NAME:

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SCHOOL/INSTITUTION:

This question paper consists of 20 printed pages not including this cover page.

SET: 3

DURATION: 2 Hours

INSTRUCTION:

1. This question paper consists of 70 multiple choice questions. Answer all questions in

the answer sheet provided using only 2B pencil.

2. Read the question carefully. Shade only ONE answer for every question in the answer

sheet.

3. Fill all of your personal information in the question paper and answer sheet provided.

4. DO NOT open the question paper till you are inform to do so.

FIRST SCREENING TEST OF MALAYSIAN BIOLOGY OLYMPIAD 2016

1

Answer all questions.

[70 marks]

1. Which treatment is most effective in breaking as many hydrogen bonds as possible an

aqueous solution (pH 7.0) of 1 mg/mL DNA and 10 mg/mL protein

A. Addition of hydrochloric acid to make the pH 1.0.

B. Addition of sodium hydroxide solution to make the pH 13.0.

C. Addition of urea to a concentration of 6 mol/L.

D. Heating the solution to 121C.

2. The movement of a ciliated protozoan is controlled by a protein called RacerX.When

this protein binds to another protein, Speed, found at the base of the cilia, it stimulate

the cilia to beat faster and the protozoan to swim faster. Speed can only bind to

RacerX phosphorylation of a specific threonine residue. How would expect the mutant

protozoan to behave if this threonine residue in Speed is replaced by an alanine residue?

A. Swims fast occasionally.

B. Always swims fast.

C. Never swims fast.

D. Switches rapidly back and forth between fast and slow swimming.

3. A given DNA sample has 60% purines. The source of this DNA is most likely to be:

A. a bacterial cell.

B. a eukaryotic cell.

C. a bacteriophage with double-stranded DNA.

D. a bacteriophage with single-stranded DNA.

4. The stage of cell division shown in the figure below represents:

A. Meiotic metaphase I with n = 4

B. Meiotic metaphase II with n = 4

2

C. Meiotic metaphase II with n = 8

D. Meiotic metaphase I with n = 2

5. Which of the following are true for the relative permeabilities of human red blood cells

and artificial phospholipid bilayers vesicles (called artificial

vesicles hereafter) to glucose and ethanol?

I. Both red blood cells and artificial vesicles are more permeable to glucose than to

ethanol.

II. Both red blood cells and artificial vesicles are more permeable to ethanol than to

glucose.

III. In both red blood cells and artificial vesicles, the permeability to ethanol is almost

the same as that to glucose.

IV. While red blood cells and artificial vesicles show almost the same permeability

to glucose, red blood cells have a higher permeability to ethanol than artificial

vesicles.

V. While red blood cells and artificial vesicles show almost the same permeability to

ethanol, red blood cells have a higher permeability to glucose than artificial

vesicles.

A. I, IV

B. I, V

C. II, IV

D. II, V

6. The central dogma originally proposed by Francis Crick has seen changes reflecting new

insights obtained from time to time. Which one of the

following schematics correctly depicts our current understanding of the replication

of genetic material in various organisms and the “flow of information” in biological

systems?

A. B.

C. D.

3

7. Two alleles G and g are present at a particular locus of a fern species. Spores were

collected from a heterozygous sporophyte with Gg genotype of the fern

species.Gametophytes were grown from the spores and self-fertilized by isolating

each sexually matured gametophyte. What is the expected ratio of the

GG : Gg : gg genotypes of the sporophytes?

A. 1:2:1

B. 2:1:1

C. 3:0:1

D. 1:0:1

8. A biologist has discovered two new species of microorganisms. Microorganism A was

isolated from a hot spring whereas microorganism B was obtained from a tropical forest.

DNA was isolated from both organisms and an analysis of the melting profile of each

DNA sample was carried out. The melting temperature

(Tm) was 80 °C for DNA from microorgaism A, and 70 °C for DNA from microorganism

B. Which statement best describes the reason for this difference in values?

A. DNA of micro-organism A has higher A+T content

B. DNA of micro-organism A has higher G+A content

C. DNA of mirooranism A has higher G+C content

D. DNA of micro-organism A has higher T+G content

9. What mechanism is responsible for the acidification of the lysosome?

A. A lysosome fuses with acidic vesicle derived from Golgi aparatus

B. A pump transports protons from the cytosol into the lysosome.

C. A pump transports protons from the lysosomal lumen to the cytosol

D. A lysosome fuses with acidic endocytosed material

10. In 1961 Mitchell proposed a highly original explanation for ATP synthesis, which he called

the chemiosmotic coupling model. Which of the following is correct?

