Bms107 Exam 2010

Question 1

1. The bird and the bat wing shown opposite have bone structures that have a common origin (e.g. the bones labelled A and B in the diagram). These structures are _____________ .
   a. homologous in the bird and bat
   b. analogous in the bird and bat
   c. homoplastic in the bird and bat
   d. derived in the bird
   e. derived in the ancestor of the bird

Answer 1

a. homologous in the bird and bat **

Question 2

1. Which of the following is a distinguishing feature of chordates?
   a. Pharyngeal slits (at some stage of development)
   b. The nerve cord
   c. The ventral notochord
   d. The bilaterally symmetrical body plan
   e. The triploblastic body plan

Answer 2

a. Pharyngeal slits (at some stage of development)**

Question 3

1. Which ONE of the following statements is CORRECT?
   a. Total body water is composed of interstitial fluid and extracellular fluid
   b. The two extracellular fluid compartments of the body are interstitial fluid and plasma
   c. Total body water is defined as all the fluid within the plasma membrane
   d. All body cells contain intracellular fluid, except for red blood cells
   e. Most body cells are in direct contact with the external environment

Answer 3

b. The two extracellular fluid compartments of the body are interstitial fluid and plasma **

Question 4

1. In a mammalian cell, which of the following solutes is at higher concentration in the intracellular fluid than in the extracellular fluid?
   a. Sodium (Na+) ions
   b. Potassium (K+) ions
   c. Chloride (Cl-) ions
   d. Bicarbonate (HCO3-) ions
   e. Calcium (Ca2+) ions

Answer 4

b. Potassium (K+) ions **

Question 5

1. Which of the following is NOT a characteristic of plasma membrane transport proteins?
   a. Competition
   b. Selectivity
   c. Saturation
   d. Higher rates of transport than ion channels
   e. They can move large molecules across the plasma membrane

Answer 5

d. Higher rates of transport than ion channels**

Question 6

1. Ion channels facilitate the diffusion of ions across plasma membranes. Which of the following best explains how ligand-gated channels can be opened or closed?
   a. They open/close in response to membrane potential, e.g. K+ channels in muscle.
   b. They open/close in response to the presence of specific molecules.
   c. They open/close via interactions with subcellular proteins in the cytoskeleton of the cell e.g. change in cell shape due to muscular activity.
   d. They open due to mechanical distortion of the cell.
   e. They are controlled through all of the above mechanisms.

Answer 6

b. They open/close in response to the presence of specific molecules. **

Question 7

1. The following graph indicates the change in rate of galactose transport across a semipermeable membrane (by facilitated diffusion) when glucose is added to the solution.The best explanation why galactose transport drops in this situation is that _________ .

• Galactose molecules always need to go against a concentration gradient
• Galactose molecules always need to go down their concentration gradient
• Glucose competes with galactose for access to the transporter proteins
• There is reduced energy available for molecule transport
• The addition of glucose alters the osmotic pressure

Answer 7

Glucose competes with galactose for access to the transporter proteins **

Question 8

1. Homeostasis is defined as _________________ .
   a. the best set of environmental conditions upon which life depends
   b. the maintenance of constancy in the internal environment
   c. the prevention of detrimental changes to the body’s physiological systems
   d. the mechanisms of control and regulation of organs and organ system functions
   e. all of the above are correct

Answer 8

b. the maintenance of constancy in the internal environment **

Question 9

1. Which ONE of the following is the BEST explanation of why adrenalin has varying effects upon different tissues?
   a. Due to the presence of different receptors
   b. Due to antagonistic control of different tissues
   c. Because the nervous system preserves ‘fitness’ of the internal environment and will therefore only allow positive actions to occur
   d. Because the different levels of activity are due to varying tonic levels of activity
   e. Because adrenalin is not a very strong signal

Answer 9

a. Due to the presence of different receptors **

Question 10

1. Four organ systems exchange material between external and internal environments. Which of the following does NOT conform to this description?
   a. Endocrine system
   b. Gastrointestinal system
   c. Reproductive system
   d. Respiratory system
   e. Urinary system

