dead organisms as a carbon source.
  Hence, IV corresponds to Bacillus.

Thus, the correct combinations are III (Only carbon from organic sources - Rhodopseudomonas) and IV (Carbon from dead organic sources - Bacillus).

Therefore, the correct answer is (3) III, IV.

Evaluating the statements. Xylem parenchyma indeed store substances like starch, but their walls are not typically highly thickened; that characteristic belongs to xylem fibers.
Companion cells are indeed associated with sieve tubes but are not controlled by them; they assist in the function of sieve tubes.
Phloem parenchyma is indeed scarce in most monocots.

Analyzing the Assertion and Reason

• Assertion (A): "Secondary growth is absent in monocots generally." This statement is correct. Monocots generally do not show secondary growth because they lack the vascular cambium, which is responsible for secondary growth.
• Reason (R): "Vascular bundles are conjoint and closed." This statement is also correct. In monocots, vascular bundles are conjoint (the xylem and phloem are arranged together) and closed (there is no vascular cambium between the xylem and phloem). The absence of vascular cambium explains the lack of secondary growth in monocots.

Conclusion: Since both the assertion and reason are correct, and the reason correctly explains the assertion, the correct answer is:

(1) A and R are correct. R is the correct explanation of A.

Step 1: Understanding the assertion (A)
Bulk flow can occur when there is either a positive or negative hydrostatic pressure gradient. Positive pressure leads to the movement of water from high pressure to low pressure, while negative pressure also enables the flow, such as in the case of transpiration pull in plants.
Step 2: Understanding the reason (R)
Movement in the xylem is not always bidirectional. Xylem primarily moves water unidirectionally, from the roots to the leaves, driven by transpiration. Therefore, the statement in reason (R) is incorrect.
Final Answer:

Plant Tissue Culture and Its Applications

In plant tissue culture, different techniques are used for plant propagation and genetic improvement:

• Meristem culture – Used to produce virus-free plants (✔ Correct pair).
• Embryos on callus – Lead to the formation of somatic embryos (✔ Correct pair).
• Somatic hybrids – Do not result in embryos; they are formed through somatic cell fusion (✘ Incorrect pair with "embryoids").
• Organogenesis – Leads to the formation of artificial seeds (✔ Correct pair).

Thus, the incorrect pair is III, IV.

Therefore, the correct answer is (B).

Genotypic Ratios in a Dihybrid Cross

In a dihybrid cross involving two traits, the genotype combinations in the F₂ progeny will follow the ratios based on Mendelian genetics:

• YyRR: This genotype arises from the cross of Yy and RR parents.
  The ratio of this genotype is 1.
• yyRR: This genotype arises from the cross of yy and RR parents.
  The ratio of this genotype is 1.
• YyRR: The cross will give this genotype with a ratio of 2.
• Yyrr: This genotype arises from the cross of Yy and rr parents.
  The ratio of this genotype is 2.

Thus, the correct ratio of genotypes is 1:1:2:2.

Therefore, the correct answer is (2) 1:1:2:2.

Step 1: Matching List A and List B
Apoplast (A): Movement of water through intercellular spaces and walls (III).
Solute potential (B): Lowering of water potential due to dissolution of solutes (IV).
Symport (C): Two types of molecules cross the membrane in the same direction (II).
Facilitated diffusion (D): Sensitive to inhibitors of proteins with side chains (I).
Final Answer:
A-III, B-IV, C-II, D-I