Practice Post UTME NOUN biology 2021 Past Questions

Question 1

In the context of hormonal coordination, what is the primary function of the hypothalamic-pituitary-adrenal (HPA) axis?

A. Regulation of body temperature

B. Maintenance of blood glu\cose levels

Correct C. Stress response and adaptation

D. Regulation of appetite and satiety

Correct Answer: C

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Question 2

A diagram of a plant cell is shown below. What is the function of the cell wall?

Correct A. Provides structural support

B. Regulates the movement of materials in and out of the cell

C. Involved in photosynthesis

D. Stores genetic information

Correct Answer: A

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Question 3

A patient is diagnosed with a bacterial infection. Which of the following is a characteristic of the bacterial cell wall?

A. Presence of a nucleus

Correct B. Presence of a cell wall

C. Presence of flagella

D. Presence of mitochondria

Correct Answer: B

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Question 4

A diagram of the human digestive system is shown below. What is the primary function of the pancreas?

A. Production of bile

Correct B. Production of digestive enzymes

C. Absorption of nutrients

D. Storage of waste

Correct Answer: B

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Question 5

A diagram of the human excretory system is shown below. What is the primary function of the kidneys?

Correct A. Production of urine

B. Regulation of blood pressure

C. Maintenance of electrolyte balance

D. Storage of waste

Correct Answer: A

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Question 6

In a eukaryotic cell, the process of cellular respiration involves the breakdown of glu\cose to produce ATP. Which of the following is the primary function of the electron transport chain in this process?

Correct A. To generate a proton gradient across the mitochondrial membrane

B. To produce NADH and FADH2

C. To generate ATP through chemiosmosis

D. To produce water and carbon dioxide

Correct Answer: A

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Question 7

A plant's xylem is responsible for transporting water and minerals from the roots to the leaves. Which of the following is a characteristic of xylem tissue?

A. It is composed of dead cells

B. It is responsible for transporting sugars and amino acids

Correct C. It is composed of tracheids and vessel elements

D. It is responsible for transporting water and minerals

Correct Answer: C

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Question 8

In a human body, the process of excretion involves the removal of waste products from the blood. Which of the following organs is primarily responsible for excretion?

A. Liver

Correct B. Kidneys

C. Lungs

D. Skin

Correct Answer: B

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Question 9

A tissue is a group of similar cells that perform a specific function. Which of the following is an example of a type of tissue that is found in the human body?

Correct A. Epithelial tissue

B. Connective tissue

C. Muscle tissue

D. Nervous tissue

Correct Answer: A

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Question 10

In a plant, the process of growth and development involves the production of new cells and tissues. Which of the following is a type of growth that occurs in plants?

A. Meristematic growth

B. Determinate growth

Correct C. Indeterminate growth

D. Secondary growth

Correct Answer: C

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Question 11

A study on the effects of light intensity on photosynthesis in a aquatic plant species revealed that the rate of photosynthesis increased by 25% when light intensity was doubled. However, when light intensity was quadrupled, the rate of photosynthesis increased by only 10%. Which of the following best explains this observation?

Correct A. The plant species has a high affinity for light energy, but is limited by its ability to absorb CO2.

B. The plant species has a low affinity for light energy, but is able to increase its rate of photosynthesis by increa\sing its stomatal density.

C. The plant species has a high affinity for light energy, but is limited by its ability to produce ATP.

D. The plant species has a low affinity for light energy, but is able to increase its rate of photosynthesis by increa\sing its chlorophyll content.

Correct Answer: A

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Question 12

A population of 1000 rabbits is introduced to an island with an initial population of 500 rabbits. The population of rabbits on the island grows according to the \logistic growth model, where the growth rate is 0.2 and the carrying capacity is 2000. What is the population of rabbits on the island after 5 years?

A. 1500

Correct B. 2000

C. 2500

D. 3000

Correct Answer: B

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Question 13

A DNA molecule consists of two complementary strands of nucleotides. If the sequence of one strand is ATCG, what is the sequence of the complementary strand?

Correct A. TAGC

B. TCGA

C. TGCA

D. TGAC

Correct Answer: A

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Question 14

A plant cell has a cell wall made of cellulose, a plasma membrane, and a large central vacuole. What is the primary function of the cell wall?

