BRITISH BIOLOGY OLYMPIAD 2012

ROUND TWO QUESTION PAPER

Time allowed 1 1/2 hours

Instructions:

• Answer all questions on the answer sheet.

• Write your names, school and centre number on the top of the answer sheet.

• Answers written in margins or on the question paper will not be marked.

• Do all rough work on the question paper.

• Use black ink or black ball-point pen.

• You may use a calculator.

• When you have completed the test and checked your answers, return all test materials to the invigilator.

Information:

• The paper consists of 57 questions scoring 94 marks.

• The marks for questions are shown in brackets.

• Answers consist of one or more letters or numerals, plus and minus signs or the results of numerical calculations.

Good luck.

BBO Round 2 - 2012

Q1 (1 mark)Two molecules of DNA (I and II) are the same size (1000bp) but differ in base composition. The first one contains 42% and the second one 66% A + T

A. How many G residues are there in DNA I?

B. Which molecule has the higher dissociation point?

Q2 (2 marks) Complete the answer table to indicate which of the following statements aretrue (+ ) and which are false (-).

A. Lipids are a group of compounds that include triglycerides and steroid hormones such as oestrogen and testosterone.

B. More ATP is produced from complete biological oxidation of one molecule of triglyceride than from one molecule of glucose.

C. The number of ATP molecules produced per oxygen molecule utilised is greater for complete oxidation of glucose than for fat.

D. Saturated fats contain fatty acids possessing one or more double bonds between adjacent carbon atoms.

Q3 (2 marks)Based on the information provided in the following table, complete the synthesis process of digestive enzymes during phagocytosis:

1 Replication 5 Endoplasmic reticulum

2 Translation 6 Vesicle

3 Transcription 7 Lysosome

4 Mitochondrion 8 Golgi apparatus

(1) mRNA-ribosome complex is transferred to A to continue B .(2) Synthesized enzymes enter C and D for modification. (3) The modified enzymes are stored in E .

Fill in the correct numbers in the table on the answer sheet.

Q4 (1 mark)If a fish species from freshwater evolved into a marine fish species, which problem(s) of osmoregulation would have to be solved?

A. Excess salt would have to be excretedB. Water would have to be reabsorbed from the initial ultrafiltrate of the kidneysC. The salt concentration of the blood would have to be adjusted to that of seawaterD. Drinking sea water would have to be avoidedE. Permeability of the skin would have to be reduced.

Write on the answer sheet the letter(s) that apply.

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BBO Round 2 - 2012

Q5 (4 marks) Write the number in the appropriate box in the answer table to indicate the locations where the various processes listed take place in the mammalian nephron.

Locations: 1. Renal corpuscle2. Proximal convoluted tubule3. Loop of Henlé4. Distal convoluted tubule5. Late distal tubule and collecting duct

Processes: A. Filtration of fluid that is isotonic to bloodB. Reabsorption of water, Na+, K+, Cl-, HCO3

-, nutrientsC. Reabsorption of water, Na+, HCO3

– D. Secretion of H+, NH4

+

Q6 (2 marks)If a man of 70kg mass ingests 40g alcohol, the alcohol level in his blood will rise to one part per thousand. About 1g alcohol is eliminated per hour per 10kg body mass. The man was involved in a traffic accident and ran away. A blood sample was taken from him after 2 hours. It contained 0.5 parts per thousand of alcohol. Assuming he did not ingest any alcohol after the accident, how much alcohol did his blood contain at the time of the accident?

A. 1.10 (parts per thousand)B. 0.95C. 0.8D. 0.65E. 0.55

Q7 (1 mark)A shark is more likely to survive for an extended period of food deprivation than is a dolphin with equivalent size because:

A. The shark maintains a higher basal metabolic rate.B. The shark expends more energy/kg body mass than the dolphin.C. The shark invests much less energy in temperature regulation.D. The shark metabolizes its stored energy more readily than the dolphin does.E. The shark has a better insulation on its body surface.

