Biosci107 2009 Exam

BIOSCI 107 FC

THE UNIVERSITY OF AUCKLAND

FIRST SEMESTER, 2009 Campus: City

BIOLOGICAL SCIENCES

Biology for Biomedical Science

GENERAL INSTRUCTIONS

Multiple Choice Questions: • Use the Teleform Sheet. • Use pencils only. Shade the rectangle completely. • Do not cross out mistakes. ERASE them completely. • Complete family name, fi rst name, initial and ID Number. Do not complete your stream. Fill spaces from left to right. • Your code is 22549609. Check this is correct on your teleform. • Failure to enter the version code or other details correctly will mean your MCQ cannot be marked.

Short Answers: • Print your name and ID Number at the top of EVERY ANSWER PAGE. • Record your answers in the spaces provided. • All questions should be attempted.

Exam Format:

Multiple choice QuestionsSection A: Theory (Cell Processes, Blood & Immune, Neurons, Muscle) 40 marksSection B: Laboratory 10 marks

Short Answer QuestionsSection C: Cell Processes 15 marksSection D: Blood and Immune 15 marksSection E: Excitable Tissues: Neurons 10 marksSection F: Muscle 10 marks

TOTAL 110 MARKS ALL QUESTIONS SHOULD BE ATTEMPTED.

Hand in the Teleform answer sheet and your short answer sheets (Sections C, D, E and F).

Retain your multiple choice question pages.

VERSION 22549609 - 2 - BIOSCI 107 FC

CONTINUED

SECTION A: THEORY

MULTIPLE CHOICE QUESTIONS

TEST VERSION CODE: 2254960940 marks

Recommended time 40 minutes

Choose the ONE correct answer from the alternatives provided

Question 1: The lipid bilayer: 1. has a low permeability to steroids. 2. is not permeable to water. 3. contains a hydrophilic core which is impermeable to ions. 4. has electrical properties that mimic those of a capacitor. 5. is formed mainly by a bilayer of cholesterol molecules.

Question 2: Diffusion of chloride into a cell: 1. is by passive diffusion through the lipid bilayer. 2. is against its concentration gradient. 3. is a form of facilitated diffusion. 4. is increased if the membrane potential is less negative. 5. is mediated by the NaK2Cl cotransporter.

Question 3: The uptake of glucose by muscle cells: 1. occurs across the basolateral membrane. 2. is driven by the electrochemical gradient for glucose. 3. occurs via a non-saturable process. 4. utilises energy stored in the sodium gradient. 5. is maintained by the conversion of glucose to glucose-6-phosphate in the cytoplasm.

Question 4: The transport of a substance across a cell membrane by a primary active transporter:

1. uses the energy stored in the ion gradients. 2. is an example of facilitated diffusion. 3. is mediated by passive diffusion. 4. involves the direct hydrolysis of ATP. 5. is an example of pinocytosis.

Question 5: Transport via the paracellular pathway is: 1. increased in the gut in a proximal to distal direction. 2. against the laws of difussion. 3. governed by the electrical resistance of the tight junctions. 4. independent of the transcellular transport pathway. 5. hormonally regulated.


CONTINUED

Question 6: A solution of 75 mM NaCl and 150 mM glucose is: 1. isosmotic. 2. isosmotic but hypotonic. 3. hyperosmotic. 4. hypotonic. 5. hyposmotic.

Question 7: Diffusion: 1. exhibits saturation as the concentration increases. 2. is mediated by primary active transporters. 3. is fast over small distances. 4. of glucose across the apical membrane of epithelial cells is dependent on sodium. 5. decreases as surface area increases.

Question 8: In epithelial cells involved in chloride secretion: 1. the uptake of chloride is the rate limiting step in transcellular transport. 2. the paracellular diffusion of sodium occurs to preserve electroneutrality. 3. chloride uptake is only coupled to the entry of sodium across the basolateral membrane. 4. ATP hydrolysis by CFTR actively pumps chloride ions across the apical membrane. 5. CFTR accumulates chloride above its electrochemical gradient.

