Biology Unit 3 2008 Trial Exam 1

© The Specialised School For Mathematics Pty. Ltd. 2008 (TSSM) Page 1 of 24

Student Name: _________________________________________________________

BIOLOGY

Unit 3 – Written examination 1

2008 Trial Examination

Reading Time: 15 minutes Writing Time: 1 hour and 30 minutes

QUESTION AND ANSWER BOOK

Structure of book Section Number of

questions Number of questions

to be answered Number of

marks A 25 25 25 B 5 5 50 Total 75

S

• Students are permitted to bring into the examination room: pens, pencils, highlighters, erasers, sharpeners and rulers

• Students are NOT permitted to bring into the examination room: blank sheets of paper and/or white out liquid/tape.

• No calculator is permitted in this examination. Materials supplied • Question and answer book of 24 pages. Instructions • Print your name in the space provided on the top of this page. • All written responses must be in English.

Students are NOT permitted to bring mobile phones and/or any other electronic devices into the examination room.

2008 BIOLOGY EXAM 1


SECTION A- Multiple-choice questions

Instructions for Section A Answer all questions. Choose the response that is correct for the question. A correct answer scores 1, an incorrect answer scores 0. Marks are not deducted for incorrect answers. If more than 1 answer is completed for any question, no mark will be given.

Question 1 Which of the following sets of elements are found in amino acids? A. Hydrogen, Carbon, Phosphorus, Nitrogen B. Carbon, Hydrogen, Sulphur, Nitrogen, Oxygen C. Oxygen, Hydrogen, Nitrogen, Sulphur D. Carbon, Nitrogen, Oxygen, Sulphur, Phosphorus Question 2 Compound X is a polymer consisting of amino acid subunits with sugar molecules attached. What term is used to identify this class of chemical? A. Polypeptide B. Glycoprotein C. Carbohydrate D. Nucleic Acid Question 3 Water is a molecule with a profound biological significance. Which of the following properties of water enable it to act as a cooling mechanism? A. It has a high surface tension B. Water molecules attract each other by hydrogen bonding C. It is a polar molecule D. It has a high specific heat capacity Question 4 The function of a protein is determined by: A. The sequence of amino acids B. The amalgamation of two or more polypeptide chains C. The tertiary structure of the protein D. The presence of disulphide bridges

SECTION A - continued

2008 BIOLOGY EXAM 1


Question 5 Two cells from the same plant were placed into different solutions. They were later removed and observed under a microscope. Diagrams of the observations are shown below, with the cytosol shown in grey.

Which of the following conclusions are correct? A. Both solutions have the same solute concentration B. Solution 2 has a higher solute concentration than solution 1 C. Solution 1 has a higher solute concentration than solution 2 D. Both solutions were isotonic to the cytosol Question 6 Each of the diagrams below show semi-permeable membranes with solute particles on both sides of the membrane. The arrows represent the direction the solute particles are moving. Which of the diagrams most accurately represents active transport?

SECTION A – continued

TURN OVER

Cell in Solution 1 Cell in Solution 2

A.

B.

C

D.

2008 BIOLOGY EXAM 1


Question 7 Pepsin is a digestive enzyme produced by the wall of the stomach. It converts proteins into amino acids. A cloudy solution of albumin (egg white) turns clear when broken down by pepsin. A student added 1mL of pepsin to 5mL of albumin and the solution cleared in 5 minutes. The solution would have cleared more rapidly if: A. The pH of the solution was increased B. The albumin was boiled C. The volume of albumin was increased to 10mL D. The volume of pepsin was increased to 2mL Question 8 Radioactively labelled amino acids are supplied to the cells lining the stomach wall, which are responsible for producing pepsin. The level of radioactivity was measured in 4 organelles over a period of several hours and the results were recorded in the table below.

Percentage of total radioactivity

Time (minutes)

Organelle 1 Organelle 2 Organelle 3 Organelle 4

5 70 12 0 0 30 22 65 13 0 60 18 22 35 10 90 16 13 47 58 120 15 11 21 47 150 14 11 12 32

Organelle 3 is most likely to be: A. Golgi apparatus B. Ribosome C. Rough endoplasmic reticulum D. Secretory vesicle

SECTION A - continued

2008 BIOLOGY EXAM 1


Question 9 Red blood cells are different to most eukaryotic cells in that they lack mitochondria, which: A. Prevents the red blood cells from utilising oxygen B. Provides additional surface area to transport glucose C. Facilitates the production of haemoglobin D. Prevents protein synthesis Question 10 Which of the graphs below best shows what happens to an enzyme-catalysed reaction, when there is a low concentration of the enzyme, combined with a high concentration of the substrate?

