the west african examinations councilb. plant cell c. protozoan d. bacterium answer: bacterium...

2010 Liberia WAEC Biology SOLUTIONS Version 1.1 By Peace Corps Liberia

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Name:______________________________

SOLUTIONS

THE WEST AFRICAN EXAMINATIONS COUNCIL

Senior High School Certificate Examination

May 2010 BIOLOGY 2 ½ hours

PAPER 1 OBJECTIVE TEST

Exam questions are listed first followed by the solution directly underneath. Please note these solutions are intended as a guide and a study tool. Independent research and study will still be necessary if a concept is unfamiliar.

1. Which of the following is the basic unit of classification? A. Kingdom B. Phylum C. Family D. Species

Answer: SPECIES KingdomPhylumClassOrderFamilyGenusSpecies REF: Longman pg. 110

2. Every multi-cellular living organism

begins life as a/an A. Prokaryote B. Embryo C. Single cell D. Trophoblast

Answer: Single cell

A cell is the smallest unit of an organism that can be considered alive. REF: Longman pg. 23, SSG pg. 26

3. Which of the following statements is

true about the origin of life on earth? A. It has been duplicated in the

laboratory. B. It required gaseous oxygen. C. It arose from living systems

brought to earth from another planet.

D. It can be explained by using our knowledge of chemistry and physics.

Answer: It required gaseous oxygen Earth’s early atmosphere was about 92% carbon dioxide, 5% nitrogen, 0% oxygen, and 3% other gases. Over time, oxygen gas started accumulating in the atmosphere. As atmospheric oxygen concentrations

401 S.H.S.C.E. May 2010 BIOLOGY 1 & 2 Objective and Essay Tests 2 ½ hours


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rose, concentrations of methane and hydrogen sulfide began to decrease, the ozone layer began to form, and the skies turned their present shade of blue.

4. The study of how diseases spread is

called A. Epidemiology B. Biochemistry C. Pathology D. Physiology

Answer: Epidemiology Epidemiology focuses on where, when, and how often diseases occur; on how diseases are transmitted; and how diseases can be controlled. REF: Longman pg. 449

5. In which of the following do the organisms have the closest taxonomic relationship? A. Man and frog B. Ameba and paramecium C. Whale and kangaroo D. Crayfish and spider

Answer: Crayfish and spider Crayfish and spiders are both arthropods. Arthropods are classified based on the number and structure of their body segments and appendages. REF: Longman pg. 125-128

6. A biologist discovered a new living

cell in a culture with a distinct cell wall but no definite nucleus. The cell is likely to be that of a/an

A. Animal cell B. Plant cell C. Protozoan D. Bacterium

Answer: Bacterium Prokaryotes (bacteria) cells do not have a nucleus. REF: Longman pg. 23, SSG pg. 56

A membrane does not surround DNA. The general area in which DNA lies is called nucleoid

7. The conceptual meaning of the term biogenesis is that A. Cells arise spontaneously from

nonliving matter B. Cells are formed by mitosis of

parent cells C. Nonliving organic material is

useful to living cells D. Living organisms are derived

from other living organisms

Answer: Living organisms are derived from other living organisms.

8. A piece of potato weighing 1.2 gm

was put into salt solution. After three hours, it was removed and weighed. The recorded weight was 1.6 gm. The experiment demonstrates that the A. Salt solution is more

concentrated than the cell sap of the potato

B. Cell sap of the potato is more concentrated than the salt solution.


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C. Salt solution ahs the same concentration as the cell sap of the potato.

D. The potato lost some water molecules to the salt solution.

Answer: Salt solution is more concentrated than the cell sap of the potato. REF: Longman pg. 41

9. Gaseous exchange in spirogyra is

carried out by means of A. Spiracles B. Simple diffusion C. Cytoplasmic strand D. Breathing trumpet

Answer: Simple diffusion REF: Longman pg. 63, SSG pg. 70

10. One characteristic that all algae have

in common is that they A. Contain chlorophyll B. Are unicellular C. Have heterogamous sexual

reproduction D. Lack alternation of generations

Answer: Contain chlorophyll In adapting to conditions of limited light, various groups have evolved different forms of chlorophyll. Each form of chlorophyll- chlorophyll a, chlorophyll b, chlorophyll c- absorbs different wavelengths of light. REF: Longman 115-116

11. In the absence of a contractile vacuole, an amoeba or paramecium would not A. Excrete carbon dioxide B. Move from one place to another

