--Ap Bio Chapter 39

Front 1

The morphological adaptations in plants for growing in darkness are called...

Back 1

Etiolation

Front 2

What are the two names for the process that occurs when leaves expand, roots elongate, and the shoot produces chlorophyll in a plant?

Back 2

De-etiolation, or "greening"

Front 3

T/F: The real definition of de-etiolation is the changes a plant shoot undergoes in response to sunlight.

Back 3

True

Front 4

T/F: Unlike most receptors which are built into the plasma membrane, the phytochrome that functions in the de-etiolation response is located in the cytoplasm.

Back 4

True

Front 5

Small molecules and ions in the plant cell that amplify the signal and transfer it from the receptor to other proteins which then carry out the response are called...

Back 5

Second messengers

Front 6

Describe the transduction pathway of the de-etiolation response.

Back 6

Light stimulates a change in shape of the phytochrome in the cytoplasm which increases the concentration of both cGMP or Ca2+. These molecules/ions activate phosphorylation cascades.

Front 7

What are the two mechanisms by which a signaling pathway can enhance an enzymatic step in a biochemical pathway?

Back 7

Transcriptional regulation and post-transcriptional modification.

Front 8

What are the proteins called that are activated by the phosphorylation cascade started by cGMP or Ca2+, which bind to specific regions of DNA promoting transcription of this protein?

Back 8

They are called specific transcription factors.

Front 9

Specific transcription factors can be _, which increase the transcription of specific genes, or _, which decrease transcription.

Back 9

activators; repressors

Front 10

A signaling molecule that is produced by one part of an organism's body and transported to other parts, where it binds to a specific receptor and triggers responses in target cells and tissues, is called a...

Back 10

Hormone (usually active at very low concentrations) (sometimes synonymous with "plant growth regulator")

Front 11

T/F: A single hormone can influence an enormous array of plant processes, while, also, many hormones can influence a single process.

Back 11

True

Front 12

Any growth response that results in plant organs curving toward or away from stimuli is called a...

Back 12

Tropism

Front 13

The growth of a shoot toward light (positive) or away from it (negative) is called...

Back 13

Positive or negative phototropism

Front 14

Physically, how do the cells of a plant change to allow it to curve toward light?

Back 14

The cells on the darker sides elongate faster, and on the lighter side they elongate slower as to create a curve

Front 15

What specific part of a plant did the Darwin's decide was responsible for detecting light changes back in the 1800s?

Back 15

The TIP of the coleoptile

Front 16

T/F: Went's experiments shows that the coleoptile curves toward light because of a higher concentration of the growth-promoting chemical on the darker side of the coleoptile.

Back 16

True

Front 17

T/F: Finally, an asymmetrical distribution of auxin moving down from the coleoptile tip causes cells on the darker side to elongate faster than cells on the brighter side.

Back 17

True

Front 18

T/F: It is hormonal balance, rather than hormones acting in isolation, that may control growth and development.

Back 18

True

Front 19

What are the 3 ways a hormone may act?

Back 19

By altering the expression of a gene, by affecting the activity of existing enzymes, or by changing properties of membranes.

Front 20

Any chemical substance that promotes elongation of coleoptiles is called...

Back 20

Auxin

Front 21

According to what model do proton pumps play a major role in the growth response of cells to auxin?

Back 21

The acid growth hyopthesis

Front 22

T/F: Auxin activates H+ proton pumps --> cell wall acidity increases --> expansins break cellulose microfibrils --> elongation, bigger ion uptake --> osmotic uptake of water --> increase cell wall plasticity --> elongation enabled.

Back 22

True

Front 23

T/F: Auxin can also act in lateral and adventitious root formation and as a herbicide.

Back 23

True

Front 24

Why are cytokinins named as such?

Back 24

Because they promote cytokinesis, or cell division.

Front 25

T/F: The ratio of cytokinins to auxin controls cell differentiation. +c = shoot buds. +a = roots.

Back 25

True

Front 26

T/F: Auxin levels actually increase the axillary buds of decapitated plants.

Back 26

True

Front 27

By inhibiting protein breakdown, stimulating RNA and protein synthesis, and mobilizing nutrients from surrounding tissues, cytokinins...