Q8 (1 mark)Increased arteriolar resistance contributes to hypertension. Which one of the following factors contributes to the increased vascular resistance most significantly?

A. Vessel lengthB. Blood viscosityC. Vascular diameterD. Total leucocyte countsE. Heart rate

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BBO Round 2 - 2012

Q9 (1 mark)A method to estimate a mammal’s blood volume uses a specific radioactive isotope of iodine (123I). This isotope, usually produced synthetically, has a half-life time of 13 hours. It decays to 123Te, which is almost perfectly stable. To estimate the blood volume, 10 ml of iodine solution are injected into the animal’s vein. The activity of the solution at the injection is 2mSv. A sample of 10 ml of the animal’s blood, taken 13 hours after the injection, is 0.0025mSv. What is the estimated volume of the animal’s blood? (mSv is a unit of radiation)

A. 10.0 LB. 8.0 LC. 4.0 LD. 2.5 LE. 1.25 L

Q10 (1 mark)A number of the following events will result in an excitatory postsynaptic potential in an experimentally stimulated neuron?

I. Increasing sodium influx.II. Blocking potassium out-flux.III. Increasing calcium influx.IV. Closing a chloride channel.

Give the letter which indicates the best combination of statements.

A. Only I & IIB. Only II & IIIC. Only I, III & IV D. Only II, III & IV E. All of them

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Q11 (1 mark)The following figure illustrates the membrane potential changes measured at three different sites (A, B, C) along a sensory neuron and the release of neurotransmitters from the axon termini when depolarizing electrical stimuli with varied intensities were applied to the dendrite. Based on the information provided in the figure below, choose the best combination of statements in the following list.

1. The membrane potential changes evoked at the A site would be proportional to the intensity of the electrical stimuli applied to the dendrite.

2. An action potential would be recorded at the B site only when the intensity of the applied current stimulus causes the membrane potential to be higher than the threshold potential in the axon hillock.

3. The frequency of the action potentials at B site is dependent on the duration of the applied current stimulus at A.

4. The quantity of the neurotransmitters released from the axon termini is unlikely to depend on the frequency of the action potential at C site.

A. Only 1 and 2B. Only 1 and 3 C. Only 2 and 3 D. Only 3 and 4 E. Only 1, 2, and 3

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Q12 -13 (4 marks)In the following figure, the structure of fish gills and the direction of water flow in the ventilation are illustrated. A & B are blood vessels.

Q12 (2 marks)During evolution the gas exchange in gills has become more effective. Give the letter(s) of the statement(s) that is/are correct.

A. A decrease in the thickness of the structure CB. A decrease in the number of cell layers in structure CC. An increase in the metabolic rate of the structure CD. An increase in the cell volume of the structure CE. An increase in the surface area of the structure C

Q13 (2 marks)Scientists found a kind of epithelial cell (X cell) in the structure of D with which fish can maintain body fluid osmolarity. Give the letter(s) of the statement(s) that is/are correct.

A. Absorb salt actively in freshwater fish B. Excrete salt actively in marine fishC. Excrete water actively in freshwater fishD. Absorb water actively in marine fishE. To generate ATP

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Q14 (2 marks)Which of the following statements about thermo-adaptation in animals are correct and which are incorrect? Write + or – against the letters on the answer sheet.

A. Blue-fin tuna are able to raise their core temperature. Therefore, it is an endothermic animal.

B. Icefish spend all their life in freezing, ice-laden, water and maintain a very stable body temperature. Therefore, icefish are homeothermic animals.

C. Shivering can help mammals to generate heat, and it is regulated by the hypothalamus. D. Brown adipose tissues help mammals to generate heat by supplying energy to skeletal

muscles. E. Brown adipose cells are rich in mitochondria for heat generation.

Q15 (3 marks)Maintenance of blood glucose level is important for normal physiological function. It is regulated by both the neural and endocrine system. The diagram below shows two different situations resulting from physiological stress or low blood glucose level. A list of organs/hormones involved is also shown.

