CXC CSEC Human and Social Biology — Paper 1 (Multiple Choice)

Total marks: 60 · Duration: 75 minutes

Instructions to candidates

• Answer ALL questions.
• Each question is worth 1 mark.
• Write your answers on the Multiple Choice Answer Sheet provided.
• Shade your answer completely using an HB pencil.
• If you need to change an answer, erase your first choice completely.
• Calculators may be used.
• This paper consists of 60 questions.

Paper

Section A — Multiple Choice (60 marks)

1. Which organelle is responsible for the production of ATP in the cell?

A) Ribosome
B) Nucleus
C) Chloroplast
D) Mitochondrion

2. The diagram shows a section through human skin.

[Image shows epidermis, dermis, sweat gland, hair follicle, and sebaceous gland]

Which structure secretes an oily substance that waterproofs the skin?

A) Adipose tissue
B) Sebaceous gland
C) Hair follicle
D) Sweat gland

3. A student tested a food sample with Benedict's solution and heated it. The solution changed from blue to brick-red. Which nutrient is present in the food?

A) Reducing sugar
B) Lipid
C) Starch
D) Protein

4. Which enzyme is responsible for the digestion of starch in the mouth?

A) Lipase
B) Salivary amylase
C) Pepsin
D) Trypsin

5. The part of the alimentary canal where most absorption of digested food occurs is the

A) colon
B) stomach
C) duodenum
D) ileum

6. Which blood vessel carries deoxygenated blood from the heart to the lungs?

A) Pulmonary vein
B) Aorta
C) Pulmonary artery
D) Vena cava

7. A person's blood type is AB. This person can receive blood from donors with blood type

A) A, B, AB and O
B) A only
C) B only
D) AB only

8. Haemoglobin in red blood cells combines with oxygen to form

A) plasma
B) carbonic acid
C) carboxyhaemoglobin
D) oxyhaemoglobin

9. During inhalation, the diaphragm

A) relaxes and flattens
B) contracts and moves upward
C) contracts and flattens
D) relaxes and moves upward

10. The process by which glucose is broken down in cells to release energy in the absence of oxygen is called

A) anaerobic respiration
B) photosynthesis
C) aerobic respiration
D) fermentation only

11. Which nitrogenous waste product is produced mainly by the liver from the breakdown of excess amino acids?

A) Uric acid
B) Urea
C) Carbon dioxide
D) Ammonia

12. Selective reabsorption in the kidney occurs mainly in the

A) glomerulus
B) Bowman's capsule
C) proximal convoluted tubule
D) collecting duct

13. A man can see distant objects clearly but cannot see near objects clearly. He is suffering from

A) hypermetropia
B) myopia
C) astigmatism
D) cataract

14. The part of the brain responsible for coordinating muscular movement and balance is the

A) medulla oblongata
B) cerebrum
C) hypothalamus
D) cerebellum

15. Which type of neurone carries impulses from receptors to the central nervous system?

A) Motor neurone
B) Sensory neurone
C) Relay neurone
D) Connector neurone

16. The hormone insulin is produced by the

A) thyroid gland
B) adrenal gland
C) pituitary gland
D) pancreas

17. At which stage of the menstrual cycle does ovulation normally occur?

A) Day 28
B) Day 21
C) Day 14
D) Day 5

18. Fertilisation in humans normally occurs in the

A) oviduct (fallopian tube)
B) ovary
C) vagina
D) uterus

19. Which structure provides the developing fetus with oxygen and nutrients from the mother's blood?

A) Amnion
B) Cervix
C) Umbilical cord
D) Placenta

20. A characteristic controlled by a dominant allele is represented by T, and the recessive allele by t. A heterozygous individual would have the genotype

A) Tt
B) TT
C) TT or tt
D) tt

21. Down syndrome is a genetic disorder caused by

A) a dominant allele
B) a sex-linked gene
C) an extra chromosome
D) a missing chromosome

22. Natural selection leads to evolution by favouring organisms that

A) are the largest in the population
B) produce the most offspring
C) are best adapted to their environment
D) have the most mutations

23. Which pathogen causes malaria?

A) Virus
B) Bacterium
C) Protozoan
D) Fungus

24. The Anopheles mosquito transmits malaria. In this relationship, the mosquito is described as a

A) host
B) pathogen
C) parasite
D) vector

25. Active immunity can be acquired by

A) vaccination with antigens
B) receiving an injection of antibodies
C) receiving breast milk containing antibodies
D) receiving antibodies from the mother through the placenta

26. Which of the following sexually transmitted infections is caused by a bacterium?

A) Genital herpes
B) Genital warts
C) HIV/AIDS
D) Gonorrhoea

27. The term 'incubation period' refers to the time between

A) vaccination and immunity
B) infection and appearance of symptoms
C) appearance of symptoms and recovery
D) infection and death

28. In a food chain, organisms that make their own food are called

A) producers
B) consumers
C) decomposers
D) herbivores

29. The diagram shows a pyramid of numbers for a food chain.

       [10 birds]
     [1000 insects]
   [10000 plant leaves]

What will happen to the number of insects if the bird population increases significantly?