C. Carry out gaseous exchange D. Regulate its water content

Answer: Regulate its water content A contractile vacuole is a cavity that is specialized to collect water when a contractile vacuole is full; it contracts abruptly, pumping water out of the organism. The expelling of excess water via the contractile vacuole is one of the ways the paramecium maintains homeostasis. REF: Longman pg. 60, SSG pg. 66-68

12. The observation of mitotic events in living cells is made possible by the use of the A. Dissecting binocular microscope B. Electron microscope C. Light microscope with oil

immersion objective D. Phase-contrast microscope

Answer: Electron microscope The best electron microscopes can produce images almost 1,000 times more detailed than light microscopes can. REF: Longman pg. 14-17

13. Which of the following processes can be found in both bacteria and protists? A. Mitosis B. Meiosis C. Binary fission D. Fusion of gametes

Answer: Binary fission


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Binary fission is a type of asexual reproduction in which an organism replicated its DNA and divides in half, producing two identical daughter cells.

14. Which of the following is not associated with nuclear and cell division in animals? A. Separation of chromosomes B. Duplication of chromosomes C. Formation of cell plate D. Constriction of the dividing cells

Answer: Formation of cell plate In plants, a structure known as the cell plate forms midway between the divided nuclei. REF: Longman pg. 360

15. Which statement best describes an

important event in the process of oxidative phosphorylation? A. ATP is changed creating

phosphate B. Phosphorus is added to glucose

molecules C. Lactic acid is produced D. ADP is converted to ATP

16. An animal with two body layers, a single opening, and a single cavity (gastro vascular cavity) is likely to be a/an A. Annelid B. Arthropod C. Coelenterate D. Mollusk

Answer: Coelenterate

17. Which characteristic is found in

roundworms but not in other simple invertebrates? A. A head end B. Three tissue layer C. Circulatory system D. Tissues organized into organs

Answer: Three tissue layer Ectoderm, mesoderm and endoderm.

18. Rhizopus is a saprophyte because it A. Grows on damp surfaces B. Feeds on other organisms C. Secretes enzyme to digest starch

externally D. Consists of branched hyphae

Answer: Feeds on other organisms REF: Longman pg. 158

19. The Unit structure of DNA is the

A. Pentose sugar B. Polymer C. Nucleotide D. Nucleus

Answer: Nucleotide REF: Longman pg. 350

20. All of the following organisms have a true coelom except A. Human being B. Earthworm C. Starfish D. Planarian


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Answer: Planarian Flatworms are known as “acoelomates” which means without a coelom.

21. In the process of cleavage, the mesoderm appears during A. The gastrula stage B. The blastula stage C. The zygote stage D. Organ formation

Answer: The blastula stage During the blastula stage the cells of the mesoderm give rise to muscles and much of the circulatory, reproductive, and excretory organ systems.

Use the diagram below to answer questions 22 to 25.

22. Which number refers to a synapse? A. 1 B. 3

C. 5 D. 6

Answer: 3 Synapse is located at which the neuron can transfer an impulse to another cell. REF: Longman pg. 324-325

23. Which number represents the cell

body of a sensory neuron? A. 1 B. 3 C. 4 D. 6

Answer: 6 REF: Longman pg. 324-325

24. The neurohumor most likely to be

secreted by the structure numbered 4 is A. Acetylcholine B. Adrenalin C. Epinephrine D. Serotonin

Answer: Acetylocholine It’s a neurotransmitter that diffuses across a synapse and produces an impulse in the cell membrane of a muscle cell. REF: Longman pg. 332

25. A myoneural junction may be located

around structure A. 1 B. 3 C. 4 D. 5


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Answer: 1

26. In guinea pigs, black is dominant. One

half of a particular litter is white. If it is assumed that the laws of chance operate, the parent cross was A. BB x Bb B. Bb x Bb C. Bb x bb D. BB x bb

Answer: Bb x bb

27. To determine whether an unknown

black guinea pig is pure or hybrid black, it should be crossed with a A. White B. Hybrid black C. Hybrid white D. Pure black

Answer: Pure black

28. In the gene pool of a given population of rabbits, 80% of the gametes carry the dominant allele for gray coat. What is the percentage of the population that is heterozygous gray? A. 64% B. 32% C. 20% D. 16%

Answer: 32%. If the allele frequency of the dominant allele is 80% (or 0.8), then by the equation p+q = 1, the frequency of the recessive allele is 20% or 0.2. The percentage of the population that is heterozygous found using the equation p2+2pq+q2=1; the heterozygous population is “2pq”. Substituting numbers gives the answer 0.32, or 32%.