Question 9: Exocrine glands: 1. produce a primary secretion that is modifi ed by the ductile cells. 2. only secrete into the blood stream. 3. perform transepithelial absorption of glucose. 4. in people with cystic fi brosis produce hypotonic sweat. 5. are connected to the epithelial surface by acini cells.

Question 10: In patients with cystic fi brosis: 1. the major cause of mortality is respiratory failure. 2. isotonic fl uid secretion is normal. 3. secretory diarrhoea is a clinical symptom. 4. there is a defect in the uptake of chloride ions. 5. the intracellular signalling pathways that regulate CFTR are defective.

Question 11: Which of the following best approximates the volume of blood in a 70 kg person?

1. 1 litre 2. 5 litres. 3. 22 litres. 4. 65 litres. 5. 50 litres.


CONTINUED

Question 12: Human plasma proteins contain which of the following? I fi brinogen II haemoglobin III immunoglobin

1. I and III only. 2. I, II and III. 3. II and III only. 4. II only. 5. I only.

Question 13: Which of the following is FALSE concerning the haemoglobin molecule? 1. It contains amino acids. 2. It is composed of four polypeptide chains. 3. It contains iron. 4. It is found in humans only. 5. It can bind four O2 molecules.

Question 14: Which of the following statements about IgG, one of the classes of immunoglobulins, is TRUE?

1. It acts as a signal to plasma cells to attack a pathogen and to kill it by endocytosis. 2. It is the fi rst immunoglobulin molecule produced after an infection. 3. It is the rarest type of immunoglobulin protein in blood. 4. It has two identical antigen binding sites. 5. It consists of two polypeptide chains with alpha helical structure.

Question 15: T cells and B cells are: 1. antibodies. 2. lymphocytes. 3. complement system components. 4. phagocytes. 5. both phagocytes and lymphocytes.

Question 16: Which of the following statements is FALSE? 1. B cells can develop into plasma cells. 2. B cells can develop into T cells. 3. Monocytes are the precursors of macrophages. 4. Leukocytes are more complex cells than erythrocytes. 5. Neutrophils can function as phagocytes.

Question 17: Clonal selection: 1. results in proliferation of antigen-specifi c lymphocytes. 2. begins with infl ammation. 3. occurs for all leukocytes. 4. occurs in response to self antigens. 5. results in innate immunity.


CONTINUED

Question 18: The following are four steps in the development of an antibody mediated immune response. What is the correct order?

I. Antibody production by plasma cells. II. T helper cell activation. III. Infl ammation. IV. B cell activation.

1. I, III, II, IV 2. III, II, I, IV 3. III, IV, I, II 4. IV, II, III, I 5. III, II, IV, I

Question 19: HIV infection leads to: 1. a decline in serum CD4+ T-lymphocyte numbers over ten years. 2. increased resistance to many infectious diseases. 3. a decline in serum HIV concentration over three years. 4. dark coloured patches on the skin within one year of infection. 5. infl uenza-like symptoms the day following infection.

Question 20: Which of the following protein molecules have mostly alpha-helical secondary structure?

1. hemoglobin and lysozyme 2. serum albumin and immunoglobulin 3. immunoglobulin and lysozyme 4. hemoglobin and serum albumin 5. immunoglobin and hemoglobin

Question 21: The resting membrane potential in neurons is affected by the permeability of the cell membrane to K+ and Na+ ions. At the resting state (i.e. when no action potentials are fi red), the permeability ratio PK+ / PNa+ is approximately:

1. 100 / 1 2. 400 / 1 3. 40 / 1 4. 10 / 1 5. 1 / 1

Question 22: The equilibrium potential for K+ (EK+) represents the point at which: 1. the infl ux of K+ along it’s concentration gradient is balanced by the effl ux of K+ along it’s concentration gradient. 2. the effl ux of K+ along it’s concentration gradient is balanced by the infl ux of K+ along the electrical gradient. 3. the activity of Na+/K+ ATPase is at it’s maximum. 4. the effl ux of K+ along the electrical gradient is balanced by the infl ux of K+ along the electrical gradient. 5. there is no potential difference between the inside and outside of the cell.


CONTINUED

Question 23: Figure A above shows an action potential recorded in an axon. What is happening during ‘stage 2’?

