INSTRUCTIONS:

BRITISH BIOLOGY OLYMPIAD 2011

ROUND TWO QUESTIONS

The paper consists of 40 questions scoring 94 marks.

Answer all questions on the answer sheet.

Most answers consist of one or more letters or numbers, ticks or plus and minus signs or the results of numerical calculations.

You have a total of one and a half hours to complete the test.

When you have completed the test artd checked your answers return all test materials to the invigilator.

Good luck.

BBSRC UNIVERSITY0F w:=Rapid 1~\ SQCIETY.OF bioscienceforthefuture BIRMINGHAM - ~ Btology

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BBO 2011 ROUND 2

Ql. (2marks) The prokaryote Bacillus thuringiensis has a gene that controls the production of an insect-killing toxin. This gene can be transferred to the genome of Agrobacterium tumifaciens. A. tumifaciens acts as a vector to transfer the gene into wheat ( Genus Triticum).

List the numbers of all of the following statements that could explain the mechanism of the insect-killing toxin.

1. The toxin is an aminopolysaccharide deaminating enzyme 2. The toxin inhibits cytochrome oxidase activity in the electron transport chain 3. The toxin is an acetylcholinesterase inhibitor 4. The toxin inhibits the production and secretion of a hormone into an insect's blood vessels 5. The toxin inhibits thoracic spiracle closure 6. The toxin inhibits the excretion of uric acid in the faeces.

Q2. (1 mark) Which one of the statements relating to the isoelectric pH of a tetrapeptide is true?

A. The amino and carboxy/ termini are not charged. B. Two internal amino acids of the tetrapeptide cannot have ionizable R groups. C. The total net charge is zero. D. There are four ionic charges. E. Only the amino and carboxyl termini contribute charge.

Q3. ( 6 marks) A bacterium has a single copy of a 4 x 106 bp circular DNA. Using a value of3 for n, 6 x 1023 for the Avogadro's number and 660 for the molecular weight of 1 bp of DNA, answer the following questions.

a) If the diameter of this spherical cell is 1 f.!m, what would be the molar concentration of DNA in this cell?

b) If the DNA assumed a conformation as proposed by Watson and Crick, what would be the linear length of the bacterial DNA in metres?

c) How many bacterial cells would be required to produce 1 mg of DNA?

Q4. (1 mark) When cAMP functions as a second messenger, which of the following statements is true?

A. Acts outside the cell to influence cellular processes. B. Acts 'second in importance' to AMP. C. Activates all cytosolic protein kinases. D. Activates the cAMP-dependent protein kinase.

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BBO 2011 ROUND 2

QS. (1 mark) Evidence indicating that chloroplasts were originally free-living prokaryotes that subsequently evolved a symbiotic relationship with a eukaryotic host includes all the following EXCEPT

A. Similarities of rRNA sequences between chloroplasts and free-living prokaryotes. B. Similarities in structure between chloroplasts and some contemporary free-living prokaryotes. C. Presence of circular DNA in chloroplasts and in free-living prokaryotes. D. Susceptibility of chloroplasts to inhibitors of prokaryotic protein synthesis. E. Ability of chloroplasts to synthesize all their own proteins

Q6. ( 4 marks) Consider the following chemical reactions:

A. pyruvate + NAD+ + H20 + CoA ~ acetyl CoA + NADH + H+ + C02. B. aspartic acid + pyruvic acid ~ oxaloacetic acid + alanine COOH-CH(NHz)-CHz-COOH CH3-CO-COOH COOH-CO-CHz-COOH CH3-CH(NHz)-COOH C. phosphoglyceric acid + ADP ~ pyruvic acid+ ATP D. protein + water ~ amino acids

E. glucose ~ starch + water

Noting that each letter may be used once, more than once or not at all, write the letter of the chemical reaction which corresponds with each of following reactions.'

a) condensation, b) transamination, c) dehydrogenation, d) decarboxylation

Q7. (4 marks) Indicate which of the following statements about transport across the plasma membrane of the cells is correct and which is incorrect by writing a + for correct and a - for incorrect against the letters on the answer sheet.