Answer 10

a. Endocrine system **

Question 11

1. The 200+ types of cells in the vertebrate body are divided into four general categories (tissue types). Which of the following is NOT one of these tissue types?
   a. Connective tissue
   b. Epithelium
   c. Muscle
   d. Nervous tissue
   e. Integument

Answer 11

e. Integument **

Question 12

1. Which of the following is the BEST definition of tissues?
   a. The smallest functional ‘unit’ able to perform life processes
   b. Collections of cells performing related functions
   c. Continuous, sheet-like layer of cells in combination with a thin, underlying, non-cellular, basement membrane
   d. Anatomically discrete collections of different cell types that perform a single function
   e. The histological view of cells

Answer 12

b. Collections of cells performing related functions

Question 13

1. Glial cells are ___________ .
   a. Cells that function in metabolic support of neurons and myelin production
   b. Schwann cells & oligodendrocytes
   c. Cells that provide mechanical support for the basement membrane
   d. Cells lining the digestive tract
   e. Cells that make up nerve sheaths

Answer 13

a. Cells that function in metabolic support of neurons and myelin production **

Question 14

1. The photomicrograph ABOVE illustrates _______________ .
   a. Epithelial tissue
   b. Dense connective tissue
   c. Loose connective tissue
   d. Secretory epithelium
   e. Neurons in the brain

Answer 14

b. Dense connective tissue

Question 15

1. Which ONE of the following statements is CORRECT?
   a. Coronary arteries are required to provide blood supply to spongy myocardium.
   b. Crocodile hearts have two aortas, allowing blood to be shunted towards the lungs during diving.
   c. All endothermic homeotherms have evolved 4-chambered hearts.
   d. Amphibians have two ventricles and a single atrium.
   e. Fish (e.g. tuna) have single chambered hearts.

Answer 15

c. All endothermic homeotherms have evolved 4-chambered hearts.**

Question 16

1. Which one of the following anatomical structures is NOT part of the lower respiratory tract?
   a. Trachea
   b. Alveoli
   c. Bronchi
   d. Pharynx
   e. Bronchioles

Answer 16

d. Pharynx

Question 17

1. Which cells are responsible for producing surfactant?
   a. Goblet cells
   b. Type I alveolar cells
   c. Type II alveolar cells
   d. Alveolar macrophages
   e. None of the above

Answer 17

c. Type II alveolar cells

Question 18

1. Which ONE of the following statements best describes the muscles involved in ACTIVE EXPIRATION in mammals?
   a. Diaphragm only
   b. Both the diaphragm and external intercostal muscles
   c. Both the diaphragm and internal intercostal muscles
   d. Abdominal muscles only
   e. Both the abdominal and internal intercostal muscles

Answer 18

e. Both the abdominal and internal intercostal muscles

Question 19

1. Which of the following is NOT a function of surfactant?
   a. Decreases cohesive forces between water molecules.
   b. Decreases work of breathing
   c. Reduces surface tension
   d. Prevents alveoli from collapse
   e. Decreases compliance

Answer 19

e. Decreases compliance

Question 20

1. A reduction, below normal, in the number or volume of red blood cells is called ___________ .
   a. Cyanosis
   b. Anaemia
   c. Alkalosis
   d. Oedema
   e. Acidosis

Answer 20

b. Anaemia **

Question 21

1. The relationship shown ABOVE describes a __________ vertebrate, which has a of _________ ml O₂/g/hour.

a.

poikilotherm

3.5

b.

poikilotherm

1.5

c.

poikilotherm

1

d.

homeotherm

3.5

e.

homeotherm

1

Answer 21

e. homeotherm 1

Question 22

1. Core body temperature is regulated only a few degrees (°C) below the point at which thermal death occurs (e.g. about 42-45°C in man). Which of the choices below BEST explains why this phenomenon is likely to have evolved in vertebrates?
   a. All animals have a critical thermal maximum (CTM), above which long-term exposure can be fatal.
   b. The affinity of haemoglobin (Hb) for oxygen (O2) decreases for temperatures above the critical thermal maximum (CTM).
   c. Above the critical thermal maximum (CTM), protein denaturation is likely to occur.
   d. Physiological function is linked to the rate of biochemical processes, and therefore performance is enhanced at the higher temperatures.
   e. All of the above.

