Animal adaptations

Question 1

define stenohaline organism

Answer 1

lives in a constant salinity (narrow range) and can be freshwater or marine

Question 2

define euryhaline organism

Answer 2

can live in a wider range of salinities. can be freshwater or marine and can be short term or long term

Question 3

what is a short term euryhaline organism

Answer 3

lives in intertidal regions and estuaries where there are short term fluctuations in salinity

Question 4

what is a long term euryhaline organism

Answer 4

they live part of their life cycle in one salinity and the other part of their lifecycle in a different salinity. this is called being diadromous and this is split into catadromous and anadromous

Question 5

what is a catadromous organism and give an example

Answer 5

these mostly live in freshwater but move into a marine environment to breed eg. eels

Question 6

what is an anadromous organism and give an example

Answer 6

these mostly live in a marine environment but move to a freshwater environment to breed eg. salmon

Question 7

what is an osmoconformer and what group are usually osmoconformers.

Answer 7

an osmoconformer changes its internal osmolarity to match the external osmolarity. this tends to be invertebrates although there is an exception, the hagfish which produces hydrogel.

Question 8

what are osmoregulators and what group are usually osmoregulators

Answer 8

osmoregulators keep their internal osmolarity constant despite changes to the external osmolarity. this is usually done by vertebrates such as elasmobranchs and teleost fish.

Question 9

what does it mean to be hyperosmotic and give an example

Answer 9

hyperosmotic organisms have an internal osmolarity that is higher than the external osmolarity such as in elasmobranchs

Question 10

what does it mean to be hypoosmotic and give an example

Answer 10

hypoosmotic organisms have internal osmolarity that is lower than the external osmolarity for example marine teleost fish

Question 11

what does it mean to be ureotelic and give an example

Answer 11

ureotelic organisms include the marine elasmobranchs which raise their internal osmolarity higher than the external osmolarity of seawater so that water can move into the the fish by osmosis. they raise their internal osmolarity using urea.

Question 12

what does it mean to be ammonotelic and give an example

Answer 12

freshwater elasmobranchs such as freshwater rays are an example of an ammonotelic organism. they dont need to convert the ammonia they produce into urea because in freshwater, they can dilute the ammonia so it’s not at toxic levels.

Question 13

how do ureotelic marine elasmobranchs prevent the toxic effects of urea

Answer 13

urea is toxic because it can denature proteins and this is prevented by using trimenthylamineoxide (TMAO) to stabilise the proteins.

Question 14

why is it an advantage to be a euryhaline elasmobranch and how are they able to move between marine to freshwater

Answer 14

its an advantage because it opens up another niche where there is less competition from other elasmobranchs (as not all of them are euryhaline). they can move to freshwater by lowering their internal osmolarity - they excrete urea and TMAO. to move back to marine they just start producing and storing urea, TMAO and other salts again.

Question 15

what adaptation allows marine elasmobranchs to excrete excess salt. and describe how it works

Answer 15

rectal gland which is found at the end of the intestine. 1.it uses a Na+,K+ pump (Na+ out into the blood and K+ into the cells of the rectal gland) to set up a conc gradient for Na+.
2. then a symporter for Na+, Cl- and K+ transports the Na+ back into the rectal gland cells down its conc gradient. the important part of this step is that Cl- is also transported in.
3. Cl- builds up and then diffuses out of the rectal gland cells into the rectal lumen.
4.Na+ diffuses directly from blood to rectal lumen through tight junctions between rectal gland cells to follow Cl-. it moves down the electrochemical gradient (+ve to -ve)
5.then both the Na+ and Cl- can be excreted.

Question 16

in marine elasmobranchs how is urea prevented from diffusing out of the gills

Answer 16

1. pump urea away from the gills and into the blood.
2. gill membranes contain sphingolipids on the side facing the external environment (these are more densely packed to make it less permeable to urea).

Question 17

describe the mechanism for pumping urea away from the gills and into the blood in marine elasmobranchs

Answer 17

Na+, K+ pump pumps Na+ out of the gills and sets up a conc gradient. then an antiporter moves one Na+ back in down its conc gradient in exchange for one urea molecule out into the blood. some urea will diffuse back in but the cells will continue to pump it out

Question 18

how is the kidney adapted in marine elasmobranchs to retain as much water as possible.