Complete the table on the answer sheet by using the appropriate letters shown below.

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Structure/hormoneα cells of the pancreatic isletsInsulinLiverAdrenal medullaCortisol

BBO Round 2 - 2012

Q16 (1 mark)The diagram below shows the cross-section of part of a plant. With reference to the list of terms select the letter which lists a combination of possibilities.

I. StemII. Root

III. Leaf stalkIV. DicotyledonV. Monocotyledon

VI. HydrophyteVII. Terrestrial plant

A. I, IV,VIB. II, V, VIIC. II, V, VID. II, IV, VIIE. III, IV,VII

Q17 (1 mark)The concentration of ions in the sap of vessels of a tomato plant is investigated at three places as shown in the diagram.

Which one of the statements below is most likely to account for the differences of ions between stem and vein?

A. Evaporation of water from the stomata.B. Capillary force of the xylem vessels.C. Intake of ions by leaf cells.D. Intake of water by leaf cells.

Q18 (1 mark)How have bryophytes (mosses & liverworts) managed to survive on land?

A. They were the first plants to have developed stomata.B. They do not require moist environments for their reproductive cycles.C. They grow close to the ground in relatively moist regions.D. The sporophyte became independent of the gametophyte.

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Q19 (1 mark)The diagram below shows a section of a green non-woody stem with a vascular bundle.

Which one of the following statements is correct?

A. Starch would be found in the cells of area IIIB. Area II differentiated from protodermC. Area IV contains ligninD. Area V is interfasicular cambium

Q20 (1 mark)Hypersensitive response is one of the plant defence responses to pathogens. Each of four pathogen strains, a to d, produce a distinct range of effectors. One of the effectors, Avr, recognized by a specific receptor protein encoded by the resistance (R) gene in the host plant, is present in strains b and c. Host plants I and IV produce the R protein. Which plant(s) are likely to develop a hypersensitive response after the host plants I to IV are infected by pathogens a to d (aI, bII, cIII, dIV), respectively?

A. I onlyB. II onlyC. III onlyD. IV onlyE. II and IIIF. II and IV

Q21 (1 mark)Ethylene is a hormone that influences plant’s growth and development. It is known that treatment with 10 ppm of 1-methylcyclopropene (MCP) can block the signal transduction of ethylene. If certain plant tissues were treated with 10 ppm MCP, which one of the following phenotypes could be observed in MCP-treated tissues?

A. Shorter hypocotyl in etiolated mung bean seedlingB. Increased degradation of chlorophyll in detached leavesC. Increased synthesis of ethylene in banana fruitsD. Inhibition of the ripening of tomato fruitsE. Induction of the senescence of cut flowers

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BBO Round 2 - 2012

Q22 (1 mark)Neil dissected a plant leaf and found bundle sheath cells full of starch granules. Which of the following combination of characteristics can be observed in this plant?

I. Stomata open at nightII. Presence of PEP carboxylase in mesophyll

III. Presence of Rubisco in bundle sheath cellsIV. High photorespiration rate on hot summer daysV. Carbon fixation can occur in both mesophyll and bundle sheath cells

VI. Carbon assimilation rate is saturated in the early morning on summer days

A. Only I, IVB. Only II, IV, VC. Only II, IV, VID. Only II, III, VE. Only II, III, V, VIF. Only II, IV, V, VI

Q23 (2 marks)The diagram shows the life cycle of a fungus.

I. Which group does the fungus belong to?A. AscomycotaB. BasidomycotaC. Zygomycota

II. Which kind of spores are spread at X?A. Haploid meiotic sporesB. Haploid mitotic sporesC. Diploid spores

III. Which lifestyle is typical for this fungus?A The fungus is a saprophyticB The fungus is parasiticC The fungus lives symbiotically

IV. Where does meiosis take place? A Meiosis takes place at XB Meiosis takes place at YC Meiosis doesn’t take place in this fungus

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BBO Round 2 - 2012

Q24 (4 marks)The spectrum of light reaching the ground under a canopy in a forest differs from the light reaching the ground in an open field. For each of questions I to IV write the one correct letter on the answer sheet.