A. ATP synthesis in mitochondria can be explained by the chemiosomotic model,but

in chloroplasts it cannot.

B. ATP synthesis in mitochondria and choloplasts can be explained by the chemiosomotic

model only when the concentration of H+ ions in the cells is higher than 0.1 mmol/L.

C. The energy source for mitochondria is electrons from nutrients, but for

choloroplasts the energy souce is electrons from water pumped into

thylakoid lumen.

D. H+ are transferred through ATP synthase both in mitochondria and

choloroplasts.

4

11. The crab-eating frog is a unique amphibian which has adapted to the marine habitat and

lives in mangroves. Different from marine bony fish, these frogs deal with the

osmotic problem by:

A. drinking sea water and excreting excess salt.

B. excreting a large amount of excess water as urine.

C. excreting nitrogen waste as ammonia.

D. storing urea in their body fluid.

12. Which of the following states occurs if the lung alveoli lose their elasticity?

I. Residual volume decreases.

II. O2 in the air inhaled has to increase in order to keep the saturation of the

hemoglobin at the same level.

III. Blood pH increases.

A. Only I

B. Only II

C. Only III

D. I and II

13. Which of the following statements about skeletal muscle is NOT correct?

A. The length of a single muscle contration depends on the concentration of Ca2+

ioncs in the sarcoplasmic reticulum.

B. Muscles with short sarcomeres contract faster than muscles with long

sarcomeres.

C. The velocity of muscle contractions is determined by myosin ATPase activity.

D. Tetanus is the effect of repeated stimulations within a very short interval.

14. Which of the following would occur if a neuron was experimentally stimulated

simultaneously at both ends?

A. The action potentials would pass in the middle and travel to the opposite end.

B. The action potentials would meet in the middle and then be propagated back to

their starting positions.

C. The action potentials would stop as they meet in the middle.

D. The stronger action potential would override the weaker action potential.

15. What essential function does gastrulation perform for the developing embryo?

A. It results in the dorsal-ventral axis formation.

B. It gives rise directly to the germ layers of the embryo.

C. It gives rise to neural crest cells.

D. It gives rise directly to endocrine cells.

5

16. What happens when the pancreatic duct of a certain mammal is temporarily ligated for an

experiment? Note that carbohydrate and other nutrients in the diet are in proper amounts and

ligation of the pancreatic duct is not critical for survival of the animal. The amount of

carbohydrate:

A. increases in feces, decreases in urine.

B. increases in feces, does not change in urine.

C. decreases in feces, increases in urine.

D. decreases in feces, does not change in urine.

17. A substance from the plant Gymnema sylvestre blocks the sweet taste of sugar and also

blocks absorption of sugar by the small intestine. What can be assumed from these two

phenomena?

A. It metabolizes sucrose to glucose and fructose.

B. It polymerizes sugar into oligosaccharides.

C. It binds with sugar receptors and transporters.

D. It binds with certain neurotransmitter receptors and transporters.

18. The most direct consequence on amphibian development upon removal of the grey

crescent would be:

A. Inability to develop from the 2-cell stage to the 4-cell stage.

B. Inability to develop form the 4-cell stage to the 8-cell stage.

C. Inability to form a blastocoel.

D. Inability to form dorsal structures.

19. When a species of poisonous fish was fertilized in vitro and cultured in an indoor plastic

tank filled with artifical seawater, they were never poisonous. Young fish grown in the

tank next divided into two groups and placed in separate pens in a bay where they were

exposed to real seawater. One pen had a horizontal net that prevented the fish from reaching

the sea bottom, while the other pen has no horizontal net. Subsequently, no poison was

detected from the fish cultured in the pen with the net, but poison was found in fish from the

other pen. What do you conclude from this experiment? To be toxic

I. some component not in artificial seawater but in natural seawater is necessary.

II. it is necessary that they grow up to adults.

III. it is necessary that they can reach the sea bottom.

A. Only I

B. Only II

C. Only III

D. Both I and II

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20. Isopods are one of the few crustacea groups that have successfully invaded terrestrial

habitats. Which of these statements is INCORRECT?