A. Steroid hormones are taken up by the cell by endocytosis.

B. Amino acids are taken up by the cell by simple diffusion.

C. Bacteria are taken up by the cell by phagocytosis.

D. Metabolic wastes are taken up by the cell by endocytosis

E. Ions can pass through channel proteins by passive transport.

F. Cholesterol is taken up by the cell as a low-density lipoprotein (LDL) by receptor-mediated endocytosis.

G. In the epithelial cells of the intestine, macromolecules are transported from the lumen to the interstitial fluid is by transcytosis.

H. The Na+/K+ pump transports 2 Na+ out of the cell and 3K+ into the cell.

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BBO 2011 ROUND 2

QS. (1 mark) Which one of the following statements shows the difference between the reaction centres of photosystem I and II ?

A. Chlorophyll a is found in photosystem I, and chlorophyll b in photosystem II. B. They preferentially absorb slightly different wavelengths of light. C. One is located in the thylakoid membrane, and the other in the stroma. D. Only photosystem I is found in the thylakoid membranes. E. None of the choices is correct.

Q9. (4 marks) a) Transgenic plants, like animals, are genetically-engineered varieties containing one or more

artificially inserted genes. Select from the following list the numbers of the methods that can be used to introduce genes into crop plants.

1. Agroinfection 2. Electroporation 3. Retroviral infection of stem cells 4. Micropropagation 5. Microinjection

b) The most significant damage to crop plants throughout the world is brought about by:

A. Fungal parasites B. Insects C. Viral infections D. Weeds E. Late frosts

c) Which of the following are advantages of micropropagation as compared to traditional horticultural techniques?

Select all the numbers of all those that apply.

1. Rapid production of new plants. 2. Preservation of desired genotypes over successive generations. 3. Cost effective. 4. Increased rate of mutation. 5. Space efficient. 6. Reduced likelihood of fungal attack.

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BBO 2011 ROUND 2

Q10. (1 mark) A suspension of algal cells which had previously been kept illuminated was supplied with 14C02 at the moment the light was switched off. The accumulation of 14C in 3phosphoglycerate (PGA) which resulted is shown below .

... c ::J 0 0

u ~

3 Light switched

off Minutes

Which statement is supported by these data?

A. The speed of the light-dependent reaction is slower than the light-independent reaction. B. Light inhibits the formation of phosphoglycerate. C. C02 acceptors are only formed in the dark. D. Light is required for the further conversion of phosphoglycerate.

Qll. (1 mark) A growing coleoptile was cut from a plant, frozen, thawed, hung on a position transducer and subjected to constant force first at pH7 and then at pHS. The following plot was obtained (note that the vertical line indicates the time at which pH was shifted from 7 to S).

Coleoptile Length

Which statement explains the increase in growth following transfer from pH7 to pHS? A. Acid conditions hydrolysed cellulose microfibrils B. Low pH stimulated auxin production C. Low pH induced sucrose uptake and so higher turgor D. Low pH weakend hydrogen bonding between wall components

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BBO 2011 ROUND 2

Q12. (3 marks) An investigation was carried out into the effect of carbon dioxide concentration and light intensity on the productivity of lettuces in a greenhouse. The productivity was determined by measuring the rate of carbon dioxide fixation in milligrams per dm2 leaf area per hour. Experiments were carried out at three different light intensities, 0.05, 0.25 and 0.45 (arbitrary units), the highest approximating to full sunlight.

The results are given in the table below.