I This difference is mostly due to which one of the following plant molecules?

A Rubisco. B. Chlorophyll, C. Phytochrome, D. Cellulose

II. In what respects does the light under a canopy differ from the light in an open field?

A. The ratio of blue to green light is higherB. The ratio of red light to far red light is higherC. The ratio of red to green light is higherD. The ratio of far red to red light is higher

III. Plants respond to the composition of light through the action of which of the following compounds?

A. Gibberellin, B. Cytokinin, C. Phytochrome, D. Cytochrome.

IV. In which of the following respects do the plants under a canopy differ from plants of the same species in an open field?

A. They have longer internodes.B. They have shorter internodes.C. They have thicker stems.D. Their anthocyanin content is higher.

Q25 (2 marks)At the time of pollination, the living pollen grain typically consists of only the tube cell and the generative cell. During the germination of pollen grain, a pollen tube is produced and the nucleus of generative cell divides and forms two male gametes. Directed by a chemical attractant (such as GABA) produced by the synergids, the tip of the pollen tube enters the ovule through the micropyle. Then, in the embryo sac, a double fertilization occurs by the two male gametes. Give the letters of whichever of the following descriptions are correct:

A. The tube cell, male gamete, and synergid are haploid, while the generative cell and the zygote are diploid.

B. During the pollination, a gradient in GABA content is formed from the stigma (low) to the ovary (high).

C. The two male gametes fertilize two eggs, but only one forming the zygote.D. After fertilization, one zygote and one endosperm initially are formed.E. The germinated pollen grain is the male gametophyte, while the embryo sac is the

female gametophyte.

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BBO Round 2 - 2012

Q26 (2 marks)Mary divided 30 pots of plant X of similar condition into 10 plants per group, with each group being treated with different types of light regime. After a month, the flowering phenotypes of each group are shown in the table below:

Treatment Light regime Flowering result(I) 12hr 12hr All 10 plants flowered(II) 14 hr 10 hr 9 plants flowered, and 1 failed to flower(III) 16 hr 8 hr All 10 plants fail to flower

Give the letters of whichever of the following descriptions of Plant X are correct:

A. Plant X is a short day plant.B. The critical dark-length required by plant X for flowering is less than 10 hours.C. If group III is given a “one-minute dark treatment” in the middle of the light period,

after one month, most plants in this group will flower.D. If group II is given a “one-minute red light treatment” in the middle of the dark period,

most plants in this group will not flower after one month.E. If the apical buds of group I plants are removed before giving the light regime

treatment, then most plants will not produce florigen required for flowering after giving light regime treatment.

Q27 (1 mark)Elizabeth conducts DNA amplification and transcription reactions in two separate test tubes. Which one of the following substances needs to be added to both reactions?

A. ATPB. DNA templateC. RNA primerD. DNA polymeraseE. DNA ligase

Q28 (1 mark)The Nobel Prize in Physiology or Medicine 2009 was awarded jointly to Blackburn, Greider and Szostak for the discovery that chromosomes are protected by telomeres and the enzyme telomerase is highly correlated with ageing and cancer in animals. Which of the following statements regarding telomere and telomerase is correct?

A. Telomerase is a DNA exonuclease.B. Telomerase is an RNA polymerase.C. Embryonic cells possess long telomeres and high telomerase activity.D. Telomeres are longer and telomerase is inactive in cancer cells.E. Telomeres are longer and telomerase is highly active in somatic cells.

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Light Darkness

BBO Round 2 - 2012

Q29 (1 mark)An X-linked gene with alleles for black and orange determines coat colour in cats. Half the offspring from crosses between pure breeding orange and black cats have orange/black mosaic coats. Which one of the following statements regarding the inheritance pattern of the mosaic phenotype is correct?