A. They live in dry conditions.

B. They must live in moist conditions.

C. Their abdominal appendages bear gills.

D. They do not have an efficient cuticular covering to conserve water.

21. Cell walls of vessels and tracheids of vascular plants contain a phenolic polymer called

“lignin”, which together with cellulose confers mechanical strength to these water-

conducting tissues. If vessels/tracheids are deficient in lignin, they:

A. burst outward when transpiration is very active.

B. burst outward when transpiration is very inactive.

C. collapse inward when transpiration is very active.

D. collapse inward when transpiration is very inactive.

22. Certain plant species such as Red Oak (Quercus rubra) can tolerate severe drought over a

long period of time without affecting its photosynthesis. Which of the following adaptations

is likely to contribute to this ability?

A. Stomatal closure

B. Large negative leaf water potential

C. Kranz leaf anatomy

D. Fibrous root system that increases root surface area

23. To examine the effect of phytohormones P1 and P2 in plant tissue culture, leaf

segments were excised from plants grown under the light, placed on medium that

contained P1 and/or P2, and cultured in the dark. As a control experiment, leaf segments

were cultured without P1 or P2 in the dark.

a) When only P1 was added to the medium, adventitious roots formed on the explants.

b) When only P2 was added to the medium, neither organogenesis nor callus

formation occurred. The explants retained green color for a longer period than the

explants of the control experiment.

c) When both P1 and P2 were added to the medium, callus formed on the explants.

Based on this information, P1 and P2 were:

A. P1: Auxin; P2: Gibberellin

B. P1: Auxin; P2: Cytokinin

C. P1: Gibberellin; P2: Auxin

D. P1: Gibberellin; P2: Cytokinin

7

24. Totally submerged aquatic plants can cause a pH change in the surrounding water

when they carry out photosynthesis. What pH change happens and what causes it?

A. The pH falls because carbon dioxide is absorbed.

B. The pH rises because carbon dioxide is absorbed.

C. The pH falls because oxygen is released.

D. The pH rises because oxygen is released.

25. If the ambient temperature rises by 5°C, photorespiration would:

A. Increase in rice, decrease in maize

B. Increase in maize, decrease in rice

C. Increase in rice, little effects on maize

D. Increase in maize, little effects on rice

26. Which of the following will harm a dicotyledonous plant the most?

A. Removal of the central pith

B. Removal of the cork

C. Removal of the bark

D. Removal of the cork cambium

27. The net assimilation of CO2 of a plant is 0.5 moles when illuminated during the day. The

net cosumption of O2 is 0.12 moles during the night. Assuming that all the gas is due to

photosynthesis and respiration of the biomass (equivalent molecular mass of 30), what is

the net production or consumption of biomass in grams during a complete 12h day: 12h

night diurnal cycle?

A. 3.6 g/day

B. 7.8 g/day

C. 11.4 g/day

D. 15.0 g/day

28. Plant chloroplasts are believed to have evolved from cynobacteria like progenitors

through endosymbiosis. Which of the following statements support this hypothesis?

I. Chloroplasts and cyanobacteria share similar photosynthetic pigments and

thylakoid membranes.

II. Cyanobacteria exhibit an oxygenic photosynthesis.

III. Chloroplasts are maternally inherited.

IV. Chloroplasts have their own DNA and ribosomes.

V. Viable chloroplasts can be isolated from cells but cannot be cultured invitro.

VI. Prokaryotic genes express well in chloroplasts.

A. I, II, IV and V

B. I, II, IV and VI

C. I, II, III and V

D. II, IV, V and VI

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29. Collenchyma and sclerenchyma are plant support tissues. Which combination of the

following statements correctly differentiates these two types of plant tissue?

I. Collenchyma cells occurs only in Dicotyledons;

sclerenchyma is an elastic tissue found in both Monocotyledons and

Dicotyledons.

II. Collenchyma cells are developed during growth; sclerenchyma cells

generally occur in organsthat have concluded their longitudinal growth.

III. Collenchyma and sclerenchyma may arise from the same cell type.

IV. Collenchyma cells have only primary walls while sclerenchyma cells have

secondary wall.