Answer 18

the kidney has multiple loops of Henle (counter current multiplier). this means that the urine is very concentrated as as much water has been reabsorbed into the blood as possible.

Question 19

how do euryhaline elasmobranchs control excretion of salts

Answer 19

they can control how much salt is excreted by changing the number of luminal pumps in the nephrons as well as from using the counter current multiplier system. (need to excrete more salt when moving into a freshwater environment).

Question 20

what is the natriuretic peptide system

Answer 20

part of the endocrine regulation in marine elasmobranchs. it is stimulated when internal conditions are too concentrated.
-increases urine production to excrete the excess urea.
-stimulates salt secretion from the rectal glands
-inhibits drinking to prevent taking in more salts.
-relaxes blood vessels to lower blood pressure which would be high due to high salt content

Question 21

what is arginine vasotocin

Answer 21

part of the endocrine regulation of marine elasmobranchs. stimulated when internal osmolarity is too low.
-reduces urine production to increase plasma osmolarity

Question 22

what is the renin angiotensin system

Answer 22

part of the endocrine regulation of marine elasmobranchs. stimulated when the blood pressure is too low, to increase it.
- reabsorbing more salt and therefore more water ( reducing urine)
-vasoconstriction
-increases drinking

antagonistic to the natriuretic peptide system

Question 23

what is the marine elasmobranch metabolic cost

Answer 23

has to use a lot of ATP and dietary protein to produce high amounts of urea.

Question 24

what are the challenges for a freshwater teleost

Answer 24

external osmolarity is lower than internal osmolarity so water moves in and salt moves out. therefore, they need to be able to secrete excess water (high volume of dilute urine) and retain salts for effective metabolism.

Question 25

what challenges do marine teleosts face

Answer 25

the external osmolarity is higher than internal osmolarity so water will move out and salts will move in. therefore water needs to be conserved and excess salts excreted. their urine has a low volume and high concentration.

Question 26

what is the difference between marine elasmobranchs and marine teleosts

Answer 26

marine elasmobranchs are hyperosmotic (so water moves in) and marine teleosts are hypoosmotic (so water moves out). therefore, marine teleosts have to drink to take in water and this leads to them also taking in large amounts of salt with the water.

Question 27

what adaptation do marine teleosts have to allow them to remove excess salts

Answer 27

gill chloride cells these are really similar to rectal gland cells. 1. Na+ is pumped out by the Na+, K+ pump, setting up a conc gradient 2. Na+ flows back in via Na+, K+, Cl- symporter. 3. Cl- builds up and diffuses into the water through a transport protein. 4. Na+ follows Cl- as it moves down the electrochemical gradient (+ve to -ve)

Question 28

how do freshwater fish retain salts

Answer 28

gill chloride cells. they pump Na+ away from the gill chloride cells into the blood using the Na+, K+ pump. then Na+ can diffuse from the water into the gill chloride cells through Na+ uniporters or Na+, K+, Cl- symporters .

Question 29

what adaptations do euryhaline teleosts have

Answer 29

short term euryhaline teleosts have both gill mechanisms for importing and exporting salt. long term (diadromous) euryhaline teleosts have one mechanism and then will make extensive changes to the gill to convert to the other mechanism. in this case the gill chloride cells change their form in response to hormones.

Question 30

what is the impact of aquaculture on euryhaline teleosts

Answer 30

aquaculture causes stress in the fish and so their gill permeability increases and they are less able to regulate their internal osmolarity. this makes them less able to acclimatise to new conditions.

Question 31

what adaptations do marine mammals have to overcome the challenges of a high salt environment.

Answer 31

they dont have rectal glands or gill chloride cells of fish or the salt glands of seabirds. therefore, cetaceans such as whales and dolphins dont usually drink water as they would have a high salt intake from this. instead they use metabolic water and water from their food. their food is therefore hypo or iso osmotic (teleosts).

