2017

Question 1

Which of the following is NOT a feature of the general vertebrate body plan?

a. A coelomic cavity
b. A ventral heart
c. Bilateral symmetry
d. Cephalisation
e. Four limbs

Answer 1

e. Four limbs

Question 2

If you have a saline drip put into the vein on your arm, which body fluid compartment will the saline enter first?

a. Blood
b. Extracellular
c. Interstitial
d. Intracellular
e. Plasma

Answer 2

e. Plasma

Question 3

A ligand-gated channel is an example of which ONE of the following functions of a plasma membrane protein?

a. Enzyme
b. Peripheral
c. Receptor
d. Structural
e. Transporter

Answer 3

e. Transporter

Question 4

Which of the following properties of exchange epithelia BEST reveals their adaptation for diffusion of gasses (O2 and CO2)?

a. Large number of mitochondria
b. Strong cell-to-cell attachment to reduce paracellular transport (movement of molecules through the spaces between adjacent cells)
c. The presence of cilia
d. Thick cell layer with large surface area
e. Thin cell layer with a large surface area

Answer 4

e. Thin cell layer with a large surface area

Question 5

The formula ABOVE describes Fick’s Law. According to this formula, how would it be possible to increase the rate of diffusion of a solute (dQs/dt) between two compartments?

a. By decreasing the concentration difference between the two compartments (dC)
b. By decreasing the concentration gradient (dC/dX)
c. By decreasing the distance separating the compartments (dX)
d. By decreasing the diffusion area (A)
e. By decreasing the diffusion coefficient (Ds) of the solute

Answer 5

c. By decreasing the distance separating the compartments (dX)

Question 6

Answer 6

Question 7

Answer 7

Question 8

When body temperature rises, the hypothalamus initiates physiological changes to decrease the body temperature. This is an example of:

a. An afferent signal response
b. An efferent signal response
c. A positive feedback loop
d. A negative feedback loop
e. Feed-forward regulation

Answer 8

d. A negative feedback loop

Question 9

Which ONE of the following is a CORRECT statement about circulatory systems?

a. In closed circulatory systems, transport molecules can move freely between the vessels and body tissues
b. Closed circulatory systems are only found in invertebrates
c. Nutrient transport in open circulatory systems is faster because it occurs via diffusion
d. Closed circulatory systems can generate higher pressures than open systems
e. Closed circulatory systems are more commonly found in animals with a low metabolic rate

Answer 9

d. Closed circulatory systems can generate higher pressures than open systems

Question 10

Answer 10

Heart rate Total peripheral resistance
decreased increased **
a.

Question 11

Which ONE of the following is a correct statement about depolarisation of a healthy mammalian heart?

a. Both ventricles depolarise together
b. Depolarisation is initiated in the semilunar valve
c. The left atrium and the left ventricle depolarise together
d. Depolarisation is initiated by nerves supplying the heart
e. The atriventricular node is specialised for quick conduction of depolarisation

Answer 11

a. Both ventricles depolarise together

Question 12

Consider blood pressure in the head, heart and feet, labelled A-F, in different body positions illustrated ABOVE (lying horizontal and standing). Which ONE of the following is a CORRECT statement about these pressures?

a. Blood pressure at A, B and C will be exactly the same
b. Gravity doesn’t affect the pressure gradient between A and B
c. The force of gravity will be higher at point F than at point A
d. Blood pressure at D will be greater than at E
e. Blood pressure at E will be greater than at F

Answer 12

b. Gravity doesn’t affect the pressure gradient between A and B

Question 13

17. Fluid is flowing into the tube illustrated ABOVE, at the point indicated by the arrow, at a flow rate of 2 L per minute. Three points along the tube are labelled 1, 2 and 3. Which ONE of the following is a correct statement about the movement of fluid in this tube?
    a. Both fluid flow and fluid velocity will be lowest at Point 2
    b. Fluid velocity will be lowest at Point 2
    c. Both fluid flow and fluid velocity will be highest at Point 2
    d. Fluid velocity will be the same at Points 1, 2 and 3
    e. Fluid flow will be lowest at Point 3

Answer 13

b. Fluid velocity will be lowest at Point 2

Question 14

Which ONE of the following is a CORRECT statement?

