Tasmanian Certificate of Education · (b) Under some conditions, certain simple organisms like the green filamentous algae Spirogyra , reproduce asexually, but should conditions deteriorate,

Pages: 7Questions: 3

©Copyright for part(s) of this examination may be held by individuals and/or organisations other than the Tasmanian

Secondary Assessment Board.

PLACE LABEL HERE

Tasmanian Secondary Assessment Board

Tasmanian Certificate of Education

External Assessment

2000

BY826 BIOLOGY

SECTION A

Time: 35 minutes

On the basis of your performance in this examination, the examiners will provide a rating of A, B, C orD on the following criterion taken from the syllabus statement:

Criterion 3 Demonstrate understanding and knowledge of biologicalprinciples and how they apply to the molecular and cellular levelsof biological organisation.

BY826 Biology

Page 2

CANDIDATE INSTRUCTIONS

Answer ALL questions. Answers must be written in the spaces provided on the examination paper.

Candidates are reminded that spelling and expression which make it difficult for the examiner tounderstand what candidates mean, will result in loss of marks.

________________________________________________________________________________

Question 1

(a) Below is a diagram of an electron micrograph of a cell.

(i) Calculate the length of the mitochondrion in the diagram above (the organelle labelled F).(1 mark)

…………………………………………………………………………………………….

(ii) What process is taking place at the cell surface? (1 mark)

…………………………………………………………………………………………….

(iii) Using the letters representing the various organelles, state the likely pathway taken byamino acids as they form a protein which is released from this cell. (3 marks)

…………………………………………………………………………………………….

…………………………………………………………………………………………….

(iv) If the diagram above were to represent a cell from a flight muscle of a bat wing instead of ageneral body cell, what major differences would there be? (2 marks)

…………………………………………………………………………………………….

…………………………………………………………………………………………….

Question 1 continues opposite.

G

5 µm

BY826 Biology

Page 3

Question 1 (continued)

(b) Below is an electron micrograph of another cell.

Explain what kind of cell it is. (3 marks)

………………………………………………………………………………………………...

………………………………………………………………………………………………...

………………………………………………………………………………………………...

(c) The graph below represents the effect on enzyme action of increasing temperature.

Temperature

Explain the enzyme activity at temperatures A, B and C. (3 marks)

A …………………………………………………………………………………………….

…………………………………………………………………………………………….

B …………………………………………………………………………………………….

…………………………………………………………………………………………….

C …………………………………………………………………………………………….

…………………………………………………………………………………………….

Total Question 1: /13

0.5µm

A B C

Enz

yme

Act

ivit

y

BY826 Biology

Page 4

Question 2

(a) The following data shows the number of amino acid differences there are in a chain of βhaemoglobin compared to a human. The total chain contains 146 amino acids.

SpeciesNo. of amino acid

differences inhaemoglobin

Human 0

Gorilla 1

Gibbon 2

Rhesus monkey 8

Mouse 27

Grey kangaroo 38

Chicken 45

Frog 67

Lamprey (fish) 125

(i) How does this data support the theory of evolution ? (2 marks)

…………………………………………………………………………………………….

…………………………………………………………………………………………….

…………………………………………………………………………………………….

(ii) How do these differences arise ? (2 marks)

…………………………………………………………………………………………….

…………………………………………………………………………………………….

…………………………………………………………………………………………….


BY826 Biology

Page 5


(b) The following table shows the sequence of base combinations to make amino acids.

(i) The order of the bases in a strand of DNA is ATG CGT. What is the code on thecomplementary strand of DNA ? (1 mark)

…………………………………………………………………………………………….

(ii) If the original code for some mRNA was AUG CGU and it was mis-copied as AUGCGC, explain if this would affect the functioning of the cell. (2 marks)

…………………………………………………………………………………………….

…………………………………………………………………………………………….

(c) Many unicellular organisms are spherical in shape.

(i) What effect would it have if this organism were to grow to twice its usual size ? (2 marks)

…………………………………………………………………………………………….

…………………………………………………………………………………………….

…………………………………………………………………………………………….

(ii) Why is this shape so common ? (3 marks)

…………………………………………………………………………………………….