Question 32

what is an endotherm and give an example of a group of endotherms

Answer 32

endotherms keep their internal body temperature regulated despite changes in the external temperature. eg. mammals and birds

Question 33

what is an exotherm and give an example of a group of exotherms

Answer 33

an exotherm cannot regulate its internal temperature but conform to the external temperature. this includes reptiles and amphibians.

Question 34

what is homeothermy

Answer 34

having a constant internal temperature (narrow range)

Question 35

what is poikilothermy

Answer 35

having a wider range of survivable temperatures

Question 36

what is the difference between adaptation and acclimation

Answer 36

adaptation is an evolutionary adjustment by natural selection to long term environmental conditions. acclimation is the physiological adjustment due to phenotypic plasticity to short term environmental fluctuations

Question 37

what are the three generic responses to a change in environment

Answer 37

avoid, conform, regulate

Question 38

what types of organisms do freeze avoidance and give some examples

Answer 38

cold adapted ectotherms anhydobiosis/cryptobiosis-drying out to prevent freezing (tardigrades do this) vitrification- liquid has glass like state when cooled so that glass crystals dont form and damage cells. antifreeze- in fish

Question 39

in what type of organism is freeze tolerance and give an example

Answer 39

cold adapted ectotherm wood frogs freeze extracellular fluid but maintain high levels of solutes in the brain and intracellular fluid so that they dont freeze. this allows the frog to stay alive whilst frozen.

Question 40

what is the thermoneutral zone

Answer 40

the temperature range where the metabolic rate doesn't change

Question 41

what is the effect on metabolic rate when the conditions get too cold for endotherms. what is the name of the temperature when this starts to occur.

Answer 41

the metabolic rate increases to release more heat lower critical temperature

Question 42

what is the effect on metabolic rate when the conditions get too hot for endotherms what is the name of the temperature when this starts to occur.

Answer 42

the metabolic rate decreases to stop releasing as much heat upper critical temperature

Question 43

what are the names of the temperatures at which the organisms cant survive

Answer 43

lower lethal temperature and upper lethal temperature.

Question 44

what kind of responses occur when the upper and lower critical temperatures are exceeded, in ectoderms and endoderms

Answer 44

when upper critical temperature is exceeded: -vasodilation -sweating -behavioural eg. find shade -lower metabolic rate when lower critical temperature is exceeded: -vasoconstriction -shivering -behavioural eg. sunbathing or exercise. -increased metabolic rate -diet induced thermogenesis -non-shivering thermogenesis ectoderms rely on behavioural rather than physiological response

Question 45

what do peripheral receptors do

Answer 45

monitor the temperature of the skin (external temperature)

Question 46

what do central receptors

Answer 46

monitor the temperature of the blood (internal temperature).

Question 47

where are the signals from the central and peripheral receptors integrated

Answer 47

anterior hypothalamus-heat loss centre posterior hypothalamus- heat production and conservation centre

Question 48

which is dominant, the peripheral sensors or the central sensors

Answer 48

central sensors.

Question 49

what factors other than temperature receptors influence thermoregulatory responses

Answer 49

-humidity -calorie intake (cold intolerant if calorie intake is low)

Question 50

what is the process of generating heat called

Answer 50

thermogenesis

Question 51

what is non-shivering thermogenesis? there are 2 methods

Answer 51

-heat produced as a waste product of the futile cycling of gluconeogenesis and glycolysis (this cant happen in humans as it is reciprocally regulated but bees can do this). -heat produced by brown adipose (human babies can do this because they cant yet shiver, and then it's usually lost by adulthood).

Question 52

how does brown adipose differ from normal adipose

Answer 52

has small lipid droplets with high surface area so that lipids can be rapidly broken down. has more mitochondria

Question 53

how does brown adipose generate heat in non-shivering thermogenesis

Answer 53

brown adipose has uncoupling protein which uncouples oxidative phosphorylation when stimulated by the sympathetic NS. Instead of H+ going through ATP synthase in the mitochondria, it goes through UCP1 (uncoupling protein 1) which dissipates the energy as heat.