Answer 22

d. Physiological function is linked to the rate of biochemical processes, and therefore performance is enhanced at the higher temperatures.

Question 23

1. Which of the following vertebrates does NOT represent an example of temporal heterothermy?
   a. A hummingbird entering torpor.
   b. A camel absorbing heat during the day (high Ta), dissipating the heat at night (low Ta).
   c. An antelope ground squirrel making brief trips out of its burrow in order to feed.
   d. An emperor penguin constricting blood flow to its legs when standing on ice, thereby reducing the temperature of its feet.
   e. A squirrel undergoing hibernation.

Answer 23

d. An emperor penguin constricting blood flow to its legs when standing on ice, thereby reducing the temperature of its feet.

Question 24

1. Select the best option given below to describe the process of Selective Brain Cooling.
   a. Certain species have a greater number of sweat glands over their scalp, in order to preferentially keep their brains cool.
   b. Blood leaving the nasal regions (where evaporative cooling takes place) cools arterial blood before it reaches the brain via a countercurrent exchange mechanism.
   c. Animals in cold environments (e.g. in Antarctic) have less insulation over their heads, in order to keep the T_brain lower than the core temperature by increasing conductance of heat.
   d. A process valuable in reducing evaporative water loss in hot environments.
   e. Both b. and d.

Answer 24

<>e.Both b. and d.

Question 25

1. Select the BEST explanation to describe the pattern demonstrated in the figure ABOVE.
   a. The animal is failing to maintain thermal homeostasis
   b. The introduction of pyrogens to the body causes the body temperature set point to re-set at an elevated value
   c. Increased insulation results in an elevated metabolism
   d. Hypothermic and hyperthermic periods are part of the normal circadian fluctuations in body temperature
   e. Selective brain cooling results in a cooler temperature

Answer 25

b. The introduction of pyrogens to the body causes the body temperature set point to re-set at an elevated value

Question 26

1. Consider the cell ABOVE, with intracellular and extracellular concentrations of unknown cations ‘X’ and ‘Y’ as shown. Assume that the cell membrane is permeable to both ions. Which ONE of the following statements is CORRECT?
   a. The chemical (concentration) gradient for ion X+ will increase if ion Y+ is removed from the cell
   b. Ion X+ will move out of the cell down its chemical (concentration) gradient
   c. At the equilibrium potential for ion X+, the electrical gradient will move ion X+ into the cell
   d. The equilibrium potential for ion Y+ will be negative
   e. Only ion Y+ will contribute to the membrane potential of the cell

Answer 26

d. The equilibrium potential for ion Y+ will be negative

Question 27

1. Which ONE of the following statements about resting membrane potential (RMP) is CORRECT?
   a. At RMP, K+ flows into the cell down its concentration gradient
   b. At RMP, Na+ is at electrochemical equilibrium
   c. At RMP, both K+ and Na+ flow into the cell down their electrical gradients
   d. At RMP, the membrane permeability to Na+ is the same as the membrane permeability to K+
   e. At RMP, the Na+/K+ ATPase pump maintains stable fluid composition by pumping Na+ into the cell and K+ out of the cell

Answer 27

c. At RMP, both K+ and Na+ flow into the cell down their electrical gradients

Question 28

1. Which ONE of the following statements is CORRECT?
   a. At equilibrium potential, the net influx of all ions in a cell down their chemical gradient is equal to the net efflux of those ions down their electrical gradient
   b. Membrane potential is the difference in charge between the inside and the outside of a cell, measured in millivolts.
   c. An anion carries a positive charge
   d. Only excitable cells have a resting membrane potential
   e. Current flow across the cell membrane is entirely determined by the intracellular and extracellular concentrations of different ions

Answer 28

b. Membrane potential is the difference in charge between the inside and the outside of a cell, measured in millivolts.

