PLANT RESPONSES

Question 1

plant hormones

Answer 1

organic compounds that occur in low conc and act as chemical messengers

Question 2

three main groups of plant hormones

Answer 2

auxins
gibberellins
abscissic acid

Question 3

auxins

Answer 3

a group of plant hormones that are mainly produced in the apical meristem, in the growing tips of stems

Question 4

functions of auxins

Answer 4

stimulates cell elongation
stimulates fruit development
causes tropism in stems & roots

Question 5

tropism

Answer 5

is a growth movement of a plant part in response to a stimulus

Question 6

positive and negative growth movements

Answer 6

pos = towards
neg = away

Question 7

phototropism

Answer 7

the growth movement of a plant part in response to light stimulus

Question 8

high auxin conc

Answer 8

in stems stimulates growth

in roots inhibits growth

Question 9

process of phototropism

Answer 9

auxins accumulate on the shaded side
cell elongation stimulated
shaded side grows faster
stem curves in the direction of the light
ACSS

Question 10

geotropism

Answer 10

the growth movement of a plant in response to a gravitational stimulus

Question 11

geotropism in roots

Answer 11

• auxins accumulate on the lower side, and cell elong is inhibited
• the upper side w lower auxin conc grows faster, roots curve downwards

Question 12

geotropism in stems

Answer 12

the auxins accumulate on lower side due to gravity, cell elong is stimulated
stem curves upwards

Question 13

gibberellins

Answer 13

plant hormones which are produced in terminal buds of stems & roots

Question 14

functions of gibberellins

Answer 14

stimulates stem elong
stimulates root growth
stimulates seed germination

Question 15

abscisic acid

Answer 15

a growth inhibitor that counteracts the functioning of auxins, produced in leaves stems & unripe fruit

Question 16

abscisic acid functions

Answer 16

promotes abscission in leaves of fruit
closes the stoma when plant wilts
causes dormancy of terminal buds and lateral buds in winter

Question 17

the use of plant hormones in agriculture

Answer 17

production of seedless fruit (growth hormones sprayed onto flowers)
fruit ripening
increasing fruit size
germination stimulation

Question 18

mechanical defense mechanisms

Answer 18

• plant outer surface can be covered in bark of waxy cuticle that prevents damage and penetration
• thorns and spines to prevent herbivores from feeding on them

Question 19

chemical defense mechanisms

Answer 19

many plants produce chemicals (secondary metabolites) help w defense: are toxic or influence the plant’s digestibility

Question 20

types of chemicals

Answer 20

• alkaloids that influence the animals metabolism - can cause death
• terpenoids that destroy their red blood cells
• phenols that disrupt endocrine activity