Correct option is B
Plants are constantly exposed to abiotic environmental stresses such as drought, salinity, flooding, and high light intensity. These stresses have specific primary effects on plant physiology.
Matching Column X (Factors) with Column Y (Effects):
Water Deficit → Water Potential Reduction (A - iv)
Water deficit (drought stress) leads to a reduction in water potential, causing osmotic stress in plants.
Plants respond by closing stomata, producing abscisic acid (ABA), and reducing transpiration.
Salinity → Ion Cytotoxicity (B - i)
Salinity stress leads to an accumulation of toxic ions (e.g., Na⁺ and Cl⁻) in plant cells, which disrupt cellular homeostasis.
High salinity can inhibit enzyme function and photosynthesis.
Flooding → Hypoxia to the Roots (C - ii)
Excess water reduces oxygen availability in the soil, leading to root hypoxia (oxygen deprivation).
This impairs respiration and root metabolism, eventually causing root rot.
High Light Intensity → Photoinhibition (D - iii)
Intense sunlight can cause photoinhibition, damaging the photosynthetic machinery in chloroplasts.
This leads to oxidative stress and a decrease in photosynthetic efficiency.
Information Booster:
1 .Drought stress reduces turgor pressure, causing stomatal closure and reduced CO₂ uptake.
2. Salt stress leads to osmotic imbalance and ion toxicity, primarily affecting root growth.
3. Flooding deprives roots of oxygen, reducing ATP production and leading to hypoxia stress.
4. Excessive light leads to photoinhibition, damaging photosystem II (PSII) and increasing reactive oxygen species (ROS).
5. Plants respond to water stress by producing osmoprotectants like proline and sugars.
6. Salt-tolerant plants (halophytes) use salt glands and ion transporters to mitigate toxicity.
7. Flood-tolerant plants develop aerenchyma (air spaces) in roots to improve oxygen supply.