a. At resting membrane potential, Na+ and K+ are both at electrochemical equilibrium
b. Ionic currents can only occur if there are open ion channels in the cell membrane
c. Only excitable cells have a resting membrane potential
d. Na+/K+ ATPase pumps move K+ ions into the cell against their chemical gradient
e. Potential difference is defined as the flow of charge

Answer 14

d. Na+/K+ ATPase pumps move K+ ions into the cell against their chemical gradient

Question 15

Which of the following statements is FALSE?

a. Glial cells do not generate action potentials
b. Schwann cells myelinate peripheral nervous system axons
c. Astrocytes myelinate central nervous system axons
d. Oligodendrocytes provide support and insulation to central nervous system axons
e. Peripheral nerves can be myelinated or unmyelinated

Answer 15

c. Astrocytes myelinate central nervous system axons

Question 16

Consider the two mammalian axons ABOVE, labelled Axon A and B. Assume the axons are identical except for their diameter (as shown). Which ONE of the following is a CORRECT statement comparing Axon A and Axon B?

a. Axon A has higher resistance to current flow along the cytoplasm
b. Axon A has a lower conduction velocity
c. Both axons will have saltatory conduction of their action potentials
d. The speed of action potential conduction in both axons will depend on the size of the stimulus that triggers the action potential
e. Current leakage across the plasma membrane of both axons would decrease if they were myelinated

Answer 16

e. Current leakage across the plasma membrane of both axons would decrease if they were myelinated

Question 17

Consider the neuron shown ABOVE, with structures labelled A-C. Which ONE of the following is a CORRECT statement about these structures?

a. A is a nerve terminal whose main function is transmitter release
b. B is the soma whose main function is transmitter release
c. C is a nerve terminal whose main function is conduction of action potentials
d. A is a dendrite whose main function is receiving input signals
e. B is the axon hillock whose main function is action potential initiation

Answer 17

d. A is a dendrite whose main function is receiving input signals

Question 18

How does the illustration above demonstrate mechanical advantage in a lever system?

a. The smaller mass of the child is able to raise the adult by being positioned on the opposite side of the fulcrum.
b. The smaller mass of the child is able to raise the adult, because the child’s body is denser and more compact.
c. The smaller mass of the child is able to raise the adult due to the greater distance between the child and the fulcrum.
d. This illustration does not represent a realistic example, as the smaller mass of the child would be unable to raise the adult.
e. None of the statements are correct.

Answer 18

c. The smaller mass of the child is able to raise the adult due to the greater distance between the child and the fulcrum.

Question 19

Connective tissues are complex because they have a variety of cells surrounded in a noncellular background called the extracellular _____.

a. collagen
b. elastin
c. mucous secretion
d. matrix
e. ground substance

Answer 19

d. matrix

Question 20

Which of the following statements about the cost of locomotion is correct?

a. The metabolic cost of locomotion is dependent on velocity.
b. The costs of locomotion differ between environments because of the combined effects of gravity and fluid properties.
c. The costs of locomotion are lowest in swimmers and highest in runners.
d. Large animals have greater total costs of locomotion, although mass-specific costs are lower.
e. All of the statements above are correct.

Answer 20

e. All of the statements above are correct.

Question 21

A Q10 = 3 for a chemical process would indicate that ____________.

a. The reaction rate increases by a factor of two with a 10°C temperature rise
b. The reaction rate at 20°C will be twice that at 10°C
c. The reaction rate at 30°C will be three times that at 10°C
d. The reaction rate increases by two-fold with each 10°C temperature rise
e. The reaction rate increases by three-fold with each 10°C temperature rise

Answer 21

e. The reaction rate increases by three-fold with each 10°C temperature rise

Question 22

‘Wind chill factor’ refers to additional heat lost due to ___________________

a. Conduction
b. Convection
c. Radiation
d. Evaporation of water
e. Metabolism

Answer 22

b. Convection

Question 23

Select the option that BEST describes the thermoregulation strategy of humans.

a. poikilothermic ectothermy
b. homeothermic ectothermy
c. homeothermic endothermy
d. temporal heterothermy
e. regional heterothermy

Answer 23

c. homeothermic endothermy

Question 24

Which ONE of the following would NOT be a mechanism used by an endothermic homeotherm in response to a HOT environment.

a. Increased conductance
b. Dilation of blood vessels in the skin
c. Panting
d. Sweating
e. Increased basal metabolic rate