V. Collenchyma originates from the protoderm; sclerenchyma is formed by the

procambium.

A. I, II, III.

B. II, III, IV C. II, IV, V

D. IV, V

30. Suppose that an illuminated suspension of Chlorella (a photosynthetic alga) was

actively carrying out photosynthesis when the light was suddenly switched off. How

would the levels of 3-phospoglycerate and ribulose 1,5 bisphospate change

during the next minute?

A. The concentration of 3-phospoglycerate would increase and that of ribulose 1,5

bisphospate would increase.

B. The concentration of 3-phospoglycerate would increase The concentration of

ribulose 1,5 bisphospate would decrease.

C. The concentration of 3-phospoglycerate would decrease The concentration of

ribulose 1,5 bisphospate would increase.

D. The concentration of 3-phospoglycerate would decrease The concentration of

ribulose 1,5 bisphospate would decrease.

31. Why did psychologists fail in teaching chimpanzees to talk like humans?

A. Chimpanzees have a different location and structure of larynx

B. They have weakly developed cerebrum

C. They have thin tongue

D. They have too large teeth

32. Why do territorial birds, which are territory owners, tend to win when they meet intruder

birds?

A. They are more aggressive and better fighters

B. They have more to gain from a fight and so they are prepared to fight harder.The

higher benefit associated with territory, the harder they fight for it

9

C. Ownership is simply a conventional settlement

D. Owners always have a larger body size

33. The vampire bat of Costa Rica is often not able to acquire blood from mammal on a

given night. Wilkinson (1984) trapped bats which were not allowed to feed for night

and found that they were given regurgitated blood by certain cave mates. Based on this

knowledge, which of the following observations are indispensable to confirm the

occurrence of reciprocal altruism in this species?

Data showing that:

I. blood is exchanged only between kin.

II. blood is exchanged between non-kin.

III. weak bats are frequently given blood even if they cannot give it to others.

IV. bats who are given blood donate it to those who have given it to them before.

Combinations of :

A. I, III

B. I, IV

C. II, III

D. II, IV

34. In a certain bird species, territory-holding males are sexually mature, have red chest

feathers and aggressively drive out intruders. Several models, shown below, were built

to test territory defense in this species. What is the most likely sequence of attackes on

these models in decreasing order of aggression?

I. A model of a normal juvenile bird with brown chest feathers

II. A model of a normal adult bird with red chest feathers

III. A model of an adult bird with brown chest feathers

IV. A model of a juvenile bird with red chest feathers

Sequences:

A. I III IV II

B. I IV III II

C. II III IV I

D. II IV III I

35. Animals can use their circadian clocks to determine direction from the position of the

sun. In a particular experiment conducted in Iceland, a bird

kept in a cage open to the sky, was trained to seek food on the western side. Its

circadian rhythm was then phase-delayed by 6 hours and after phase

shifting, the bird was returned to its open cage at 12.00 noon real time. It was observed to

seed food in the:

A. north.

B. south.

10

C. east.

D. west.

36. Coho Salmon is a fish found in the freshwater streams of North America. The males

this species have two reproductive strategies to fertilize the eggs laid by females.

Larger males are able to fight with each other successfully but smaller males are

unable to do so. The latter adopt another strategy, that of sneaking, in which they

hide behind rocks and quickly approach females to fetilize the eggs before the

larger males are able to do so. Which of

following graphs depicts the correct strategies?

37. While studying the frogs of a certain species in their natural habitat during the mating

season, you observe a chorus of male frogs in which some individuals are calling

while others remain silent. On further observation, you see

the silent frogs are sitting closer to those that are calling. Which of the following

is most likely to explain the behavior of this chorus of frogs?

A. The individuals who are not calling are staggering their calls with those of the

others and are likely to call later in the season after the latter have finished mating.

B. The silent frogs are close genetic relatives of the calling individuals and do not

expend valuable energy in calling as the matings that the latter will

receive would provide adequate indirect fitness to them.

C. The silent frogs have evaluated that their calls are inadequate in attracting

females, as compared to those of the calling individuals, and lie in wait to sneak

matings with the females that approach the calling males.

A. B.

C. D.

11

D. The silent frogs do not expend energy in themselves calling as the female

frogs that are attracted to the calls of the others are anyway likely to visually

inspect the closely-spaced males and then choose their mating partners.

