All questions of Plant Diversity Of India for BPSC (Bihar) Exam

Effect of Temperature on Plants

Statement 1: Excessive high-temperature results in the death of plant due to coagulation of protoplasmic proteins.

Explanation:
When plants are exposed to excessive high temperatures, it can have detrimental effects on their growth and survival. One of the major impacts is the coagulation of protoplasmic proteins. Protoplasm is the living substance within a plant cell that includes the cytoplasm and nucleus. It consists of various proteins that perform essential functions for the plant's survival.

When the temperature rises above a certain threshold, the protoplasmic proteins may undergo denaturation or coagulation. Denaturation refers to the alteration of the protein's structure, leading to loss of its biological activity. In the case of coagulation, the proteins may become insoluble and clump together, rendering them dysfunctional. This disruption of protein structure and function can ultimately result in the death of the plant.

Therefore, statement 1 is correct as excessive high-temperature can indeed lead to the death of plants due to the coagulation of protoplasmic proteins.

Statement 2: It disturbs the balance between respiration and photosynthesis, thereby causing depletion of food resulting in greater susceptibility to fungal and bacterial attack.

Explanation:
Temperature plays a crucial role in the balance between respiration and photosynthesis in plants. Both these processes are essential for the plant's energy metabolism and nutrient production.

Photosynthesis is the process by which plants convert sunlight, water, and carbon dioxide into glucose (food) and oxygen. It is an energy-capturing process that occurs in the presence of chlorophyll. Higher temperatures can enhance the rate of photosynthesis up to a certain limit. However, excessive high temperatures can disrupt the balance of this process. The enzymes involved in photosynthesis may become less efficient, leading to a decreased rate of photosynthesis. This can result in a depletion of food production in the plant.

Simultaneously, high temperatures can also increase the rate of respiration in plants. Respiration is the process by which plants break down glucose to release energy for various cellular activities. When the rate of respiration exceeds the rate of photosynthesis, it can lead to a net loss of food reserves in the plant.

Furthermore, the depletion of food reserves due to disturbed balance between respiration and photosynthesis can make plants more susceptible to fungal and bacterial attacks. This is because plants with reduced food reserves have weakened defense mechanisms, making them more vulnerable to pathogens.

Therefore, statement 2 is correct as high temperatures can disturb the balance between respiration and photosynthesis, leading to a depletion of food reserves and increased susceptibility to fungal and bacterial attacks.

Conclusion:
Both statement 1 and statement 2 are correct. Excessive high temperatures can cause the death of plants due to the coagulation of protoplasmic proteins. It can also disturb the balance between respiration and photosynthesis, resulting in a depletion of food reserves and greater susceptibility to fungal and bacterial attacks.

Effect of Frost on Plants

Introduction:
Frost is a condition where the temperature drops below freezing point, causing ice crystals to form on plant surfaces. This can have various effects on plants, including damage to their cells and dehydration.

Statement 1: As a result of frost, water in the intercellular spaces of the plant gets frozen into ice which withdraws water from the interior of the cells.

Explanation:
- When frost occurs, the water present in the intercellular spaces of the plant freezes, forming ice crystals.
- As the ice crystals form, they withdraw water from the interior of the cells due to osmotic pressure.
- This withdrawal of water can lead to dehydration of the cells, causing damage to the plant tissues.

Statement 2: This results in decreasing concentration of salts and dehydration of cells.

Explanation:
- When water is withdrawn from the interior of the cells due to the formation of ice crystals, the concentration of salts in the remaining water increases.
- This increase in salt concentration can disrupt the normal functioning of the cells and lead to dehydration.
- Dehydration of cells can cause wilting, tissue damage, and even death of the plant.

Conclusion:
Based on the explanations provided, it can be concluded that Statement 1 is correct. Frost causes the water in the intercellular spaces of the plant to freeze into ice, which withdraws water from the interior of the cells, leading to dehydration. However, Statement 2 is incorrect as it suggests a decrease in the concentration of salts, whereas the actual effect is an increase in salt concentration due to water withdrawal. Therefore, the correct answer is option 'A' - 1 only.