BPSC CCE Prelims
Plant Physiology Previous Year Questions (PYQs)

Detailed Explanation:

Plants have two main types of buds: apical buds (terminal buds) located at the tip of branches that enable vertical growth, and axillary buds (lateral buds) located at the base of leaves in the leaf axil that develop into side branches or flowers.

Therefore, buds are found at both locations – at the tip of branches and at the base of leaves.

Detailed Explanation:

Trees grow in height from apical meristems (shoot and root tips), not by elongating the trunk itself.

The nail remains at 1 m height because secondary growth (cambium activity) only increases girth, not vertical position of existing trunk sections.

Detailed Explanation:

Dark reaction (Calvin cycle) occurs in the stroma of the chloroplast, the fluid-filled region surrounding the grana.

Granum (stacks of thylakoid membranes) and grana lamella (connections between grana) are sites of light reactions, not dark reactions.

Detailed Explanation:

Xylem is a vascular tissue that transports water and dissolved minerals upward from roots to stems and leaves.

Phloem transports organic nutrients (food and amino acids), while gases diffuse through stomata and intercellular spaces, not through xylem.

Detailed Explanation:

Augustin Pyramus de Candolle was the first botanist to use vascular tissue characteristics (xylem and phloem) for plant classification, dividing plants into vascular (tracheophytes) and non-vascular (bryophytes) groups.

Engler and Prantl developed a phylogenetic system later, while Bentham and Hooker used morphological traits in their natural system, neither being first to use vascular tissues.

Detailed Explanation:

Mango is a drupe fruit with three layers in its fruit wall (pericarp).

The epicarp is the outer skin, the mesocarp is the thick, fleshy, edible middle layer, and the endocarp is the hard stone surrounding the seed.

We eat the mesocarp – the juicy, sweet flesh of the mango.

Detailed Explanation:

Quinine is an alkaloid drug used to treat malaria, extracted from the stem bark of the Cinchona tree.

The bark tissues contain the highest concentration of quinine and related alkaloids, which are harvested, dried, and processed for medicinal use; leaves and roots contain negligible amounts.

Detailed Explanation:

Turmeric powder is obtained from the dried rhizome (underground stem) of the turmeric plant, not from root, foot, or seed.

A rhizome is botanically a modified stem that grows horizontally underground; it is distinct from true roots which absorb water and nutrients.

Options 1 ("Dried foot" - not a plant part), 2 ("Dried root" - incorrect organ), and 3 ("Seed" - turmeric rarely produces viable seeds) are all incorrect, making Option 4 ("None of the above") the correct answer.

Detailed Explanation:

Chlorophyll is the green pigment in plants that absorbs light energy, primarily in the blue and red wavelengths.

This absorbed light energy drives the light-dependent reactions of photosynthesis, converting light into chemical energy (ATP and NADPH).

Detailed Explanation:

Stomatal opening and closing is regulated by the turgor pressure in guard cells.

When guard cells absorb water, they become turgid and the stomata open; when they lose water, they become flaccid and the stomata close.

✅ Option 3 – Correct: The amount of water in cells directly controls the opening and closing of stomata through changes in turgor pressure.
❌ Option 1 – Incorrect: Position of nucleus does not affect stomatal movement.
❌ Option 2 – Incorrect: While proteins are involved in water transport mechanisms, the immediate cause is water content, not protein composition change.

Detailed Explanation:

Chlorophyll is the green pigment in plants that absorbs red and blue wavelengths of sunlight most effectively for photosynthesis.

Green light is reflected (not absorbed), which is why plants appear green to our eyes.

Detailed Explanation:

✅ Statement 1 – Correct: Petiole is the stalk that attaches the leaf blade to the stem.
❌ Statement 2 – Incorrect: Trees have thick, hard stems with branching near the top, not near the base; shrubs have branching near the base.
✅ Statement 3 – Correct: Creepers have weak stems that cannot stand upright and grow along the ground (e.g., pumpkin, watermelon).

Detailed Explanation:

Transpiration is the primary mechanism responsible for the upward movement of water in tall trees.

Transpiration creates a negative pressure (suction pull) at the top of the plant as water evaporates from leaf stomata, pulling the entire water column upward through xylem vessels via cohesion-tension theory.

While evaporation occurs from leaf surfaces, it is specifically the transpiration process (evaporation through stomata) that generates the pulling force; absorption by roots is passive and responds to this pull rather than creating it.

Detailed Explanation:

Halophytes are plants specially adapted to survive in high-salt environments, tolerating concentrations up to 1M NaCl. Common examples include mangroves and salt marsh vegetation.

Xerophytes thrive in dry/desert conditions, Mesophytes in moderate environments, and Glycophytes are salt-sensitive plants that cannot tolerate saline conditions.

Therefore, salt-loving plants are Halophytes, making Option 3 the correct answer.

Detailed Explanation:

Fungi are heterotrophic organisms that lack chlorophyll, the pigment essential for photosynthesis. Without chlorophyll, they cannot synthesize their own food from sunlight and must absorb nutrients from organic matter in their environment.

They require oxygen (most are aerobic), utilize carbon dioxide in respiration, and grow in various light conditions—thus these components are not lacking. Their cell walls contain chitin, distinguishing them from true plants.

Therefore, chlorophyll is the key component fungi lack, making Option 2 the correct answer.