29. Which set of parents could not be the parents of a child with type O blood? A. Father type A, mother type O B. Father type A, mother type B C. Father type B, mother type O D. Father type AB, mother type O

Answer: Father type A, mother type B A and B blood types are co-dominance so no child with blood type O could be born. REF: SSG pg. 285

30. Which of the following conditions is represented by co-dominance? A. Polyploidy B. AB blood group C. Sickle cell anemia D. Dwarfism

Answer: AB blood group The alleles for type A and B are co-dominant, people with type AB blood can receive blood from all groups. REF: SSG pg. 285

The diagram below illustrates a biochemical reaction. Use it to answer Questions 31 to 33.


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31. Stage II in the diagram represents A. An inorganic catalyst B. A denatured enzyme C. A vitamin D. An enzyme-substrate complex

Answer: An enzyme-substrate complex REF: Longman pg. 219, SSG pg. 40

32. Which substance is needed for the

biochemical reaction above to occur? A. Benedict solution B. Water C. Table salt D. Iodine

Answer: Benedict solution

33. The area labeled X is known as A. A temperature regulator B. A pH indicator C. An active site D. An atomic nucleus

Answer: An active site REF: Longman pg. 219, SSG pg. 40

34. Pancreatic juice acts in the presence

of A. KOH B. NA2CO3 C. NaCl D. H2CO3

35. Which of the following item is not properly grouped with the others? A. Calcium ions

B. Vitamin B2 C. Thromboplastin D. Vitamin K

Answer: Vitamin B2 Blood clotting is made possible by a number of plasma proteins and cell fragments called platelets. Calcium and vitamin K aide in converting prothrombin into thrombin.

36. Which of the following structures is

not present in the vascular bundles of a dicot stem? A. Parenchyma, xylem and

collenchyma B. Epidermis, sclerenchyma and

xylem C. Parenchyma, collenchyma and

sclerenchyma D. Sclerenchyma, xylem and

collenchyma

Answer: Parenchyma, collenchyma and sclerenchyma Vascular bundles in plant stems contain the xylem and phloem tissue. REF: Longman pg. 372

37. Mosses belong to the group of plants

called A. Pteridophytes B. Bryophytes C. Schizophytes D. Gymnosperms

Answer: Bryophytes Bryophytes include mosses, liverworts, and hornworts. REF: Longman pg. 120


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38. The elephant grass is propagated vegetatively by means of A. Corms B. Suckers C. Stolons D. Runners

Answer: Stolons Stolons in plants are long, trailing stems that produce roots when it touches the ground.

39. All of the following are characteristics of flowering plants except A. Autotrophic gametophytes B. Seed dispersal C. Double fertilization D. The formation of pollen tubes

Answer: The formation of pollen tubes Pollen tubes form in gymnosperms (cones) not angiosperms (flowering plants).

40. The organs constantly in touch with the liver are the A. Pancreas, colon and caecum B. Duodenum and stomach C. Ileum, stomach and colon D. Stomach and gall bladder

Answer: Stomach and gall bladder REF: Longman pg. 204, ORC Biology A2 pg. 38

41. The following functions are

associated with the liver except A. Regulation of blood sugar

B. Production of heat C. Production of fibrinogen D. Production of vitamin D

Answer: Production of fibrinogen Fibrinogen is a protein responsible for the ability of blood to clot.

42. Using iodine solution, Bluret test,

Benedict reagents and ethanol, respectively in testing for reducing sugars, which of the following trends of color changes would be observed? A. BlueBlackBlueBrownCle

ar B. BrownBlueBrick

redClear C. BrownVioletBlueClear D. BrownBlueVioletMilky

Answer: BrownBlueBrick redClear REF: Longman pg. 199, ORC Biology pg. 112-113

43. To which of the following kingdoms

do arthropods belong? A. Prokaryotae B. Plantae C. Animalia D. Protoctista

Answer: Animalia REF: Longman pg. 124

44. Which of the following diseases could

be a hazard to the fish farmer? A. Typhoid B. Bilharzias C. Trypanosomiasis D. Athlete’s foot

Answer: Trypanosomiasis


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REF: Longman pg. 114

Use the information below to answer questions 45 to 48. Each student in a biology laboratory received two solutions. One solution was distilled water. The other was a salt solution with a concentration of salts slightly greater than that of a living cell. The solutions were labeled X and Y, respectively. The students were instructed to place some fresh-water protozoan in each of the solutions and to identify the solutions on the basis of observations. The protozoan in solution X swelled and burst. Those in solution Y shriveled up.