…………………………………………………………………………………………….

…………………………………………………………………………………………….

…………………………………………………………………………………………….


BY826 Biology

Page 6

Question 3

(a) The graph below shows the action spectrum for photosynthesis in a green plant.

(i) Use the graph above to explain why leaves are usually green. (2 marks)

…………………………………………………………………………………………….

…………………………………………………………………………………………….

…………………………………………………………………………………………….

(ii) Variegated leaves contain yellow areas. Explain what effect will this have on the growth ofthe plant. (2 mark)

…………………………………………………………………………………………….

…………………………………………………………………………………………….

…………………………………………………………………………………………….


Rat

e of

Pho

tosy

nthe

sis

violet blue green yellow red

Colour of Light

BY826 Biology

Page 7


(b) An artificial cell made from a semi-permeable membrane and filled with a water solution wasplaced in a beaker containing a different solution. The membrane is permeable to water and thesmaller sugar molecules, glucose and fructose, but is impermeable to the disaccharide, sucrose.

(i) Which solute(s) will show net diffusion into the cell ? (1 mark)

…………………………………………………………………………………………….

(ii) Which solute(s) will show net diffusion out of the cell ? (1 mark)

…………………………………………………………………………………………….

(iii) In which direction will there be a net movement of water and what effect will that have onthe size of the artificial cell ? (2 marks)

…………………………………………………………………………………………….

…………………………………………………………………………………………….

…………………………………………………………………………………………….

(iv) A single-celled animal, of a similar membrane permeability, was placed in the samesolution and the level of sucrose increased inside the cell. Explain what process must havetaken place. (2 marks)

…………………………………………………………………………………………….

…………………………………………………………………………………………….

…………………………………………………………………………………………….





PLACE LABEL HERE



External Assessment

2000

BY826 BIOLOGY

SECTION B

Time: 35 minutes


Criterion 4 Display understanding and knowledge of biological principles andhow they apply to the organism.

BY826 Biology

Page 2



Note: Candidates have a choice in Question 6. Answer parts (a) and (b) OR parts (c) and(d).


________________________________________________________________________________

Question 4

(a)Diabetes is a disease in which the bodycells of an affected person cannotabsorb glucose from the blood. Thishappens because the pancreas fails toproduce one of the two hormonesinvolved in glucose control.

A glucose tolerance test was carried outon a healthy person and a person withdiabetes. In this test, 75 g of glucose isgiven to a person who has not eatensince the night before. The level ofglucose in the blood is then tested forthe next few hours.

(i) Which person has diabetes ? (1 mark)

…………………………………………………………………………………………….

(ii) Explain your choice in part (i) above. (1 mark)

…………………………………………………………………………………………….

…………………………………………………………………………………………….

(iii) During phase X in a healthy person, the pancreas increases the rate of production ofinsulin, one of the two hormones involved in glucose control. What is its action ?

(1 mark)

…………………………………………………………………………………………….

…………………………………………………………………………………………….

(iv) During phase Y in a healthy person, the pancreas increases the rate of production ofglucagon, the second of the two hormones involved in glucose control. What is its action?

(1 mark)

…………………………………………………………………………………………….

…………………………………………………………………………………………….


5

10

15

20

blood glucosemmol/L

0

person A

person B

-10 30 60 90 120

glucose givenphase X

phase Y

minutes after glucose

BY826 Biology

Page 3


(b) The diagram below shows the direction of blood flow through the main parts of the body of afish.

Give reasoned comparisons for the following:

(i) the concentration of urea in the blood plasma at P and S; (2 mark)

…………………………………………………………………………………………….

…………………………………………………………………………………………….

(ii) the blood pressure at Q and P; (2 mark)

…………………………………………………………………………………………….

…………………………………………………………………………………………….

(iii) the amount of oxyhaemoglobin per unit volume of blood at S and R; (2 mark)

…………………………………………………………………………………………….

…………………………………………………………………………………………….

(iv) the level of amino acid in the blood plasma at P and R. (2 mark)

…………………………………………………………………………………………….

…………………………………………………………………………………………….