Question 54

what signalling occurs to stimulate non-shivering thermogenesis in brown adipose

Answer 54

1.when cold sympathetic NS is stimulated 2.noradrenaline is released at G-protein coupled receptors called Beta receptors on the brown adipose cell membrane. 3. g-protein coupled receptors stimulate the cAMP pathway of cell signalling to phosphorylate and activate PKA. 4. PKA stimulates a transcription factor for uncoupling protein 1 (UCP 1) production. 5. cAMP pathway also stimulates breakdown on triacylglycerol and Beta-oxidation 6. products of beta oxidation enter electron transport chain which sets up proton gradient 7. protons move through UCP1 dissipating energy as heat.

Question 55

give three examples of animals which use brown adipose other than humans

Answer 55

-rats produce more in the winter to acclimatise to the cold. -bats use it to warm up after hibernation -pigs have the gene for it but it has a mutation that means they can't do non-shivering thermogenesis and are therefore vulnerable to the cold as new-borns.

Question 56

what 2 plants use uncoupling proteins

Answer 56

-potatoes use uncoupling proteins to increase cold tolerance -skunk cabbage uses the aroma of rotting flash and also heats itself to the temperature of a rotting animal using uncoupling proteins, to attract flies for pollination. this is not using brown adipose

Question 57

describe diet induced brown adipose tissue recruitment in mice and why they do this.

Answer 57

low protein, high fat diet would lead to the mouse becoming very fat. therefore it increases brown adipose levels so that it can get rid of excess calories by dissipating it as heat. this is less energy efficient but it means the mouse doesn't get as fat. this process is regulated by leptin.

Question 58

in adults where is brown adipose likely to be retained and who is likely to retain it or lose it

Answer 58

around the shoulder blades. women more likely to retain it than men hard to detect in people with diabetes. people who are obese are more likely to have lost it. so, is brown adipose regulating our body composition or is our body composition regulating brown adipose?

Question 59

what is 2,4-dinitrophenol

Answer 59

same role as UCP1- dissipates voltage as heat. found in diet pills and munitions factories. people do lose weight but it is also lethal as it can cause malignant hyperthermia (overheating). does link brown adipose to weight loss so a good case study for the potential biomedical applications of inducing brown adipose.

Question 60

name the fins found on fish

Answer 60

pelvic/ventral fins (paired)-upper part of the ventral side pectoral fins (paired)-on the side dorsal fin (singular)-on the back anal fin (singular) -lower part of the ventral side tail/caudal fin (singular)

Question 61

what is the significance of paired fins for the evolution of locomotion

Answer 61

paired fins are the phylogenetic source of tetrapod limbs. over time they developed to support the weight of the organism and allowed the transition onto land.

Question 62

what are the functions of fins in water

Answer 62

-stability- controls pitch (up and down), roll (rotation) and yaw (side to side). -steering like a rudder of a boat -braking action

Question 63

what is the structure of a fin

Answer 63

bones in order of size (largest to smallest) from proximal to distal end of the fin): girdle basals radials dermal fin rays (most distal)-keratinised in elasmobranchs, ossified or chondrified in bony fish.

Question 64

what are the three types of fin (shape wise). describe their shape and give an example.

Answer 64

-ray finned (narrow base, broad fin eg. clown fish) -lobe finned (fleshy muscular lobe at the base eg. Sarcopterygii such as coelacanth and lungfish) -fin fold fins (broad base narrow fin eg. Chondrichthyes such as sharks)

Question 65

what is significant about the lobed paired pectoral and pelvic fins of the coelacanth and lungfish

Answer 65

they have a central appendage which is a bone running down the centre of the fin. this suggests it was the precursor to tetrapod limbs because it would be useful for supporting the body of the fish on land. coelacanths have a ball and socket joint at the girdles.

Question 66

describe locomotion in water

Answer 66

there is lateral undulations caused by sequential contraction of each side of the body and the caudal fin sweeps from side to side. The resistance of the water against the fins is what causes the forward movement.

Question 67

describe early terrestrial locomotion

Answer 67

fins cant support body weight so the ventral side of the fish remains on the ground. one pectoral fin is planted on the ground and acts as a peg for the fish to pivot around and move forward using the same lateral undulations as in water. repeated using the other pectoral fin.

