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Question 1

how do cytokinins regulate growth?

Answer 1

by binding to cytokinin receptors of target cells. receptors activate genes that regulate cell division.

Question 2

what happens when theres no cytokinin?

Answer 2

cell division stops

Question 3

functions of cytokinins

Answer 3

• promote cell division in the presence of auxin
• promote chloroplast development and break lateral bud dormancy
  -delay aging
• produced in root apical meristems

Question 4

Gibberellins/gibberellic acid (GA) function

Answer 4

• promote stem growth via both cell elongation and division
• promote seed germination.
• produced in apical meristems, immature seeds, and pollen producing anthers.

Question 5

why are seeds dormant after being first released?

Answer 5

• allow time for dispersal
  _ allow germination during a favorable season

Question 6

________ produced by the germinating embryo, triggers the production of endosperm degrading enzymes in the aleurone layer.

Answer 6

Gibberellins

Question 7

how do gibberellins trigger production of endosperm degrading enzymes in the aleurone layer?

Answer 7

1. gibberellin synthesized by the embryo and released into the starchy endosperm through the scutellum.
   2 gibberellins diffuse to the aleurone layer.
2. aleurone layer cells are induced to synthesize and secrete amylase and other hydrolases into the endosperms
3. starch and other macromolecules are broken down and transported back to embryo.

Question 9

does GA stimulates growth?

Answer 9

yes

Question 10

GA stimulates _____ in long day plants

Answer 10

flowering

Question 12

Abscisic acid functions

Answer 12

• inhibits bud growth and seed germination
• induces closure of stomata in response to water stress.
• acts as a stress hormone analogous to cortisol in humans
• produced in almost all cells

Question 13

ABA accumulates during:

Answer 13

seed and bud maturation

Question 14

ABA induces

Answer 14

accumulation of reserves,
accumulation of osmolytes.
- desiccation
- dormancy
- survival during cold seasons

Question 15

viviparous mutatn

Answer 15

embryos developing on mother plant without dormant seed phase

Question 16

two hormones initiate and halt growth as environmental conditions change
1. ______ stimulate plant growth
2. _____ _____ inhibits growth

Answer 16

1. Gibberellins
2. Abscisic acid

Question 17

Ethylene
- what form it exists in
- what its involved in
- what it induces
- where is it produced when plants are stressed

Answer 17

• exists in gas form
• involved in fruit ripening
• induces senescence of fruits, flowers, and leaves
• produced in all organs when plants are under stress.

Question 18

what is the hormone responsible for senescence?

Answer 18

ethylene

Question 19

three aspects of senescence that ethylene is associated with

Answer 19

1. fruit ripening
2. flower fading
3. leaf abscission

Question 20

During fruit ripening
- starch is converted to ____
- cell walls are _____
- chlorophyll is ____ _____ and pigment and aromas are produced

Answer 20

• sugar
• degraded
• broken down

Question 21

as leaves age, auxin levels drop and the _____ _____ of petioles become more sensitive to ethylene:
- increased ethylene sensitivity activates enzymes that weaken the walls of cells in abscission zone and leaf falls off

Answer 21

abscission zone