45. The results indicate that A. Solution X is salt water B. Solution Y is distilled water C. Solution Y is salt water D. Solution X had other additions

46. The organisms in solution X swelled up and burst because A. An antagonistic substance was

placed in the solution B. The organisms could not adjust to

the new environment C. Osmotic pressure failed to

operate D. A disproportionate amount of

water diffused into the animals

Answer: Osmotic pressure failed to operate Hypotonic: solution has a lower concentration than the cell it swells up and bursts.

47. In order to keep the organisms alive in the available solutions X and Y, the laboratory instructor should A. Dilute solution Y with solution X

and place the organisms in the new solution

B. Boil solution Y and cool, then place the animals in it

C. Acidify solution X, and then add the organisms

D. Evaporate and condense solution X, then add the organisms

48. What would happen to the protozoan if they were placed in pond water? A. They would shrink and

disintegrate B. They would swell and burst C. They would remain unchanged D. They would reproduce at an

unusual rate

49. The concave shape of a bird’s wing during flight ensures that the greater air pressure under the wing will A. Counteract the effect of gravity B. Lift the bird so that it can

remain airborne C. Enable the pectoral muscles to

contract easily D. Change the direction of the flying

bird

Answer: Lift the bird so that it can remain airborne

50. Which of the following will ease the friction between the ends of bones in a movable joint?


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A. Serum B. Tissue C. Blood plasma D. Synovial fluid

Answer: Synovial fluid Synovial fluid enables the surfaces of the joint to slide over each other smoothly. REF: Longman pg. 301

51. The Eustachian tube connects the middle ear with the A. Semicircular canals B. Larynx C. Pharynx D. Cochlea

Answer: Cochlea REF: Longman pg. 337

52. All of the following pairs represent

homologous structures except A. Flipper of a whale; arm of a

human being B. Wing of a bat; wing of a bird C. Flipper of a whale; lateral fin of a

fish D. Arm of a human being; forelimb of

a horse

Answer: Wing of a bat; wing of a bird REF: SSG pg. 295

53. All of the following generalizations

are consistent with the physical and chemical factors found in a food chain except that

A. The secondary consumers are usually larger in size than the primary consumers

B. The biomass of a food chain is greatest at the producer end

C. An increase in the number of organisms occurs in successive links of the food chain

D. The amount of available energy decreases in successive links of the food chain

Answer: An increase in the number of organisms occurs in successive links of the food chain A decrease occurs not an increase.

54. After being in a small, poorly

ventilated room for an hour with eleven other persons, a student noticed that his rate of breathing had increased. The most probable reason for this is that the A. Excess water in the body had to

be eliminated B. Carbon dioxide concentration

in his blood had increased C. Oxygen concentration in his blood

had increased D. Air in the room had become hot

Answer: Carbon dioxide concentration in his blood had increased Cells in its breathing center monitor the amount of carbon dioxide in the blood. As carbon dioxide level rises, nerve impulses from the breathing center cause the diaphragm to contract, bringing air into the lungs.


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55. All of the following statements about white blood cells are true except that A. They are formed in lymph

glands B. They are formed in bone marrow C. They move like a paramecium D. They are phagocytic

Answer: They are formed in lymph glands REF: Longman pg. 246

56. Which of the following represents the

correct sequence in blood clotting? A. Platelets, fibrinogen, pro-

thrombin, fibrin, thrombin B. Platelets, pro-thrombin,

thrombin, fibrinogen, fibrin C. Platelets, thrombin, fibrin, pro-

thrombin, fibrin D. Platelets, fibrin, fibrinogen,

thrombin, pro-thrombin

Answer: Platelets, pro-thrombin, thrombin, fibrinogen, fibrin REF: Longman pg. 253

57. Which of the following carries urine

during excretion and semen during ejaculation? A. Urethra B. Fallopian tube C. Vas deferens D. Seminiferous tubule

Answer: Urethra REF: SSG pg. 268

58. Genetic drift, which can lead to the

loss of certain genes by chance, is particularly significant in

A. Determining the fitness of a species

B. The evolution of small populations

C. Determining the survival of mutations

D. Accounting for the total gene pool of a species

Answer: The evolution of small population Genetic drift is random change in allele frequencies that occur in small populations.

59. Which of the below statements are

true for both aerobic respiration and photosynthesis? (1) Synthesizes ATP (2) Makes use of molecules of oxygen (3) Makes use of electron transport

system (4) Is controlled by enzymes

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

Answer: 1,3, and 4

60. Organic compound containing

carbon, hydrogen, and oxygen atoms in which the ratio of the hydrogen to oxygen is 2:1 is called A. Fats B. Proteins C. Carbohydrates D. Glycerol

Answer: Carbohydrates Carbohydrates are compounds made up of carbon, hydrogen and oxygen atoms usually a ration of 1:2:1.