Carbon dioxide Productivity at different light intensities I mg dm2 h-1 concentration /ppm At 0.05 units At 0.25 units At 0.45 units

light intensity light intensity light intensity 300 12 25 27 500 14 30 36 700 15 35 42 900 15 37 46

1100 15 37 47 1300 12 31 46

A carbon dioxide concentration of 300 ppm is approximately equivalent to that in atmospheric air. For each of the three light intensities, 0.05 units, 0.25 units and 0.45 units, work out the maximum increase in productivity that was obtained compared with that at 300 ppm and use it to calculate the percentage increase in productivity at each light intensity.

Q13. (4 marks) The total respiration (R) of a young growing plant is described by the following expression:

R = 0.27 P + 0.015 W,

where P is the total amount of glucose produced per day and W is the average mass of the plant.

Ofthe processes listed below, some influence the factor 0.27 of the above equation whereas the others do not.

1. Movement of water within the cells. 2. Reduction of nitrate (N03-) ions to ammonium (NH/) ions. 3. Uptake ofK+ ions through the plasma membrane ofendodermal cells. 4. Uptake of C02 in cells of palisade parenchyma. 5. Opening and closing of stomata. 6. Lengthening of a polypeptide chain. 7. Absorption of light by chlorophyll a. 8. Synthesis of starch.

Indicate with plus(+) and minus(-) signs, respectively, in the table on the answer sheet, which of these processes do or do not affect the factor 0.27.

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BBO 2011 ROUND 2

Q14. (1 mark) A man has a small injury in the retina of the left eye. This injury is situated at the top of the retina, in the direction of the left ear. He is looking with his left eye at a paper with a cross and a spot on it. The image of the spot is exactly projected on the injury of the retina. Choose from the diagram below the letter of the correct position of spot and cross on the paper.

DODD A B c D

Q15. (6 marks) The diagram shows a section of a mammalian kidney tubule. ~c~

A I u The statements below refer to the composition of tubular fluid or to the properties or processes associated with the tubular wall at the regions A, B and C.

1. Fluid becomes hypertonic 2. Fluid is isotonic at the start becoming hypotonic further along 3. Fluid is very hypotonic 4. Na+ and Cl-are actively transported out of the tubule 5. The wall of the tubule is relatively impermeable to Na+ and Cl-, 6. Na+ and cl- move out of the tubule down their concentration gradient 7. The tubule wall is virtually impermeable to water 8. The tubule wall is permeable to water. 9. The tubule wall is permeable to Na+ & CI-10. Water moves out of the tubule by osmosis

Write all the relevant statement numbers against each of the regions A, B & C

Q16. (4 marks) The figure below shows three small blood vessels in transverse section. The vessels A, B & C have diameters in the ratio 1.0 : 0.75 : 0.5.

A B c

Tranwerse sections of three small blood vessels

a). If the peripheral resistance to blood flow in a vessel is proportional to the fourth power of its diameter, calculate the ratio of the resistance to blood flow (1/d4) in the vessels A, B & C.

b). Using the letter P for cardiac output, Q for arterial blood pressure and R for peripheral resistance, indicate the relationship that exists between them.

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BBO 2011 ROUND 2

Q17. (4 marks) +$0 +20 +10

G -10

> -20 E-30

-40 --so -tO -70 ...eo

Action Potential

c

1 I 6

a) With reference to the regions labelled A ,B,C & D, place ticks in the appropriate spaces in the table on the answer sheet to show if the Na+ and K+ gates are open or closed.

b) Which letter indicates a state of hyperpolarisation?

c) What is the total voltage change during the course of the action potential?

Q18. (2 mark) The following question concerns respiration. Write down the numbers ofthe statements which are correct.

1. In muscles in the absence of oxygen, pyruvate is converted into lactic acid and carbon dioxide.

2. Oxygen is the final electron acceptor. 3. ATPase is located on the outer membrane of a mitochondrion. 4. NADH passes on its electrons to cytochrome oxidase. 5. 2 molecules ofFADHz are produced for every one molecule of glucose oxidised. 6. The link reaction takes place in the cytoplasm. 7. Oxaloacetate has 4 carbon atoms.

Q19. (2 marks) The following hormones affect the level of blood glucose in the mammal.