Liver Heart Gills HeadAlimentary

CanalBody and

Tail

Kidney

R S Q

P

BY826 Biology

Page 4

Question 5

(a) Alkaptonuria is a disease which causes body tissues and urine to be stained dark. The shadedareas in the diagram below represent an affected individual.

(i) Explain whether alkaptonuria is caused by a dominant or recessive allele. (2 marks)

…………………………………………………………………………………………….

…………………………………………………………………………………………….

…………………………………………………………………………………………….

(ii) Give the most likely genotype for the individuals listed below. Only include the allelesyou are sure of. Use ‘A’ for the dominant allele and ‘a’ for the recessive allele.

(2 marks)

George: ………………….

Arlene: ………………….

Sam: ………………….

Sandra: ………………….

(iii) Carefully explain if there is any evidence that the disease is sex linked. (2 marks)

…………………………………………………………………………………………….

…………………………………………………………………………………………….

…………………………………………………………………………………………….


Unaffected Male

Affected Male

Unaffected Female

Affected Female

George Arlene

Sandra Tom Sam Jane Ann Michael

Daniel Alan Tina

Carla

Christopher

BY826 Biology

Page 5


(b) Under some conditions, certain simple organisms like the green filamentous algae Spirogyra,reproduce asexually, but should conditions deteriorate, sexual reproduction occurs. What is theadvantage in being able to reproduce by both modes? (4 marks)

………………………………………………………………………………………………...

………………………………………………………………………………………………...

………………………………………………………………………………………………...

………………………………………………………………………………………………...

………………………………………………………………………………………………...

………………………………………………………………………………………………...


BY826 Biology

Page 6

Question 6

Answer parts (a) and (b) OR parts (c) and (d) of this question.

(a) The diagram below shows the cross section of an artery and a vein respectively.

(i) What is the role of each of the tissues that makes up the arteries and veins? (2 marks)

…………………………………………………………………………………………….

…………………………………………………………………………………………….

…………………………………………………………………………………………….

(ii) Why do we describe an artery and a vein as organs? (2 marks)

…………………………………………………………………………………………….

…………………………………………………………………………………………….

…………………………………………………………………………………………….

(iii) What differences in structure are there between an artery and a vein? (2 marks)

…………………………………………………………………………………………….

…………………………………………………………………………………………….

(iv) Why are they structured differently? (2 marks)

…………………………………………………………………………………………….

…………………………………………………………………………………………….

…………………………………………………………………………………………….


connective tissue

muscle and elastic tissue

endothelium

lumen

T.S. Artery T.S. Vein

BY826 Biology

Page 7


(b) Water balance is very difficult to maintain, especially in very salty and/or very dry conditions.The shore of Lake Eyre in Central Australia is one such environment.

Explain two likely adaptations a small mammal, the Spinifex hopping mouse for example, mighthave to survive in the environment. (4 marks)

………………………………………………………………………………………………...

………………………………………………………………………………………………...

………………………………………………………………………………………………...

………………………………………………………………………………………………...

………………………………………………………………………………………………...

………………………………………………………………………………………………...

Question 6 alternative choice is over the page.

BY826 Biology

Page 8

Question 6 (alternative choice)

OR

(c) The diagrams below show the xylem and phloem of flowering plants.

(i) Are the xylem and phloem tissues or organs? Explain. (2 marks)

…………………………………………………………………………………………….

…………………………………………………………………………………………….

…………………………………………………………………………………………….

(ii) What can be said about the structure of the xylem and the phloem which makes themsuitable for their function of transport ? (2 marks)

…………………………………………………………………………………………….

…………………………………………………………………………………………….

…………………………………………………………………………………………….

(iii) Both the xylem and the phloem have no nucleus. What functions cannot be carried out ifthe nucleus is absent ? (2 marks)

…………………………………………………………………………………………….

…………………………………………………………………………………………….

…………………………………………………………………………………………….

(iv) There are many mitochondria in the phloem. Explain what can be inferred about themechanism of transport in phloem. (2 marks)

…………………………………………………………………………………………….

…………………………………………………………………………………………….

…………………………………………………………………………………………….