A. Half of all male cats are mosaic.B. The mosaic phenotype is a consequence of gene interaction.C. The mosaic phenotype is correlated with genetic recombination.D. The mosaic phenotype results from random X-chromosomal inactivation.E. The offspring from matings of orange males and black females are mosaic.

Q30 (1 mark)Gregor Mendel discovered that segregation of genes on non-homologous chromosomes is independent of each other in his garden pea hybridisation experiments. Four genes A, B, C and D are located on four different non-homologous chromosomes. Which of the following genotypes will have the highest chance to produce the dominant trait in all four loci when it mates with an organism with the genotype AaBbCcDd?

A. aabbccddB. AaBbCcDdC. AaBBccDdD. AaBBCCddE. aaBBCCdd

Q31 (1mark)One locus has 5 alleles A1, A2, A3, A4, A5. How many different genotypes can exist in a population of a diploid organism if the dominance hierarchy of these alleles is A1> A2 > A3 > A4 > A5?

Q32 (2 marks)The diagram shows genotype frequencies during subsequent generations in a population.

a) What was the frequency of allele A at generation 0, assuming a Hardy-Weinburg equilibrium at that point?

b) What would be the frequency of aa after a very large number of generations?

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Q33 (2marks)Fur of guinea pigs can have different colours (black or white). Hairs can be with different textures (rough or smooth). Alleles Q and q are coding for colour, alleles R and r for type of hair. There is no linkage between the two genes. A number of guinea pigs with exactly the same genotype (the parental group) are allowed to mate and the result is a large number of F1 offspring. Most of these have black, rough fur. A small number have white smooth fur. About the same number of offspring are white and rough, or black and smooth.

a) Using the given letters, indicate the genotype of the guinea pigs in the parental group.

b) If 1024 F1 offspring were born, what is the expected number of the black and smooth?

Q34 (4 marks)a) Guinea pigs often have a spotted pattern. According to a simplified model spotted

pattern is determined by one gene with two alleles: G and g. If G is present the guinea pig is spotted. Students investigated the population of guinea pigs in a territory and found out that 84 % were spotted. Presuming this population is in (Hardy-Weinberg) equilibrium, calculate the frequency of G. Give your answer to one decimal place.

b) In one day all unspotted guinea pigs were removed. What will be the frequency of unspotted guinea pigs appearing in the next generation? Give your answer as a percentage without decimals.

Q35 (3 marks) In a specific type of legume, where seed colour is controlled by an autosomal gene, grey seed colour is dominant to white seed colour. In the following experiments, parents with known phenotypes but unknown genotypes produced offspring as follows:

PARENTS GREY WHITE1 Grey x White 82 812 Grey x Grey 118 393 White x White 0 504 Grey x White 74 05 Grey x Grey 90 0

If the symbol (G) is used for grey and (g) for white, indicate using + or – on the answer sheet, which of the following statements is true or false:

A. In cross 1 the white parent is gg B. In cross 1 both parents are homozygous C. In cross 2 one parent is Gg and the other is GG D. In cross 3 both parents are gg E. In cross 4 the grey parent is Gg F. In cross 5 the parents can’t be unambiguously determined

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BBO Round 2 - 2012

Q36 (2 marks)In Drosophila an autosomal transformer allele can be observed. If present, the transformer allele brings about a male appearance if an animal has two X-chromosomes, but such animals are sterile as their testes are underdeveloped. In Drosophila the red and white eye color is determined by a gene on an X-chromosome. A cross is performed between a red eyed Drosophila female heterozygous for both loci and a white eyed Drosophila male heterozygous for transformer. They produce a large number of offspring. What fraction of their offspring looks like white eyed males?

Q37 (3 marks) Oyster catchers are birds that look for prey such as bivalve molluscs in the shallow water of sea coasts. The shells in a habitat are of different sizes and these sizes correlate with the amount of energy in the shell meat:

• Small shells can be opened quickly and easily (benefit) but provide less food energy (cost).

• Big shells provide more energy (benefit), but they are more difficult and time-consuming to open (cost).