Answer 24

e. Increased basal metabolic rate

Question 25

Select the BEST option: Which of the following animals would you identify as using temporal heterothermy as a survival strategy?

a. Camel
b. Naked mole-rat
c. Human
d. Arctic fish
e. Reptile

Answer 25

a. Camel

Question 26

Which of the following statements is TRUE for nitrogenous waste excretion?

a. Nitrogen waste is formed from carbohydrate metabolism
b. Water is needed for the storage and excretion of uric acid and therefore there is a minimum obligatory water loss associated with this form of nitrogen excretion
c. Urea is less toxic than ammonia, requiring ten times less water for storage and excretion at non-toxic concentrations
d. Uric acid is very toxic and requires 400 ml of water to dilute each gram to a non-toxic concentration
e. Synthesis of uric acid requires less energy than urea synthesis

Answer 26

c. Urea is less toxic than ammonia, requiring ten times less water for storage and excretion at non-toxic concentrations

Question 27

A solute that has little effect on macromolecular function and can accumulate to high concentration without deleterious effects on cellular processes is called a(n) ___________________ .

a. electrolyte
b. perturbing solute
c. compatible solute
d. counteracting solute
e. organic solute

Answer 27

c. compatible solute

Question 28

What is an advantage of excreting ammonia compared with uric acid?

a. Ammonia production uses less energy than required for uric acid synthesis
b. Ammonia uses more energy than storage of uric acid crystals
c. Ammonia is not as toxic as uric acid, and can therefore accumulate in the body fluids
d. Ammonia can be stored; uric acid cannot be stored
e. Ammonia can be excreted with only small volumes of water

Answer 28

a. Ammonia production uses less energy than required for uric acid synthesis

Question 29

Vertebrates can obtain water through a number of sources. Which of the following is NOT a source of water?

a. Drinking free-standing water
b. Fat metabolism
c. Metabolic water
d. Preformed water in food
e. Respiratory evaporative water

Answer 29

e. Respiratory evaporative water

Question 30

Which of the following statements concerning mechanisms by which mammals can limit their water loss is FALSE?

a. Limiting their activity in the heat of the day (e.g. becoming nocturnal).
b. Increasing the rate at which they breathe.
c. Alter their feeding times or feeding on a selection of particular plant species.
d. Allowing their body temperature to increase in the heat, thereby saving water that would otherwise be used for evaporative cooling.
e. Switching between urea and uric acid synthesis and excretion.

Answer 30

e. Switching between urea and uric acid synthesis and excretion.
ps. ..

b is also incorrect in that increasing rate of breathing would increase water loss; however in the context of osmoregulation, animals tend to alter breath volume, not rate

Question 31

Marine birds are able to drink seawater due to their __________ and subsequent ability to excrete high concentrations of electrolytes.

a. extra large kidneys
b. creatinine wastes
c. nasal salt glands
d. ability to produce concentrated urine
e. lack of salt taste buds

Answer 31

c. nasal salt glands

Question 32

An increase in circulating concentration of anti-diuretic hormone (ADH) will result in ___________ by the collecting duct.

a. more sodium reabsorption
b. more potassium reabsorption
c. more water reabsorption
d. less water reabsorption
e. both (a) and (d)

Answer 32

c. more water reabsorption

Question 33

Which of the following parts of the nephron makes the renal medullary interstitium hypertonic via a counter current multiplier effect?

a. Glomerulus.
b. Loop of Henle.
c. Vasa recta.
d. Proximal convoluted tubule.
e. Distal convoluted tubule

Answer 33

b. Loop of Henle.

Question 34

Whilst working outdoors, a person receives a painful bee sting on the hand. Which ONE of the following receptors is most likely to be involved in the perception of this event?

a. Pacinican corpuscle
b. Nociceptor
c. Ruffini’s ending
d. Merkel’s disk
e. Meissner’s corpuscle

Answer 34

b. Nociceptor

Question 35

Which ONE of the following is a function of Type II taste receptor cells?

a. Detect salty tastes
b. Detect sour tastes
c. Act as support cells for Type III taste receptor cells
d. Communicate with afferent nerves via ATP
e. Commuicate the afferent nerves via Type I support cells

Answer 35

d. Communicate with afferent nerves via ATP

Question 36

Which ONE of the following correctly describes how the intensity of a mechanical stimulus from the skin is encoded as information transmitted to the central nervous system?

