13

Question 1

If you have higher ABA/GA ratio, does germination occur?

Answer 1

No

Question 2

If you have lower ABA/GA ratio, does germination occur?

Answer 2

Yes

Question 3

Gibberellin is important for germination, but it is also important for? 2*

Answer 3

*Cell elongation
*Flowering

Question 4

What really is a seed?

Answer 4

Its an embryonic plant that is now a diploid tissue by fusing of male and female gametes which were haploid.

Question 5

Seed anatomy? 4*

Answer 5

*Seed coat: what is interacting with the environment and is important in first defense of seed against that environment.
*Embryo: What will start producing roots and shoots. The only alive tissue of the seed where gibberellins will be produced.
*Endosperm: food storage of the plant.
*Aleurone: Source of the a-amylase enzyme used to break down starch into sugars.

Question 6

seed germination requires? 4*

Answer 6

*rehydration, *oxygen, *suit temperatures, and *demobilization of energy reserves.

Question 7

What conformation of the red light absorbing chromophore facilitates germination?

Answer 7

Pfr

Question 8

germination is induced/inhibited by gibberellin?

Answer 8

Induced

Question 9

Steps for plant germination?

Answer 9

Seed absorbs water and oxygen and germination begins. Then, gibberellin diffuse from embryo to cells in aleurone layer. The aleurone cells synthesis and release digestive enzyme a-amylase to the endosperm. a-amylase digest starch, and release sugars and other molecules to growing plant.

Question 10

Is ratio or quantity more important in hormones?

Answer 10

Ratio

Question 11

If you have a high ABA/GA ratio, then?

Answer 11

Seed dormancy

Question 12

If you have a low ABA/GA ratio?

Answer 12

Seed germination

Question 13

What does ABA do in the seed?

Answer 13

inhibits the synthesis of a-amylase in the aleurone layer. No nutrients will be available for germination.

Question 14

Precocious germination vivipary14 (vp14) mutant of maize encourages germination with ABA acid being present by?

Answer 14

Vp14 being an ABA deficient mutant and also over-produces GA.

Question 15

ABA synthesized in roots travels using the _____ and promotes stomatal closing even in presence of water?

Answer 15

Xylem

Question 16

in the stomata, how does it open in presence of blue light?

Answer 16

Blue light phosphorylation pHOT1/PHOT2 and H+ pumping by H+-ATPase increase. This creates a gradient to import K+ and Cl-. K+ goes in electrochemical gradient while Cl- goes against and goes in by a cotransporter. Solute potential decrease, water potential decrease, turgor pressure increase, and guard cells increase in size.

Question 17

How does stomata close when ABA is present?

Answer 17

ABA is sensed by an ABA receptor that inhibits H+ pumping by H+-ATPases. Inward-directed H+/Cl- cotransporters stop working and outward directed Cl- channels open. Cl- exits along its favorable electrochemical gradient. The change in membrane potential closes inward-directed K+ channels and opens outward-directed K+ channels. K+ exits in its favorable electrochemical gradient. Solute potential in guard cells increase, water potential increase, water leave guard cell. This decreases turgor pressure within the guard cell. Guard cells shrink.

Question 18

Cytokinins (CKs) are regulators of leaf senescence. Senescence is?

Answer 18

Senescence is? A mechanism that involves degradative biochemical processes that lead to death. It is sensed by environment or natural response due to aging.

Question 19

stages of leaf senescence?

Answer 19

*initiation phase: transition from nutrients sink to nitrogen source cells. Photosynthesis declines and early signaling events.
*Degenerative phase: dismantling of cellular constituents degradation of macromolecules.
*terminal phase: loss of cellular integrity; cell death; leaf abscission (shedding).

Question 20

What light typically gets absorbed by leaves that do not have chlorophyll?

Answer 20

The light blues and some greens.

Question 21

treatments with cytokinin in plants do what?

Answer 21

delay leaf senescence

Question 22

ethylene gas in plants do?

Answer 22

promote fruit ripening.

Question 23

Ripening in fruits describe what?

Answer 23

the transition to aging and death of plant tissues. This facilitates reproduction by facilitating seed dispersal and preparing the seed-bearing organ for detachment from the plant.

Question 24

do all fruits require ethylene for ripening?

Answer 24

No. non ethylene ripening plants ripen by ABA.

Question 25

Climacteric fruit?

Answer 25

ripen by a response of ethylene.

Question 26

what is the structure of ethylene?

Answer 26

gaseous, non-polar, hydrophobic molecule that freely diffuses across the plasma membrane.