Question 29

1. Consider a typical mammalian neuron sitting at resting membrane potential. Which ONE of the following statements is CORRECT?
   a. Calcium influx will hyperpolarise the membrane potential
   b. Chloride influx will hyperpolarise the membrane potential
   c. Sodium influx will repolarise the membrane potential
   d. Potassium efflux will depolarise the membrane potential
   e. Influx of both calcium and chloride will hyperpolarise the membrane potential

Answer 29

b. Chloride influx will hyperpolarise the membrane potential

Question 30

1. Which ONE of the following statements about action potentials is CORRECT?
   a. Threshold is the membrane potential at which regenerative opening of voltage-gated sodium channels occurs
   b. Action potentials only involve active current flow
   c. The repolarisation phase is associated with potassium influx
   d. A stronger stimulus will produce a larger amplitude action potential
   e. The depolarisation phase is caused by opening of the inactivation gate on voltage-gated sodium channels

Answer 30

a. Threshold is the membrane potential at which regenerative opening of voltage-gated sodium channels occurs

Question 31

1. Consider the diagram ABOVE and then choose ONE CORRECT statement about the cells labelled in the diagram.
   a. Cells ‘A’ and ‘B’ are both oligodendrocytes, whose function is to form myelin
   b. Cell ‘B’ is an astrocyte, whose main functions include supplying nutrients to neurons
   c. Cell ‘C’ is an oligodendrocyte, whose main functions include forming the blood-brain barrier
   d. The main function of cell ‘D’ is to clean up debris in the brain and spinal cord
   e. Cell ‘E’ is a microglia, whose main function if to line the ventricles

Answer 31

c. Cell ‘C’ is an oligodendrocyte, whose main functions include forming the blood-brain barrier

Question 32

1. Consider a cell with a potassium equilibrium potential of –90 mV and a sodium equilibrium potential of +30 mV. Which ONE of the following statements is CORRECT about the movement of ions across the cell membrane?
   a. At a membrane potential of –70 mV there will be net potassium movement out of the cell
   b. At a membrane potential of –10 mV there will be net movement of sodium out of the cell
   c. At a membrane potential of –90 mV there will be no net movement of either sodium or potassium ions
   d. At a membrane potential of –30 mV there will be no net movement of either sodium or potassium ions
   e. At a membrane potential of +30 mV, sodium influx will be exactly balanced by potassium efflux

Answer 32

a. At a membrane potential of –70 mV there will be net potassium movement out of the cell

Question 33

1. Consider the diagram ABOVE. The arrows indicate the direction of information flow. Which ONE of the following statements relating to the diagram is CORRECT?
   a. Neuron ‘A’ is a bipolar neuron
   b. Neuron ‘B’ is a central neuron
   c. Neuron ‘C’ is an afferent neuron
   d. Both neurons ‘A’ and ‘B’ are peripheral neurons
   e. Both neurons ‘C’ and ‘B’ are efferent neurons

Answer 33

d. Both neurons ‘A’ and ‘B’ are peripheral neurons

Question 34

1. What is another name for a receptor potential produced at sensory receptors?
   a. Generator potential
   b. Sensory potential
   c. Synaptic potential
   d. Detector potential
   e. Afferent potential

Answer 34

a. Generator potential **

Question 35

1. Which ONE of the following skin receptors is matched to its correct function?
   a. Merkel’s disks detect movement of hairs in the skin
   b. Ruffini’s corpuscles detect light pressure and high frequency vibration
   c. Meissner’s corpuscles detect touch and low frequency vibration
   d. Pacinian corpuscles detect heavy sustained pressure
   e. Nociceptors detect gentle mechanical stimuli

Answer 35

c. Meissner’s corpuscles detect touch and low frequency vibration

Question 36

1. When we enter a dark room after being in bright sunlight, which ONE of the following needs to occur before we can see well?
   a. Retinal and opsin molecules within the rods must bleach
   b. Retinal and opsin molecules within the rod must dissociate
   c. Retinal and opsin molecules within the cones must dissociate
   d. Retinal and opsin molecules within the rods must associate
   e. Retinal and opsin molecules within the cones must associate

Answer 36

d. Retinal and opsin molecules within the rods must associate

Question 37

1. The transduction of sound waves into neural impulses occurs in which ONE of the following?
   a. The ear ossicles
   b. The organ of Corti
   c. The semicircular canals
   d. The utricle
   e. The neuromast