Back 27

Promote anti-aging in plants

Front 28

T/F: Gibberellins work in harmony with auxin to create stem elongation AND cell division for growth.

Back 28

True (also help in fruit growth and germination)

Front 29

T/F: The functions of brassinosteroids are extremely similar to those of auxins.

Back 29

True (promote growth)

Front 30

What are the 3 main effects of ABA (abscisic acid)?

Back 30

Slowing of growth, seed dormancy, and drought tolerance.

Front 31

When is ethylene mostly produced?

Back 31

During mechanical stress on the plant.

Front 32

Describe the triple response that a plant undergoes when it reaches a physical barrier to its growth and ethylene is subsequently released.

Back 32

(1) Stem elongation slows, (2) the stem thickens, and (3) a curvature causes the stem to being growing horizontally, away from the barrier stopping its growth.

Front 33

The programmed death of plant cells, organs, or the entire plant itself is called...

Back 33

Senescence

Front 34

T/F: Ethylene is required for senescence and apoptosis, and is a positive feedback response in fruit ripening (sweeter and softer)

Back 34

True

Front 35

The effects of light on plant morphology are called...

Back 35

Photomorphogenesis

Front 36

T/F: Plants can detect not only the presence of light, but also it's direction, intensity, and wavelength.

Back 36

True

Front 37

What are the two major classes of light receptors?

Back 37

Blue-light photoreceptors and photochromes (mostly red light)

Front 38

What are the two subunits of a phytochrome?

Back 38

A peptide and a chromophore.

Front 39

Explain the Pr Pfr isomerism in a phytochrome.

Back 39

When exposed to red light, all Pr isomers convert to Pfr isomers and germination is stimulated. When exposed to far red light, all Pfr isomers convert to Pr isomers and germination is inhibited.

Front 40

Such cycles (say, e.g.,of the leaves of a legume going up at noon and down at midnight) which have a frequency of about 24 hours and are not directly controlled by any environmental variable are called...

Back 40

Circadian rhythms

Front 41

The relative lengths of the night and day is known as the...

Back 41

Photoperiod

Front 42

A physiological response to photoperiod, such as flowering, is called...

Back 42

Photoperiodism

Front 43

Plants which require a light period SHORTER than a critical length to flower are called...

Back 43

Short-day plants (there are also long-day plants and day-neutral plants which only flower when mature and ready, self-explanatory)

Front 44

Why are short-day plants ACTUALLY long night plants?

Back 44

Because when the day was given total darkness flowering was not affected, but if night was interrupted with light flowering would not occur.

Front 45

The use of pretreatment with cold to induce flowering is called...

Back 45

Vernalization

Front 46

What is a plants reaction to gravity called?

Back 46

Gravitropism

Front 47

What are statoliths and how do they affect gravitropism?

Back 47

They are specialized plastids containing dense starch grains which are pulled by gravity to the bottom of the seed and promote root growth at the bottom.

Front 48

The changes in form of a plant resulting from mechanical perturbation are called...

Back 48

Thigmomorphogenesis

Front 49

The directional growth of a plant (like a vine coiling around something it touches) is called...

Back 49

Thigmotropism

Front 50

Electric responses that travel throughout a plant (although slowly) in response to stimuli are called...

Back 50

Action potentials

Front 51

What proteins can used to stop the denaturaton of other proteins in excessive heat?

Back 51

Heat-shock proteins

Front 52

Pathogens against which a plant has little specific defense are said to be...

Back 52

Virulent pathogens

Front 53

Strains of pathogens that only mildly harm but do not kill the host plant are said to be...

Back 53

Avirulent pathogens

Front 54

A widespread form of plant disease resistance that involves recognition of pathogen-derived molecules by the protein products of specific plant disease resistance (R) genes is called...

Back 54

Gene-for-gene recognition

Front 55

The recognition of pathogen-derived molecules called ____ by R proteins triggers signal transduction pathways leading to the activation of an arsenal of defense responses.

Back 55

Elicitors

Front 56

A long-lasting systemic response that primes the plant for resisting a broad spectrum of pathogens is called a...

Back 56

Systemic acquired response

Front 57

The genetically programmed death of infected cells is called...

Back 57

Hypersensitive response