A Xylem Vessel A Phloem Sieve Tube

sieve plate

sieve pore

cytoplasmic strands

lignin thickening

lignified wall

pits

BY826 Biology

Page 9


(d) Water balance is very difficult to maintain, especially in very salty and/or very dry conditions.The shore of Lake Eyre in Central Australia is one such environment.

Explain two of the likely adaptations an evergreen tree, like River Red Gum or Mulga, mighthave to survive in this environment. (4 marks)

………………………………………………………………………………………………...

………………………………………………………………………………………………...

………………………………………………………………………………………………...

………………………………………………………………………………………………...

………………………………………………………………………………………………...

………………………………………………………………………………………………...





PLACE LABEL HERE



External Assessment

2000

BY826 BIOLOGY

SECTION C

Time: 35 minutes


Criterion 5 Demonstrate understanding and knowledge of biologicalprinciples and how they apply to the interrelationships betweenorganism and environments.

BY826 Biology

Page 2




________________________________________________________________________________

Question 7

(a) Corn is a major crop grown in Europe and in the past it was either ruined by attack from the cornborer larvae or the crop was intensively sprayed with pesticides each year. The biotech company,Novartis, gained approval to insert a Bt gene into corn. This gene codes for a protein that killsthe larvae feeding on it. The genetically engineered Bt corn initially thrived without the additionof any pesticides, but the corn plants are again suffering damage from pests.

Use your understanding of biology to suggest two possible reasons why the Bt corn is againunder attack from pests. (6 marks)

(i) …………………………………………………………………………………………….

…………………………………………………………………………………………….

…………………………………………………………………………………………….

…………………………………………………………………………………………….

(ii) …………………………………………………………………………………………….

…………………………………………………………………………………………….

…………………………………………………………………………………………….

…………………………………………………………………………………………….


BY826 Biology

Page 3


(b) The extract below was prepared by the Tasmanian Department of Environment and Wildlife.

The orange-bellied parrot is endangered because it is so rare (only 200 birdsleft) and its habitat is quickly disappearing. There are only about 50 breedingpairs of this bird left. It is a breeding endemic of Tasmania which means that itonly breeds in Tasmania. In fact it only breeds in one place in Tasmania andthat is in our Southwest National Park. It arrives here in summer, nesting ineucalypt tree hollows adjacent to the parrots’ feeding grounds of extensivecoastal buttongrass plains.

To try and increase the numbers of birds, there has been a captive breeding program in placesince 1986.

Outline two important aspects of the captive breeding program needed to ensure a viablepopulation is maintained. (4 marks)

(i) …………………………………………………………………………………………….

…………………………………………………………………………………………….

…………………………………………………………………………………………….

(ii) …………………………………………………………………………………………….

…………………………………………………………………………………………….

…………………………………………………………………………………………….

(iii) How else could the future survival chances of the parrot be improved ? (2 marks)

…………………………………………………………………………………………….

…………………………………………………………………………………………….

…………………………………………………………………………………………….


BY826 Biology

Page 4

Question 8

In February this year there was sufficient rain to flood Lake Eyre, an event that only happensapproximately every 5 years. There was a rapid increase in the population of many different species,many of which had been trapped in isolated pools (fish), hibernated deep within burrows (frogs) andsurvived as eggs (brine shrimps) or spores (algae). Many birds (egrets, pelicans and harriers) arrivedat the lake. The lake dried out rapidly, however, due to evaporation and the saltpan returned, trappingmany organisms within the salt crust. The diagram below shows a partial food web that occurs duringflooding.

(a) Why can detritivores be considered to be at the top of the feeding hierarchy? (2 marks)

………………………………………………………………………………………………...

………………………………………………………………………………………………...

………………………………………………………………………………………………...


Egrets

Fish

Tadpoles

Algae

Pelicans

Frogs

Brine Shrimp

Detritus

BY826 Biology

Page 5


(b) Complete the graph below by drawing lines to show the change in populations for algae, brineshrimp, fish and harriers. Harriers are both predators and scavengers. The line must representboth the time and the biomass of each organism. (6 marks)

(c) How does the trapping of the organisms within the salt crust contribute to the rapid increase inbiomass when the rains come ? (2 marks)

………………………………………………………………………………………………...