Answer 37

b. The organ of Corti

Question 38

1. The saccule detects movement in which ONE of the following directions?
   a. Angular acceleration, as when nodding the head “yes”
   b. Angular acceleration, as when shaking the head “no”
   c. Angular acceleration, from side to side
   d. Linear acceleration forward and backward
   e. Linear acceleration up or down

Answer 38

e. Linear acceleration up or down

Question 39

1. Whether the hair cells in the semicircular canals are depolarised or hyperpolarised depends on which ONE of the following?
   a. The extent to which the stereocilia are bent
   b. The speed at which the stereocilia are bent
   c. The speed at which the head rotates
   d. The speed with which sodium ions enter the hair cells from the endolymph
   e. The direction toward which the stereocilia are bent relative to the kinocilium

Answer 39

e. The direction toward which the stereocilia are bent relative to the kinocilium

Question 40

Answer 40

b.

Question 41

1. Which of the following vertebrates are referred to as ‘osmo-conformers’?
   a. Sharks and rays.
   b. Marine teleosts.
   c. Freshwater teleosts.
   d. Mammals.
   e. All of the above.

Answer 41

a. Sharks and rays.

Question 42

1. What nitrogenous waste product is important in egg-laying terrestrial Vertebrates because it is relatively insoluble and non-toxic, and therefore can be stored?
   a. Ammonia.
   b. Urea.
   c. Uric acid.
   d. CO2.
   e. NO2.

Answer 42

c. Uric acid.

Question 43

1. Which of the following statements is FALSE regarding nitrogenous waste excretion?
   a. Water is needed for the storage and excretion of urea and therefore there is a minimum obligatory water loss associated with this form of nitrogen excretion.
   b. Urea is less toxic than ammonia, requiring ten times less water for storage and excretion at non-toxic concentrations.
   c. Synthesis of uric acid requires more energy than urea synthesis.
   d. Uric acid is very toxic and requires a quantity of H2O to dilute it to a non-toxic concentration.
   e. When amino acids are oxidised or converted to other kinds of molecules, the amino (NH2) group must be removed.

Answer 43

d. Uric acid is very toxic and requires a quantity of H2O to dilute it to a non-toxic concentration.

Question 44

1. Plasma is filtered from the blood and enters the renal tubule at ________.
   a. A
   b. B
   c. C
   d. D
   e. E

Answer 44

c. C

Question 45

1. The process whereby fluid is removed from the tubules of the kidney via an active process is called __________ and occurs principally at region __________ .
   a. Filtration C
   b. Filtration E
   c. Reabsorption E and D
   d. Secretion E and D
   e. Secretion C

Answer 45

c. Reabsorption E and D

Question 46

1. Which part of the nephron makes the renal medulla interstitium hypertonic via a counter current multiplier effect?
   a. Proximal convoluted tubule A
   b. Proximal convoluted tubule E
   c. Loop of Henle A
   d. Loop of Henle D
   e. Collecting duct B

Answer 46

c. Loop of Henle A

Question 47

1. The major site of storage of glycogen is the___________.
   a. liver
   b. brain
   c. skeletal muscle
   d. adipose tissue
   e. intestine

Answer 47

1. liver

Question 48

1. The largest metabolic reserves for the average adult are stored as ___________.
   a. carbohydrates.
   b. proteins.
   c. glycogen.
   d. triglycerides.
   e. fatty acids.

Answer 48

d. triglycerides.

Question 49

1. The quality of food influences the time required for its digestion as well as the amount of energy eventually released. Choose the answer below that best describes the general features of ‘high quality food’:
   a. Animals expend a minimal amount of energy to capture and eat the food, it has a higher rate of digestion, and produces more energy.
   b. Animals expend a maximal energy to capture and eat the food, it has a higher rate of digestion, and produces more energy.
   c. Animals expend a minimal amount of energy to capture and eat the food, it has a slower rate of digestion, and produces more energy.
   d. Animals expend a minimal amount of energy to capture and eat the food, it has a slower rate of digestion, and produces less energy.
   e. Animals expend a maximal amount of energy to capture and eat the food, it has a slower rate of digestion, and produces less energy.

