12

Question 1

Light induces fast/slow transitions (High Pfr:Pr ratio)?

Answer 1

Fast

Question 2

Night induces fast/slow reversion (Low Pfr:Pr ratio)?

Answer 2

Slow

Question 3

How to plants sense the ratio of the Pfr:Pr ratio?

Question 4

Short night plants need a relatively high/low Pfr:Pr ratio at sunrise?

Answer 4

High

Question 5

Long night plants need a very high/low Pfr:Pr ratio at sunrise?

Answer 5

Low

Question 6

Primary compound?

Answer 6

Essential for growth

Question 7

Secondary compound?

Answer 7

Not essential but does benefit the plant.

Question 8

Auxin roles? 4•

Answer 8

•wound response
•flowering
•fruit growth and development
•ethylene biosynthesis

Question 9

Auxin at high concentrations are powerful?

Answer 9

Herbicides.

Question 10

Herbicides?

Answer 10

Plant killers

Question 11

!!!!!!!Auxin is responsible for?

Answer 11

•Cell elongation
•Gravitational pull

Question 12

Once PHOT1 is phosphorylated, then?

Answer 12

A phototropic response is initiated.

Question 13

Where in the plant is the blue light sensed?

Answer 13

By coleoptile tip.

Question 14

Where is the response of the bend of the plant occurring?

Answer 14

In the lower coleoptile

Question 15

How does the lower coleoptile bend if the tip senses?

Answer 15

There is chemical diffusion that transports through the plant

Question 16

When light hits the plant, how does that induce bending?

Answer 16

Auxin gets hit by the light, and goes into the dark side of the plant. There is a higher concentration in that side, and diffuses down. There is still a higher concentration down the plant. Since auxin causes cell elongation, it facilitates cell elongation on the shaded side.

Question 17

Acid growth hypothesis?

Answer 17

Plants are able to loosen their cell wall by raising its pH by auxin binding to an ABP1 receptor, which facilitates H+/ATPase proton pump. Protons will pump outside of the cell. Potassium will facilitate diffuse inside of the cell. This decreases solute potential, which decreases water potential, and water will diffuse into the cell. This increases turgor pressure.

Question 18

Expansion?

Answer 18

Proton pumping also ends to loosening of cellulose micro-fibrils in cell wall by activating expansion. It break bonds between cellulose microfibris. It weakens the cell wall. It is a signal for cell wall synthesis (button example)

Question 19

!!!!!!When does expansin get activated?

Answer 19

When the cell wall gets acidified

Question 20

Gravitropism?

Answer 20

•Roots will grow towards gravity, and shoots grow against gravity. •Roots have a tip with sensors called the columella cells. •Amyloplasts are pulled towards a specific side in the cell by gravity. •Auxin are evenly distributed when roots are growing downwards. •When amyloplasts are not distributed evenly, then auxin will flow towards amyloplasts, and there will be a difference of concentration, auxin-induced asymmetric growth. This will INHIBIT cell elongation at the side with most amyloplasts since there are WAY TOO MANY auxin. The other side grows normally.