Correct A. To provide structural support to the cell

B. To regulate the movement of materials in and out of the cell

C. To produce ATP through photosynthesis

D. To store water and nutrients

Correct Answer: A

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Question 15

A species of bird has a beak shape that is adapted for cracking open nuts. However, the beak shape also makes it difficult for the bird to eat seeds. What is an example of a trade-off in this scenario?

A. The bird's ability to crack open nuts is reduced, but its ability to eat seeds is increased

Correct B. The bird's ability to crack open nuts is increased, but its ability to eat seeds is reduced

C. The bird's ability to crack open nuts is not affected, but its ability to eat seeds is increased

D. The bird's ability to crack open nuts is not affected, but its ability to eat seeds is reduced

Correct Answer: B

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Question 16

In a population of Drosophila melanogaster, the frequency of the recessive allele 'a' is 0.2. If the population is in Hardy-Weinberg equilibrium, what is the frequency of the homozygous dominant genotype 'AA'?

Correct A. 0.64

B. 0.36

C. 0.48

D. 0.16

Correct Answer: A

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Question 17

A researcher is studying the effect of temperature on the rate of enzyme-catalyzed reactions. Which of the following statements best describes the relationship between temperature and enzyme activity?

A. Enzyme activity increases with increa\sing temperature.

Correct B. Enzyme activity decreases with increa\sing temperature.

C. Enzyme activity remains cons\tant with increa\sing temperature.

D. Enzyme activity increases with decrea\sing temperature.

Correct Answer: B

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Question 18

A diagram of a plant cell is shown below. What is the function of the structure labeled 'X'?

Correct A. Site of protein synthesis

B. Site of lipid synthesis

C. Site of carbohydrate synthesis

D. Site of nucleic acid synthesis

Correct Answer: A

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Question 19

A population of bacteria is growing exponentially. If the initial population size is 100 and the growth rate is 0.05 per hour, what is the population size after 5 hours?

Correct A. 1000

B. 500

C. 2000

D. 2500

Correct Answer: A

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Question 20

A diagram of a human eye is shown below. What is the function of the structure labeled 'Y'?

A. Detects light and color

Correct B. Focuses light on the retina

C. Transmits visual signals to the brain

D. Regulates the amount of light entering the eye

Correct Answer: B

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Question 21

In a study on the epidemio\logy of malaria, researchers found that the prevalence of the disease was significantly higher in areas with high levels of rainfall. Which of the following is a likely explanation for this observation?

Correct A. The presence of s\tanding water allows the mosquito vector to breed more easily.

B. The increased rainfall leads to a higher concentration of the disease-cau\sing parasite in the water.

C. The warmer temperatures associated with high rainfall allow the parasite to develop more quickly.

D. The increased humidity makes it easier for the mosquito to fly and transmit the disease.

Correct Answer: A

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Question 22

A cell is placed in a solution with a pH of 5. If the cell membrane is permeable to hydrogen ions, what will happen to the cell?

Correct A. The cell will swell and eventually burst due to the influx of hydrogen ions.

B. The cell will shrink and lose water due to the efflux of hydrogen ions.

C. The cell will remain unchanged as the hydrogen ions will not affect the cell membrane.

D. The cell will undergo a process of osmoregulation to maintain its internal pH.

Correct Answer: A

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Question 23

A population of bacteria is growing in a culture medium. If the growth rate is 0.5 per hour, and the initial population is 1000 cells, what will be the population after 3 hours?

A. 3000

B. 5000

C. 10000

Correct D. 20000

Correct Answer: D

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Question 24

A genetic disorder is caused by a mutation in a gene that codes for a protein involved in the breakdown of a particular amino acid. Which of the following is a likely consequence of this mutation?

Correct A. The individual will experience a buildup of the amino acid in their body.

B. The individual will have a deficiency of the amino acid.

C. The individual will have a normal level of the amino acid.

D. The individual will have an excess of the amino acid.

Correct Answer: A

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Question 25

A plant is placed in a greenhouse with a temperature of 25°C and a relative humidity of 60%. If the plant requires a temperature of 20°C and a relative humidity of 80% to grow optimally, what will happen to the plant?

A. The plant will grow optimally.

B. The plant will grow slowly.

Correct C. The plant will not grow at all.

D. The plant will die.

Correct Answer: C

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