Flowering Plants Behavior

Question 1

Give 2 examples of plant responses to internal or environmental stimuli.

Answer 1

Phototropism; plants responding to light
Tropism: growth response that depends on a stimulus that occurs in a particular direction.

Question 2

Describe the 3 stages of cell signaling in plants and why it is important.

Answer 2

Receptors or sensors: proteins become activated when they receive a specific type of signal.
Second Messengers: transmits messages from types of activated receptors.
Effectors: causes a cellular response.

Question 3

Define auxins, Gibberellins, Ethylene, Abscisic acid, and Brassinosteroids and give examples of what they do.

Answer 3

Auxins are the “master” plant hormones, they influence plant structure, development, and behavior. Gibberellins promote shoot development and stimulate cell division and elongation. Ethylene influences cell expansion, often with auxin, cells tend to expand in all directions rather than elongating. Abscisic acid slows or stops plant metabolism when growing conditions are poor. Brassinosteroids trigger water uptake to trigger growth.

Question 4

Describe how plant roots respond to gravity and touch.

Answer 4

Gravity causes changes in calcium ion second messengers that affect the direction of auxin transport, changes direction of root or shoot growth. Touch causes release of calcium ion second messengers that influence gene expression. Humans also breed specific plants for specific needs.

Question 5

Give 2 examples of how plants respond to flood and drought.

Answer 5

Flood: they produce internal airways in aerenchyma
Drought: Stomatal closure