Fill in the blank: Gibberellins are involved in breaking seed dormancy and stimulating the elongation of ___ and ___ in the presence of auxins.

Shoots and stems

What is the primary role of auxins in plant growth?

Auxins promote the growth of plants by influencing cell division, elongation, and differentiation, particularly at the tips of stems and roots.

True or False: Cytokinins encourage the aging of leaves and do not play a role in fruit growth.

False. Cytokinins help delay the aging of leaves and promote fruit growth.

What is the effect of abscisic acid on plant growth?

Abscisic acid inhibits plant growth.

• Promotes seed dormancy.

• Closes stomata to reduce water loss.

• Causes wilting and leaf drop.

Riddle: I help plants grow tall and strong, but too much of me can do harm. What am I?

Auxins

Describe phototropism and its significance in plant growth.

Phototropism is the movement of plant parts toward light, allowing shoots to grow towards light sources, which is vital for maximizing photosynthesis.

Fill in the blank: Roots exhibit ___ geotropism as they grow towards the direction of gravity, while shoots exhibit ___ geotropism.

Positive; negative

What is chemotropism and how does it relate to pollen tubes?

Chemotropism directs pollen tube growth.

• Plant organs respond to chemicals.

• Pollen tubes move towards sugar.

• Essential for plant reproduction.

True or False: Heliotropism refers to the growth of plant parts in response to water availability.

False. Heliotropism refers to the movement of plant parts in response to the direction of the Sun.

What role do thigmotropic responses play in weak-stemmed plants?

Thigmotropic responses help plants climb.

• Support weak stems effectively.

• Enable access to sunlight.

• Enhance survival in tight spaces.