JAMB Biology 2017

24 reviewed questions with answers and explanations.

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Question 1

Piercing and sucking mouthparts for taking blood are found in female

  1. grasshoppers
  2. mosquitoes
  3. termites
  4. cockroaches
Answer and explanation

B: mosquitoes

Female mosquitoes have mouthparts adapted to pierce tissue and take a blood meal. The other listed insects have primarily biting and chewing mouthparts.

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Question 4

Which group includes familiar animals adapted to arid environments?

  1. locust, camel, lizard and snakes
  2. monkeys, chameleon, earthworm and grasshopper
  3. monkeys, grasshopper, snail and snakes
  4. lungfish, duck, butterfly and lizards
Answer and explanation

A: locust, camel, lizard and snakes

Camels and many desert reptiles are adapted to dry conditions, and locusts include arid-region forms. The other groups include organisms strongly dependent on moist or aquatic environments.

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Question 5

Suture joint is found in the

  1. hip
  2. ankle
  3. skull
  4. elbow
Answer and explanation

C: skull

Sutures are fibrous joints between many skull bones. They provide strong connections with little movement, unlike the freely movable joints of the limbs.

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Question 6

The organelle responsible for osmoregulation in Paramecium is

  1. flame cell
  2. nephridia
  3. contractile vacuole
  4. Malpighian tubule
Answer and explanation

C: contractile vacuole

A contractile vacuole expels excess water entering a freshwater Paramecium. This helps maintain water balance in a cell whose surroundings are usually hypotonic.

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Question 8

The platelets in mammalian blood are responsible for

  1. transporting oxygen
  2. initiating clotting
  3. removing carbon (IV) oxide
  4. destroying micro-organisms
Answer and explanation

B: initiating clotting

Platelets adhere at damaged blood vessels and help form a platelet plug. They also support clotting reactions that stabilise the plug with fibrin.

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Question 10

When testing for the presence of starch in a leaf, the reason for dipping the decolourised leaf in hot water is to

  1. detect the starch
  2. kill the leaf
  3. soften the leaf
  4. remove the chlorophyll
Answer and explanation

C: soften the leaf

Alcohol removes chlorophyll but leaves the leaf brittle. Rinsing the decolourised leaf in hot water softens it before iodine is added to test for starch.

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Question 11

If a remora benefits from transport by a shark while the shark is unaffected, the relationship is

  1. parasitism
  2. amensalism
  3. mutualism
  4. commensalism
Answer and explanation

D: commensalism

Commensalism describes a relationship in which one organism benefits while the other is not appreciably affected. A remora receiving transport under this assumption fits that definition.

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Question 12

The major characteristic of a fresh water habitat is the possession of

  1. high turbidity
  2. high density
  3. low salinity
  4. high current
Answer and explanation

C: low salinity

Freshwater habitats have low concentrations of dissolved salts compared with marine habitats. Their turbidity and current speed vary between rivers, ponds and lakes.

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Question 13

The causative organism of cholera is

  1. Clostridium sp
  2. shigella sp
  3. Vibrio cholerae
  4. Salmonella Typhi
Answer and explanation

C: Vibrio cholerae

Cholera is caused by toxigenic strains of Vibrio cholerae. Infection can produce severe watery diarrhoea through the action of cholera toxin in the intestine.

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Question 14

The process that takes place in the dark stage of photosynthesis is

  1. oxidation of water
  2. photolysis of water
  3. oxidation of carbon (IV) oxide
  4. reduction of carbon (IV) oxide
Answer and explanation

D: reduction of carbon (IV) oxide

In the Calvin cycle, carbon derived from carbon dioxide is reduced using energy and reducing power supplied by the light reactions. The cycle does not require darkness.

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Question 15

Historically, CFC refrigerants could escape into the atmosphere from

  1. crude oil refining
  2. coal mining
  3. motor vehicle exhaust
  4. cooling system
Answer and explanation

D: cooling system

Older refrigeration and air-conditioning systems used CFC refrigerants. Leakage or improper handling could release them into the atmosphere, where they contribute to ozone depletion.

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Question 18

Which is a typical feature of wind-pollinated flowers?