………………………………………………………………………………………………...

………………………………………………………………………………………………...

(d) Some small fish, that had sheltered in the isolated pools, follow the flood water to the lake andcontinue to swim to find another tributary. What evolutionary advantage would this give thespecies as the majority of the individuals die within the lake ? (3 marks)

………………………………………………………………………………………………...

………………………………………………………………………………………………...

………………………………………………………………………………………………...

………………………………………………………………………………………………...


Bio

mas

s

Lake starts fillingTime

Lake dries

BY826 Biology

Page 6

Question 9

Forestry companies are buying thousands of hectares in Tasmania to convert to plantations, partly totake advantage of possible government greenhouse initiatives.

(a) In mature forests, the land is first logged and then clear felled before it is burnt, ploughed andreplanted with a single species, such as the Shining Gum Eucalyptus nitens. Discuss thechanges in the following for this ecosystem by comparing immediately before logging, pre-planting and 20 years later.

(i) carbon dioxide levels; (3 marks)

…………………………………………………………………………………………….

…………………………………………………………………………………………….

…………………………………………………………………………………………….

…………………………………………………………………………………………….

(ii) nutrient levels; (3 marks)

…………………………………………………………………………………………….

…………………………………………………………………………………………….

…………………………………………………………………………………………….

…………………………………………………………………………………………….

(iii) biodiversity. (3 marks)

…………………………………………………………………………………………….

…………………………………………………………………………………………….

…………………………………………………………………………………………….

…………………………………………………………………………………………….

(b) Grass farmland in high rainfall areas is also being converted to plantations. The land is simplyploughed and then planted. Compare nutrient levels in the farmland to the mature forest at thetime of planting. (2 marks)

………………………………………………………………………………………………...

………………………………………………………………………………………………...

………………………………………………………………………………………………...





PLACE LABEL HERE



External Assessment

2000

BY826 BIOLOGY

SECTION D

Time: 35 minutes


Criterion 8 Develop feasible hypotheses and design controlled experiments totest hypotheses.

BY826 Biology

Page 2




________________________________________________________________________________

BY826 Biology

Page 3

Question 10

(a) Small populations of Pink Galahs are found around Ulverstone, Launceston and Hobart. It isthought that the birds escaped from aviaries some years ago.

(i) Write a reasonable hypothesis to account for why Pink Galahs have not spread to areasaround Lake St. Clair in the Central Highlands.

(3 marks)…………………………………………………………………………………………….

…………………………………………………………………………………………….

…………………………………………………………………………………………….

(ii) How would you test for the outcomes of your hypothesis? (3 marks)

…………………………………………………………………………………………….

…………………………………………………………………………………………….

…………………………………………………………………………………………….

(b) The tip of a broad bean was carefully marked at 2 mm intervals using a water proof ink. Afterseveral days it was noted that the marks were no longer the same distance apart.

Suggest two alternative hypotheses that could account for these results. (6 marks)

(i) …………………………………………………………………………………………….

…………………………………………………………………………………………….

…………………………………………………………………………………………….

(ii) …………………………………………………………………………………………….

…………………………………………………………………………………………….

…………………………………………………………………………………………….


broad beanseed

plumule

radicle

Radicle is markedat equal intervalswith indian ink.

After a few days, themarks in some partsof the radicle havebecome further apart.

BY826 Biology

Page 4

Question 11

Many garden books recommend dipping the end of a plant stem into a hormonal ‘cutting’ powdersuch as Clonex, to help the plant stem grow roots more quickly. Many home gardeners believe thatusing a sugar solution is just as effective.

A possible hypothesis for this observation is that a sugar solution is just as effective as Clonex atpromoting root growth in plant cuttings.

(a) (i) What is the independent variable? (1 mark)

…………………………………………………………………………………………...

(ii) What is the dependent variable? (1 mark)

…………………………………………………………………………………………...

(b) (i) What results would be expected if the hypothesis is supported? (2 marks)

…………………………………………………………………………………………...

…………………………………………………………………………………………...