Question 11 The Krebs cycle is a stage of cellular respiration where a series of reactions occur. Acetyl Coenzyme A (Acetyl CoA) is broken down to ultimately produce carbon dioxide, water and ATP.A section of the Krebs cycle is as follows: Acetyl CoA citrate isocitrate α-ketoglutarate succinate If the enzyme responsible for the conversion of citrate to isocitrate is inactivated, which of the following is most unlikely to occur as a result? A. Accumulation of citrate B. Slower breakdown of Acetyl CoA C. Decreasing concentration of α-ketoglutarate D. Increasing concentration of succinate

SECTION A – continued TURN OVER

A. B.

C. D.

2008 BIOLOGY EXAM 1


Question 12 Plants close their stomata in hot, dry conditions in order to minimise water loss and prevent wilting. Which of the following will happen as a result? A. Photosynthesis will decrease because light will be unable to reach the chloroplasts B. Photosynthesis will increase to replace glucose C. Photosynthesis will decrease because carbon dioxide concentration has decreased D. Photosynthesis will increase because water availability increases

The following information relates to Questions 13 and 14. The diagram below is a representation of some of the processes that occur during the carbon cycle.

Question 13 Which of the arrows represent the process of cellular respiration? A. 1 only B. 1 and 5 C. 2,5 and 6 D. 2 and 6


Atmospheric carbon dioxide

Fossil fuel combustionAnimals

Organic matter decomposing

Plants

1

26

3 4

5

7

Product X

2008 BIOLOGY EXAM 1


Question 14 Product X is most likely to be A. Oxygen B. Water C. Glucose D. Carbon dioxide

Question 15 Anaerobic respiration in plants produces the following product/s: A. Glucose and ATP B. Carbon dioxide and ethanol C. Water and carbon dioxide D. Lactic acid Question 16 Normal blood glucose levels are between 4.5 and 5.5 mmol/L. Blood glucose levels can fluctuate and are regulated by the hormones insulin and glucagon. The graph below shows the blood glucose concentration in an individual for a period of 5 hours after consuming a meal.

What conclusions can be drawn from this graph? A. Blood glucose concentration is regulated by positive feedback B. Insulin concentration is greatest an hour after eating C. Glucagon is being secreted 2 hours after eating D. The person being monitored suffers from insulin-dependent diabetes


TURN OVER

2008 BIOLOGY EXAM 1


Question 17 Nervous impulses are transmitted electrochemically. Which of the following statements regarding the transmission of impulses is most correct? A. Impulses travel from the axons to the dendrites B. Neurotransmitters are taken up by the presynaptic terminal C. Dendrites release neurotransmitters D. There is a refractory period between impulses Question 18 Resting potential in an axon is maintained by the sodium-potassium ion pump. The inside of an axon is negatively charged, compared to the outside, because the pump expels 3 sodium ions for every 2 potassium ions that enter the axon. Which of the following statements correctly describes what is happening when an axon is at resting potential? A. Sodium ion concentration is higher outside the cell than potassium ions inside the cell B. Sodium ion concentration is lower inside the cell than potassium ions outside the cell C. Sodium ion concentration outside the cell is identical to potassium ion concentration

inside the cell D. Sodium ion concentration inside the cell is identical to potassium ion concentration

outside the cell Question 19 The venom of some snakes contains a neurotoxin which binds to the receptor site for acetylcholine in nerve cells, resulting in paralysis. If a person is bitten by such a snake, they need to be injected with antivenom as soon as possible. This is an example of: A. An inflammatory response B. Active immunity C. Passive immunity D. Non specific immunity Question 20 Viruses are considered to be non-cellular pathogens because: A. They lack DNA B. They can only reproduce inside a host cell C. They lack organelles D. They are surrounded by a protein coating


2008 BIOLOGY EXAM 1


Question 21 Myasthenia gravis is a neuromuscular disease caused by circulating antibodies which block acetylcholine receptors at the postsynaptic terminal of nerves, preventing muscle contraction. This disease is an example of: A. A hypersensitivity reaction B. A bacterial infection C. Autoimmunity D. Cytotoxicity Question 22 White blood cells fulfil a range of functions in the immune system. The table below lists four of these cells and their functions. X indicates that the cell possesses that function.

