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JAMB Biology Past Questions 1990

10 questions from the JAMB 1990 Biology paper, with answers and explanations. Tap "Show answer" under each one when you are ready.

JAMB 1990Question 1 · Ecology and Environment
which of the organisms will have the lowest population in an ecosystem?
  1. A.Hawk
  2. B.Cowpea
  3. C.Praying mantis
  4. D.Mouse
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Answer: A. Hawk

As a top predator the hawk receives the least energy and normally has the smallest population.

JAMB 1990Question 2 · General Past Questions
Hydra removes undigested food by
  1. A.passing it through the anus
  2. B.passing it through the mouth
  3. C.means of a contractile vacuole
  4. D.egesting it through the body surface
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Answer: B. passing it through the mouth

Hydra has a single gastrovascular opening so undigested food leaves through the mouth.

JAMB 1990Question 3 · General Past Questions
In the tapeworm the suckers on the scolex are used for
  1. A.sucking the blood of the host
  2. B.holding fast to the host
  3. C.reproduction
  4. D.locomotion
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Answer: B. holding fast to the host

The suckers anchor the scolex firmly to the intestinal wall of the host.

JAMB 1990Question 4 · General Past Questions
Which type of the following cells is thin-walled and living at maturity?
  1. A.Collenchyma
  2. B.Sieve tube
  3. C.xylem vessel
  4. D.sclerenchyma
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Answer: B. Sieve tube

Sieve-tube elements are living thin-walled cells at maturity unlike vessels and sclerenchyma.

JAMB 1990Question 5 · General Past Questions
Transpiration can be measured with a
  1. A.photometer
  2. B.hygrometer
  3. C.potometer
  4. D.barometer
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Answer: C. potometer

A potometer estimates transpiration rate by measuring water uptake by a shoot.

JAMB 1990Question 6 · General Past Questions
Fruits which develop without fertilization are described as
  1. A.simple
  2. B.pathencorpic
  3. C.aggregate
  4. D.compound
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Answer: B. pathencorpic

Parthenocarpic fruits develop without fertilization and are commonly seedless.

JAMB 1990Question 7 · General Past Questions
In organism where the 2nd number of chromosomes is 16, the number of chromosomes in each gamete will be
  1. A.32
  2. B.16
  3. C.8
  4. D.4
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Answer: C. 8

Gametes are haploid and therefore contain half of the diploid number sixteen which is eight.

JAMB 1990Question 8 · General Past Questions
Physiological adaptation to very dry condition in animals is called
  1. A.hibernation
  2. B.aestivation
  3. C.rejuvenation
  4. D.xeromorphism
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Answer: B. aestivation

Aestivation is a period of dormancy that helps animals survive hot dry conditions.

JAMB 1990Question 9 · General Past Questions
Free nitrogen is released to the atmosphere by
  1. A.Nitrogen-fixing bacteria
  2. B.nitrifying bacteria
  3. C.denitrifying bacteria
  4. D.saprophytic bacteria
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Answer: C. denitrifying bacteria

Denitrifying bacteria reduce nitrates and release molecular nitrogen back into the atmosphere.

JAMB 1990Question 10 · Microbiology and Disease
Which set of disease is spread mainly by insect vectors?
  1. A.Cholera, tenia and gonorrhoea
  2. B.Poliomyelitis, tuberculosis and syphilis
  3. C.Cholera, malaria and tuberculosis
  4. D.Malaria, cholera and river blindness
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Answer: D. Malaria, cholera and river blindness

Malaria and river blindness are both transmitted by insect vectors whereas the alternatives contain fewer vector-borne diseases.

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