…………………………………………………………………………………………...

(ii) Name four variables that should be controlled in an experiment to test this hypothesis.(2 marks)

…………………………………………………………………………………………...

…………………………………………………………………………………………...

…………………………………………………………………………………………...

(iii) Before the treatments are promoted for use by gardeners, what further tests should bedone? (3 marks)

…………………………………………………………………………………………...

…………………………………………………………………………………………...

…………………………………………………………………………………………...


BY826 Biology

Page 5

Question 12

Omega-3 fatty acids, commonly found in oily fish, have been found to be very effective at loweringblood levels of low density cholesterol which reduce the risk of heart disease. Dieticians nowrecommend eating fish three times a week. It is even possible to buy HiQ bread that has been enrichedwith Omega-3 fatty acids.

As a result of eating more of these Omega-3 fatty acids, people have claimed other benefits to theirhealth such as decreased levels of hyperactivity in children, increased ability to learn and relief fromarthritic pain. Design an experiment to test one of these claims. (12 marks)

…………………………………………………………………………………………………………

…………………………………………………………………………………………………………

…………………………………………………………………………………………………………

…………………………………………………………………………………………………………

…………………………………………………………………………………………………………

…………………………………………………………………………………………………………

…………………………………………………………………………………………………………

…………………………………………………………………………………………………………

…………………………………………………………………………………………………………

…………………………………………………………………………………………………………

…………………………………………………………………………………………………………

…………………………………………………………………………………………………………

…………………………………………………………………………………………………………

…………………………………………………………………………………………………………

…………………………………………………………………………………………………………

…………………………………………………………………………………………………………

…………………………………………………………………………………………………………

…………………………………………………………………………………………………………

…………………………………………………………………………………………………………

…………………………………………………………………………………………………………

…………………………………………………………………………………………………………

…………………………………………………………………………………………………………

…………………………………………………………………………………………………………

…………………………………………………………………………………………………………





PLACE LABEL HERE



External Assessment

2000

BY826 BIOLOGY

SECTION E

Time: 35 minutes


Criterion 9 Analyse, interpret and evaluate information and data gained (fromindividual investigations and the investigations of others) and toevaluate the methods used and conclusions drawn from theseinvestigations.

BY826 Biology

Page 2




_______________________________________________________________________________

Question 13

(a) Potatoes grown in Tasmania usually require irrigation in dry periods and this is often equivalentto 2.5 cm of rain applied at regular intervals. In an experiment to see if this irrigation wasnecessary to increase the yield of potatoes, investigators applied three different treatments tocrops grown in open fields, with uniform soil and other environmental conditions. Theexperiment was conducted over 5 years. The results are shown in the table below.

Treatment Full Watering (A) Half Watering (B)(ie. every alternate time)

No Watering (C)

Yield (kg/Ha) 4014 3708 2083

(i) Describe the effect watering has on the yield of potatoes. (1 mark)

…………………………………………………………………………………………….

…………………………………………………………………………………………….

(ii) Do the results show that potato growth is limited by the volume of water added or by thefrequency of watering? (4 marks)

…………………………………………………………………………………………….

…………………………………………………………………………………………….

…………………………………………………………………………………………….

…………………………………………………………………………………………….

…………………………………………………………………………………………….


BY826 Biology

Page 3


(b) In 1900 Brown and Escombe measured the diffusion of carbon dioxide through holes ofdifferent sizes. Some of their results are shown in the table below.

Column 1 Column 2 Column 3

Diameter of Hole (mm) Volume of CO2 Diffusing

per Hour (cm3 )

CO2 Diffusing per square

cm of Hole per Hour (cm3 )

22.70 0.24 0.06

12.06 0.10 0.09

6.03 0.06 0.22

3.23 0.04 0.48

2.00 0.02 0.76

(i) What interpretation can be given by comparing Column 1 and 2? (1 mark)

…………………………………………………………………………………………….

…………………………………………………………………………………………….

(ii) What interpretation can be given by comparing Column 1 and 3? (2 marks)

…………………………………………………………………………………………….

…………………………………………………………………………………………….