a. The amplitude of action potentials transmitted to the central nervous system is greater for a stronger stimulus
b. The frequency of action potentials transmitted to the central nervous system is greater for a stronger stimulus
c. Different afferent neurons transmit information about stimuli of varying intensities
d. Stimuli with different intensities are transmitted to different areas of the brain
e. The neurotransmitter released from an afferent neuron differs with stimuli of differing intensities

Answer 36

b. The frequency of action potentials transmitted to the central nervous system is greater for a stronger stimulus

Question 37

Which ONE of the following is a function of the anterior chamber of the eye?

a. Provide nutrients to the sclera
b. Provide nutrients to the cornea and lens
c. Focus light on the retina
d. Directs light through the pupil
e. Maintain the blood supply to the ciliary body

Answer 37

b. Provide nutrients to the cornea and lens

Question 38

Which ONE of the following receptors is the “odd one out” in relationship to its modality?

a. Organ of Corti
b. Thermoreceptor
c. Ruffini’s corpuscle
d. Meissner’s corpuscle
e. Pacinian corpuscle

Answer 38

b. Thermoreceptor

Question 39

In aquatic animals, which one of the following is a function of Ampullae of Lorenzini?

a. Navigation by magnetodetection
b. Detection of sound in the water
c. Detection of chemicals in the water
d. Prey location by echodetection
e. Prey location by electrodetection

Answer 39

e. Prey location by electrodetection

Question 40

Which ONE of the following refers to the receptor potential produced at sensory receptors?

a. Synaptic potential
b. Sensory potential
c. Detector potential
d. Generator potential
e. Efferent potential

Answer 40

d. Generator potential

Question 41

Which ONE of the following would cause bending of the stereocilia on hair cells in the cochlea in the inner ear so that potassium channels opened?

a. A sound of long duration
b. A sound of high amplitude
c. A sound of low amplitude
d. A high frequency sound
e. A low frequency sound

Answer 41

b. A sound of high amplitude

Question 42

The saccule detects movement in which ONE of the following directions?

a. Angular acceleration in the vertical plane
b. Angular acceleration in the horizontal plane
c. Linear acceleration in both the vertical and horizontal planes
d. Linear acceleration in the vertical plane
e. Linear acceleration in the horizontal plane

Answer 42

d. Linear acceleration in the vertical plane

Question 43

The uptake of nutrients across the epithelial cells of the gastrointestinal tract and into the bloodstream is called ________.

a. absorption
b. excretion
c. filtration
d. reabsorption
e. secretion

Answer 43

a. absorption **

Question 44

Which of the following best explains how a ruminant obtains glucose for neural function?

a. From glucose in the diet
b. Starch is broken down to form glucose
c. Cellulose is broken down to form glucose
d. Glucose is produced by conversion of volatile fatty acids (propionate) in the liver
e. Glucose is formed through gluconeogenesis from protein

Answer 44

d. Glucose is produced by conversion of volatile fatty acids (propionate) in the liver

Question 45

Answer 45

Question 46

The largest metabolic reserves for the average adult are stored as ________ .

a. Carbohydrates.
b. Proteins.
c. Glycogen.
d. Triglycerides.
e. Fatty acids.

Answer 46

d. Triglycerides.

Question 47

Any excess glucose in the liver that is not required for energy and not stored as glycogen will __________ .

a. Be converted into fatty acids.
b. Be converted into amino acids.
c. Be immediately released back into the bloodstream.
d. Accumulate within the cell until released.
e. Become attached to a triglyceride and be deposited into adipose tissue

Answer 47

a. Be converted into fatty acids.

Question 48

During the post-absorptive (i.e. fasting) state, glucose is released from ____________ .

a. Fatty acids stores
b. Glycogen stores
c. Muscle proteins
d. Triglycerides
e. Ketone bodies

Answer 48

b. Glycogen stores

Question 49

Which of the following statements is CORRECT regarding basal metabolic rate (BMR)?

a. BMR is a measure of the maximum rate of energy expenditure of an animal under certain controlled conditions
b. BMR represents the energy required by the body to perform the basic physiological processes that maintain life such as pumping blood and transporting ions
c. BMR is measured immediately after a meal
d. BMR is a measure of the total energy expenditure of an animal over a 24-hour period, including the costs of locomotion and thermoregulation
e. BMR is measured while the animal is asleep

