Plant Physiology

Let's examine each term from List - I and match it with the correct term from List - II.

A) Pyriform-shaped gametes: These are characteristic of the Pheophyceae (IV), commonly known as brown algae. In these algae, the gametes are typically pyriform (pear-shaped) in structure.

B) Auxospores: Auxospores are a type of spore seen in Diatoms (III). Diatoms are a group of algae that produce auxospores when they experience a decrease in cell size after division. These spores help in the regeneration of diatom cells.

C) Carpogonium: Carpogonium is the female reproductive organ found in Rhodophyceae (II), also known as red algae. It is involved in the sexual reproduction process of red algae and produces gametes.

D) Hormogonium: Hormogonia are short, free-living filaments of cells formed in Cyanophyceae (I), commonly referred to as blue-green algae. These filaments can move and are involved in reproduction. Thus, the correct matching is:
- A) Pyriform shaped gametes → Pheophyceae (IV)
- B) Auxospores → Diatoms (III)
- C) Carpogonium → Rhodophyceae (II)
- D) Hormogonium → Cyanophyceae (I) Hence, the correct answer is (3) A-IV, B-III, C-II, D-I.

Step 1: Understanding Floridean Starch Floridean starch is the primary storage polysaccharide in Rhodophyceae (Red Algae). It is chemically similar to amylopectin and glycogen because it has a highly branched structure.

Step 2: Evaluating the Assertion and Reason - Assertion (A) is correct: Rhodophyceae stores food as floridean starch. - Reason (R) is also correct: Floridean starch has a structure resembling amylopectin and glycogen. - (R) correctly explains (A), as it justifies why floridean starch is used as a storage material. Thus, both (A) and (R) are correct, and (R) is the correct explanation of (A).

Step 1: Understanding Ascocarps Ascocarps are fruiting bodies of fungi belonging to the Ascomycota division. They enclose and protect ascospores during development. There are three primary types of ascocarps:
- Perithecium: A flask-shaped ascocarp with a small apical opening (ostiole) through which spores are released.
- Cleistothecium: A completely enclosed ascocarp with no opening.
- Apothecium: A cup or disk-shaped ascocarp that is open, allowing the spores to disperse easily.
- Cystocarp: A reproductive structure found in red algae, not an ascocarp of fungi.
Step 2: Identifying the Correct Answer Since the question describes an ascocarp that is flask-shaped with an apical opening, it matches the Perithecium.

Step 3: Verifying the Options - Option (1) Perithecium (Correct)
- Option (2) Cleistothecium (Incorrect – it has no opening)
- Option (3) Apothecium (Incorrect – it is cup/disc-shaped)
- Option (4) Cystocarp (Incorrect – it is not an ascocarp)
Thus, the correct answer is (1) Perithecium.

Step 1: Understanding Water Potential Water potential ( ) is the potential energy of water per unit volume relative to pure water, and it determines the direction of water movement. It is influenced by:
- Solute concentration: Higher solute concentration lowers water potential.
- Pressure potential: Physical pressure on water increases water potential.

Step 2: Analyzing the Given Diagram - Cell A contains 10\% solute concentration.
- Cell B contains less solute than A, meaning higher water potential.
- Cell C contains 15\% solute concentration, meaning lower water potential than both A and B. Since water moves from higher to lower water potential, and B has the lowest solute concentration, B has the highest water potential.

Step 3: Identifying the Correct Answer - Option (1) Incorrect → Water moves from higher to lower potential, A does not have the highest potential.
- Option (2) Incorrect → Water does not move from C to A, as C has the lowest water potential.
- Option (3) Correct → B has the highest water potential because it has the lowest solute concentration.
- Option (4) Incorrect → C has the lowest water potential, not the highest.