(iii) In what ways do these findings account for the size and number of stomata found inleaves? (3 marks)

…………………………………………………………………………………………….

…………………………………………………………………………………………….

…………………………………………………………………………………………….

…………………………………………………………………………………………….


BY826 Biology

Page 4

Question 14

(a) An enzyme isolated from a micro-organism causes compounds A and B to form C. The activityof this enzyme was tested at various temperatures in vitro (in a test tube) and in vivo (in theliving organism). The results are shown in the table below.

Temperature (˚C) In Vitro Yield of C In Vivo Yield of C

5 3 75

10 6 72

15 11 71

20 17 71

25 23 71

30 32 74

35 42 78

40 54 84

45 68 92

50 75 93

55 70 82

60 58 64

65 20 20

(i) Describe the relationship between temperature and the activity of the enzyme in vitro.(2 marks)

…………………………………………………………………………………………….

…………………………………………………………………………………………….

…………………………………………………………………………………………….

(ii) Describe the differences in the yield from in vitro to in vivo at each temperature.(2 marks)

…………………………………………………………………………………………….

…………………………………………………………………………………………….

…………………………………………………………………………………………….

(iii) What can be deduced from the information about the micro-organism and its habitat?(2 marks)

…………………………………………………………………………………………….

…………………………………………………………………………………………….

…………………………………………………………………………………………….

…………………………………………………………………………………………….


BY826 Biology

Page 5


(b) The graph below shows the effect of temperature on the dissociation of oxygen fromhaemoglobin.

(i) What is the general relationship between the partial pressure of the oxygen and thesaturation of haemoglobin? (1 mark)

…………………………………………………………………………………………….

…………………………………………………………………………………………….

(ii) At a partial pressure of oxygen ( pO2 ) of 20 mm Hg, what is the effect of increasingtemperature?

(1 mark)

…………………………………………………………………………………………….

…………………………………………………………………………………………….

(iii) What effect will the increase in temperature have on an exercising muscle? (2 marks)

…………………………………………………………………………………………….

…………………………………………………………………………………………….

…………………………………………………………………………………………….


100

80

60

40

20

0 20 40 60 80 100

Per

cent

Sat

urat

ion

of H

aem

oglo

bin

partial pressure of oxygen (pO2) mm Hg

10˚C

20˚C

38˚C

43˚C

BY826 Biology

Page 6

Question 15

American doctors observed that patients taking aspirin seemed to be less affected by heart disease sothey designed an experiment called the “Physicians’ Health Study” to test the hypothesis that ‘takingaspirin will lower the rate of heart attack by 20-30%’.

They chose 22 000 healthy male doctors within the age range of 40 to 84 years as subjects. Such alarge number was chosen because the rate of heart attack is low. The doctors were assigned randomlyto one of two groups. Each group was asked to take a tablet each day for 60 months. Group 1 wasgiven aspirin and Group 2 was given a placebo, a tablet that looked identical but had no medical effect.A double blind technique was used so that neither the researchers nor the subjects knew who wasreceiving which treatment.

The results showed that aspirin takers suffered a 44% reduction in heart attack compared to theplacebo takers. There is only 1/100 000 chance of this occurring naturally. The doctors consideredthis to be an outstanding result and stopped the trial early and the Food and Drug Authority (FDA)approved the labelling of aspirin for the treatment of patients against heart disease.

(a) Why was a placebo considered necessary in this experiment? Support your answer withexamples. (3 marks)

………………………………………………………………………………………………...

………………………………………………………………………………………………...

………………………………………………………………………………………………...

………………………………………………………………………………………………...

………………………………………………………………………………………………...

(b) From the information given about the Physicians’ Health Study was the FDA justified inapproving taking aspirin for reducing the risk of heart attack? (6 marks)

………………………………………………………………………………………………...

………………………………………………………………………………………………...

………………………………………………………………………………………………...

………………………………………………………………………………………………...

………………………………………………………………………………………………...

………………………………………………………………………………………………...


Documents

Tasmanian Certificate of Education · (b) Under some conditions, certain simple organisms like the green filamentous algae Spirogyra , reproduce asexually, but should conditions deteriorate,