Answer 49

a. Animals expend a minimal amount of energy to capture and eat the food, it has a higher rate of digestion, and produces more energy.

Question 50

1. During the post-absorptive state, _____________ .
   a. Blood levels of insulin and glucagon both increase.
   b. Blood levels of insulin and glucagon both decrease.
   c. Blood levels of insulin increase, whereas blood levels of glucagon decrease.
   d. Blood levels of insulin decrease, whereas blood levels of glucagon increase.
   e. Blood levels of glucagon increase, whereas blood levels of insulin do not change.

Answer 50

d. Blood levels of insulin decrease, whereas blood levels of glucagon increase.

Question 51

1. 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 cells until released.
   e. become attached to a triglyceride and be deposited into adipose tissue.

Answer 51

a. be converted into fatty acids.

Question 52

1. The uptake of nutrients across the epithelial cells of the gastrointestinal tract into the bloodstream is called ________ .
   a. excretion
   b. secretion
   c. reabsorption
   d. absorption
   e. filtration

Answer 52

d. absorption

Question 53

1. Define each of the three body water compartments described below:

Plasma:

Answer 53

Plasma: Extracellular fluid within the heart and blood vessels (ECF is fluid inside outer epithelial layer but outside plasma membrane)

Question 54

Define each of the three body water compartments described below:

Total body water

Answer 54

Total body water: all fluid within outer epithelial layer

Question 55

Define each of the three body water compartments described below:

Intracellular fluid:

Answer 55

Intracellular fluid: All fluid within plasma/cell membrane

Question 56

Name ONE of the major types of membrane lipids and briefly explain how it contributes to the structure of the plasma membrane.

Answer 56

May say any of the following (don’t need all for full marks) Phospholipids: Main structural component of lipid bilayer, polar molecule (hydrophilic head, hydrophobic tail), polarity stops ‘flipping’ but allows lateral fluidity. Polarity promotes membrane repair

Cholesterol: Hydrophobic molecule located in middle of plasma membrane, increases membrane flexibility, decreases water permeability, restricts migration to lipid-soluble molecules

Question 57

Answer 57

Question 58

Briefly explain TWO special properties of blood flow in the cardiovascular system (that do not apply to fluid flow generally).

1.

Answer 58

Blood viscosity is variable – could either say that depends on number of red blood cells, so can decrease during anemia, increase with RBC overload (e.g. during blood doping) OR that viscosity increases if RBC shape changes e.g. sickle cell anemia OR that blood viscosity depends on flow rate (blood is a non-Newtonian fluid), so viscosity will be higher at low flow rates

Question 59

Briefly explain TWO special properties of blood flow in the cardiovascular system (that do not apply to fluid flow generally).

2.

Answer 59

Blood pressure is pulsatile – pressure gradient for blood flow is not constant, but peaks during ventricular contraction (systole) and decreases during ventricular relaxaion (diastole). Might mention elastic recoil of arterial walls maintaining pressure during diastole, but not neccessary

Question 60

Briefly explain TWO special properties of blood flow in the cardiovascular system (that do not apply to fluid flow generally).

3.

Answer 60

Blood vessel walls are distensible (not rigid) – blood vessels can be compliant (stretch in response to pressure) and elastic (provide recoil, which maintains BP. Veins particularly compliant, recoil of arteries especially important for maintaining BP during diastole.

Question 61

1. Complete EACH of the following sentences by CIRCLING ONE of the options given. (3 marks)

Circle ONE correct alternative:

• The ___________________ contains deoxygenated blood.

PULMONARY VEIN

RIGHT ATRIUM

LEFT VENTRICLE

• The _____________ pumps blood into the aorta.

RIGHT VENTRICLE

LEFT VENTRICLE

RIGHT ATRIUM

LEFT ATRIUM

• Arterial pressure is lowest during _____________.

VENTRICULAR SYSTOLE

VENTRICULAR DIASTOLE

Answer 61

1. Complete EACH of the following sentences by CIRCLING ONE of the options given. (3 marks)

Circle ONE correct alternative:

• The ___________________ contains deoxygenated blood.

RIGHT ATRIUM **

• The _____________ pumps blood into the aorta.

