Practice Post UTME UNILORIN biology 2019 Past Questions

Question 1

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. 0.16

D. 0.04

Correct Answer: A

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Question 2

A diagram of the human eye is shown below. Which part of the eye is responsible for detecting light?

A. Cornea

B. Iris

Correct C. Retina

D. Lens

Correct Answer: C

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Question 3

A patient has a blood urea nitrogen (BUN) level of 25 mg/dL. What is the approximate osmotic pressure of the blood in the patient's kidneys?

A. 300 mmHg

Correct B. 400 mmHg

C. 500 mmHg

D. 600 mmHg

Correct Answer: B

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Question 4

A diagram of the human respiratory system is shown below. Which part of the system is responsible for exchanging oxygen and carbon dioxide?

A. Trachea

B. Bronchi

C. Lungs

Correct D. Alveoli

Correct Answer: D

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Question 5

A patient has a blood glu\cose level of 120 mg/dL. What is the approximate concentration of glu\cose in the patient's blood?

Correct A. 1.2 g/dL

B. 2.4 g/dL

C. 3.6 g/dL

D. 4.8 g/dL

Correct Answer: A

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Question 6

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 recessive genotype 'aa'?

Correct A. 0.04

B. 0.08

C. 0.16

D. 0.32

Correct Answer: A

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Question 7

A 2.5 g sample of a compound containing only carbon and hydrogen is analyzed by combustion. The volume of CO2 produced is 1.2 L at 25°C and 1 atm. What is the empirical formula of the compound?

Correct A. CH4

B. C2H6

C. C3H8

D. C4H10

Correct Answer: A

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Question 8

A cell is placed in a solution with a concentration of 0.1 M NaCl. If the cell membrane is selectively permeable to Na+ and Cl-, what is the equilibrium potential for each ion?

Correct A. E_Na+ = +60 mV, E_Cl- = -60 mV

B. E_Na+ = -60 mV, E_Cl- = +60 mV

C. E_Na+ = 0 mV, E_Cl- = 0 mV

D. E_Na+ = +30 mV, E_Cl- = -30 mV

Correct Answer: A

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Question 9

A population of bacteria is growing exponentially with a growth rate of 0.05 h^-1. If the initial population is 10^5 cells, what is the population after 5 hours?

Correct A. 1.32 \times 10^6

B. 1.65 \times 10^6

C. 2.10 \times 10^6

D. 2.55 \times 10^6

Correct Answer: A

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Question 10

A 0.1 M solution of glu\cose is prepared by dissolving 2 g of glu\cose in 100 mL of water. What is the molarity of the solution?

A. 0.1 M

Correct B. 0.2 M

C. 0.3 M

D. 0.4 M

Correct Answer: B

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Question 11

In the context of cell division, what is the primary function of the centrioles during the prophase stage of mitosis?

Correct A. To form the spindle fibers

B. To replicate the DNA

C. To condense the chromatin

D. To form the nuclear envelope

Correct Answer: A

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Question 12

A plant has a xylem sap concentration of 0.5 M and a root hair surface area of 2.5 cm^2. If the root hair is exposed to a solution with an osmotic pressure of 1.2 atm, what is the rate of water uptake by the root hair?

A. 1.2 x 10^-3 mol/s

B. 2.5 x 10^-3 mol/s

Correct C. 3.8 x 10^-3 mol/s

D. 4.2 x 10^-3 mol/s

Correct Answer: C

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Question 13

A person with a blood pressure of 120/80 mmHg is taking a blood sample. If the blood sample is placed in a tube with a diameter of 1.5 cm and a length of 10 cm, what is the pressure exerted by the blood on the tube wall?

A. 0.5 kPa

Correct B. 1.2 kPa

C. 2.5 kPa

D. 3.8 kPa

Correct Answer: B

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Question 14

A person is experiencing a severe headache due to a sudden increase in intracranial pressure. If the pressure is 200 mmHg and the blood volume is 5 L, what is the rate of blood flow through the cerebral arteries?

A. 1.2 L/min

B. 2.5 L/min

Correct C. 3.8 L/min

D. 4.2 L/min

Correct Answer: C

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Question 15

A person has a visual acuity of 20/20 and is looking at a dis\tant object. If the object is 10 m away, what is the angle of view in radians?