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PAPER 2 1 ½ hours

ESSAY

1. With the aid of well labeled diagrams, show the following eye defects and describe how each can be corrected.

Answer: REF: SSG pg. 259

(a) Myopia- short sight- long eyeball; distant objects cannot be focused and can be

corrected by diverging lens. (b) Hypermetropia- long sight- short eyeball; near objects cannot be focused and can be

corrected by converging lens.


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Study the diagram below and use it to answer Question 2.

2. (a) Identify the structure in the diagram i. Name the parts labeled I to VI.

Answer: I= Renal vein, VI= ureter REF: Longman pg. 285, SSG pg. 242

ii. State the functions of the parts labeled I, II, III, and V.

Answer: I= the renal vein carry blood out of the kidney, II= blood comes from the renal artery, III= the cortex is the outer layer of the kidney used for protection and V= this part is the pelvis which is a cavity that receives urine from the nephrons. REF: Longman pg. 285, SSG pg. 242

(b) With what organ system of the mammalian body is this structure associated?

Answer: The kidney is associated with the excretory system within the mammalian body. REF: Longman pg. 283

3. (a) List and briefly discuss the five major nutritive processes involved in the digestive system.

Answer: 1. The digestion of carbohydrates- carbohydrates are absorbed as monosaccharides. The main function of carbohydrates is to provide energy, from respiration.


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2. The digestion of proteins- proteins are absorbed as amino acids which are then assembled according to the genetic instructions within the organism. 3. The digestion of lipids- Lipids are absorbed as glycerol and fatty acids. Lipids have three important functions: respiration, component of cell membranes and insulation & protection. 4. The digestion of vitamins- Vitamins are required in small amounts in the diet; they are micronutrients which are in many cases necessary for enzymes to work properly. 5. The digestion of minerals- Mineral are inorganic molecules which can be important in the formation of more complex organic molecules. REF: Longman pg. 207, SSG pg. 198

(b) State the fuctions of the following enzymes during digestion: (i) protease; (ii) amylase (iii) lipase.

Answer: Protease- breakdown proteins. Amylase- breakdown starch. Lipase- digests fats and oils. REF: SSG pg. 207

4. (a) List six characteristic features of insects.

Answer: 1. They have wings 2. They have six legs 3. They have three body parts- head, thorax, and abdomen 4. They have an open circulatory system 5. They have antennae 6. They have compound eyes

(b) Give two reasons why some insects are described as social insects.

Answer: Bees and termites are social insects. The colony can be considered as a superorganism; each individual belongs to a caste and its anatomy and physiology are adapted for it to perform its specific function (s). Individuals cannot change into another type of caste. REF: Longman pg. 102

(c) Name and state the functions of three different types of individuals found in a named social insect group.


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Answer: Honey Bees & Termites 1. The workers- build and repair the nest, search for food (wood & grass) and feed other members of the colony. They look after the nymphs and tend the gardens where they grow fungi. 2. The soldiers- defend the colony against invaders, using their powerful jaws as weapons. 3. The queen (bees, termites) & king (termintes)- to lay eggs and reproduce

5. In the course of plant evolution, natural selection has favored the dominance of the

sporophyte generation.

(a) Cite evidence to substantiate the above.

Answer: It is diploid rather than haploid. Having two sets of genes can avoid expression of deleterious traits. The seed plant pattern of large sporophyte is a very effective system. Remember the key features: Large sporophyte nutrures the tiny female gametophytes, there are millions of tiny male gametophytes (pollen) that can be carried great distances, either by wind or by animal and new sporophytes arise from very mobile, usually very tough, seeds that contain energy supply and tiny plant in suspended animation.

(b) Explain why the gametophyte generation continues to exist in the life cycle of plants.

Answer: The gametophyte generation continues to exist as a small part of the life cycle, which is its haploid stage. The alteration of generation is highly significant in plants, as it increases the chances of the plants survival in the long run. The next generation becomes even more adapted to the environment. The formation of spores from parent cells, cause shuffling of genes, conducing to new, different and stronger genetic make-ups. Then in the gametophyte stage, when gametes are formed with non reduction division, the zygote formed is better adapted to the environment. Thus, the gametophyte and sporophyte generations are truly significant phases in the life cycle of a plant.

6. The immune responses of organisms involve antigens, antibodies, and other factors.

Describe the immune response and discuss its role in the following;

(a) Blood transfusion;

(b) Rh incompatibility; and


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(c) Disease resistance

the west african examinations councilb. plant cell c. protozoan d. bacterium answer: bacterium...

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