The following table provides information about shells living in a feeding territory.1. the total amount of energy in shells of different size2. the frequency of distribution of all shell sizes present3. the frequency of distribution of the shells selected4. number of shells of each size selected by birds5. Energy content (relative units) of shells selected by birds

Total amount of energy per shell (E)

Shells present (n) Energy present (E) Shells selected (n) Energy consumed (E)

1 1 1 0 02 17 34 0 03 11 33 1 34 9 36 3 125 6 30 6 306 7 42 7 427 20 140 11 778 22 176 10 809 19 171 14 12610 13 130 13 13011 6 66 6 6612 2 24 2 2413 1 13 1 13

Totals 134 896 74 603

Using the information in the table determine the following:

1) What total amount of energy could be expected from 74 shells that were randomly selected from 134 shells?

2) What is a) the absolute total amount of energy units and b) the total amount of energy as a percentage, that can additionally be consumed from 74 shells that were selected by birds?

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BBO Round 2 - 2012

Q38 (2marks) The following graphs show the changes in values of various biological factors/parameters in relation to increasing density of fish.

Write the appropriate curve number against the description letter on the answer sheet.

A. Total fish production B. Individual growth C. Food potential not used D. Expenditure of energy of each fish in the search of food

Q39 (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.

Q40 (1 mark)A group of students would like to know how the discharge of waste water from a factory might influence water quality of a river. The diagram shows 7 potential sampling locations in relation to the locations of the factory and the river. Which locations are essential to be included in the sampling in order to draw valid conclusions about the pollution of the river by the factory?

A. Locations 1, 2, 4, 7B. Locations 1, 3, 4, 7C. Locations 1, 2, 5, 7D. Locations 2, 3, 4, 6E. Locations 2, 5, 6, 7

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Q41 (2marks)When comparing closely-related bird species, mortality of breeding individuals appears to be higher for species in temperate regions than in tropical regions. Therefore, predation risks to parents themselves, their young and eggs are given different priorities by species in different regions. Predator I is a predator of the young and eggs, predator II is a nocturnal predator, and predator III is a diurnal predator of adult birds. An experiment where specimens of the three different predators were placed at close distances to the nests during the day in the breeding period was carried out. Give the letters of the following responses which can be expected?

A. The predator II specimen is more strongly avoided by the parents than the predator III specimen.

B. With the predator I specimen, the parents of tropical species reduce the frequency of returning to the nests and feeding the young to a lesser degree than parents of temperate species.

C. With the predator III specimen, the parents of tropical species reduce the frequency of returning to the nests and feeding the young to a lesser degree than parents of temperate species.

D. With the predator III specimen, the parents of tropical species reduce the frequency of returning to the nests and feeding the young to a greater degree than parents of temperate species.

E. The degree to which the parents reduce their frequency of returning to the nests and feeding the young when predator specimen is present is not affected by the type of predators or the latitudes in which the species occurs.

Q42 (3 marks) From the list of behavioural terms (1 to 12) given below, select the number of the one correct term to describe each of the following three descriptions of behaviour:

A. Gull chicks peck at the tip of the parent’s bill where there is a red spot. At this moment the parent regurgitates food and presents it to the chick.

B. Mice, placed into a maze, soon learn the most direct route to the cheese.C. During web-building an Indian spider (Araneus nauticus) lays a triangular frame of

plain thread, runs radii across the web and then spins a sticky thread, crossing each radius three or four times. If parts of the plain thread are removed, leaving the animal without any support between some radii, it does not repair the damage but struggles on with laying the viscid thread.

1. Circadian rhythm 2. Classical reflex conditioning3. Displacement activity 4. Habituation5. Imprinting 6. Instinct7. Insight learning or reasoning. 8. Instrumental conditioning9. Kinesis. 10. Orientation by stellar compass11. Reflex. 12. Sign stimuli.