1. insulin 2. growth hormone 3. glucagon 4. thyroxine 5 adrenaline

a) Write down the 2 numbers which represent opposing control factors.

b) Write down all the numbers which represent supporting control factors.

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BBO 2011 ROUND 2

Q20. ( 4 marks) The diagram represents certain pathways in mammalian respiration.

Glycogen

Carbon dioxide and water

A

Hexose diphosphate (fructose 1,6 biphosphate

c

I ~E D / Pyruvate . "":a.

Glucose

Lactic acid

Select the letter of the chemical pathway in the diagram that applies to each of the following:

I. Involves the reoxidation ofNADH withoutATP formation. II. Occurs exclusively within mitochondria III. Involves hydrolysis of a polymer IV. Involves synthesis of ATP outside the mitochondria

Q21. (2 marks) The relative growth rates of four organs of the human body are shown in the following graphs .

.!: (/) (/) (/).:!:::::: ca :J E-o ...._ca 0 100 '#.

c (/) (/) (/).:!:::::: ca :J E-o ...._ca 0

'#.

p

1

. !: (/) (/) (/)+-' caS E-o ...._ca 0

'#. 100

.!: (/) (/) (/)+-' caS E-o ...._ca 0 LOO '#.

Q

10 20 Age (years)

s

1 Age (years)

Match the graphs with the organs shown on the answer sheet by putting a tick mark (".!) in the appropriate box of the table.

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BBO 2011 ROUND 2

Q22 (2 marks ) Animal behaviour patterns, in which an individual endangers its life to benefit other members of the group, are called altruistic. It is believed that altruistic behaviour is favoured by kin selection. Indicate in the table on the answer sheet by which of the following examples given.below show kin-selection(+) and which do not(-).

I. Suicidal attack by a worker bee guarding its hive. II. Protection of the queen of an ant species by "soldier" ants. III. Protection of lion cubs by a lioness who is not their mother. IV. Cries of a bird warning other individuals about approaching danger.

Q23 (1 mark) All of the following are examples of aggressive behaviour except which one?

A. The behaviour of a prey animal that is under the threat of being killed. B. The behaviour of animals in response to predator 'alarm calls' given by other members of

their species. C. An animal's behaviour against an intruder in order to protect its territory. D. Behaviour of an animal towards another animal which tries to steal its food. E. Behaviour of a predator towards its prey.

Q24 (1 mark) Response to sign stimuli or releasers is generally based upon ...

A. How colourful they are. B. A few isolated features of the stimulus. C. Whether all members of the species have them. D. Whether the stimulus is adaptive.

Q25 (1 mark) The group of four cells produced from a single meiotic division is known as a tetrad. A student isolates 24 tetrads from a plant that is heterozygous for the alleles A and a of a single gene and determines the genotype of each of the resulting 96 cells. The expected composition of this population is:

A. All 96 will be Aa. B. Approximately 0.5A and 0.5a allowing for sampling error. C. 72A and 24a. D. 48A and 48a. E. Approximately 0.75A and 0.25a allowing for sampling error.

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BBO 2011 ROUND 2

Q26 (8 marks) In a particular plant species, red flowers are produced by a dominant allele A while the recessive allele a gives white flowers. A second gene determines leaf shape with the dominant allele B giving dissected leaves and the recessive allele b giving smooth leaves. The two genes are located on different chromosomes. Four crosses were carried out between plants of different phenotype with the results shown below. For each cross give the precise genotypes of the two parents.

Cross Phenotype of parent Progeny phenotypes Red Red White White

dissected smooth dissected smooth

1 red, dissected X red, dissected 55 18 20 7 2 white, dissected X red, smooth 23 27 26 24 3 red, dissected X white, smooth 46 0 54 0 4 red, dissected X white, dissected 39 11 36 14

Q27 (1 mark) In cats, alleles for coat colour are sex-linked and are carried on the non-homologous part of the X chromosome. Allele B produces a black coat, b produces a yellow coat and the heterozygote is called tortoiseshell. A cross was made between a yellow female and a black male. Which of the following statements could be true about this cross? Give all that apply.

