Lecture 12

Question 1

Define Etiolation

Answer 1

Morphological adaptations for growing in the darkness.

Question 2

Define De-Etiolation

Answer 2

After exposure to light, a potato undergoes a change called de-etiolation, in which the shoots and roots grow normally.

Question 3

A potato’s response to light is an example of _____.

Answer 3

Cell-Signal Processing

Question 4

What are the stages of cell-signal processing?

Answer 4

Reception-Transduction-Response

Question 5

What happens in the reception stage?

Answer 5

The ligand binds to the receptor.

Question 6

What happen in the Transduction Stage?

Answer 6

Relay proteins and secondary messengers carry the signal over to where it is intended to go.

Question 7

What do plant hormones help us do?

Answer 7

Coordinate growth, development, and stimuli responses.

Question 8

Define Plant Hormones

Answer 8

Chemical signals that modify/control more specific physiological processes within a plant.

Question 9

What are the 5 plant hormones?

Answer 9

Auxin-Cytokinin-Gibberellins-Abscisic Acid-Ethylene ACG-AE

Question 10

What is something to note about the production of plant hormones?

Answer 10

They are produced in VERY LOW concentrations; however, a minute amount can greatly affect growth and development of a plant organ.

Question 11

How exactly do plant hormones control plant growth and development?

Answer 11

By affecting the division, elongation, and differentiation of cells.

Question 12

Define Tropism

Answer 12

Any response resulting in a curvature of organs towards or away from a stimulus is called tropism.

Question 13

What did Darwin and his son discover regarding plants?

Answer 13

That a grass seedling could bend toward light only if the tip of the coleoptile was present.

Question 14

Define Auxin

Answer 14

Any chemical that promotes elongation of the coleoptiles. We specifically refer to indoleacetic acid. (IAA)

Question 15

Where is IAA produced and to where is it transported to?

Answer 15

It is produced in shoot tips and it is transported down the stem.

Question 16

What does Auxin stimulate?

Answer 16

Proton pumps in the plasma membrane.

Question 17

What do proton pumps that are stimulated by Auxin do?

Answer 17

They lower the pH in the cell wall, activating expansins, enzymes that loosen the wall’s fabric and allowing the cell to expand.

Question 18

Define Expansins

Answer 18

Enzymes that loosen the wall’s fabric and allowing the cell to expand.

Question 19

What does the polar transport of Auxin play a role in?

Answer 19

Pattern formation of the developing plant.

Question 20

What does reduced Auxin flow from the shoot of a branch lead to?

Answer 20

It stimulates growth in lower branches.

Question 21

What does Auxin transport play a role in?

Answer 21

Phyllotaxy, the arrangement of leaves on the stem.

Question 22

What does the polar transport of Auxin from leaf margins direct?

Answer 22

Leaf venation (vein) pattern.

Question 23

The activity of which important system is under the control of Auxin transport?

Answer 23

The Vascular Cambium

Question 24

What does indolbutyric acid (IBA) stimulate?

Answer 24

It stimulates the adventitious roots

Question 25

Can an overdose of synthetic auxin kill plants? If so, give an example.

Answer 25

Yes, it can; 2,4-D is used as a herbicide on eudicots.

Question 26

Where are Cytokinins produced?

Answer 26

In actively growing tissues such as roots, embryos, and fruits.

Question 27

What do Cytokinins and Auxins work together to do?

Answer 27

To control cell division and cell differentiation.

Question 28

Which chemicals interact in the control of apical dominance? What does “control of apical dominance” mean?

Answer 28

Cytokinins, auxins, and strigolactone; control of apical dominance is a terminal bud’s ability to suppress development of the axillary buds.

Question 29

What happens if the terminal bud of a plant is removed?

Answer 29

A plant becomes bushier.

Question 30

What do Gibberellins affect?

Answer 30

Stem elongation, fruit growth, and germination.

Question 31

Where are Gibberellins produced?

Answer 31

They are produced in young roots, stems, and leaves.

Question 32

How do Gibberellins stimulate the growth of the leaves and stems?

Answer 32

Via cell division and elongation.

Question 33

In many plants, what has to be present for the fruit to be able to develop?

Answer 33

Auxins and Gibberellins.

Question 34

In seeds, after water is imbibed, what does the release of Gibberellins do?

Answer 34

Release of gibberellins from the embryo signals seeds to germination, and the endosperm to break down.

Question 35

What is role of Abscisic Acid?

Answer 35

It plays an important role in seed dormancy and ensures that the seed will germinate only in optimal conditions.

Question 36

When is dormancy in seeds broken down?

Answer 36

Only when ABA (Abscisic Acid) is removed by heavy rain, light, or prolonged cold.

Question 37

What internal signal allows plants to withstand drought?

Answer 37

ABA

Question 38

What does the accumulation of ABA lead to?

Answer 38

It causes the stomata to close rapidly.

Question 39

What do plants produce Ethylene in response to?

Answer 39

Stresses such as drought, flooding, mechanical pressures, and injury.

Question 40

The effects of Ethylene include response to:

Answer 40

Mechanical Stress- Senescence-Leaf Abscission-Fruit Ripening M-SAF

Question 41

What does Ethylene include and what does that thing allow for?

Answer 41

Triple Response; allows a growing shoot to avoid obstacles.

Question 42

What does the Triple Response consist of?

Answer 42

Slowing of the stem elongation, a thickening of the stem, and horizontal growth.

Question 43

Define Senescence

Answer 43

The programmed death of cells or organs.

Question 44

What is a burst of ethylene associated with?

Answer 44

Apoptosis, the programmed destruction of cells, organs, or whole plants.

Question 45

Define Leaf Abscission

Answer 45

The process that occurs in autumn when a leaf walls.

Question 46

A change in the balance of what things controls the abscission of leaves?

Answer 46

Auxin and Ethylene.

Question 47

What does a burst of ethylene production in a fruit lead to?

Answer 47

It triggers the ripening process; ethylene triggers ripening, and ripening triggers release of more ethylene.

Question 48

How do fruit producers control ripening?

Answer 48

By picking green fruit and controlling ethylene leaves.