LEFT VENTRICLE **

• Arterial pressure is lowest during _____________.

VENTRICULAR DIASTOLE **

Question 62

Complete EACH of the following sentences by CIRCLING ONE of the options given.

• Early in ventricular systole, the volume of blood in the ventricle is _____________.

INCREASING

CONSTANT

DECREASING

• Blood leaving the left ventricle enters the _____________.

SUPERIOR VENA CAVA

PULMONARY ARTERY

AORTA

RIGHT ATRIUM

• The right ventricle depolarises at the same time as the _____________ .

LEFT ATRIUM

RIGHT ATRIUM

LEFT VENTRICLE

Answer 62

• Early in ventricular systole, the volume of blood in the ventricle is _____________.

CONSTANT **

• Blood leaving the left ventricle enters the _____________.

AORTA**

• The right ventricle depolarises at the same time as the _____________ .

LEFT VENTRICLE **

Question 63

1. Using the following heat balance equation as a guide, list three ways that vertebrates reduce their heat loss in a cold environment.

H_{metabolic heat}+ H_conduction+ H_convection+ H_radiation+ H_evaporation= T_b

Answer 63

1. Body size – dec. SA:volume
2. Inc. insulation
3. Dec. peripheral blood supply
4. Countercurrent mechanisms
5. Dec. thermal gradient (T_a ¬ T_b) by allowing T_b to drop

Question 64

a) Fill in the four empty boxes to label the four main parts of the neuron below

Answer 64

Box 1: Dendrites
Box 2: Soma or cell body
Box 3: Axon (the part the line is pointing to is technically a Node of Ranvier, but that isn’t a ‘main part of a neuron’ as asked for in the question, so I would probably mark it wrong, given it’s such an easy question
Box 4: Nerve terminal (or (pre)synaptic terminal or synaptic knob or synaptic bouton or synaptic button)

Question 65

b) On the picture of the neuron, draw in arrows to indicate the direction of information flow through the cell.

Answer 65

B) Information flows from top to bottom (from dendrites –> cell body –> axon –> nerve terminal)

Question 66

c) What is the primary function of the lipid-rich structure indicated by ‘A’?

Answer 66

C) I think ‘A’ pointed to the myelin sheath, primary function is to insulate the nerve axon and therefore increase action potential conduction velocity. May also say promote saltatory conduction.

Question 67

The diagram below depicts signal transduction for SALTY tastes, with steps labelled 1 to 3.

a. Name the ion that is passing through the ion channel in Step 1

Answer 67

Na+ (sodium) = (sodium ions)

Question 68

b. What is the effect of the ion in Step 1 on the cell membrane potential?

Answer 68

Depolarise

Question 69

c. Name the ion involved in Step 2

Answer 69

Ca2+ (calcium) = (calcium ions)

Question 70

d. As the result of the ion entering the cell in Step 2, what is occurring in Step 3?

Answer 70

Neurotransmitter release

Question 71

1. FILL IN THE BLANKS to complete the sentence below describing how the eye accommodates for near vision.

“The ciliary muscle ______________, causing the ______________fibres to become ______________ , and the lens to becomes ______________.”

Answer 71

“The ciliary muscle contracts, causing the zonule (= zonular) fibres to become loose (= relaxed = slack), and the lens to becomes convex (= round = fat)

Question 72

1. Match the properties listed to either rods OR cones. CIRCLE ONE of the options given.(2 Marks)

A

Circle ONE correct alternative:

Type of vision

Black and white Night (dim light)

RODS

CONES

Colour Day (bright light)

RODS

CONES

Sensitivity to light

High

RODS

CONES

Low

RODS

CONES

Abundance

100 million per retina

RODS

CONES

3 million per retina

RODS

CONES

Visual acuity

High

RODS

CONES

Low

RODS

CONES

Answer 72

1. Match the properties listed to either rods OR cones. CIRCLE ONE of the options given.(2 Marks)

A

Circle ONE correct alternative:

Type of vision

Black and white Night (dim light)

RODS**

Colour Day (bright light)

CONES**

Sensitivity to light

High

RODS**

Low

CONES**

Abundance

100 million per retina

RODS**

3 million per retina

CONES**

Visual acuity

High

CONES**

Low

RODS**

Question 73

Describe THREE conditions you would need to control to ensure you measure the Basal Metabolic Rate of a dog?

