F: LESSON 12

Question 1

morphological
adaptations for growing in
darkness, collectively

Answer 1

etiolation

Question 2

Stages of cell signal processing

Answer 2

-reception
-transduction
-response

Question 2

exposure to light, a
potato undergoes changes
called ____________, in which
shoots and roots grow
normally

Answer 2

de-etiolation

Question 2

A potato’s response to light is an example of ___________

Answer 2

cell signal processing

Question 2

What stage: hormone or environmental stimulus binds to the receptor

Answer 2

Reception

Question 3

What stage: Relay proteins and second messengers

Answer 3

Transduction

Question 4

What stage: Activation of cellular responses

Answer 4

Response

Question 5

Reception: In de-etiolation, the receptor is a __________ capable of detecting light

Answer 5

phytochrome

Question 5

Two types of second messengers play an important role in de-etiolation:

Answer 5

Ca2+ ions and cyclic GMP (cGMP)

Question 5

The phytochrome receptor responds to light by

Answer 5

-Opening Ca2+ channels, which increases Ca2+ levels in the cytosol
-Activating an enzyme that produces cGMP

Question 5

Transduction: transfer and amplify signals
from receptors to proteins that cause responses

Answer 5

Second messengers

Question 6

Response: A __________________ leads to regulation of one or more cellular activities

Answer 6

signal transduction pathway

Question 7

response can occur by _________ or ________

Answer 7

transcriptional regulation or post- translational modification

Question 8

involves modification of existing proteins in the signal response

Answer 8

Post-translational modification

Question 9

Modification often involves the ___________

Answer 9

phosphorylation of specific amino acids

Question 10

The second messengers cGMP and Ca2+
activate___________directly

Answer 10

protein kinases

Question 11

_______________- “switch off” the signal
transduction pathways by dephosphorylating
proteins

Answer 11

Protein phosphatases

Question 12

Specific transcription factors bind directly to
specific regions of DNA and control _________

Answer 12

transcription of genes

Question 13

Some transcription factors are ________ that
increase the transcription of specific genes

Answer 13

activators

Question 14

Other transcription factors are _________ that
decrease the transcription of specific genes

Answer 14

repressors

Question 15

De-etiolation activates enzymes that

Answer 15

-Function in photosynthesis directly
-Supply the chemical precursors for chlorophyll
production
-Affect the levels of plant hormones that regulate growth

Question 16

are chemical signals that modify or
control one or more specific physiological processes within a plan

Answer 16

Plant hormones

Question 17

Each hormone has multiple effects, but multiple hormones
can influence a _______

Answer 17

single process

Question 17

Plant hormones are produced in __________, but can have profound effects on growth and
development

Answer 17

very low concentrations

Question 18

_________ depend on amount and concentration of specific hormones and often on the combination of hormones present

Answer 18

Plant responses

Question 19

The major plant hormones include

Answer 19

-Auxin -Cytokinins -Gibberellins -Abscisic acid -Ethylene -Brassinosteroids -Jasmonates -Strigolactones

Question 20

Stimulates cell elongation; regulates branching and organ bending

Answer 20

Auxin

Question 21

Any response resulting in curvature of organs toward or away from a stimulus is called a ____

Answer 21

tropism

Question 22

In the late 1800s, Charles Darwin and his son Francis conducted experiments on ______, a plant’s response to light

Answer 22

Phototropism

Question 23

Charles Darwin and Francis observed that a grass seedling could bend toward light only if the tip of the ________ was present

Answer 23

coleoptile

Question 24

They postulated that a signal was transmitted from the tip to the elongating region

Answer 24

Charles Darwin and Francis (Darwin's son)

Question 25

In 1913, __________demonstrated that the signal was a mobile chemical substance

Answer 25

Peter Boysen-Jensen

Question 26

refers to any chemical that promotes elongation of coleoptiles

Answer 26

auxin

Question 27

common auxin in plants

Answer 27

Indoleacetic acid (IAA)

Question 28

Auxin is produced in ______ and is transported down the stem

Answer 28

shoot tips

Question 29

Auxin transporter proteins move the hormone from the____________ into the a_____________

Answer 29

basal end of one cell into the apical end of the neighboring cell

Question 29

According to the ______________, auxin stimulates proton pumps in the plasma membrane

