Plant Stress

Question 1

What are the two types of stresses that affect plant survival, growth, and reproduction?

Answer 1

Abiotic stress and Biotic stress

Abiotic stress is due to nonliving factors, while biotic stress is due to living factors.

Question 2

What are three common abiotic stresses discussed?

Answer 2

• Drought stress
• Cold stress
• Salt stress

These stresses can adversely affect plant health and development.

Question 3

What happens to plants during drought stress?

Answer 3

Plants may wilt when water loss by transpiration exceeds absorption

Prolonged drought can lead to plant death.

Question 4

What hormone is stimulated by water deficit during drought stress?

Answer 4

Abscisic acid (ABA)

ABA helps close stomata to reduce transpiration.

Question 5

How do grasses respond to drought stress?

Answer 5

Leaves roll into a tube-like shape

This reduces the surface area to decrease transpiration.

Question 6

What is the effect of cold stress on plant cell membranes?

Answer 6

Cell membranes lose fluidity when cooled below a critical temperature

This affects transport across the membrane and cell function.

Question 7

How do plants respond to cold stress at the membrane level?

Answer 7

By altering lipid composition to increase unsaturated fatty acids

This helps maintain membrane fluidity at low temperatures.

Question 8

What occurs when water in the cell wall freezes?

Answer 8

Reduces extracellular water potential, causing water to leave cytosol

This leads to high solute concentration in the cytoplasm, which can be harmful.

Question 9

What do frost-tolerant plants do before winter to prevent dehydration?

Answer 9

Increase cytoplasmic levels of specific solutes such as sugars

These solutes help reduce water loss from the cell.