  1. flowers lack nectar
  2. flowers are conspicuous
  3. flowers have perianths
  4. flowers are bisexual
Answer and explanation

A: flowers lack nectar

Wind-pollinated flowers typically do not offer nectar to animal visitors. They commonly have exposed anthers, receptive stigmas and abundant lightweight pollen.

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Question 20

In the usual diploid animal life cycle, chromosome number is halved during gamete production by

  1. implantation
  2. fertilisation
  3. mitosis
  4. meiosis
Answer and explanation

D: meiosis

In animals, meiosis in the germ line reduces chromosome number during gamete production. Fertilisation then joins haploid gametes and restores the diploid number.

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Question 21

A dish weighs 20 g and contains 7.5 g of dry soil. After burning, dish and soil weigh 25 g. Assuming the mass lost represents humus, its percentage in the initial dry soil is

  1. 9.1
  2. 37.5
  3. 12.5
  4. 33.3
Answer and explanation

D: 33.3

The remaining soil weighs 25 − 20 = 5 g. The mass lost is 7.5 − 5 = 2.5 g, so the estimated humus percentage is (2.5 ÷ 7.5) × 100 = 33.3%.

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Question 25

The outermost tissue of a young herbaceous root is the

  1. cuticle
  2. pericycle
  3. epidermis
  4. endodermis
Answer and explanation

C: epidermis

The epidermis is the outer tissue of a young herbaceous root. Root hairs arise from epidermal cells and increase the surface available for absorption.

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Question 26

The respective tissues that transport water and manufactured food in plants are

  1. xylem and phloem
  2. phloem and tracheid
  3. phloem and xylem
  4. xylem and tracheid
Answer and explanation

A: xylem and phloem

Xylem carries water and dissolved mineral nutrients, while phloem transports sugars and other organic solutes between sources and sinks. The order is xylem, then phloem.

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Question 30

With other conditions comparable, which soil type generally has the least ability to retain nutrients?

  1. sandy loam
  2. clay loam
  3. loam
  4. sand
Answer and explanation

D: sand

Sandy soil generally has less surface area and lower nutrient retention than comparable soils containing more clay and organic matter. Dissolved nutrients can be readily leached.

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Question 32

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The part labelled III acts as

  1. water outlet
  2. food strainer
  3. exchange surface
  4. blood transporter

Question 33

Overcrowding can encourage individuals to leave a population. This movement is

  1. immigration
  2. reduced competition
  3. emigration
  4. reduced mortality
Answer and explanation

C: emigration

Overcrowding can increase competition for resources and encourage individuals to leave an area. Movement out of a population is called emigration.

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Question 34

The two specific vertebrae involved in nodding and rotating the head are the

  1. axis and cervical
  2. atlas and thoracis
  3. axis and atlas
  4. atlas and cervical
Answer and explanation

C: axis and atlas

The atlas supports the skull and participates in nodding, while the atlas–axis joint permits rotation around the axis dens. Together these are the first two cervical vertebrae.

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Question 35

The DNA markers commonly compared in paternity testing are located in the

  1. centrosome
  2. ribosome
  3. nucleus
  4. mitochondria
Answer and explanation

C: nucleus

Paternity comparisons commonly examine markers in nuclear DNA. An individual inherits nuclear genetic material from both biological parents, allowing marker comparisons.

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Question 37

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The part labelled II is the

  1. arch
  2. filament
  3. slit
  4. raker

Question 38

The modified insect-trapping structure of Venus flytrap leaves is an example of a

  1. adaptive coloration
  2. structural adaptation
  3. environmental adaptation
  4. behaviour adaptation
Answer and explanation

B: structural adaptation

The Venus flytrap has leaves modified into traps that can retain insects. The shape and specialised parts of those leaves are structural adaptations for obtaining nutrients.

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Question 39

Morphological variation in humans include

  1. height, skin, colour and tongue rolling
  2. weight, finger prints and body shape
  3. height, weight and blood group
  4. skin colour, blood and height
Answer and explanation

B: weight, finger prints and body shape

Weight, fingerprint patterns and body shape describe bodily characteristics. Blood group concerns biochemical antigen differences, while tongue rolling concerns an ability.

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