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Q43 (1 mark) As shown below, as soon as a domestic hen chick hatches it starts pecking at grains that look like food, and as it grows older its aim at food grains improves. Note that if a chick is prevented from pecking at food during its second day, it will still be better at pecking in its third than on its first day; however, it will not be as accurate as it would have been if it had been allowed to practise. Give the letter of whichever option is most important in the development of accurate pecking in chicks.

A. Accurate pecking develops following maturation of the nervous system,B. Accurate pecking develops by learning, allowing chicks to distinguish between

alimentary items,C. Both processes of maturation and learning are involved in accurate pecking,D. There is a critical period (ranging from day 1 to day 7) during which the chicks learn

how to peck food on the ground,

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Q44 (1 mark) Great tit birds (Parus major) inhabiting forests (dense vegetation) and woodlands (patchy vegetation) have different song patterns. It is documented that high frequency sounds become less degraded in open habitat than in places with dense vegetation. Consider the following graphs showing song characteristics of great tits from 6 locations. Which one of the following statements is correct?

A. There is less variability in song frequency in low-latitude regions. B. Forest inhabitants are more varied in song frequency than woodland inhabitants. C. Songs of forest inhabitants have more notes per phrase than those of woodland

inhabitants.D. The variation of song type has nothing to do with habitat type.E. If an individual moves from forests to open grassland, the variation of the song among

its descendants is likely to increase.

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Q45 (2 marks) Systematic positions of some butterflies such as satyrids (ringlets, etc.), nymphalids (brush foots, etc), and danaids (milkweed butterflies, etc.) were controversial. Some researchers regarded them as distinct families, while others disagreed. Recent studies support the view to pool them into a single family Nymphalidae. Below is a phylogeny of these butterflies reconstructed by Freitas & Brown (2004), who support this view. Answer the following questions based on this phylogeny.

Indicate whether the statements are true or false by using + or – in the table on the answer sheet:

A. Danaoid butterflies may still be a distinct family according to Freitas & Brown’s phylogeny if Nymphalidae is still allowed to divide into several families.

B. Calinaginae butterflies resemble Danaoid butterflies in appearance, so they should be classified as Danaoid butterflies.

C. If we want to define the family Nymphalidae to include Apaturinae, Satyrinae and Brassolinae have to be included as well.

D. Danaoid butterflies may be considered as the ancestors of Nymphaloid and Satyroid.

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Q46 (3 marks)

The following table shows the main characteristics of 8 different animals (taxa 1 to 8). A + sign indicates that the animal possesses a characteristic, and a “blank” indicates that the animal does not possess a characteristic:

Characteristic

Taxon

1 2 3 4 5 6 7 8

Amnion + + +

Mammary glands +Lateral line system + + +Cycloid scales +Sternum + + +Semicircular canals + + + + + + +Ventral nerve cord +

Answer the following questions using the information in the table above:

a) Which one of the following taxa most likely belongs to the same Class as Taxon 4?

A. Taxon 1B. Taxon 2C. Taxon 3D. Taxon 5E. Taxon 6

(b) Taxon 8 is least likely to be which of the following organisms?

A. Earthworm B. Grasshopper C. Lobster D. Starfish E. Spider

(c) Taxon 1 is most likely to be which of the following organisms?

A. Shark B. Eel C. Sea lion D. Turtle E. Frog

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Q47 (1 mark)How do polypeptides find their way from the place of synthesis at cytoplasmic ribosomes to their destination in mitochondria?

A. By specific transport along the cytoskeletonB. By specific amino-terminal targeting signalsC. By specific carboxy-terminal targeting signalsD. It is not necessary because the synthesis takes place on the surface of the

organellesE. Mitochondria synthesise all proteins inside the organelle

Q48 (1 mark)The differential permeability of which of the following structures would be sufficient for the process of plasmolysis?

I plasmalemmaII tonoplastIII each biomembrane enclosing a compartmentIV the middle lamella

A. I onlyB. II onlyC. 1 and IIID. III onlyE. III and IV

Q49 (1 mark)In some cells, synthesis of isoleucine from threonine is catalysed by the sequential action of five enzymes a, b, c, d and e, which produce 4 intermediates A, B, C and D, and the end product isoleucine, respectively. What is most likely to happen when isoleucine is overproduced and there is an ample supply of threonine in cells?