Question 68

describe an investigation using bashir fish that shows plasticity and could indicate how terrestrial locomotion may have developed

Answer 68

one group of Bashir fish were brought up terrestrially and another group in water. the terrestrial ones displayed developmental plasticity as they lifted their heads higher and planted their fins more efficiently than the ones raised in water. their musculature and bones were also different and demonstrated similar changes to those seen in the fossil record when the transition to land was made.

Question 69

what is the significance of tiktaalik and give three features.

Answer 69

the intermediate between lobed finned fish and tetrapod. 1. could plant fins and support itself well on flexible distal fin elements (like wrists and ankles). 2. had lungs as well as gills 3. eyes on the top of the head instead of the sides.

Question 70

what are tetrapods

Answer 70

4 footed all tetrapod limbs have the same basic plan.

Question 71

describe the basic plan of a tetrapod limb (proximal to distal)

Answer 71

humerous-radius and ulna-carpals-metacarpals-phalanges. femur-tibia and fibula-tarsals-metatarsals-phalanges.

Question 72

describe early tetrapod limbs

Answer 72

-short -horizonal first section

Question 73

describe the locomotion of early tetrapods

Answer 73

walk similarly to fish moving laterally around a peg, possible due to the axial torque of the vertebral column which allows the limbs to be lifted (have to move the limb forward in an overarm fashion which is inefficient).

Question 74

how did early tetrapods maintain stability

Answer 74

-living partially in water (stability from buoyancy). -belly walking for another point of contact with the ground. -tail on the ground for another point of contact (tripodal- front leg, opposite back leg and tail form a triangle) -development of a lateral sequence gait

Question 75

what are perpendicular limbs

Answer 75

limbs are drawn up under the body, first section does from horizontal to vertical.

Question 76

why are perpendicular limbs more efficient than horizontal limbs

Answer 76

in a horizontal limb, the adductor muscles in the thigh are constantly contracted which expends a lot of energy. this isn't the case in perpendicular limbs. Additionally perpendicular limbs can swing underarm which uses less energy than an overarm swing in a horizontal limb.

Question 77

what did the development of perpendicular limbs lead to

Answer 77

bipedalism (walking on two legs instead of four) eg. dinosaurs, birds and some reptiles.

Question 78

what evolutionary steps led to bipedalism

Answer 78

1. back limbs lengthened and strengthened. 2. knees rotated anteriorly and toes point forwards allowing the limb to swing like a pendulum. 3. lateral to vertical flexion in the vertebral column

Question 79

what is vertical extension of the vertebral column useful for

Answer 79

increasing stride length eg cheetah

Question 80

what are the types of terrestrial locomotion (6)

Answer 80

cursorial- running fossorial-digging saltatorial-hopping arboreal- trees (split into brachiation- swinging and scansorial- climbing with claws)

Question 81

what are adaptations required for fossorial locomotion

Answer 81

-fusiform body shape (spindle shaped) -loss of eyes (don't need them and would increase risk of infection) -lack of tail (would increase drag) - loss of ears (would create drag and increase risk of infection). -modified forelimbs (short and stout with long claws for digging)

Question 82

what are the types of locomotion for organisms with no limbs such as snakes (4)

Answer 82

-serpentine/lateral undulations (alternate contraction of each side of the body) -rectilinear (in a straight line) -concertina (coil up then straighten forwards) -sidewinder (lateral undulation with parts of the body not in contact with the floor to reduce friction- move diagonally).

Question 83

why are there no biological wheels and name an exception

Answer 83

not suitable for uneven terrain so limbs favoured. exception is flagellum.

Question 84

what is the equation for measuring the speed of cursorial animals

Answer 84

speed= stride length x rate of stride

Question 85

what is the average max speed of a cheetah

Answer 85

70-75 mph

Question 86

what is the paradox that you encounter when trying to maximise speed of cursorial animals. describe the solution to this problem.

