plant responses

Question 1

define etiolation and de-etiolation. 4 features of each?

Answer 1

etiolation: adaptations to growing in darkness
- focus on stem elongation
- unexpanded leaves
- no chlorophyll
- few short roots

de-etiolation: adaptations to growing in light
- stem elongation slows
- leaves expand
- sunlight stimulates chlorophyll production
- roots grow+elongate

Question 2

2 functions of plant hormones?

Answer 2

• coordinate and control growth, development, and responses to stimuli
• affect division, elongation, differentiation of cells

Question 3

5 major plant hormones?

Answer 3

• auxins
• cytokinins
• gibberellins
• abscisic acid
• ethylene

Question 4

production location and major functions of auxin?

Answer 4

• produced mostly in shoot tips (apical meristem)
• promotes cell elongation
• apical dominance
• regulates tropisms (phototropism)
• root formation (adventitious root growth)

Question 5

auxin is actively transported down the stem at what rate?

Answer 5

1cm/hr

Question 6

how does auxin trigger cell elongation?

Answer 6

by stimulating the production of enzymes that loosen the cell wall, allowing the cells to expand as water enter vacuole.

Question 7

auxin can be used to?

Answer 7

• stimulate adventitious roots
• kill weeds

Question 8

production location and major functions of cytokinins?

Answer 8

• produced in actively growing tissues such as roots, embryos and fruits
• work with auxin to control cell division
• slows the aging of some plants

Question 9

how to cytokinins slow the aging of some plants?

Answer 9

• mobilizing nutrients from surrounding tissues
• stimulating RNA and protein synthesis
• inhibiting protein breakdown

Question 10

production location and major functions of gibberellins?

Answer 10

• produced in young roots and leaves
• stimulates germination

Question 11

____, along with auxin, stimulates fruit growth and stimulates stem elongation

Answer 11

gibberellin

Question 12

production location and major functions of abscisic acid

Answer 12

• found in seeds and leaves
• prevents seeds from germinating in unfavourable conditions
• stimulates stomata to close to prevent dehydration

Question 13

production location and major functions of ethylene

Answer 13

• produced by all plant tissues in response to stresses (drought, flooding, mechanical stress)
• involved in senescence
• involved in fruit ripening
• controls leaf abscission

Question 14

in increase in ____ and decrease in ____ leads to the browning and falling off of leaves in the autumn/winter

Answer 14

increase in ethylene, decrease in auxin

Question 15

what is photoropism

Answer 15

turning towards/away from light