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POST UTME AAUA 2020 Biology | Objective

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Question 1

In a population of 1000 individuals, the frequency of the recessive allele 'a' is 0.2. Assuming Hardy-Weinberg equilibrium, what is the frequency of the homozygous dominant genotype?

Correct A. 0.16

B. 0.24

C. 0.36

D. 0.48

Correct Answer: A

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Question 2

A 5-year-old child is diagnosed with a rare genetic disorder. The child's parents are both carriers of the recessive allele. What is the probability that their next child will be affected?

A. 0.25

Correct B. 0.5

C. 0.75

D. 0.9

Correct Answer: B

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Question 3

In a certain e\cosystem, the primary producers are phytoplankton. What is the role of phytoplankton in the e\cosystem?

A. Decomposers

B. Primary consumers

Correct C. Producers

D. Omnivores

Correct Answer: C

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Question 4

A certain species of bird has a unique mating system. The male bird builds a nest and attracts a female bird to lay her eggs. What is the mating system of this species?

Correct A. Monogamy

B. Polygyny

C. Polyandry

D. Promiscuity

Correct Answer: A

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Question 5

A certain species of plant has a unique adaptation to survive in a dry environment. The plant has a waxy coating on its leaves that prevents water loss. What is the name of this adaptation?

A. CAM photosynthesis

B. C4 photosynthesis

Correct C. Waxy coating

D. Drought tolerance

Correct Answer: C

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Question 6

In the context of evolutionary theory, what is the primary mechanism by which natural selection acts on genetic variation?

A. Genetic drift

B. Mutation

C. Gene flow

Correct D. Differential reproduction

Correct Answer: D

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Question 7

A plant cell is placed in a solution with a high concentration of salt. What is the expected outcome in terms of water potential?

A. Water potential increases

Correct B. Water potential decreases

C. Water potential remains unchanged

D. Water potential becomes zero

Correct Answer: B

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Question 8

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

Correct A. Filtering waste from the blood

B. Regulating blood pressure

C. Maintaining electrolyte balance

D. Producing hormones

Correct Answer: A

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Question 9

A population of bacteria is growing exponentially. What is the rate of growth of the population after 3 hours, given that the initial population was 100 and the growth rate is 0.05 per hour?

A. 200

B. 250

Correct C. 300

D. 350

Correct Answer: C

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Question 10

A diagram of a plant root system is shown below. What is the primary function of the structure labeled 'B'?

Correct A. Absorbing water and nutrients

B. Supporting the plant's structure

C. Producing hormones

D. Regulating transpiration

Correct Answer: A

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Question 11

In a photosynthetic pathway, what is the primary function of the enzyme RuBisCO?

Correct A. Fixation of CO2

B. Reduction of NADP+

C. Regeneration of RuBP

D. Oxidation of NADPH

Correct Answer: A

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Question 12

A patient with a history of recurring kidney stones is diagnosed with a genetic disorder affecting the reabsorption of calcium in the kidneys. Which of the following is the most likely disorder?

A. Cystinuria

Correct B. X-linked hypophosphatemia

C. Familial hypocalciuric hypercalcemia

D. Primary hyperparathyroidism

Correct Answer: B

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Question 13

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

Correct A. To focus light on the retina

B. To re\fract light entering the eye

C. To detect changes in light intensity

D. To regulate the amount of light entering the eye

Correct Answer: A

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Question 14

A patient is diagnosed with a bacterial infection that has developed resis\tance to multiple antibiotics. Which of the following is the most likely mechanism of resis\tance?

A. Efflux pumps

B. Enzymatic inactivation of antibiotics

Correct C. Target modification

D. Biofilm formation

Correct Answer: C

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Question 15

A diagram of the human circulatory system is shown below. What is the function of the structure labeled 'B'?

A. To pump blood throughout the body

Correct B. To carry oxygenated blood from the lungs to the heart

C. To carry deoxygenated blood from the heart to the lungs

D. To regulate blood pressure

Correct Answer: B

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Question 16

In the context of cellular respiration, what is the primary function of the electron transport chain?

A. To produce NADH and FADH2

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

C. To produce ATP through substrate-level phosphorylation

D. To reduce oxygen to water

Correct Answer: B

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Question 17

A plant cell is placed in a solution with a high concentration of sucrose. What will happen to the cell?

A. The cell will shrink due to water loss

Correct B. The cell will swell due to water uptake

C. The cell will remain unchanged

D. The cell will burst due to osmotic pressure

Correct Answer: B

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Question 18

A population of bacteria is growing exponentially. If the initial population size is 100 and the growth rate is 20% per hour, what will be the population size after 3 hours?

A. 1000

B. 2000

Correct C. 4000

D. 8000

Correct Answer: C

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Question 19

A solution contains 2M glu\cose and 1M fructose. What is the total concentration of sugars in the solution?

A. 2M

Correct B. 3M

C. 4M

D. 5M

Correct Answer: B

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Question 20

A plant is placed in a greenhouse with a temperature of 25°C and a relative humidity of 60%. What is the saturation vapor pressure of the air?

A. 0.02 kPa

Correct B. 0.03 kPa

C. 0.04 kPa

D. 0.05 kPa

Correct Answer: B

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Question 21

In a population of Escherichia coli, the average generation time is 30 minutes. If the population size is 10^6 cells, and the growth rate is 0.5 h^-1, what is the rate of increase of the population per hour?

Correct A. \( 10^6 \times e^{0.5 \times 1} \)

B. \( 10^6 \times \( 1 + 0.5 \ \) )

C. \( 10^6 \times \( 1 - 0.5 \ \) )

D. \( 10^6 \times e^{-0.5 \times 1} \)

Correct Answer: A

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Question 22

A 2.5 L flask contains 1.5 L of a solution with a pH of 4.5. If 0.5 L of 0.1 M HCl is added to the solution, what is the new pH?

Correct A. 3.5

B. 4.5

C. 5.5

D. 6.5

Correct Answer: A

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Question 23

A cell has a volume of 10^-12 L and contains 2.5 x 10^6 molecules of a protein. If the protein has a molecular weight of 50,000 g/mol, what is the concentration of the protein in the cell?

Correct A. \( 2.5 \times 10^6 \times \frac{50,000}{10^{-12}} \) M

B. \( 2.5 \times 10^6 \times \frac{50,000}{10^{-12}} \) g/L

C. \( 2.5 \times 10^6 \times \frac{50,000}{10^{-12}} \) g/mol

D. \( 2.5 \times 10^6 \times \frac{50,000}{10^{-12}} \) M/L

Correct Answer: A

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Question 24

A 1.0 L solution contains 0.5 M glu\cose. If 0.5 L of 0.1 M glu\cose is added to the solution, what is the new concentration of glu\cose?

Correct A. \( 0.5 + 0.1 \) M

B. \( 0.5 - 0.1 \) M

C. \( 0.5 \times 0.1 \) M

D. ( 0.5 div 0.1 ) M

Correct Answer: A

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Question 25

A 2.0 L solution contains 0.2 M NaCl. If 0.5 L of 0.1 M NaCl is added to the solution, what is the new concentration of NaCl?

Correct A. \( 0.2 + 0.1 \) M

B. \( 0.2 - 0.1 \) M

C. \( 0.2 \times 0.1 \) M

D. ( 0.2 div 0.1 ) M

Correct Answer: A

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