Answer 49

b. BMR represents the energy required by the body to perform the basic physiological processes that maintain life such as pumping blood and transporting ions

Question 50

Which of the following is TRUE regarding respiration?

a. Carbon dioxide will diffuse from a region of low partial pressure to a region of high partial pressure of carbon dioxide.
b. The thickness of the respiratory membrane is not important in gas exchange as both carbon dioxide and oxygen readily diffuse through all tissues.
c. Gas exchange at the respiratory membrane is by bulk flow.
d. In mammals, the intrapleural space is usual less than atmospheric pressure and helps keep the lungs partially inflated.
e. Internal respiration is defined as the movement of air in and out of the lungs.

Answer 50

d. In mammals, the intrapleural space is usual less than atmospheric pressure and helps keep the lungs partially inflated.

Question 51

Which of the following is TRUE?

a. Bulk flow increases when the resistance of the airway is increased.
b. Of the lower respiratory tract, the bronchioles have the least overall impact on resistance to air flow.
c. Oxygen is 20 times more soluble in water than carbon dioxide.
d. During inspiration, the lung volume increases and as a consequence pressure in the alveoli will increase
e. The % of oxygen in the air is lower at high altitudes.

Answer 51

b. Of the lower respiratory tract, the bronchioles have the least overall impact on resistance to air flow.

Question 52

Which of the following is TRUE?

a. Reptiles use their intercostal muscles to breath which is why when they are running respiration can be affected.
b. Gas exchange in fish is cross current flow across the gills.
c. Birds have a low metabolic rate and therefore do not require an efficient system of gas exchange.
d. The lungs of the frog have a very large surface area to facilitate transfer of oxygen.
e. The avian respiratory system is very efficient as gas exchange can occur in both the air sacs and lungs.

Answer 52

a. Reptiles use their intercostal muscles to breath which is why when they are running respiration can be affected.

Question 53

Contraction of which ONE of the following muscles is involved in inspiration?

a. Diaphragm only
b. External intercostals only
c. Both the diaphragm and external intercostals
d. Abdominal muscles only
e. Diaphragm, abdominal and external intercostal muscles

Answer 53

c. Both the diaphragm and external intercostals

Question 54

Which of the following is TRUE of gas transportation in blood.

a. Oxygen is well dissolved in blood.
b. Carbon monoxide binds to a separate location on haemoglobin to oxygen and therefore does not interfere with oxygen transportation in blood.
c. Carbon dioxide is predominantly transported in blood bound to haemoglobin
d. Carbon dioxide is predominantly directly dissolved in the blood for transportation.
e. Carbon dioxide is predominantly transported in blood as bicarbonate.

Answer 54

e. Carbon dioxide is predominantly transported in blood as bicarbonate.

Question 55

Which of the following is an example of convergent evolution?

a. Similar morphology in three lineages of nectar-feeding birds
b. Large tusks in African elephants
c. Reduction in the size of homs in male bighorn sheep
d. Galapagos finches
e. Longer legs in cane toads at an invasion front

Answer 55

a. Similar morphology in three lineages of nectar-feeding birds

Question 56

Bergman’s rule states that __________ .

a. Homoeothermic animals from higher altitudes and latitudes, or bred at lower temperatures, tend to be larger
b. Surface-to-volume ratio decreases for larger objects; smaller objects lose heat faster as a consequence
c. The size of extremities (limbs, tail, ear, etc.) increases from colder to warmer climates in the same species or in closely related species
d. Bone remodelling occurs in response to intermittent stress
e. Dwarfing occurs over time when animal populations experience a restriction in territorial size

Answer 56

a. Homoeothermic animals from higher altitudes and latitudes, or bred at lower temperatures, tend to be larger
ps. ..

a is the correct definition for Bergman’s Rule. Option b explains the mechanism why it works. You would be correct selecting b but it is not the BEST option to select

Question 57

The following images illustrate mammalian red blood cells which have been placed into different solutions.