Answer 29

acid growth hypothesis

Question 29

Auxin in Cell Elongation: The proton pumps lower the pH in the cell wall, activating _______, enzymes that loosen the wall’s fabric

Answer 29

expansins

Question 29

Auxin in Cell Elongation: With the cellulose loosened, __________

Answer 29

the cell can elongate

Question 30

The Role of Auxin in Cell Elongation (Process)

Answer 30

1. Proton pump activity increases. 2. Acidity increases 3. Low pH activates expansins 4. Cell wall-loosening enzymes cleave cross-linking polysaccharides 5. Sliding cellulose microfibrils allow cell to elongate

Question 31

Auxin also alters _________ and stimulates a sustained growth response

Answer 31

gene expression

Question 32

______________ plays a role in pattern formation of the developing plant

Answer 32

Polar transport of auxin

Question 33

____________ from the shoot of a branch stimulates growth in lower branches

Answer 33

Reduced auxin flow

Question 34

Auxin transport plays a role in _______, the arrangement of leaves on the stem

Answer 34

phyllotaxy

Question 35

Polar transport of auxin from leaf margins directs __________

Answer 35

leaf venation pattern

Question 36

The activity of the ________ is under control of auxin transport

Answer 36

vascular cambium

Question 37

stimulates adventitious roots and is used in vegetative propagation of plants by cuttings

Answer 37

auxin indolbutyric acid (IBA)

Question 37

An overdose of synthetic auxins can kill plants, For example _____ is used as an herbicide on eudicots

Answer 37

2,4-D

Question 37

are so named because they stimulate cytokinesis (cell division)

Answer 37

Cytokinins

Question 38

Cytokinins are produced in actively growing tissues such as _____, ______, and _____

Answer 38

roots, embryos, and fruit

Question 39

Cytokinins work together with auxin to control ______________ and __________

Answer 39

cell division and differentiation

Question 40

e interact in the control of apical dominance, a terminal bud’s ability to suppress development of axillary buds

Answer 40

Cytokinins, auxin, and strigolactone

Question 41

If the terminal bud is _______, plants become bushier

Answer 41

removed

Question 42

Cytokinins slow the ______ of some plant organs by inhibiting protein breakdown, stimulating RNA and protein synthesis, and mobilizing nutrients from surrounding tissue

Answer 42

aging

Question 42

have a variety of effects, such as stem elongation, fruit growth, and seed germination

Answer 42

Gibberellins

Question 42

Gibberellins are produced in

Answer 42

young roots and leaves

Question 43

Gibberellins stimulate growth of

Answer 43

leaves and stems

Question 43

In stems, they stimulate cell elongation and cell division

Answer 43

Gibberellins

Question 44

In many plants, both auxin and gibberellins must be present for ______to develop

Answer 44

fruit

Question 44

Gibberellins are used in spraying of ________________

Answer 44

Thompson seedless grapes

Question 44

After water is imbibed, release of gibberellins from the embryo signals seeds to _______

Answer 44

germinate

Question 45

slows growth

Answer 45

Abscisic acid (ABA)

Question 45

Two of the many effects of ABA

Answer 45

o Seed dormancy o Drought tolerance

Question 46

ensures that the seed will germinate only in optimal conditions

Answer 46

Seed dormancy

Question 46

In some seeds, dormancy is broken when __________by heavy rain, light, or prolonged cold

Answer 46

ABA is removed

Question 46

______________ can be caused by inactive or low levels of ABA

Answer 46

Precocious (early) germination

Question 46

ABA accumulation causes stomata to _____ rapidly

Answer 46

close

Question 46

________is the primary internal signal that enables plants to withstand drought

Answer 46

Abscisic acid (ABA)

Question 46

chemically similar to the sex hormones of animals

Answer 46

Brassinosteroids

Question 47

Brassinosteroids induce _______ and ______ in stem segments

Answer 47

cell elongation and division

Question 47

Brassinosteroids also slows _______________ and promote _____________

Answer 47

Slow leaf abscission and promote xylem differentiation

Question 47

Mediate plant defenses against insect herbivores; regulate a wide range of physiological processes

Answer 47

Jasmonates

Question 47

Mediates fruit ripening and the triple response

Answer 47

Ethylene

Question 47

Regulate apical dominance, seed germination, and mycorrhizal association

Answer 47

Strigolactones