4.4

Question 1

homeostasis

Answer 1

condition in which internal conditions of body remain constant despite outside changes

Question 2

negative feedback

Answer 2

helps an organism maintain homeostasis by regulating physiological processes and counteracting changes as they are detected

Question 3

steps of negative feedback

Answer 3

sensor detects stress, control center receives info and sends message to adjust stress, effector receives message, produces response to reestablish homeostasis

Question 4

positive feedback

Answer 4

amplifies responses in biological organisms, moves variable away from set point

Question 5

characteristics of positive feedback

Answer 5

time limitation- processes in body that must be completed within time frame are often modified by + feedback, intensification of stress- initial imbalance is intensified

Question 6

hormone

Answer 6

signaling molecule (long distance) produced in small amounts where it triggers response in target cells

Question 7

tropism

Answer 7

growth response that results in plant curvature toward or away stimuli

Question 8

phototropism

Answer 8

toward or away from light

Question 9

auxin

Answer 9

any chemical that promotes elongation of coleoptiles- produced predominantly in shoot tips, moves to regions of cell elongation

Question 10

acid growth hypothesis

Answer 10

protein pumps play major role in growth response to auxin, auxin stimulates plasma membrane’s proton (H+) pumps which lowers pH, acidification activates enzymes called expansions that break H bonds in cell wall loosening wall, increased turgor and cell wall plasticity cause elongated cell

Question 11

cytokinins

Answer 11

class of plant hormones that retard aging

Question 12

apical dominance

Answer 12

ability of apical bud to suppress development of auxiliary buds

Question 13

gibberellin

Answer 13

stimulates growth in stem and leaves

Question 14

abscisic acid (ABA)

Answer 14

stunts growth, antagonizes effects of growth hormones, drought tolerent

Question 15

ethylene

Answer 15

gaseous plant hormone responsible for cell death, response to mechanical stress for cell death

Question 16

triple response

Answer 16

plant maneuver in response to mechanical stress, stem grows horizontally

Question 17

senescense

Answer 17

programmed death of cells/plant, plant salvages breakdown products, associated with a burst of ethylene

Question 18

abscission layer

Answer 18

leaves change colors when abscission layer forms, sugar is no longer supplied and chlorophyll breaks down

Question 19

regulator

Answer 19

animal for which mechanisms of homeostasis moderate internal changes in face of external fluctuation of a variable

Question 20

conformer

Answer 20

animal for which internal condition changes with changes in environmental variable

Question 21

interstitial fluid

Answer 21

fluid that surrounds body cells

Question 22

set point

Answer 22

value maintained for particular variable

Question 23

sensor

Answer 23

receptor that detects stimulus

Question 24

response

Answer 24

physiological activity that helps return variable to set point

Question 25

thermoregulation

Answer 25

process by which animals maintain body temperature within normal range

Question 26

endothermic

Answer 26

warmed by heat generated by metabolism

Question 27

ectothermic

Answer 27

gain heat from external sources

Question 28

4 processes of thermoregulation

Answer 28

radiation, evaporation, convection, and conduction, heat transferred from high to low temperature

Question 29

vasodialation

Answer 29

widening of superficial blood vessels, blood flow in outer layer of body increases, warms skin and increases transfer of body heat to environment

Question 30

countercurrent exchange

Answer 30

transfer of heat between fluids flowing in opposite directions, ex: warm blood moving to body core, cold to extremities, heat exchange between

Question 31

acclimatization

Answer 31

physiological adjustment to environmental changes, ex: unsaturated lipids keep membranes fluid at lower temperatures, sensors responsible for thermoregulation in hypothalamus