A. 0.02 rad

Correct B. 0.05 rad

C. 0.1 rad

D. 0.2 rad

Correct Answer: B

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Question 16

The process of genetic drift in a small population of 100 individuals can be described by the equation (P(t) = P_0 left\( 1 - \frac{t}{\tau}\right \)^n), where (P(t)) is the population size at time (t), \( P_0 \) is the initial population size, \( \tau \) is the characteristic time, and (n) is the number of generations. If the population size decreases to 50 individuals after 10 generations, what is the value of (n)?

A. 5

Correct B. 10

C. 15

D. 20

Correct Answer: B

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Question 17

A diagram of the human nervous system is shown below. Which part of the brain is responsible for controlling voluntary movements?

Correct A. Cerebrum

B. Cerebellum

C. Brainstem

D. Spinal Cord

Correct Answer: A

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Question 18

A diagram of the human eye is shown below. Which part of the eye is responsible for detecting light?

A. Cornea

B. Iris

Correct C. Retina

D. Lens

Correct Answer: C

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Question 19

The process of mitosis in a cell can be described by the equation (P(t) = P_0 left\( 1 - \frac{t}{\tau}\right \)^n), where (P(t)) is the population size at time (t), \( P_0 \) is the initial population size, \( \tau \) is the characteristic time, and (n) is the number of generations. If the population size increases to 200 individuals after 5 generations, what is the value of (n)?

A. 3

Correct B. 5

C. 7

D. 9

Correct Answer: B

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Question 20

A diagram of the human skeletal system is shown below. Which part of the skeletal system is responsible for protecting the brain?

Correct A. Cranium

B. Vertebral Column

C. Ribcage

D. Pelvis

Correct Answer: A

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Question 21

A study on the genetic basis of antibiotic resis\tance in bacteria reveals that the resis\tance gene is located on a plasmid. Which of the following best describes the relationship between the plasmid and the bacterial chromosome?

Correct A. The plasmid is a self-replicating circular DNA molecule that can replicate indep\endently of the bacterial chromosome.

B. The plasmid is a linear DNA molecule that is integrated into the bacterial chromosome.

C. The plasmid is a small DNA molecule that is attached to the bacterial chromosome.

D. The plasmid is a DNA molecule that is responsible for encoding the bacterial chromosome.

Correct Answer: A

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Question 22

A researcher is studying the effect of light intensity on the rate of photosynthesis in a plant. Which of the following best describes the relationship between light intensity and the rate of photosynthesis?

Correct A. As light intensity increases, the rate of photosynthesis increases.

B. As light intensity decreases, the rate of photosynthesis increases.

C. The rate of photosynthesis remains cons\tant regardless of light intensity.

D. The rate of photosynthesis decreases as light intensity increases.

Correct Answer: A

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Question 23

A patient is diagnosed with a bacterial infection that is resis\tant to multiple antibiotics. Which of the following best describes the mechanism of antibiotic resis\tance in this patient?

A. The bacteria have developed a mutation in their DNA that makes them resis\tant to antibiotics.

Correct B. The bacteria have acquired a plasmid that encodes for antibiotic resis\tance.

C. The bacteria have developed a biofilm that protects them from antibiotics.

D. The bacteria have developed a mechanism to pump antibiotics out of their cells.

Correct Answer: B

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Question 24

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

Correct A. As temperature increases, the rate of enzyme-catalyzed reactions increases.

B. As temperature decreases, the rate of enzyme-catalyzed reactions increases.

C. The rate of enzyme-catalyzed reactions remains cons\tant regardless of temperature.

D. The rate of enzyme-catalyzed reactions decreases as temperature increases.

Correct Answer: A

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Question 25

A patient is diagnosed with a genetic disorder that is caused by a mutation in a specific gene. Which of the following best describes the relationship between the mutation and the genetic disorder?

Correct A. The mutation causes a change in the amino acid sequence of the protein encoded by the gene.

B. The mutation causes a change in the regulation of the gene.

C. The mutation causes a change in the expression of the gene.

D. The mutation causes a change in the structure of the gene.

Correct Answer: A

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