For each, indicate the tonicity of the solution involved:

Answer 57

Hypertonic

isotonic

hypotonic

Question 58

Consider the nerve action potential illustrated below. Four times on this trace are labelled A, B, C and D. Threshold potential is marked by the dotted line labelled E. For each of the sentences below, circle ALL of the times A-E that the statement accurately describes. You may choose more than one time for each statement.

a) A graded potential is firing.
Time A / Time B / Time C / Time D
b) Potassium (K+) leak channels are open.
Time A / Time B / Time C / Time D
c) There is a potential difference across the cell membrane.
Time A / Time B / Time C / Time D
d) The cell membrane potential is depolarised.
Time A / Time B** / Time C / Time D
e) The cell membrane potential is repolarising.
Time A / Time B / Time C / Time D
f) The main ion movement is sodium (Na+) flowing into the cell through regenerative opening of voltage-gated Na+ channels

Time A / Time B / Time C / Time D

Answer 58

a) A graded potential is firing.
Time A**
b) Potassium (K+) leak channels are open.
Time A** / Time B** / Time C** / Time D**
c) There is a potential difference across the cell membrane.
Time A** / Time B** / Time C** / Time D**
d) The cell membrane potential is depolarised.
Time A** / Time B** / Time C**
e) The cell membrane potential is repolarising.
Time C**
f) The main ion movement is sodium (Na+) flowing into the cell through regenerative opening of voltage-gated Na+ channels.
Time B**

Question 59

Terrestrial animals require strong bones and postural muscles. Would you expect the postural muscles to be composed predominantly ‘red’ or ‘white’ type muscle fibres and why?

Answer 59

Red (‘slow-twitch’)

2 of the following bits of info:
“red” slow twitch, oxidative muscle fibres
characteristic of efficient long-term, steady-state activity.
Requires circulating oxygen,
Produces more ATP at slow rate
Can utilise a variety of fuels (carbohydrate, protein, fat)

Question 60

\List FOUR factors that can influence the basal metabolic rate of a human.

Answer 60

Temperature
Age
Sex
Body composition
Diet

Activity
Growth and reproduction
Chemical state (i.e. drugs)

Question 61

List FOUR factors that affect gas diffusion across the respiratory membrane.

Answer 61

Surface area
Diffusion coefficient
Partial pressure gradient
Diffusion distance

Question 62

The following questions refer to the following structures:
1. Larynx
2. Trachea
3. Bronchi
4. Bronchioles
5. Alveoli
Each number may be used more than once.
a. Where is overall/total resistance the least? _________________________________
b. Where will you find ciliated epithelium? ________________________________
c. Which structure (s) has the most smooth muscle? ____________________________
d. Which structure(s) contain cartilage? __________________________________
e. In which structures will gas exchange occur? ________________________________
f. Where will you find the most goblet cells? __________________________
More than one number can be used to answer each part a to f and Numbers can be used more than once. Each part is worth ½ mark and to get the ½ mark you must include only the correct numbers.

Answer 62

The following questions refer to the following structures: (3 marks)
1. Larynx
2. Trachea
3. Bronchi
4. Bronchioles
5. Alveoli
Each number may be used more than once.
a. Where is overall/total resistance the least?

4
b. Where will you find ciliated epithelium?

1 to 4

c. Which structure (s) has the most smooth muscle? 4
d. Which structure(s) contain cartilage?

1 to 3
e. In which structures will gas exchange occur?

5
f. Where will you find the most goblet cells?

1 and/or 2

Question 63

What are the names and functions of the two main cell types in the alveoli?

Answer 63

i) Type 1 Alveolar epithelial cells (Type 1 pneumocytes) form the structure of alveoli; site of gas exchange
ii) Type 2 Alveolar epithelial cells synthesize surfactant.

Question 64

Describe four physiological advantages and four physiological constraints experienced by vertebrates due to increasing body size

Physiological advantage:

Answer 64

Greater mobility – able to access additional food and water resources
Lower relative costs of transport
Lower mass-specific metabolic rate
Larger thermal inertia
Safety - Size protects from most predators

Question 65

Describe four physiological advantages and four physiological constraints experienced by vertebrates due to increasing body size

Physiological constraint:

Answer 65

• Larger bodies mean more restrictions on body shape and its movement
• Reduced trunk flexibility e.g. fused lungs and ribcage in elephants
• Reduced limb flexion
• Skeleton modified
• compressive forces increased, shear forces reduced
• Major support shifts from muscle to bone
• Limb bones pillar-like, vertical
• Horizontal joint surfaces
• Proximal portions longer than distal
• Feet large, may be padded
• Normally all digits are retained.
• Slow reproduction means that rapid extinction can be a risk - e.g. large herbivores in the Americas when humans arrived