A. All males will be yellow. B. All females will be tortoiseshell. C. Females could be yellow or tortoiseshell. D. Males could be black or tortoiseshell. E. All males will be black.

Q28 (marks) The inability to synthesise the essential amino acid acid arginine was found to exist in three different gene mutants of the bacterium E. coli. The functions of the non-mutant form of the genes are shown in the diagram. Thus the gene 1 mutant cannot produce enzyme 1.

gene 1 gene 2 gene 3

l l l enzyme 1 enzyme2 enzyme 3

precursor substance ----~ ornithine ----~ citrulline ----~argmme

When the three mutants are grown together as adjacent colony streaks on a solid nutrient medium with a very small amount of arginine to start growth, each different colony was able to supply the other two with accumulated products except arginine.

Give the letter(s) of the mutant(s) which would be expected to show the best growth. A. gene 1 mutant B. gene 2 mutant C. gene 3 mutant D. gene 1 and 2 equally E. gene 1 and 3 equally F. gene 2 and 3 equally G. all three mutants equally

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BBO 2011 ROUND 2

Q29 (2 marks) A large population of laboratory animals has been allowed to breed randomly for a number of generations. After several generations, 49 percent of the animals display a recessive trait (bb), the same percentage as at the beginning of the breeding program. The rest of the animals show the dominant phenotype, with heterozygotes indistinguishable from the homozygous dominants.

a) What is the most reasonable conclusion that can be drawn from the fact that the frequency of allele b has not changed over time?

A. The population is undergoing genetic drift. B. The two phenotypes are equally adaptive under laboratory conditions. C. The genotype BB is lethal. D. There has been a high rate of mutation of allele B to allele b. E. There has been sexual selection favoring allele b.

b) What percentage of the population is heterozygous?

Q30 (1 mark) In the classical model of transcriptional control described by Jacob and Monod, a repressor protein binds to which of the following?

A. An enhancer B. An AUG sequence C. An operator D. A ribosome binding site E. ATATAbox

Q31 (1 mark) The Golden Retriever breed is an inbred line of dogs. The pedigree below is for a rare, but relatively mild, hereditary disorder of the skin.

I

II

III

IV 1 2 3 4 5 . 6 7 8 9

How is the disorder most likely inherited? Tick one box in the table on the answer sheet.

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BBO 2011 ROUND 2

Q32 (1 mark) Isolated protoplasts of two albino mutants of potatoes were fused. A variegated plant was obtained. Where are the mutant genes, which have caused the chlorophyll deficiency, located? (A new mutation, plastid communication and plastid DNA recombination should be excluded.)

A. In the nucleus of one mutant, in the plastids of the other one. B. In the nucleus of both mutants. C. In the plastids of both mutants.

Q33 (1 mark) Some mutations in mitochondrial DNA can cause a disease in humans called Leber's hereditary opti9 neuropathy (LHON). This is characterised by a sudden onset of blindness in adults. Give the letter(s) ofwhichever of the statements is/are true.

A. Only women can develop LHON B. Both men and women can develop LHON C. A person will develop LHON only if both their mother's and father's mitochondria carry the

mutation D. A person will develop LHON if their father has the disease but their mother is healthy E. A person will develop LHON if their mother has the disease but their father is healthy.

Q34 (1mark) In a particular species of fish, the body colours dark and pale are determined by alternative alleles of a single gene. When a pale female was crossed with a dark male all the offspring were dark. However, when a dark female was crossed with a pale male all the male offspring were dark while all the female offspring were pale. The parents were true breeding in each cross.

For each of the following questions, underline the correct response on the answer sheet.

a) b) c)

Which is the heterogametic sex?

Which body colour is dominant ?

Is the inheritance sexlinked?