1. activation of voltage-gated K+ channels 2. rapid effl ux of sodium ions out of the cell 3. cell membrane depolarisation due to inhibition of Na-K ATPase (Na+/K+ pump). 4. rapid infl ux of potassium ions due to activation of voltage-gated K+ channels 5. activation of voltage-gated Na+ channels

Question 24: ‘Saltatory’ conduction along nerve fi bres: 1. occurs only in unmyelinated axons. 2. can be described by the Goldman equation. 3. occurs only in the peripheral nervous system. 4. requires the presence of nodes of Ranvier. 5. is slower than in nerve fi bres which are not insulated with myelin.

Question 25: The fastest conduction velocity in myelinated nerve fi bres is approximately: 1. 1000 m/sec 2. 10000 m/sec 3. 10 m/sec 4. 1 m/sec 5. 100 m/sec

1 1

2

3

4

Mem

bran

e po

tent

ial (

mV

)

Time (in sec)

Figure A


CONTINUED

Question 26: The process by which an increased amplitude of excitatory postsynaptic potentials (EPSPs) can be observed when two groups of excitatory synapses located on a single neuron are activated simultaneously (or almost simultaneously) is called:

1. temporal summation. 2. postetanic potentiation. 3. dendritic summation. 4. spatial summation. 5. dendritic facilitation.

Question 27: During an Honours project conducted in the Neurophysiology Laboratory a student conducted an experiment on brain tissue kept in vitro. She used a patch pipette to record the membrane potential from a neuron. This also allowed her to control the intracellular concentration of ions. When she increased concentration of K+ inside the neuron she observed:

1. the equilibrium potential for K+ become more positive. 2. increased activity of Na/K ATPase. 3. cell membrane depolarisation. 4. no effect on the resting membrane potential. 5. cell membrane hyperpolarisation.

Question 28: Excitatory Postsynaptic Potentials (EPSPs): 1. are produced by opening of channels in the postsynaptic membrane that are permeable to several cations (Na+, K+ and often Ca2+) 2. have an equilibrium (reversal) potential of approximately -60 mV. 3. are produced in neuronal cell bodies but not in dendrites. 4. are usually effective in depolarizing the trigger zone (axon hillock) to threshold and evoking action potentials, when produced by activation of only one excitatory synapse. 5. cause hyperpolarisation of the postsynaptic membrane.

Question 29: The main excitatory neurotransmitter in the central nervous system is: 1. GABA 2. ATP 3. glutamate 4. dopamine 5. acetylcholine

Question 30: Recently neuroscientists have identifi ed in neurons a new type of K+ channel known as the K(ATP) channel. The channel is normally closed, but opens when the intracellular level of ATP (adenosine triphosphate) is reduced; for example during lack of oxygen. When the K(ATP) channel opens:

1. the resting membrane potential becomes less negative. 2. the resting membrane potential becomes more negative. 3. the Na/K ATPase (ie. the Na/K pump) becomes more active, which triggers infl ux of Na+ ions into the cell. 4. membrane potential moves away from the EK+ (the equilibrium potential for K+) towards ENa+ (the equilibrium potential for Na+). 5. neurons depolarise.


CONTINUED

Question 31: Sarcomeric striations can be seen: 1. None of the other options are correct. 2. in microscopic images of cardiac muscle cells. 3. in microscopic images of smooth muscle cells. 4. in microscopic images of tendons. 5. with the naked eye.

Question 32: The force-velocity curve of muscle predicts: 1. the relationship between length and tension. 2. that maximum force occurs when the muscle contracts fastest. 3. None of the other options are correct. 4. that minimum force occurs when the muscle is “pumped” . 5. that maximum force is developed when muscle is stretched.

Question 33: Only single nuclei occur in muscle cells from: 1. skeletal and cardiac muscle only. 2. smooth and skeletal muscle only. 3. neither smooth, cardiac nor skeletal muscle. 4. none of the other options are correct. 5. cardiac and smooth muscle only.

