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ZIMSEC A Level · 9190/1 · N2004

Biology Paper 1 November 2004

Questions
40
Syllabus code
9190/1

Sit this paper online

Questions
40
Pass mark
24
Sit this paper

Answer every question in the printed order, get marked at the end, then see the answers.

The questions

Question 1

cell fractionation

A fresh leaf was homogenised and the suspension subjected to differential centrifugation. The procedure is shown in the flow chart below.

Which of the following represents the order in which these organelles were removed from the suspension?

  1. Afraction 1 chloroplasts, fraction 2 mitochondria, fraction 3 nuclei, fraction 4 ribosomes
  2. Bfraction 1 nuclei, fraction 2 mitochondria, fraction 3 chloroplasts, fraction 4 lysosomes
  3. Cfraction 1 nuclei, fraction 2 chloroplasts, fraction 3 ribosomes, fraction 4 lysosomes
  4. Dfraction 1 nuclei, fraction 2 chloroplasts, fraction 3 mitochondria, fraction 4 ribosomes

Question 2

cell structure

The diagrams show cells obtained from different organs.

Which cell is adapted for secretion?

  1. AA
  2. BB
  3. CC
  4. DD

Question 3

microscopy
Which feature in microscopy enables specimens to be viewed in detail?
  1. Acondensor lens
  2. Bmounting fluid
  3. Cobjective lens
  4. Dradiation type

Question 4

water
Which properties explain the role of water in synovial fluid and amnion of a mammal?
  1. Asynovial fluid high cohesion, amnion low viscosity
  2. Bsynovial fluid high adhesion, amnion high specific heat
  3. Csynovial fluid low viscosity, amnion high cohesion
  4. Dsynovial fluid high surface tension, amnion high adhesion

Question 5

lipids
Which property of lipids correctly matches its biological function?
  1. Aproperty insoluble, function water conservation
  2. Bproperty insulator, function storage
  3. Cproperty low density, function bouyancy
  4. Dproperty non polar, function protection

Question 6

lipids
Which structure represents a phospholipid molecule?
  1. AA
  2. BB
  3. CC
  4. DD

Question 7

enzyme inhibition

The diagrams show the molecular structures of p-aminobenzoic acid (PABA) and prontosil. PABA is used by bacterial cells to make folic acid which is essential for growth. If bacteria are exposed to prontosil they make less folic acid.

What can be deduced about prontosil from the above information?

  1. AIt acts as a coenzyme.
  2. BIt acts as an end product inhibitor.
  3. CIt acts as a non competitive inhibitor.
  4. DIt acts as a competitive inhibitor.

Question 8

enzymes
Which of the following statements correctly identifies an enzyme catalysed reaction measured by rate of disappearance of substrate?
  1. Ameasuring the volume of carbon dioxide in a yeast-glucose reaction
  2. Bmeasuring time taken for thin potato discs to rise to the surface of a solution containing hydrogen peroxide
  3. Crecording time taken for colour change in an amylase-starch-iodine in potassium iodide reaction
  4. Dcounting number of bubbles produced per minute of oxygen in a test tube containing liver and hydrogen peroxide

Question 9

cell division

Cancer development involves the following stages:

1 loss of contact inhibition
2 carcinogen exerting its effect
3 metastasis
4 proto-oncogenes switched on

Which one is the correct sequence of events? (initial to final)

  1. A1 → 2 → 3 → 4
  2. B2 → 3 → 4 → 1
  3. C4 → 1 → 3 → 2
  4. D2 → 4 → 1 → 3

Question 10

mitosis

The graph below indicates movements during mitosis. Curve 1 represents the distance between centromeres of chromosomes and poles of the spindle. Curve 2 represents the distance between centromeres of sister chrommatids.

Which stage of cell cycle shown below does X represents?

  1. AA
  2. BB
  3. CC
  4. DD

Question 11

nucleic acids
Which statement correctly explains why a purine always pairs with a pyrimidine?
  1. AThe width is uniform at 2nm.
  2. BHydrogen bonds form between nitrogenous bases.
  3. CPurines have two rings and pyrimidines have one.
  4. DThe helix makes one full turn at 3.4nm.

Question 12

protein synthesis

The two equations represent reactions that occur during protein synthesis.

equation 1: amino acid + ATP + tRNA --(specific activator enzymes)--> amino acid + tRNA complex + Amp + phosphate

equation 2: amino acid + amino acid --(peptidyl transferase)--> dipeptide

At which stages of protein synthesis do they occur?

  1. Aequation 1 activation, equation 2 transcription
  2. Bequation 1 activation, equation 2 translation
  3. Cequation 1 translation, equation 2 transcription
  4. Dequation 1 transcription, equation 2 translation

Question 13

mutation
What are the characteristics of all mutations?
  1. Ainherited, spontaneous, rare
  2. Bsomatic, common, spontaneous
  3. Ccommon, inherited, undesirable
  4. Dspontaneous, random, rare

Question 14

genetic engineering
Which substances are produced by bacteria to defend themselves against viral infections?
  1. Aantibiotics
  2. Bantibodies
  3. Cligase enzymes
  4. Drestriction enzymes

Question 15

genetic engineering

The diagram shows a procedure which can be used to produce human insulin.