A. Isoleucine associates with threonine to inhibit the activity of enzyme a.B. Isoleucine associates with intermediate D to inhibit the activity of enzyme e.C. Isoleucine binds to enzyme a and inhibits its activity.D. Isoleucine binds to enzyme e and inhibits its activity. E. Threonine is converted into isoleucine continuously through the 5 enzymes.

Q50 (1 mark)Which structural or physiological feature of bacteria is commonly used as a drug target to kill bacteria effectively but with very little harm to human cells?

A. Glycolysis B. Components of plasma membrane C. Components of ribosome D. Components of the electron transport chain in aerobic respirationE. Requirement of oxygen

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Q51 (1 mark)DNA is a double helix molecule containing four different types of nitrogenous bases. Which of the following statements regarding both the replication and chemical composition of DNA is correct?

A. Base sequences of both strands are the same. B. The amount of purine is equal to that of pyrimidine in a double-stranded DNA.C. Both strands are synthesised continuously in 5’ - 3’ direction.D. The first base of the newly synthesized nucleic acid is catalysed by DNA polymerase.E. The proof-reading activity of DNA polymerase proceeds in the 5’- 3’ direction.

Q52 (1 mark)EcoRI restriction enzyme is a DNA endonuclease that can recognize the sequence GAATTC. It was first discovered in Escherichia coli; therefore it was named EcoRI. To produce a large quantity of the endonuclease, the DNA fragment encoding the gene was subcloned into an expression plasmid and the resultant recombinant plasmid was transformed into E. coli cells to produce recombinant enzyme for a study. Why is the host DNA not cleaved by the recombinant EcoRI?

A. The host DNA does not contain EcoRI cleavage sites.B. EcoRI is secreted out of the host cells. C. Environmental factors such as temperature and pH value inhibit EcoRI activity.D. The E. coli host produces inhibitors to block EcoRI activity.E. The EcoRI cleavage sites within the host DNA are modified.

Q53 (1 mark)The drug AZT, is given to AIDS patients to slow down the progress of the disease. The structure of the drug is given here. The drug is effective because it:

A. Targets the HIV envelope proteins which prevents CD4 bindingB. Inhibits DNA replication of HIVC. Binds to metabolic enzymes of the virusD. Interferes with the protease activity of HIV

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BBO Round 2 - 2012

Q54 (1 mark)A very toxic compound isolated from the mushroom Amanita phalloides, has a very high affinity for actin polymers. Phalloidin can be marked by covalently linking it to a fluorescent molecule, like fluorescein, without affecting its affinity properties. If a microscope slide with methanol-fixed sperm is stained with a reagent containing fluorescein-marked phalloidin (excess reagent being washed away), which part of the spermatozoids will be glowing under a fluorescence microscope?

A. AcrosomeB. FlagellumC. HeadD. MitochondriaE. Whole spermatozoid.

Q55 (1 mark)What are the fibre types forming the cytoskeleton called?

A. Tubulin, lignin, kinesinB. Microtubules, myosin, microfilamentsC. Keratin, myosin, kinesinD. Microtubules, intermediate filaments, microfilamentsE. Actin, myosin, intermediate filaments

Q56 (1 mark)Give the number(s) of the following statements which support(s) the chemiosmotic theory about oxidative phosphorylation?

I. During electron transport, a proton gradient develops across the inner membrane of mitochondria.

II. A closed membrane or vesicular structure is required for oxidative phosphorylation. III ATP synthesis starts when a proton gradient develops in mitochondria.

Q57 (3 marks)The diagram represents the structure of the human immunodeficiency virus (HIV).

1. lipids2. glycoprotein3. capsid (protein)4. capsule5. viral DNA6. viral RNA7. reverse transcriptase8. restriction endonuclease

Select the number of the correct response from the above list to complete the table on the answer sheet.

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