38. Young laughing gull chicks peck at the tip of the parent‟s beak which, in turn,

induces the adult gull to regurgitate food. Experiments were conducted with one-

day old and three-day old chicks, the latter being reared with their parents.

These chicks were presented with the following models of the parent head and the

following responses were obtained:

Choose the correct interpretation of the experiment.

A. Pecking behavior is a fixed action pattern where any long pointed object acts

as an equally effective stimulus.

B. The pecking rate of laughing gull chicks increases with age.

C. The response of one-day old chicks is more pronounced when the model is closer

to that of the parent.

D. Act of pecking is an innate behavior while the discriminatory capacity of the

chicks is a result of learning.

12

39. Mating of Recurvirostra avosetta, a wading bird is preceded by some peculiar movements.

Both male and female clean their feathers nervously. After some time, the

female takes a horizontal position (see picture) and this triggers the male to copulate. The

horizontal position of the female corresponds to:

A. a conditioned reflex.

B. a displacement activity.

C. an innate response.

D. a sign stimulus. 40. In terms of the benefits and harms received by each of the two parties interacting,

which of the following pairs of biological interactions are most similar to each other? A. Clownfish and sea anemones; mistletoes and apple trees B. Sea stars and bivalves; locusts and grasshoppers. C. Lichens and maples; mistletoes and oaks. D. Caterpillars and parasitic wasps; food plants and caterpillars.

For question 41 and 42, please refer to following statement and figure:

A rare human disease afflicted a family as shown in the following pedigree.

41. What is the most likely mode of inheritance of this disease?

A. Mode of inheritance is autosomal recessive.

B. Mode of inheritance is autosomal dominant.

C. Mode of inheritance is X-linked recessive.

D. Mode of inheritance is X-linked dominant.

42. What is the probability that the first child of the marriage between cousins, 1 x 4, is

a boy with the disease?

A. 1/2

B. 1/4

C. 1/8

D. 0

13

43. A mutation results in the absence of sweat glands, a disease called anhidrotic ectodermal

dyslasia. A woman suffering from this disease has a mosaic of skin patches lacking sweat

glands. The woman is likely to be:

A. homozygous for an autosomal recessive mutation.

B. heterozygous for an autosomal dominant mutation.

C. homozygous for a X-linked recessive mutation.

D. heterozygous for a X-linked recessive mutation.

44. A mink breeder allows random mating among his minks. He discovers that, on an

average 9% of his micks have rough fur that fetches

money when sold. So he decides to focus upon smooth fur and does not allow minks with

rough fur to mate. Rough fur is linked to an autosomal recessive allele.

What is the percentage of minks with rough fur that he will obtain in the next generation?

A. 7.3

B. 5.3

C. 25

D. 23

For question 45 and 46, please refer to the following statement.

The wild-type flower color of harebell plants (genus Campanula) is blue. Using radiation,

three mutants with white petals were produced, white 1, white 2 and white. They all look the

same, so it was not known whether they are genetically identical. The mutant srains

are available as homozygous pure-breeding lines. The mutant strains were crossed with the wild-

type blue genotype and each other to produce the following results:

45. Using these results, determine which is the correct conclusion for this study.

A. The mutant genes in white 1 and 3 are allelic and are different to the mutant gene in

white 2.

B. The mutant genes in white 2 and 3 are allelic and are different to the mutant gene in

white 1.

C. The mutant genes in white 1 and 2 are allelic and are different to the mutant gene in

white 3.

D. The mutant genes in white 1, 2 and 3 are all allelic.

Parental Cross F1 Phenotype F2 Segregation Ratio

White 1 x blue all blue 3/4 blue : 1/4 white

White 2 x blue all blue 3/4 blue : 1/4 white

White 3 x blue all blue 3/4 blue : 1/4 white

White 1 x white 2 all white no data available

White 1 x white 3 all blue no data available

White 2 x white 3 all blue no data available

14

46. The type of gene action operating among the crosses between the mutants in this study is

A. complete dominance.

B. dominant epistasis.

C. Recessive (Complementary) epistasis

D. duplicate gene interaction.

47. In a breed of rabbits, multiple alleles with the following dominance relationships

control coat coloration:

C (agouti) > cch

(chinchilla) > ch (Himalayan) > c (albino).