Question 34: Smooth muscle contraction: 1. none of the other options are correct. 2. is stopped by phosphorylation of myosin. 3. is regulated by calmodulin-dependent protein kinase. 4. occurs over a sarcomere range of 2.0 to 2.2 micrometers. 5. is regulated by troponin.

Question 35: In general, skeletal muscle fi bers: 1. none of the other options are correct. 2. line hollow contractile organs. 3. attach to bone directly. 4. receive input from one nerve cell. 5. are myogenic.

Question 36: Which of the following statements about cardiac muscle cells is CORRECT ? 1. none of the other options are correct. 2. contractile fi laments are connected at dense bodies. 3. are primarily aerobic in metabolism. 4. do not contain more than one nucleus. 5. are innervated at the neuromuscular junction.

Question 37: Which of the following statements about skeletal muscle is CORRECT ? 1. none of the other options are correct. 2. shortening generates more action potentials. 3. shortening generates more force. 4. shortening leads to sarcomere elongation. 5. shortening leads to more ATP consumption.


CONTINUED

Question 38: Which of the following statements about smooth muscle shortening is CORRECT?

1. it fatigues quickly. 2. it requires high levels of Ca2+ to maintain contraction. 3. none of the other options are correct. 4. it requires action potentials to start shortening. 5. A-bands approach I bands.

Question 39: Involuntary muscle is: 1. the cause of uncontrolled facial twitches. 2. controlled by hormones not nerves. 3. None of the other options are correct. 4. smooth muscle. 5. postural muscle.

Question 40: Actin is: 1. found in the A band only. 2. found in the M-line. 3. made up of fi brous monomers. 4. found only in the I band. 5. found in both A and I bands.


CONTINUED

Question 41: For a dilution factor of 5, how much diluent must be added to 3 mL of blood? 1. 6 mL 2. 0.6 mL 3. 9 mL 4. 15 mL 5. 12 mL

Question 42: Osmolarity is dependent on the number of particles in solution. Many compounds dissociate in solution, and therefore can exert osmotic pressure. Assuming complete dissociation, how many osmoles per litre would be produced for every mole of CaCl2 dissolved in 1 litre?

1. 2 osm/l 2. 4 osm/l 3. 2.5 osmol/l 4. 1 osm/l 5. 3 osm/l

Question 43: In Lab 4, you were supplied with “’washed” red blood cells in which the plasma was replaced with an isotonic solution in order to maintain the original haematocrit of the blood sample. What was the bathing solution used?

1. 300 mM glucose 2. distilled water 3. 300 mM NaCl 4. 150 mM NaCl 5. 150 mM Urea

SECTION BPRACTICAL

MULTI CHOICE QUESTIONS

N.B. All students in laboratory classes must complete the following 10 multiple-choice questions which count towards the Practical mark for the course. Students repeating the course and who have a Practical mark Carried-Forward do not have to complete the following 10 questions.

10 marksRecommended time 10 minutes

Choose the ONE correct answer from the alternatives provided.


CONTINUED

Question 44: In Lab 4 (Osmolarity), some students were surprised when the blood sample added to 50 mM NaCl failed to form layers after centrifugation, and was a light pink colour throughout. What is the most likely explanation for this result?

1. The NaCl solution was hypoosmotic and the red blood cells had lysed. 2. These students mixed up their tubes and must have been reading the 300 mM NaCl sample. 3. Red blood cells in the hypotonic solution has shrunk so much that they formed a pellet at the bottom of the sample. 4. The sample had not been centrifuged for suffi cient time. 5. The red blood cells had swollen to maximal volume and as a consequence the haematocrit reading was 100 %.

Question 45: Wright’s stain is a common stain for white blood cells. What cell component does the acidic dye stain?

1. cytosol 2. collagen 3. cytoplasmic granules 4. nucleus 5. cell membrane

Question 46: In adult humans, typical haematocrit values for males average higher than females. What measure is primarily responsible for this difference?

1. red blood cell count 2. mean red blood cell volume 3. white blood cell count 4. mean cell haemoglobin 5. platelet density

Question 47: The doctor calls for a peripheral blood smear examination for a patient. What is she most likely to be looking for?

