Plant and animal responses.

Question 1

Name the 3 chemical defences in plants

Answer 1

• Tannins
• Alkaloids
• Pheromones

Question 2

What is meant by a tropism?

Answer 2

A directional growth response of plants

Question 3

What are tannins, where are they found and what do they do?

Answer 3

• Chemicals toxic to micro-organisms and larger herbivores.
• They are found in the upper epidermis
• They impact herbivore digestion
• They prevent infiltration in roots

Question 4

What are alkaloids, where are they located and what do they do?

Answer 4

• Chemical defences that are derived from amino acids
• Located in growing tips and flowers as well as peripheral layers (stem and roots)
• Act as a feeding deterrent by making plants taste bitter

Question 5

What are pheromones?

Answer 5

Chemicals released by one individual plant that can affect the behaviour and physiology of another.

Question 6

What is meant by tropism?

Answer 6

A directional growth response towards or away from a stimulus

Question 7

Name 4 different tropisms?

Answer 7

• Phototropism
• Geotropism
• Chemotropism
• Thigmotropism

Question 8

Are shoots negatively or positively phototropic

Answer 8

Positively phototropic

Question 9

Are roots positively or negatively phototropic?

Answer 9

Negatively phototropic

Question 10

Are roots positively or negatively geotropic?

Answer 10

Positively gravitropic (they grow with the pull of gravity)

Question 11

What is meant by chemotropism and give an example

Answer 11

• Growth towards/away from chemical stimulus
• On a flower, pollen tubes grow down the style, attracted by chemicals towards the ovary for fertilisation

Question 12

What is meant by thigmotropism and what is an example?

Answer 12

Directional response towards physical contact.
Shoots of climbing plants (such as ivy) wind around other plants or structures to gain support.

Question 13

What decides whether a plant is positively tropic or negatively tropic?

Answer 13

• If a plant responds towards a stimulus it is positively tropic
• If a plant responds away from a stimulus it is negatively tropic

Question 14

What is a non-directional plant response called?

Answer 14

Nastic response/movement

Question 15

What plant exhibits a nastic movement

Answer 15

Mimosa pudica

Question 16

What type of response do mimosa pudica plants do?

Answer 16

Thigmonasty

Question 17

What is photoperiod?

Answer 17

The active timing plants have depending on daylight which influences their flowering

Question 18

When do ‘long day plants’ flower?

Answer 18

• Summer

Question 19

When do ‘short day plants’ flower?

Answer 19

• Spring and Autumn

Question 20

List hormones in plants

Answer 20

• Cytokinins
• Auxins (IAA)
• Abscisic acid
• Gibberellins
• Ethene

Question 21

What does IAA stand for?

Answer 21

Indole-3-acetic acid

Question 22

What are the effects of cytokinins?

Answer 22

• Promotes cell division
• Delays leaf senescence
• Overcomes apical dominance
• Promotes cell expansion

Question 23

What are the effects of abscisic acid?

Answer 23

• Inhibits seed growth and germination
• Closes stomata when plant is stressed by low water availability

Question 24

What are the effects of auxins (such as IAA)

Answer 24

• Promotes cell elongation
• Inhibits growth of lateral buds
• Inhibits leaf abscission

Question 25

What are the effects of gibberellins?

Answer 25

• Promotes seed germination and growth of stems

Question 26

What are the effects of ethene?

Answer 26

• Fruit ripening

Question 27

How do plant hormones move around the plant?

Answer 27

• Active transport
• Diffusion
• Mass flow

Question 28

What are auxins responsible for?

Answer 28

Regulating plant growth