An experimental cross between agouti and Himalayan produced 50% agouti and

50% Himalayan progeny. Which of the following crosses could produce this result?

I. Cch X c

hch

II. Cc X chc

III. Cch X c

hc

IV. Cc X chch

A. I, II and III

B. II, III and IV

C. I, III and IV

D. I, II and IV

48. Alleles IA

and IB

present on chromosome 9 are responsible for blood groups

A and B, respectively. Blood group O results when these alleles are either absent or not

expressed. The alleles IA

and IB are expressed only if the

H allele is present on chromosome 19, either in the homozygous or heterozygous

conditions condition, where h stands for the recessive allele.

Gilbert belongs to the AB blood group. His sister Helen belongs to the A group

while their father belongs to the O group. Identify the maternal and paternal

genotypes.

Mother Father

A. H/H, IA

/IB

H/h, IO

/IO

B. H/h, IB

/IO

h/h, IA

/IO

C. h/h, IO

/IO

h/h, IA

/IO

D. H/H, IA

/IO

H/h, IB

/IO

15

49. In a population of mice, 40% of males showed a dominant X-linked trait. Assuming

random mating, the most frequent mating is expected between the genotypes:

A. XB

Xb and X

bY

B. XB

XB

and XbY

C. XB

Xb and X

BY

D. XbX

b and X

bY

50. A man with a genetic disease marries a phenotypically normal woman. They have four girls

and boys. All of the girls have the same disease as their father, but none of the

boys does. What is the most likely explanation?

The disease is caused by:

A. an autosomal dominant allele.

B. an autosomal recessive allele.

C. an X-linked dominant allele.

D. an X-linked recessive allele.

51. What does the energy input into most food webs typically depend on? Choose the most

likely factor from the following.

A. Grazing rate of the primary consumers

B. Material cycling efficiency rate of the whole ecosystem

C. Efficiency rate of producers converting solar radiation energy into chemical

energy

D. Action of nitrogen-fixing bacteria

52. The table below shows the results of measurements of production in two ecosystems in the

temperature zone: a rainforest and a field with an annual crop. All results are stated in

MJ/m2 / year (1 MJ = 10

6J)

Of these two ecosystems, which has a higher ratio of respiration by heterotrophic

organisms to net primary production (NPP)? What is the reason? Choose the correct

option from A to F.

A. [I] < [II]：The rainforest has larger GPP and more consumers than the crop field.

B. [I] < [II]：The rainforest has larger NPP and more consumers than the crop field.

C. [II] < [I]：The rainforest has smaller NPP and more consumers than the crop field.

Rainforest [I] Field with an annual crop [II]

Gross Primary Production (GPP) 188 102

Respiration (autotrophs) 134 38

Respiration (heterotrophs) 54 3

16

D. [II] < [I]：The rainforest has smaller NPP and less consumers than the crop field.

53. Which factor most promotes the stability of population dynamics in a developed

terrestrial ecosystem?

A. Food webs that have many trophic levels each of which consists of few species

only

B. A few species of producers with very high production rates

C. Rapid nutrient recycling by active decomposers

D. Food webs that have very few trophic levels and limited niche overlaps

54. Hay is boiled in water and cooled. Some pond water, containing only heterotrophic

protozoa, is added to it and kept in the dark for a long time.

Which of the following are true?

A. Heterotrophic succession of protozoa will occur with increase in total biomass.

B. The energy of the system is maximum at the beginning.

C. Succession will occur, eventually reaching a steady state in which energy

flow is maintained.

D. The ecosystem may undergo succession but finally all organisms will die

or go into resting stages.

A. I and III

B. II and IV

C. II and III

D. I and IV

55. In an aquatic ecosystem, the total dry biomass of each of three groups of organisms

is as follows:

I. Ciliates: 1.1041 g

II. Midge larvae: 0.9845 g

III. Oligochaetes: 1.005 g

The correct food chain that they represent is:

A. I II III

B. II I III

C. I III II

D. III II I

17

56. Marine bony fishes have much lower internal osmotic concentration than the seawater

around them. Which of the following statements DOES NOT EXPLAIN the osmotic

regulation of marine bony fishes:

A. They lose water by osmosis and gain salt by diffusion

B. They drink seawater

C. They actively absorb sodium chloride across gills.

D. They absorb sodium chloride from stomach

57. Animal species X and Y have atemporal negative correlation of population abundances, in

which arrows indicate the anticlockwise orbit of population dynamics.