Which two stages make use of exactly the same enzyme?

  1. A1 and 3
  2. B1 and 5
  3. C2 and 4
  4. D2 and 6

Question 16

inheritance

In insects long wings (L) is dominant to short wings (l) and the female is homogametic sex and the gene for wing colour is sex linked. Black body (B) is dominant to grey body (b).

How many of the resultant genotypes contain only two dominant alleles if heterozygotes for long winged black bodied males were allowed to mate with long winged black bodied female heterozygotes?

  1. A1
  2. B2
  3. C4
  4. D6

Question 17

selection
Which statement is correct about how mutation exerts a selective advantage?
  1. AEvolution occurs if division of somatic cells is affected.
  2. BEvolution occurs if recessive genes are affected.
  3. CEvolution occurs if the environment changes.
  4. DEvolution occurs if allele frequency is low in a population.

Question 18

photosynthesis

The graph shows the relationship between the rate of photosynthesis and light intensity in C₃ and C₄ plants.

Which conclusion can be made from the graph?

  1. AC₄ plants are more efficient in photosynthesis.
  2. BC₄ plants photosynthesize less at low light intensities than C₃ plants.
  3. CCarbon dioxide concentration limits photosynthesis in C₄ plants.
  4. DC₃ plants photorespire more than C₄ plants.

Question 19

photosynthesis
Which feature is an adaptation for efficient transport of water during photosynthesis?
  1. Aetiolation
  2. Bchloroplasts in mesophyll cells move
  3. Clarge central midrib
  4. Dnumerous air spaces in spongy mesophyll

Question 20

respiration
Which reactions of photosynthesis and respiration synthesize ATP using the chemiosmotic mechanism?
  1. Aphotosynthesis photolysis, respiration dehydrogenation
  2. Bphotosynthesis photophosphorylation, respiration oxidative phosphorylation
  3. Cphotosynthesis photoactivation, respiration oxidative decarboxylation
  4. Dphotosynthesis photophosphorylation, respiration substrate level phosphorylation

Question 21

respiration
In animals, which substance acts as the hydrogen acceptor under anaerobic conditions?
  1. Acoenzyme A
  2. Blactic acid
  3. Cethanal
  4. Dpyruvic acid

Question 22

transport in animals
Which instrument measures blood pressure?
  1. Arespirometer
  2. Bstethoscope
  3. Csphygmomanometer
  4. Dspirometer

Question 23

transport in plants

The photomicrograph shows a transverse section through a dicot root.

Which visible features of xylem vessels are related to water transport?

  1. Alarge lumen, thick walls, hollow lumen
  2. Bpits, thick, lignified walls
  3. Cannular rings, hollow lumen, narrow diameter
  4. Dlignified walls, pits, continuous tube

Question 24

transport in plants

The following is a list of mechanisms that explain the transport of water and solutes in plants.

1 mass flow
2 cytoplasmic streaming
3 root pressure
4 cohesion-tension

Which mechanisms would be affected by the shortage of ATP in plant cells?

  1. A1 and 2 only
  2. B3 and 4 only
  3. C1, 2 and 3
  4. D2, 3 and 4

Question 25

transport of gases
Which equation shows buffering reaction in the blood?
  1. Acarbon dioxide + haemoglobin → carbaminohaemoglobin
  2. Bcarbon dioxide + water --(carbonic anhydrase)--> carbonic acid
  3. Coxy-haemoglobin + hydrogen ions → haemoglobinic acid + oxygen
  4. Dcarbonic acid → bicarbonate ions + hydrogen ions

Question 26

transport in animals

The graph shows changes in the velocity of blood as it flows through the circulatory system.

What conclusions can be drawn from the flow of blood in regions P, Q and R?

  1. AP thick walls withstand pressure, Q increased lumen volume of capillaries reduces velocity, R large diameter offers less resistance
  2. BP vasodilation of arteries and arteries reduces blood flow, Q velocity reduced by few capillaries, R large lumen transport more blood
  3. CP elastic recoil of arteries and arterioles smoothens blood flow, Q narrow diameters of capillaries offer resistance to blood flow, R large diameter offers less blood resistance
  4. DP pulsating action of arteries and arterioles reduces blood flow, Q capillaries vasodilate to reduce velocity of blood, R valves and muscle assist flow

Question 27

excretion

70% of nephron ATP is utilised in the thick ascending limb when Na⁺ and Cl⁻ ions are actively taken up into the medulla.

In which process(es) is the remaining ATP used?