1. differential leucocyte count 2. red blood cell count 3. haemoglobin content 4. haematocrit 5. mean red blood cell volume

Question 48: If the red blood count of a healthy adult human was estimated at 6 x 106 cells /μL what density of white blood cells would you expect?

1. 5,000 cells / μL 2. 500 cells / μL 3. 50 cells / μL 4. 6 x 109 cells / μL 5. 6,000,000 cells / μL


CONTINUED

Question 49: After addition of ATP a glycerinated muscle fi bre contracts by 30 %. What could you add to the preparation to make the fi bre relax back to its original length?

1. EDTA 2. calcium ions 3. NaCl 4. Mg-ATP 5. glycerol

Question 50: Nobel laureate Albert Szent-Gryorgi discovered that treating muscle with 50 % glycerol:

I. I Causes muscle fi bres to relax so that their ability to contract upon the addition of ATP and salts can be measured.

II. II Facilitates active transport (by ATP pumps) of calcium back into the sarcoplasmic reticulum.

III. III Destroys the sarcoplasmic reticulum without affecting the fi bres. IV. IV Allows the muscle to be stored cold for long periods of time and

retain its contractility. V. V Permits investigations of muscle contraction using an electrical

stimulus.

1. I and II only 2. I and IV only 3. III and V only 4. II and V only 5. III and IV only


CONTINUED

SHORT ANSWER QUESTIONS FOLLOW

THERE ARE NO QUESTIONS ON THIS PAGE.


CONTINUED

THE UNIVERSITY OF AUCKLAND

BIOSCI 107

Short Answer Questions Section

Instructions

• Print your name and ID in the box above• Print your name and ID at the top of each answer page.• Record your answers in the spaces provided. Only answers in the specifi ed areas will be

marked.• All questions should be attempted.

Short Answer Format

Section C: Cell Processes 15 marksSection D: Blood and Immune Systems 15 marksSection E: Excitable Tissues: Neurons 10 marksSection F: Muscle 10 marks

Total: 50 marks. Recommended time: 50 minutes.

CP B&I ET:N M ALL

Admin Use Only

ID NUMBER: ___________________________

SURNAME: ____________________________ FIRST NAME: ______________________

15 15 10 10 50


CONTINUED

THERE ARE NO QUESTIONS ON THIS PAGE.


CONTINUED

QUESTION/ANSWER SHEET

ID NUMBER: ___________________________


SECTION C: CELL PROCESSES

15 marksRecommended time: 15 minutes

10Circles for use of markers only

51. With reference to the diagram below complete the table and answer the following questions about glucose absorption:

(a) Complete the table. (6 marks)Transport Protein Type of transport

proteinFunction in Cl- secretion

NaK ATPase

SGLT

GLUT

(b) With reference to the above diagram briefl y explain how Oral Rehydration Therapy stimulates water uptake in people suffering from diarrhoea. (4 marks)


CONTINUED

5

52. If the box below represents the plasma membrane of a cell with a resting membrane potential of -80mV, then:

(a) Indicate the relative concentrations (high or low) of sodium, potassium, chloride and calcium ions on the extracellular and cytoplasmic sides of the membrane.

(2 marks)

(b) Via the use of arrows, indicate the direction in which sodium, potassium, chloride and calcium ions would diffuse down their respective electrochemical gradients.

Extracellular

Cytoplasm

(2 marks)

(c) If the membrane potential increases to -100mV describe what effect the change in the

electrical gradient would have on the movement of chloride ions. (1 mark)

____________________________________________________________________

____________________________________________________________________


CONTINUED


ID NUMBER: ___________________________


SECTION D: BLOOD AND IMMUNE SYSTEMS


5

53. Indicate the relevant parts of the diagram by writing the appropriate number in the space provided below. (5 marks)

(a) Write the number indicating the T-cell. ___________

(b) Write the number indicating the MHC binding site on the T-cell. ____________

(c) Write the number indicating the MHC protein. ___________

(d) Write the number indicating the cell carrying antigen. ___________

(e) Write the number indicating the part of the MHC with bound antigenic peptide. ___________


CONTINUED

54. Construct nine true sentences by matching words from the first column (labels A-G) below with items from the second column (labels 1-7) below. (5 marks)

A Plasma cell 1 Is an APC (antigen presenting cell)B platelet 2 Can develop into a plasma cellC macrophage 3 Secretes antibody moleculesD B cell 4 Is a phagocyteE neutrophil 5 Is activated by T helper cellsF erythrocyte 6 Activates T helper cellsG T helper cell 7 Is activated by APCs

Answer the question by placing matching letters and numbers in the table below. An example of a correct answer would be “C4” (macrophage is a phagocyte). Note: A word in the first column can be used to make more than one correct sentence.