Cytotoxic Phagocytic Produces Antibodies

Recognises Antigens

Cell 1 X X Cell 2 X Cell 3 X X Cell 4 X X

The two cells most likely to play a role in the specific immune system are: A. 1 and 2 B. 3 and 4 C. 2 and 3 D. 2 and 4 Question 23 Internal bacterial infections are frequently treated by ingesting antibiotics. Many antibiotics are produced by moulds as a defence against bacterial infection and antibiotics may act in a variety of ways. One example of this is that the antibiotic tetracycline interferes with the attachment between tRNA and mRNA at the ribosome, resulting in the death of the bacteria because: A. The bacteria are unable to produce essential enzymes B. Protein channels governing material transport are damaged C. The process of transcription is prevented D. The bacterial genome is degraded

SECTION A – continued TURN OVER

2008 BIOLOGY EXAM 1


Question 24 In Australia, there is a programme of vaccination where many young children are immunised against diseases such as diphtheria and measles. Some children are not immunised, but they have a low chance of being exposed to the pathogen. This is taking advantage of A. Active immunity B. Passive immunity C. Humoral immunity D. Herd immunity Question 25 Class 1 MHC markers are found on the surface of most somatic cells. Their role in the immune system is to: A. Assist differentiation between self and non-self B. Activate B plasma cells C. Bind to and inactivate antibodies D. Induce apoptosis in cells invaded by viruses

END OF SECTION A

2008 BIOLOGY EXAM 1


SECTION B- Short-answer questions

Instructions for Section B Answer all questions in the spaces provided.

Question 1 Androgens are natural or synthetic compounds which stimulate or control the development and maintenance of masculine secondary sexual characteristics. In human males, the main androgen is the steroid hormone testosterone. a. Identify where in a cell you would expect to find the androgen receptors for testosterone.

Justify your answer.

2 marks

SECTION B - Question 1- continued TURN OVER

2008 BIOLOGY EXAM 1


Gonadotrophin releasing hormone (GnRH) is a polypeptide hormone which stimulates the anterior pituitary gland to release luteinising hormone (LH). This, in turn, acts upon the testes, causing them to produce testosterone. High levels of testosterone inhibit the production of GnRH. b. In the space below, draw a negative feedback diagram showing the effect of high levels of

GnRH. Your diagram must include identification of all of the components of a negative feedback response and a statement of what is happening at each point.

3 marks c. Anabolic steroids are steroid hormones which are similar in structure to testosterone. They

have three main modes of action: increasing the rate of protein synthesis, increasing the number of muscle cells produced and decreasing the breakdown rate of muscle cells. A male athlete takes anabolic steroids. State what you would expect to happen to the level of testosterone he secretes, and explain why this would occur.

2 marks

SECTION B - Question 1- continued

2008 BIOLOGY EXAM 1


d. Hormones can be classified as: autocrine, endocrine, exocrine and paracrine; depending upon the distance they have to travel to bind to their target cells. Which of these classifications does Luteinising hormone fall into?

1 mark

e. Would it be correct to assume that a man’s somatic cells will respond more rapidly to a

hormone like GnRH than to testosterone? Explain your reasoning.

2 marks

f. GnRH is a neurohormone. Explain what this means.

1 mark

Total 11 marks Question 2 Photosynthesis is an endergonic reaction, which occurs in the chloroplasts of plants. Chlorophyll is a green pigment, which catalyses the reaction. a. Explain what the term endergonic means.

1 mark


2008 BIOLOGY EXAM 1


b. Explain what occurs during the light-dependent stage of photosynthesis.

2 marks

c. Identify the energy rich compound that is produced during the light-dependent stage of

photosynthesis.

1 mark

d. Identify the structure in the chloroplast where the light-dependent reaction occurs.

1 mark

e. What is the purpose of the NADP molecules in the process of photosynthesis?

1 mark


2008 BIOLOGY EXAM 1


f. During an exam, a student refers to the dark stage of photosynthesis. Is this biologically accurate? Justify your response.

2 marks

g. Write down the complete, balanced chemical equation for photosynthesis.

1 mark

h. Use the information from the equation above to explain what will occur to the rate of

carbohydrate production, when carbon dioxide becomes a limiting factor.

2 marks

Total 11 marks

SECTION B - continued TURN OVER

2008 BIOLOGY EXAM 1


Question 3 Clostridium botulinum is a species of bacteria that produces botulinum toxin, which is commonly known as botox. Botulism is a disease caused by ingesting minute amounts of the toxin, which is then absorbed through the intestines. One nanogram is sufficient to have a fatal effect on most adults. The toxin acts by binding to the presynaptic terminal of nerves in the peripheral nervous system. Symptoms of food-borne botulism include: difficulty swallowing, slurred speech, drooping eyelids, muscle weakness, blurred vision, paralysis and death. a. Use the information above to explain why ingesting botulinum toxin can have a fatal

effect.

