Chapter () - Animal Form and Function

Question 1

homeostasis definition

Answer 1

the maintenance of a relatively stable internal environment despite changing external conditions

Question 2

how are internal fluctuations coordinated?

Answer 2

by processes of chemical and or electrical signalling

Question 3

do homeostatic mechanisms maintain internal conditions at a constant value?

Answer 3

no, they maintain it within a relatively small range of values

Question 4

regulator definition

Answer 4

uses mechanisms of homeostasis to moderate internal change in the face of external fluctuations

Question 5

conformer definition

Answer 5

allows some conditions within its body to vary with certain external changes

Question 6

osmoregulation definition

Answer 6

management of the body’s water content and solute composition

Question 7

what percent of the earth’s surface is covered with water?

Answer 7

71% (mostly seawater)

Question 8

osmosis definition

Answer 8

diffusion of water across a selectively permeable membrane

Question 9

osmolarity definition

Answer 9

osmoles of solute particles / volume (L) (1 osmole = 1 mole of osmotically active particles)

Question 10

osmoconformer definition

Answer 10

animal that does not actively adjust its internal osmolarity because it is isoosmotic with its environment

Question 11

osmoregulator definition

Answer 11

animal whose body fluid has a different osmolarity than that of the environment
- animal that lives in a hypoosmotic environment must discharge excess water
- animal that lives in a hyperosmotic environment must take in water
- expends energy to control its internal osmolarity

Question 12

water balance in fresh water. what do the organisms have to deal with?

Answer 12

osmoregulators, gain water by osmosis and food, lose salts by diffusion and in urine, regain salts in food and by active uptake from surroundings, excrete large amounts of dilute urine

Question 13

water balance in the ocean - what do most marine invertebrates do?

Answer 13

they are osmoconformers, total osmolarity = seawater, individual [solute] does not equal seawater
- they conform to osmolarity of the ocean, but regulate internal ionic composition

Question 14

water balance in the ocean - what do most marine vertebrates do?

Answer 14

they are osmoregulators, lose water by osmosis, gain water and salt in food and by drinking seawater, dispose of salt by active transport out of gills and in urine, produce small quantities of urine

Question 15

stenohaline definition

Answer 15

organisms that cannot tolerate substantial changes in external osmolarity

Question 16

euryhaline definition

Answer 16

organisms that can tolerate substantial changes in external osmolarity

Question 17

transport epithelium definition

Answer 17

layer(s) of specialized cells that regulate solute movements
- most important feature: the ability to move specific solutes in controlled amounts in particular directions
- cells joined by tight junctions
- in most animals: arranged into tubular networks with extensive surface areas

Question 18

animals regulate solute content of body fluid that bathes their cells

Question 19

anhydrobiosis definition

Answer 19

“life without water”, the ability to survive in a dormant state when an organisms habitat dries up

Question 20

what is the largest problem with osmotic balance on land

Answer 20

desiccation; adaptations that reduce water loss are key to survival on land

Question 21

how is water loss reduced for organisms that live on land?

Answer 21

body coverings, nocturnal habit, drinking and eating moist foods, using metabolic water

Question 22

elements of homeostatic systems (3)

Answer 22

sensor, integrator, effector

Question 23

sensor in a homeostatic system

Answer 23

the sensor perceives a change and notifies the integrator

Question 24

integrator in a homeostatic system

Answer 24

the integrator compares the sensor’s input with an internal setpoint, it then gives orders to the effector

Question 25

effector in a homeostatic system

Answer 25

the effector brings about a response

Question 26

two types of control systems (which one is more common?)

Answer 26

negative feedback (more common): change in internal environment in counteracted, and positive feedback: change in internal environment is augmented

Question 27

when is positive feedback regulation typically used?

Answer 27

when there is need for an immediate response (eg dire situation) eg a blot clot after an injury uses positive feedback

Question 28

thermoregulation definiton

Answer 28

regulation of body temperature

Question 29

list the 4 physical processes that account for heat gain or loss

Answer 29

conduction, convection, radiation, evaporation

Question 30

conduction definition

Answer 30

direct contact and heat exchange between the organism and the environment (eg object on a rock)

Question 31

convection definition

Answer 31

mass movement of the air or water etc. on the organism

Question 32

radiation definition

Answer 32

either from the sun - absorption or release of heat from the organism - emission of EMR waves

Question 33

evaporation definition

Answer 33

the removal of heat energy from the surface of a liquid that is losing some of its molecules to become gaseous

Question 34

two main types of thermal strategies

Answer 34

tolerance (body temperature is allowed to vary with ambient temperature) and regulation (body temperature is not allowed to vary with ambient temperature)

Question 35

what happens when organisms regulate (anything)?

Answer 35

they pay (in the form of ATP)

Question 36

classifications based on the source of thermal energy (2)

Answer 36

ectotherm: environment determines body temp
endotherm: animal generates internal heat to maintain body temp

Question 37

classifications based on the stability of body temperature (2)

Answer 37

poikilotherm: variable body temp
homeotherm: stable body temp

Question 38

costs of ectothermy

Answer 38

inability to physiologically regulate body temp, restricted to geographical regions with appropriate ambient temps, very limited time of high activity/ energy bursts, not as good at avoiding predators through “flight”

Question 39

benefits of ectothermy

Answer 39

lower metabolic rates, slower, lower energy approach to life, requires less food/water, can function with much smaller body mass than endotherms

Question 40

costs of endothermy

Answer 40

considerable metabolic cost, requiring high metabolic rate, lots of food and water, very susceptible to dehydration in hot/dry climates, only small amount of energy budgeted for growth and reproduction

Question 41

benefits of endothermy

Answer 41

can sustain long periods of intense activity, enzymes function optimally in narrow range of body temps, can be active at times of day or year that are too cold for ectotherms, not limited to geographic areas, more likely to survive weather fluctuations

Question 42

define evaporative cooling

Answer 42

eg sweating in humans to cool the surface (skin)