Choose the most likely combination of explanation and its reasoning.

Relationship between species

X and Y

Reasoning

A. Interspecific competition

between X and Y

Y decreases at high density of X

Y increases at low density of X

B. Interspecific competition

between X and Y

Y increases at intermediate density of X

X decreases at intermediate density of Y

C. Predator (X) and prey (Y) Y decreases when X increases from low

density

Y increases when X decreases from high

density

D. Predator (Y) and prey (X)

No of individuals in species X

No o

f in

div

idu

als

in

sp

ecie

s Y

18

58. One hypothesis predicts that most of the CO2 produced in the soil originates from

microorganisms feeding on dead plant material. To which trophic level do these

microorganisms belong?

A. Primary producers

B. Secondary producers

C. Decomposers

D. First order consumers

59. Isopods are one of the few crustacean groups that have successfully invaded terrestrial

habitats. Which of these statements is INCORRECT?

A. They live in dry conditions.

B. They must live in moist conditions.

C. Their abdominal appendages bear gills.

D. They do not have an efficient cuticular covering to conserve water

60. Suppose Species B disappears from an ecosystem in which the interrelationship

among the component species can be described by the food web below.

Which of the following will be a consequence of its elimination?

A. Species X loses its only prey.

B. Species A loses its only prey.

C. Species D benefits because it is most distant from Species B.

D. Species C benefits because the competition between species B and C is reduced.

61. The following characteristics correspond to: unicellular organisms, eukaryotic cell with

micronuclei and macronuclei, asexual reproduction by transverse binary fission and sexual

reproduction by conjugation. Most are free-living.

A. Rhizopoda

B. Apicomplexa

C. Zoomastigophora

D. Ciliophora

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62. The Orchidaceae family present

A. superior ovary, three-carpellate, one loculed ovary

B. showy labellum, pollen grains united in a mass

C. plants with terrestrial habitat only

D. androecium with two whorls of stamens of six stamens each

63. Development in marine mollusсs may be characterized by

A. trochophore larva only

B. trochophore and veliger larva

C. direct development without larval state

D. all of them are correct

64. The main characteristics of the Asteraceae family are

A. calyx in the form of a pappus, sympetalous corolla

B. inferior ovary

C. seed separated from the pericarp

D. all of them are true

65. Although Echidna lays eggs, it has been classified as a mammal due to the

mammary glands. Which of the folloiwng additional features support its inclusion in

the class Mammalia?

I. Hair over parts of the body.

II. Complete separation of pulmonary and systemic circulation in a 4-chambered

heart

III. A diaphragm separating thoracic and abdominal cavities.

IV. Regulation of body temperature irrespective of ambient temperature.

V. Enucleated red blood cells.

A. III and VI

B. I, IV and V

C. I and IV

D. I, III and V

66. Development in marine mollusсs may be characterized by:

A. trochophore larva only.

B. trochophore and veliger larva.

C. direct development without larval state.

D. all of them are correct

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67. The main characteristics of the Asteraceae family are:

A. calyx in the form of a pappus, sympetalous corolla.

B. inferior ovary.

C. seed separated from the pericarp.

D. all of them are true.

68. The Pinophyta are characterized by:

A. seedlings with two cotyledons.

B. anatropous ovule.

C. double fertilisation.

D. prothallus (primary endosperm) as storage tissue of the seed.

69. The Liliopsida are characterized by:

A. a tap root system.

B. typical netlike veins

C. flower parts are usually in multiples of three.

D. ring-like arrangement of vascular bundles.

70. The flower parts in the Solanaceae are:

A. Calyx of 4 sepals, corolla of 4 petals, androecium of 6 stames usually, parietal

placentation.

B. Calyx of 5 sepals, corolla of 5 petals, androecium of 5 stames usually, axile

placentation.

C. Calyx of 5 sepals, corolla of 5 petals, androecium of 10 stames usually, margina

placentation.

D. Calyx of 5 sepals, corolla of 5 petals, androecium of 4 stames usually, axile

placentation.

END OF QUESTION PAPER