2 marks

b. What is the function of acetylcholine?

1 mark


2008 BIOLOGY EXAM 1


c. Many species of bacteria can be killed or inactivated by sterilisation procedures. However, botulinum toxin is heat-stable, and it remains undamaged when an attempt is made to control it by sterilisation. Many organisations are currently investigating the possibility of producing an antitoxin by rational drug design. Identify the field of research involved in rational drug design and describe the purpose of rational drug design.

2 marks


2008 BIOLOGY EXAM 1


Most new drugs are tested on animals, such as rats, prior to being approved for use by humans. This procedure is carried out to test the effectiveness of the drug, as well as identify possible side effects. d. Assume a pharmaceutical company has designed a drug that they believe will be an

effective antitoxin for botulinum toxin. Design an experimental protocol that could be used to test the effectiveness of this drug.

3 marks Total 8 marks

SECTION B - continued

2008 BIOLOGY EXAM 1


Question 4 When a heart attack occurs, the supply of blood flowing to the cardiac muscle cells is interrupted due to blockage of the coronary arteries, which supply the heart with oxygenated blood. a. Explain why weakness is one of the symptoms of a heart attack.

2 marks


2008 BIOLOGY EXAM 1


b. In severe cases a person may require a heart transplant. The graph below shows the number of organ donors in a number of countries in 2006.

International Organ Donors 2006

05

10152025303540

New Zea

land

Greece

Austra

lia UK

Denmark

Canad

a

Sweden

German

y

Norway

Irelan

d

Hunga

ryIta

lyUSA

France

Spain

Country

Don

ors

per m

illio

n po

pula

tion

Approximately how many organ donors were there in Australia in 2006?

1 mark

c. Briefly explain the importance of providing transplant recipients with immunosuppressive

drugs such as cortisol or cyclosporine.

1 mark


2008 BIOLOGY EXAM 1


d. One of the actions of cyclosporine is to inhibit the signaling pathway leading to the production of Interleukin 2 (IL-2), a cytokine responsible for activating cytotoxic T cells. Explain the mode of action of cytotoxic T cells.

2 marks e. Is the action of cytotoxic T cells classified as cell-mediated or antibody-mediated

immunity?

1 mark

f. People with elevated triglycerides and low levels of HDL cholesterol have an increased

risk of having a heart attack. Can triglycerides be considered polymers? Justify your answer.

2 marks


2008 BIOLOGY EXAM 1


g. Explain why it is recommended that transplant patients never receive either live or attenuated vaccines after transplantation.

1 mark

h. After a period of 6 months, transplant patients are able to receive certain types of immunisations, and it is highly recommended that they be immunised against influenza on an annual basis. Identify a type of vaccine that could be used to safely immunise a transplant patient and explain why it is safe to do so.


Question 5 Staphylococcus aureus is a circular bacteria that is most commonly found living on the skin or nasal linings of human beings, but may also be found in the respiratory and urinary tracts. This bacterium can cause diseases ranging from mild skin infections to conditions that can be fatal such as meningitis and septicemia. a. Identify a method of transmission for S. aureus.

1 mark

b. Identify a primary defence mechanism against a respiratory infection caused by S. aureus.

1 mark


2008 BIOLOGY EXAM 1


Methicillin-resistant Staphylococcus aureus (MRSA) is a strain of S. aureus which has acquired resistance to a range of antibiotics, including penicillin. The effectiveness of antibiotics is tested using small paper disks that have been infused with the antibiotic. These disks are then placed onto an agar plate containing a lawn culture of the bacteria being tested. The agar plate is then incubated for 24hours. After this time, the plate is examined for zones of inhibition, which are areas surrounding the paper disks where no growth has occurred. Three strains of S. Aureus were exposed to methicillin and penicillin and the diameter of the zone of inhibition was measured in each case.

Zone of inhibition (mm)

Bacterial strain Methicillin Penicillin 1 12 14 2 2 4 3 7 9

c. Identify which of the bacterial strains is most likely to be MRSA? Use the data to support

your answer.

2 marks


2008 BIOLOGY EXAM 1


d. A person became infected with S. aureus, but recovered within two weeks. Three years later, the same person was reinfected with S. aureus, but this time their symptoms were much milder and they recovered in 5 days. Explain why this occurred.

2 marks e. A strain of S. aureus has the following structure. Use the space below to draw an appropriate diagram of an antibody specific for this bacterium. Label the diagram, including identification of the constant and variable regions of the antibody.


END OF QUESTION AND ANSWER BOOK

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Biology Unit 3 2008 Trial Exam 1