Q.Light plays an important role in the life of all organisms. Name any three physiological processes in plants which are affected by light.

Light governs several distinct physiological processes in plants. Three examples: Photosynthesis — the light reactions capture light energy and convert it to chemical energy (ATP and NADPH) used to fix carbon dioxide into sugars. Photoperiodism — the relative length of day and night, sensed by the leaves, determines whether and when a plant flowers (long-day, short-day or day-neutral response). Photomorphogenesis (including seed germination) — light, sensed through pigments such as phytochrome, controls the germination of light-sensitive (photoblastic) seeds and the pattern of seedli …

Light is far more than just an energy source for plants — it is also an environmental signal that plants sense and respond to. Three distinct physiological processes it governs are:

• Photosynthesis. The light reactions of photosynthesis absorb light energy using chlorophyll and other pigments and convert it into chemical energy (ATP and NADPH). This chemical energy then powers the fixation of atmospheric carbon dioxide into sugars in the dark reactions. Without light, this entire process — the basis of the plant's food production — cannot proceed.
• Photoperiodism. Many plants flower only when the relative durations of day and night match a species-specific requirement. Long-day plants flower when the day length exceeds a critical value, short-day plants flower when it falls below a critical value, and day-neutral plants flower independent of day length. The signal is perceived by the leaves and triggers the transition from vegetative to reproductive growth. …

Method: Cataloguing How an Environmental Factor Affects Plant Development

Use this method whenever a question asks you to name multiple physiological processes influenced by one environmental factor (light, temperature, water, etc.).

Steps

Step 1: Separate intrinsic vs extrinsic control

Recall that plant growth and development are governed by both intrinsic (internal, genetically programmed) and extrinsic (environmental) factors. The factor named in the question — light — falls in the extrinsic category, alongside temperature, water, oxygen and nutrition.

Step 2: List the distinct levels at which the factor can act

Work through the levels systematically rather than picking one effect at random: (a) does it influence a phase or stage of growth,

(b) does it influence overall development (growth + differentiation),

(c) does it interact with other requirements like water/nutrient status that growth itself depends on.

Step 3: Pick three genuinely distinct processes …