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male I female dark I pale yes I no

BBO 2011 ROUND 2

Q35 (3 marks) The shell of the land snail shows variation in both colour and banding pattern. In order to construct a 5-figure banding formula, bands are numbered from the top of the largest whorl, as shown in the diagram. 0 is used to represent the absence of a band and square brackets indicate the fusion of two bands.

(banding formula = 1 2 3 4 5)

pink green

brown brown

a) Using the appropriate letter, indicate the banding formula of ShellS.

A. 030[45] c. 02045

B. 03045 D. 003[45]

b) Thrushes (which have good colour vision) smash the shells of land snails against stones (anvils) in order to feed on the soft inner body. If snail types P, Q, R & S began in equal numbers in a habitat of grassland, which would be the most likely to enjoy the greatest selective advantage? Write P,Q, R orSon the answer sheet.

c) A survey of broken shells collected from thrush anvils amongst dead beech leaves in a woodland area was carried out. Predict which of the following sets of results was obtained.

% number of broken shells of each type p Q R s

A 13 33 1 5 B 11 1 34 6 c 5 1 14 32 D 6 21 20 5

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BBO 2011 ROUND 2

Q36 (1 mark) Which of the following is responsible for the summer and winter stratification of lakes?

A. Water is densest at 4C B. Oxygen is most abundant in deeper waters. C. Winter ice may carry over until spring thaw. D. Stratification is caused by a thermocline. E. Stratification always follows the fall and spring turnovers.

Q37 (2 marks) Indicate which of the following statements are correct ( +) and which are incorrect (-) in relation to the carrying capacity of an area for a particular species.

A. The carrying capacity of an area is determined by the availability of resources

B. When a population that inhabits an area is larger than its carrying capacity, the population is likely to decrease.

C. The carrying capacity of an area can vary as a result of the environmental conditions.

D. The carrying capacity of an area can be zero.

Q38 (2 marks) Springtails are small insects that are common inhabitants of many kinds of soils, and are eaten in large quantities by predatory mites. DDT and aldrin are organochlorine insecticides used to control the numbers of these organisms. Aldrin is equally toxic to springtails and mites, but DDT is more toxic to mites than to springtails.

time/months time/months

4

time/months time/mon!.hs

If DDT and aldrin are applied separately to different plots of land at the start of treatment, which of the graphs above represent their effects on the population of springtails and mites?

a) Effect ofDDT.

b) Effect of aldrin.

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BBO 2011 ROUND 2

Q39 (2 marks) The growth of an animal population depends upon the biological characteristics of the individuals within, such as; life expectancy, fecundity (number of offspring from a female during her entire life), duration of the reproductive period, whether fecundity is evenly distributed throughout a female's life, the age at which animals first reproduce and the the age structure of the population (i.e. the proportions of the population in different age categories).

Consider two populations X and Y. ,Indicate which of these two populations will undergo the more rapid growth, in the situation described in each of the following statements, all other factors being constant.

A. Population X is mostly composed of young individuals, whereas population Y is characterised by a stable age structure.

B. Inside population X, females reach sexual maturity two times faster than in B, however females from Y survive 1/3 longer.

C. In population X, female fecundity is uniformly distributed during all their life, whereas for Y it is concentrated at the beginning of adult life.

D. In population Y, female fecundity is two times higher than in X but the life expectancy is two times shorter than in X.

Q40 (4 marks) The characteristics of eight taxonomic groups (indicated with letters A to H) are shown in the table below: Group Amniotic Notochord Hair Legs Bony Teeth/

egg endoskeleton Jaws

A - + - - - -

B + + + + + +

c - + - - + +

D - + - + + +

E + + + + + +

F + + + + + +

G - + - - - +

H - - - - - -

Key: + feature present - feature absent

Based upon these features complete the evolutionary tree shown on the answer sheet by writing the correct taxon group letters in the corresponding branches.

END OF QUESTIONS

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