C4

55. Fill in the second row of the table below by matching the words from the 1st column (labels A-H) with words from the 2nd column (labels 1-8). Note that the fi rst and last answers have been already fi lled in. (3 marks)

A Gp41 1 PolyproteinB AZT 2 Trimeric target for neutralizing antibodiesC Env 3 Fusion proteinD Gp120 4 99 amino acid dimeric proteinE Proteinase 5 Polymerase enzymeF Reverse transcriptase 6 T-cell receptor for HIVG CD4 7 polymeraseH HIV 8 Cause of AIDS

A B C D E F G H

3 8

56. Draw a graph showing how the T helper count changes with time in the 10 years after infection with HIV. Mark the time point at which AIDS usually begins. Label both axes clearly and include the units. (2 marks)

10


CONTINUED 5


ID NUMBER: ___________________________


SECTION E: EXCITABLE TISSUES: NEURONS


57. An Honours student conducted an experiment on brain tissue kept in vitro. He used the patch-clamp technique that allowed him to change the concentration of ions inside and outside the neuron. In the experiment, the extracellular concentration of K+ ([K+]o) was

5 mM and the intracellular ([K+]i) 160 mM.

(a) Give the simplifi ed form of the Nernst equation.

The simplifi ed form of the Nernst equation: EK+ = _______________________

(1 mark)

(b) Using the simplifi ed form of the Nernst equation calculate the equilibrium potential for potassium (EK+) for this neuron. In your calculation use the constant 60 mV

instead of 61.5 mV. (Note that log 160/5 = 1.5, and log 5/160 = -1.5. You will have to use one of these

logarithms for your calculation). (4 marks)

EK+ in the neuron: ____________________mV


CONTINUED

5

58. The picture below represents electrical stimulation of an unmyelinated nerve fi bre with a pair of stimulating electrodes. Indicate on the picture:

(a) the fl ow of the main component of the current in the extracellular solution (draw an arrow and label); (1 mark)

(b) the fl ow of the main component of the current inside the fi bre (draw an arrow and label); (1 mark)

(c) the electrode under which the cell membrane is depolarised (point with an arrow and label) (1 mark)

(d) the electrode under which the cell membrane is hyperpolarised (point with an arrow and label); (1 mark)

(e) the part of the membrane in which an action potential (AP) will be evoked by a suprathreshold stimulus (use a ‘star’ to indicate the point of AP initiation).

(1 mark)


10

59. Complete the following paragraph by entering the correct word in the spaces indicated. Note some words may be required more than once.

In all muscles ___________________ is the only naturally occurring ion which

activates contraction. In ________________ and ________________ muscles, the

activator __________________ion binds to troponin to cause ___________________ to

move and release inhibition of the ___________________ fi lament and ___________-

_____________ formation. In smooth muscle, the activator ___________________ ion

binds to ___________________ which then activates ___________________ to

phosphorylate _______________ _______________ __________________. The smooth

muscle cell contraction is switched off by the action of ___________________ which

remove the ___________________ from the _______________ ______________.

Relaxation requires that the activator ___________________ ion be

___________________ back to where it came from, in the case of skeletal muscle, this

is the ___________________ ___________________, in cardiac and smooth muscle

the activator is pumped back to the ____________ _____________ and ____________

_____________. While this leads to automatic relaxation of skeletal and cardiac

muscle, ___________________ muscle will not relax unless the myosin _____________

_______________ are also ___________________. (10 marks)


ID NUMBER: ___________________________


SECTION F: MUSCLE


Biosci107 2009 Exam

Documents

Transcript of Biosci107 2009 Exam