Answer 86

to maximise stride length you should lengthen the limbs but this increases their weight which decreases the rate of stride. the solution is lengthening the limbs but using more tendons instead of muscle to make the limbs lighter.

Question 87

state and describe the three types of foot posture. give examples.

Answer 87

-plantigrade (phalanges/digits, metatarsels, tarsels and heel in contact with the ground eg. humans and squirrels). -digitigrade (phalanges/digits in contact with the ground but metatarsals, tarsals and heel off of the ground eg. dogs) -unguligrade (similar similar to digitigrade but less digits and lengthened metatarsals and tarsals eg. deer).

Question 88

give four adaptations needed to increase stride length in cursorial animals.

Answer 88

- lengthened limbs and appropriate foot posture - floating clavicle (provides wider range of movement because it is absent or reduced and not articulated with the scapula and sternum) - reorientation of the scapula (in the same plane as the humerous rather than over the back) - vertical flexion and flexibility of the spine (so that the hind legs can overtake the forelegs)

Question 89

why cant a horse run faster than a cheetah despite its longer legs

Answer 89

horses have less flexible spines so their back legs cant over take their forelegs and they have a shorter stride length as a result.

Question 90

give four ways that the rate of stride can be increased

Answer 90

-position of the insertion of the muscle at the joint (proximal-closer to the joint- leads to increase in speed and distal -further from the joint- leads to strength) -replace muscle with tendons which are lighter and reduce energetic cost as use elastic potential energy. - reduce number of digits to reduce weight

Question 91

what are the types of gait (6) in order from slowest to fastest

Answer 91

walk amble trot pace gallop pronk

Question 92

what is a walk pattern of footfalls

Answer 92

right forelimb right hindlimb left forelimb left hindlimb

Question 93

how many independent footfalls and how many points of contact are there in walk

Answer 93

4 independent footfalls 3 points of contact

Question 94

what is an amble

Answer 94

has the same pattern of footfalls as a walk but is quicker. used to large animals such as elephants when they want to move faster but they cant break out of a walk into a trot as they are restricted by their size.

Question 95

what is the pattern of footfalls in a trot

Answer 95

right forelimb and left hindlimb left forelimb and right hindlimb (diagonals)

Question 96

how many independent beats are in a trot and how many points of contact

Answer 96

2 beat gait 2 points of contact

Question 97

what is the pattern of footfalls in a pace

Answer 97

right forelimb and right hindlimb left forelimb and left hindlimb

Question 98

how many independent beats in a pace and how many points of support are there

Answer 98

2 beat gait 2 points of contact

Question 99

what is the advantage of the pace over the trot

Answer 99

there is less likelihood of interference between forelimbs and back limbs (overreach). A trot has a diagonal sequence where a forelimb goes back as a hindlimb goes forward. A pace doesn't have this and so it is less likely to result in injury.

Question 100

what is the pattern of footfalls in a gallop (there are two types, name these and state whether there is most momentum from the forelimbs or the hindlimbs).

Answer 100

transverse gallop-horse (most momentum from hind limbs) right forelimb left forelimb right hindlimb left hindlimb rotary gallop-cheetah (most momentum from the forelimbs) right forelimb left forelimb left hindlimb right hindlimb

Question 101

how many independent beats in a gallop and how many points of contact are there

Answer 101

4 beat gait has a point of suspension where all four limbs are off of the ground

Question 102

what is a pronk

Answer 102

a gait more for social display than locomotion. it is a hop with a moment of suspension when all limbs are off of the ground. all the limbs leave the floor at once and land back on the floor at once. eg. lamb

Question 103

describe human locomotion

Answer 103

bipedal. can walk with a two beat gait can run to increase the speed of locomotion. A walk has no suspension but a run does have suspension to lower energetic cost.

Question 104

why is it hard for humans to maintain an upright posture?

Answer 104

-they are bipedal so there is only two point support -the top part of the body is the heaviest so the centre of gravity is off balance

Question 105

what skeletal adaptation allows humans to maintain an upright posture

Answer 105

the pelvis tilts backwards to make the lumbar region of the spine concave rather than convex. in apes the spine is one smooth curve rather than having multiple curves.