A) Decrease
B) Become extinct
C) Remain constant
D) Increase

30. Which gas contributes most to global warming?

A) Carbon dioxide
B) Hydrogen
C) Nitrogen
D) Oxygen

31. Eutrophication of water bodies is primarily caused by

A) decrease in water pH
B) lack of oxygen in water
C) excessive nutrients from fertilisers and sewage
D) increase in water temperature

32. Which practice helps to conserve soil fertility?

A) Overgrazing
B) Crop rotation
C) Deforestation
D) Monoculture

33. A population is defined as

A) all organisms in an ecosystem
B) all animals in a food web
C) all plants in a habitat
D) all organisms of the same species living in the same area

34. The use of biological control to manage pests involves

A) removing all vegetation
B) using chemical pesticides
C) introducing natural predators or parasites
D) using antibiotics

35. Which vitamin is necessary for the proper clotting of blood?

A) Vitamin D
B) Vitamin A
C) Vitamin K
D) Vitamin C

36. Kwashiorkor is a nutritional deficiency disease caused by lack of

A) fats
B) carbohydrates
C) proteins
D) vitamins

37. Rickets is caused by deficiency of

A) Vitamin A
B) Vitamin B
C) Vitamin C
D) Vitamin D

38. Peristalsis in the alimentary canal is produced by the contraction of

A) circular muscles only
B) longitudinal muscles only
C) both circular and longitudinal muscles
D) cardiac muscles

39. The function of bile in digestion is to

A) digest proteins
B) digest carbohydrates
C) digest nucleic acids
D) emulsify fats

40. Which valve prevents the backflow of blood from the left ventricle into the left atrium?

A) Bicuspid (mitral) valve
B) Tricuspid valve
C) Semilunar valve
D) Aortic valve

41. Arteries have thick muscular walls to

A) withstand high blood pressure
B) regulate body temperature
C) store blood
D) allow diffusion of materials

42. White blood cells protect the body by

A) transporting oxygen
B) clotting blood
C) destroying pathogens
D) carrying carbon dioxide

43. The trachea is kept open by

A) bone
B) cartilage rings
C) elastic fibres only
D) muscle tissue

44. Gas exchange in the lungs occurs in the

A) bronchioles
B) trachea
C) bronchi
D) alveoli

45. Which factor does NOT affect the rate of transpiration in plants?

A) Temperature
B) Light intensity
C) Humidity
D) Soil pH

46. The skin helps to regulate body temperature by

A) producing hormones
B) altering blood flow and sweating
C) producing melanin
D) growing hair

47. Homeostasis is best defined as

A) the breakdown of food
B) the removal of waste products
C) the production of energy
D) the maintenance of a constant internal environment

48. The reflex arc includes all of the following EXCEPT

A) motor neurone
B) cerebrum
C) sensory neurone
D) receptor

49. Tropisms are growth responses in plants. A plant's roots growing downward in response to gravity is an example of

A) geotropism
B) phototropism
C) hydrotropism
D) thigmotropism

50. The hormone that prepares the body for 'fight or flight' responses is

A) testosterone
B) insulin
C) adrenaline
D) thyroxine

51. The amniotic fluid surrounding a fetus functions to

A) provide nutrients
B) produce hormones
C) remove waste products
D) protect against mechanical shock

52. Identical twins are formed when

A) one egg is fertilised by two sperm
B) one fertilised egg splits into two embryos
C) two eggs are fertilised by two sperm
D) two eggs are fertilised by one sperm

53. In a genetic cross between two heterozygous parents (Tt × Tt), what proportion of offspring will show the recessive phenotype?

A) 25%
B) 0%
C) 50%
D) 75%

54. Variation in a population is important because it

A) prevents reproduction
B) allows adaptation to environmental changes
C) eliminates weak individuals
D) ensures all organisms are identical

55. Which practice in sewage treatment involves the use of bacteria to break down organic matter?

A) Screening
B) Chlorination
C) Biological filtration
D) Sedimentation

56. The most effective method of preventing the spread of HIV/AIDS is

A) using antibiotics
B) practising safe sex and avoiding sharing needles
C) avoiding mosquito bites
D) vaccination

57. Tuberculosis (TB) is transmitted mainly through

A) airborne droplets
B) contaminated water
C) insect bites
D) direct contact with infected blood

58. An example of a non-communicable disease is

A) influenza
B) diabetes mellitus
C) cholera
D) tuberculosis

59. Which lifestyle factor increases the risk of coronary heart disease?

A) High-fibre diet
B) Cigarette smoking
C) Low salt intake
D) Regular exercise

60. The greenhouse effect is essential for life on Earth because it

A) prevents all radiation from reaching Earth
B) keeps the Earth's temperature within a suitable range
C) increases oxygen in the atmosphere
D) reduces carbon dioxide levels