2021 - JAMB Biology Past Questions and Answers - page 4

31
Mass of a crucible = 10g,

Mass of a crucible and soil before heating =29g

Mass of a crucible and soil after heating = 18g

From the information above, determine the percentage of water in the given soil sample?

A

20%

B

25%

C

40%

D

60%

correct option: d
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32
I. Stomata --> Spirogyra

II. Alveoli --> Earthworm

III. Malpighian tubule -> Mammal

IV. Contractile vacuole -> Protozoa

Which of the above structures is correctly matched with the organisms in which it is found?

A

II

B

I

C

IV

D

III

correct option: c

Stomata allow a plant to take in carbon dioxide, which is needed for photosynthesis. They also help to reduce water loss.

The alveoli are where the lungs and the blood exchange oxygen and carbon dioxide during the process of breathing in and breathing out.

The Malpighian tubules are tubular structures that are free floating in the haemolymph and function as excretory and osmoregulatory organs of insects. 

 Contractile vacuoles (in the cells of the lower organisms) protect a cell from absorbing too much water and potentially exploding by excreting excess water.

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33
The sequence of the one-way gaseous exchange mechanism in a fish is?
A

mouth --> operculum -> gills

B

mouth -> gills > operculum

C

operculum > gills -> mouth

D

gills -> operculum --> mouth

correct option: b

Fish exchange gases by pulling oxygen-rich water through their mouths and pumping it over their gills. In some fish, capillary blood flows in the opposite direction to the water, causing counter-current exchange. The gills push the oxygen-poor water out through openings in the sides(opercula) of the pharynx.

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34
Which of the following is true in blood transfusion?
A

A person of blood group AB can donate blood only to another person of blood group AB

B

Persons of blood groups A and B can donate or receive blood from each other

C

A person of blood group AB can receive blood only from persons of blood group A or B

D

A person of blood group O can donate only to a person of blood group O

correct option: a

People with type AB+ blood are universal recipients because they have no antibodies to A, B or Rh in their blood and can receive red blood cells from a donor of any blood type.

 Donors with blood type AB can donate to recipients with blood type AB only.

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35
The plants that grow in deserts or very dry areas are referred to as?
A

hydrophytes

B

epiphytes

C

xerophytes

D

mesophytes

correct option: c

Plants that live in water and adapt to their environment are known as hydrophytes.

Epiphyte, also called air plant, any plant that grows upon another plant or object merely for physical support.

 Plants that grow in dry habitat are called xerophytes.

Mesophytes are terrestrial plants which are neither adapted to particularly dry nor particularly wet environments.

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36
The most abundant group of organisms in the animal kingdom?
A

Mammalia

B

Aves

C

Insecta

D

Annelida

correct option: c

The phylum Arthropoda is the largest in the animal kingdom, having its class Insecta as 70% of all known species of animals.

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37
The movement of part of a plant in response to external stimulus of no particular direction is?
A

taxism

B

tropism

C

haptotropic movement

D

nastic movement

correct option: d

Taxism: oriented movement of a motile organism in response to an external stimulus, as toward or away from light.

A tropism is a biological phenomenon, indicating growth or turning movement of a biological organism, usually a plant, in response to an environmental stimulus.

 In tropisms, this response is dependent on the direction of the stimulus.

The movement or directional growth of plants or plant organs (as the tendrils of climbing plants) in response to the stimulus of touch.

The non-directional movement (of plants) in response to a stimulus (e.g. humidity, temperature, light irradiance, nutrients, gravity, etc.

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38
The mutation theory of organic evolution was propounded by?
A

Gregor Mendel

B

Hugo de Vries

C

Jean Lamarck

D

Charles Darwin

correct option: b

Gregor Mendel, through his work on pea plants, discovered the fundamental laws of inheritance

 Hugo de Vries (1901) put forward a theory of evolution, called mutation theory

Jean Baptiste Lamarck believed that traits changed or acquired over an individual's lifetime could be passed down to its offspring.

The Theory of Evolution by natural selection was first formulated in Charles Darwin's book "On the Origin of Species" published in 1859.

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39
If both parents are heterozygous for a trait. the probability that an offspring will be recessive for that trait is?
A

1/2

B

1/4

C

1

D

3/4

correct option: a
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40
Blood circulation in a mammal is said to be double because? 
A

it passes twice through the heart in a complete circuit

B

it moves in both arteries and veins

C

it circulates in both the heart and other organs

D

the heart contains auricles and ventricles

correct option: a

It is called a double circulatory system because blood passes through the heart twice per circuit. 

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