Plant Responses Chp32

Question 1

What is a stimulus

Answer 1

anything that causes a reaction in an organism or in any of its parts

Question 2

What is a response

Answer 2

the activity of a cell or organism as a result of a stimulus

Question 3

What are the structures needed for response

Answer 3

a chemical/hormonal system, a nerve/sense organ system, a method of movement, a defence/immune system

Question 4

What are the external factors effecting plant growth

Answer 4

light, day length, gravity, temperature

Question 5

What is a tropism

Answer 5

a change in the growth of a plant in response to an external stimulus

Question 6

What is a positive tropism

Answer 6

when the growth is towards the stimulus

Question 7

What is a negative tropism

Answer 7

when the growth is away from the stimulus

Question 8

What is phototropism

Answer 8

the change in growth of a plant in response to light (stem)

Question 9

What is geotropism

Answer 9

the change in growth of a plant in response to gravity (root)

Question 10

What is thigmotropism

Answer 10

a change in growth of a plant in response to touch

Question 11

What is hydrotropism

Answer 11

a change in growth of a plant in response to water

Question 12

What is chemotropism

Answer 12

a change in plant growth in response to chemicals

Question 13

What is a growth regulator

Answer 13

a chemical that controls the growth of a plant

Question 14

What is a growth promoter

Answer 14

a chemical that causes increased growth in plants

Question 15

What is an example of a growth regulator

Answer 15

Auxins/IAA

Question 16

Where are auxins produced

Answer 16

meristematic tissue in the tips of shoots

Question 17

What are the functions of auxins

Answer 17

stimulate stem elongation, developing fruit, apical dominance, causing phototropism

Question 18

What are the effects of auxins

Answer 18

causes cell elongation/growth on opposite side of the sun bending the plant toward the light

Question 19

Describe the role of IAA in phototropism

Answer 19

IAA diffuses down the shaded side of the plant, this causes the cells to elongate more, as a result the stem bends towards the light

Question 20

What are growth inhibitors

Answer 20

a chemical that causes a reduction in growth of plants

Question 21

How are growth regulators used in horticulture

Answer 21

ethene is used to ripen fruits and rooting powders are used to stimulate rapid root formation on stem cuttings

Question 22

2 ways plants are anatomically adapted for protection

Answer 22

epidermis or bark prevents the entry of pathogens and reduce the loss of water, guard cells shrivel due to a lack of water reducing further water loss

Question 23

2 ways plants are chemically adapted for protection

Answer 23

heat-shock proteins surround enzymes to protect them from being denatured in high heat, plant produces phytoalexins (stress proteins) damaging micro-organisms by attacking cell walls