Answer 73

Post absorptive (i.e. not digesting food)

Resting (no physical activity)

Ambient temperature (needs to be within the thermoneutral zone of the dog)

Question 74

1. Define and give an example of the following terms

Definition

Example

• Adaptive niche

.

Answer 74

1. Define and give an example of the following terms

Definition

Example

• Adaptive niche

Definition: The environmental conditions (biological and physical) under which an organism/species can exist. “The role of an organism in its community; what and where it eats, and what eats it”

Examples: Any valid lifestyle definition: e.g., herbivory, carnivory, frugivory.

Question 75

Define and give an example

• Allopatric speciation

Answer 75

• Allopatric speciation

Definition: Speciation by geographical/physical isolation of diverging populations. “Allopatric” means “different homelands”.

Example: diverging species separated by mountain range, waterway or other physical barrier

Question 76

Define and give an example

• Speciation by post-fertilisation reproductive isolation.

Answer 76

• Speciation by post-fertilisation reproductive isolation.

Definition: Fertilization can occur between different species but the hybrids die or are sterile.

Example: Mules

Question 77

Define and give an example

Allen’s rule.

Answer 77

• Allen’s rule.

Definition: The size of extremities (limbs, tail, ears, etc.) increases from colder to warmer climates in the same species or in closely related species. Body heat is dispersed more readily by large extremities.

Example: Snowshoe rabbit vs. jackrabbit; Inuit vs. desert-adapted humans.

Question 78

Define and give an example

Allometric growth.

Answer 78

• Allometric growth.

Definition grow at different rates: Different body parts

Example: Human baby – relative head size declines with age (or any similar example)

Question 79

Describe the TWO main differences between the nervous systems of cnidarians (radially symmetrical organisms) and vertebrates (bilaterally symmetrical organisms).

Answer 79

Nerve nets in cnidarians (diffuse, connected arrays of nerves with no clear input/output) vs centralized nervous system in vertebrates (presence of ganglia with many cell bodies, clustering of nerves into brain/spinal chord)

Emergence of cephalisation (integration centres e.g. brain towards anterior end) in vertebrates, not present in cnidarians

Question 80

1. In humans, which ONE of the following regions of the body surface is the ability to discriminate between 2 points the greatest (that is, has the greatest tactile acuity)?
   a. Back
   b. Front of upper arm
   c. Back of lower leg
   d. Forehead
   e. Lips

Answer 80

e. Lips

Question 81

If a mammalian neuron is at a resting membrane potential of – 70 mV, then opening of voltage-gated sodium channels will lead to sodium ____________________________ and ______________________________ of the cell membrane potential. Once the cell has returned to resting membrane potential, opening of voltage-gated potassium channels a few milliseconds later will lead to potassium ______________________________ and ______________________________ of the cell membrane potential. When voltage-gated potassium channels return to their closed state, ___________________ of the membrane will return the cell to resting membrane potential. If transmitter binding then opens ligand-gated chloride channels, leading to an influx of chloride ions, it will cause ______________________________ of the membrane potential.

Answer 81

If a mammalian neuron is at a resting membrane potential of – 70 mV, then opening of voltage-gated sodium channels will lead to sodium INFLUX____________________________ and DEPOLARISATION ______________________________ of the cell membrane potential. Once the cell has returned to resting membrane potential, opening of voltage-gated potassium channels a few milliseconds later will lead to potassium EFFLUX______________________________ and HYPERPOLARISATION______________________________ of the cell membrane potential. When voltage-gated potassium channels return to their closed state, REPOLARISATION___________________ of the membrane will return the cell to resting membrane potential. If transmitter binding then opens ligand-gated chloride channels, leading to an influx of chloride ions, it will cause HYPERPOLARISATION______________________________ of the membrane potential.

Question 82

1. On the diagram below, clearly label TWO types of glial cell with their correct names.

State the main function of each of the glial cell types you identified in the diagram above. (1 mark)

Glial cell type

Function

1.

2.

Answer 82