  1. Aselective reabsorption, pinocytosis and tubular secretion along the kidney tubules
  2. Bactive reabsorption of sodium ions in distal convoluted tubules and water reabsorption in the collecting ducts
  3. Cultrafiltration in the glomerulus
  4. Dreabsorption of water and urea in the distal convoluted tubules and collecting ducts

Question 28

nervous coordination

Multiple sclerosis is a disease that causes destruction of the myelin sheath. The diagram shows a transverse section through a neurone.

Which part is affected and what effect on nervous transmission does the disease have?

  1. Apart X, effect transmission slowed
  2. Bpart Y, effect transmission slowed
  3. Cpart X, effect transmission speeded
  4. Dpart Y, effect transmission speeded

Question 29

nervous coordination

The diagram shows three neurones P, Q and R forming two synapses.

A drug is injected which relaxes muscles. Which of the following correctly states the effect of the drug at synaptic gaps and the state of transmission at X?

  1. Aeffect postsynaptic receptors blocked, transmission none
  2. Beffect cholinesterase cannot remove acetylcholine, transmission present
  3. Ceffect calcium ions cannot be taken up by vesides, transmission none
  4. Deffect sodium channels remain open, transmission present

Question 30

homeostasis
Ethanol in alcoholic drinks suppresses the secretion of the hormone anti-duretic hormone (A.D.H). What effect does ethanol have on the concentration of urea and the water potential of the urine?
  1. Aconcentration of urea low, water potential high
  2. Bconcentration of urea low, water potential low
  3. Cconcentration of urea high, water potential low
  4. Dconcentration of urea high, water potential high

Question 31

the nitrogen cycle

The flow diagram below shows part of the nitrogen cycle.

Which labelled part is directly affected by ploughing?

  1. AA
  2. BB
  3. CC
  4. DD

Question 32

statistics in ecology

A student after determining the density of two species in an ecosystem obtained the following results after a statistical analysis.

t calculated value = 1.58
t table value = 1.87 at 5% level

What conclusion can the student make?

  1. AThe two species do not differ in abundance in the ecosystem.
  2. BThe two species differ significantly in abundance.
  3. CThe sample size is too small to make a valid conclusion.
  4. DThe ecosystem is stable enough to sustain the two species.

Question 33

the nitrogen cycle

The two equations summarise reactions occurring in soil microorganisms.

(i) 2NH₃ + 3O₂ --(organism 1)--> 2HNO₃ + 2H₂O + energy
(ii) 2HNO₂ + O₂ --(organism 2)--> 2HNO₃ + energy

What could be the identity of organism 2?

  1. ARhizobium
  2. BNitrosomonas
  3. CNitrobacter
  4. DPseudomonas

Question 34

plant reproduction
The diagram shows a longitudinal section of a pea pod. Which structure is the funicle?
  1. AA
  2. BB
  3. CC
  4. DD

Question 35

plant reproduction

The photomicrograph shows a transverse section through an anther.

What is the genetic condition of structures X, Y and Z?

  1. AX diploid, Y haploid, Z diploid
  2. BX diploid, Y diploid, Z haploid
  3. CX haploid, Y diploid, Z haploid
  4. DX haploid, Y diploid, Z diploid

Question 36

plant reproduction

The diagram shows a longitudinal section through a fruit containing a single seed.

Which labelled parts are derived from the endosperm nucleus, the integuments and the ovary wall of a carpal?

  1. Aendosperm nucleus 1, integument 2, ovary wall 3
  2. Bendosperm nucleus 3, integument 4, ovary wall 5
  3. Cendosperm nucleus 4, integument 1, ovary wall 2
  4. Dendosperm nucleus 3, integument 2, ovary wall 1

Question 37

reproduction
The diagram shows a mammalian oocyte. Which part forms the impermeable fertilisation membrane?
  1. AA
  2. BB
  3. CC
  4. DD

Question 38

gaseous exchange

The following events occur during the development of emphysema.

1 Phagocytes move from blood to line airways.
2 Alveolar tissue is replaced by scar tissue.
3 Elastase digests elastin in alveolar walls.
4 Mucus accumulates and inflammation occurs.
5 Alveoli lose elasticity and burst.

In which order do these events occur?

  1. A1 → 2 → 3 → 4 → 5
  2. B4 → 1 → 3 → 5 → 2
  3. C4 → 5 → 3 → 1 → 2
  4. D1 → 3 → 4 → 2 → 5

Question 39

classification
If two animals belong to the same class to which grouping are they also members?
  1. Afamily
  2. Bgenus
  3. Corder
  4. Dphylum

Question 40

classification
Which of the following features could be used to distinguish a nematode, an annelid and a snake?
  1. Aradial symmetry and dorsal nerve cord
  2. Bsegmentation and dorsal nerve cord
  3. Csegmentation and bilateral symmetry
  4. Dbilateral symmetry and acoelomate

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