Exam 3 study guide

Question 1

Halophytes

Answer 1

salt-tolerant plants with adaptations such as salt glands that pump salts out across the leaf epidermis

Question 2

Thigmomorphogenesis

Answer 2

the changes in form due to mechanical perturbation

Question 3

Thigmotropism

Answer 3

Directional growth in response to touch

Question 4

Action Potentials

Answer 4

Electrical impulses that travel through a plant

Question 5

Gravitropism

Answer 5

Responses to gravity

Question 6

Photoperiodism

Answer 6

A physiological response to specific night or day lengths (such as flowering)

Question 7

Long Day Plant (Short Night Plant)

Answer 7

requires a light period longer than a certain number of hours (14), (Flowers only if the night is shorter than a critical dark period)

Question 8

Short Day Plant (Long Night Plant)

Answer 8

requires a light period shorter than a critical length to flower (Flowers when night exceeds critical dark period)

Question 9

Day-neutral Plants

Answer 9

Unaffected by photoperiod and flower when they reach a certain stage of maturity

Question 10

Phytochromes

Answer 10

another class of photoreceptor that regulate plant responses to light such as seed germination and shade avoidance

Question 11

Red Light

Answer 11

promotes germination and can interrupt night length (plants synthesize phytochrome r)

Question 12

Far-red light

Answer 12

inhibits germination and can reverse the night interruption by red light

Question 13

Phototropism

Answer 13

the light-induced opening of stomata and light-induced slowing of hypocotyl elongation which occurs when a seedling breaks the ground

Question 14

Cryptochromes

Answer 14

blue light photoreceptor involved in the inhibition of stem elongation

Question 15

Photomorphogenesis

Answer 15

The growth and developmental responses to light

Question 16

Fruit ripening

Answer 16

a burst of ethylene production triggers ripening process, Enzymatic breakdown of cell wall components softens the fruit, Conversion of starches and acids to sugars makes the fruit sweet, Production of new scents and colors helps make the fruit appear ripe.

Question 17

Leaf abscission

Answer 17

The loss of leaves (less auxin more ethylene is leaf loss)

Question 18

Senescence

Answer 18

the programmed death of certain cells or organs or the entire plant

Question 19

Triple response

Answer 19

enables shoot to avoid obstacles
Slowing stem elongation, thickening of the stem (makes it stronger), curvature of the stem

Question 20

Ethylene (C2H4)

Answer 20

Produced in most parts of the plant, in high concentration during senescence, leaf abscission, and ripening of some fruits
Synthesis is also stimulated by wounding and stress
Promotes ripening of fruit, leaf abscission, and triple response in seedlings; enhances rate of senescence; promotes root and root hair formation and flowering in pineapple family

Question 21

Abscisic Acid (ABA)

Answer 21

Almost all cells produce it and is found in every major organ and living tissue
Inhibits growth; promotes stomatal closure during drought stress; promotes seed dormancy and inhibits early germination; promotes leaf senescence; promotes desiccation tolerance

Question 22

Gibberellins (GA)

Answer 22

Meristems of apical buds and roots, young leaves, and developing seeds
Stimulate stem elongation; pollen development, tube growth; fruit growth, seed development and germination; regulate sex determination and transition from juvenile to adult phases

Question 23

Cytokinins (CK)

Answer 23

stimulate cytokinesis or cell division
Produced in roots, but there are many minor sites of productions as well, transported to other organs
Regulate cell division in shoots and roots; modify apical dominance and promote lateral bud growth; promote movement of nutrients into sink tissues; stimulate seed germination; delay leaf senescence

Question 24

Tropism

Answer 24

a growth response that results in plant organs curving toward or away from stimuli

Question 25

Auxin (IAA)

Answer 25

any chemical substance that promotes elongation of coleoptiles Produced in shoot apical meristems, young leaves, and root apical meristem High levels found in seeds and fruits, stimulates stem elongation (low conc.) Promotes formation of lateral and adventitious roots, regulates fruit development, enhances apical dominance, aids phototropism and gravitropism, promotes vascular differentiation, retards leaf abscission

Question 26

Plant Growth Regulator

Answer 26

organic compounds, either natural or synthetic, that modify or control one or more specific physiological processes within a plant

Question 27

Etiolation

Answer 27

morphological adaptations for growing in darkness

Question 28

De-etiolation

Answer 28

a profound change caused when a shoot reaches light

Question 29

Xerophyte

Answer 29

plants adapted to arid environments (Ex. cactus)

Question 30

CAM plant

Answer 30

a plant that does a specialized form of photosynthesis in succulents, leaves take in CO2 at night, stomata close during the day

Question 31

Cavitation

Answer 31

The formation of a water vapor pocket at low pressure (in the xylem)

Question 32

Cohesion-Tension Hypothesis

Answer 32

Transpiration pulls up the xylem sap, and the cohesion of the water molecules pulls along the entire length of the xylem from the shoots to the roots

Question 33

Casparian Strip

Answer 33

A belt made of suberin (waxy material impervious to water and dissolved minerals) Located in the transverse and radial walls of each endodermal cell Forces water and minerals to pass through an endodermal cell’s selectively permeable membrane, helps keep unneeded or toxic substances out

Question 34

Endodermis

Answer 34

the innermost layer of cells in the root cortex

Question 35

Bulk flow

Answer 35

the movement of liquid in response to a pressure gradient, occurs from higher to lower pressure, independent of solute concentration

Question 36

Apoplast

Answer 36

everything external to the plasma membranes of living cells

Question 37

Symplast

Answer 37

consists of mass of cytosol of all the living cells in a plant, plasmodesmata, and cytoplasmic channels

Question 38

Routes for water and solute transportation

Answer 38

Apoplastic - water and solutes move along cell walls and extracellular spaces Symplastic - water and solutes move along cytosol, requires substances to cross plasma membrane Transmembrane route - water and solutes move from cell to cell across cell walls

Question 39

Developmental Plasticity

Answer 39

The ability to alter form in response to local environment conditions

Question 40

Three Processes of Development

Answer 40

growth, morphogenesis, cell differentiation

Question 41

Bark

Answer 41

composed of tissues external to vascular cambium (secondary phloem, periderm)

Question 42

Cork cambium

Answer 42

cylinder of dividing cells that arises in the outer cortex of stems, and the pericycle in roots

Question 43

Vascular cambium

Answer 43

a cylinder of meristematic cells between primary xylem and primary phloem

Question 44

Secondary xylem

Answer 44

forms towards the inside of the vascular cambium

Question 45

Secondary phloem

Answer 45

forms towards the outside of the vascular cambium

Question 46

Heartwood

Answer 46

older layers of secondary xylem no longer transport water and minerals, closer to the center of a stem or root