ALLCBTs

GAOKAO 2025 Biology Past Questions for Exams

Published on Jul 4, 2025 • Education

Welcome back to AllCBTs!
Today, we’ll explore some General Biology past questions from GA (General Aptitude), focusing on cell structure, genetics, and molecular biology. This guide is ideal for students preparing for major exams such as JUPEB, WAEC, NECO, GCE, or even JAMB.

Let’s dive right into it!

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You can watch the full class in the video below:

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https://www.youtube.com/watch?v=fd9yroTDiEA&t=6s

Question 1: Organelle Responsible for Energy Production

Which organelle is responsible for energy production in animal cells?

Options:

• A. Ribosome
• B. Mitochondrion
• C. Lysosome
• D. Golgi body

Correct Answer: B. Mitochondrion

Explanation:
The mitochondrion is often referred to as the "powerhouse of the cell" because it generates ATP, the cell’s energy currency.

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Question 2: Phase of DNA Replication

DNA replication occurs in which phase of the cell cycle?

Options:

• A. G1 Phase
• B. S Phase
• C. G2 Phase
• D. M Phase

Correct Answer: B. S Phase

Explanation:
During the Synthesis (S) Phase, DNA is replicated in preparation for cell division.

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Question 3: Organelle That Synthesizes Proteins

Which structure synthesizes proteins?

Options:

• A. Ribosome
• B. Nucleus
• C. Lysosome
• D. Vacuole

Correct Answer: A. Ribosome

Explanation:
Ribosomes are the sites of protein synthesis in cells. They translate genetic information into proteins.

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Question 4: Difference Between Prokaryotic and Eukaryotic Cells

Main difference between prokaryotic and eukaryotic cells?

Options:

• A. Shape
• B. Size
• C. Presence of nucleus
• D. DNA content

Correct Answer: C. Presence of nucleus

Explanation:
Prokaryotic cells lack a true nucleus, while eukaryotic cells have a membrane-bound nucleus.

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Question 5: ATP Production Site

ATP is produced during which cellular process?

Options:

• A. Photosynthesis
• B. Glycolysis
• C. Krebs Cycle
• D. Electron Transport Chain

Correct Answer: D. Electron Transport Chain

Explanation:
ATP is primarily produced during the electron transport chain, the final stage of aerobic respiration.

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Question 6: Probability of Recessive Disorder Inheritance

What is the probability that a child inherits a recessive disorder if both parents are carriers?

Options:

• A. 0%
• B. 25%
• C. 50%
• D. 100%

Correct Answer: B. 25%

Explanation:
If both parents are heterozygous (carriers), the Mendelian Punnett square reveals a 25% chance of the offspring inheriting the recessive trait.

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Question 7: RNA Base Identification

Which base is NOT found in RNA?

Options:

• A. Adenine
• B. Thymine
• C. Uracil
• D. Cytosine

Correct Answer: B. Thymine

Explanation:
Thymine is found in DNA. In RNA, it's replaced by Uracil (U).

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Question 8: Phenotypic Ratio of Dihybrid Cross

What is the phenotypic ratio in a typical dihybrid cross (AaBb x AaBb)?

Options:

• A. 1:1
• B. 3:1
• C. 9:3:3:1
• D. 1:2:1

Correct Answer: C. 9:3:3:1

Explanation:
A dihybrid cross between heterozygous parents gives a phenotypic ratio of 9:3:3:1 for two traits.

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Question 9: Determinant of Child’s Sex

The sex of a child is determined by:

Options:

• A. Egg cell
• B. Sperm cell
• C. Both cells
• D. Hormones

Correct Answer: B. Sperm cell

Explanation:
Sperm cells can carry either an X or a Y chromosome, determining if the child is male (XY) or female (XX).

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Question 10: Genetic Message Carriers

Which molecule carries genetic instructions from DNA to the ribosome?

Correct Answer: mRNA (messenger RNA)

Explanation:
mRNA transcribes information from DNA and carries it to the ribosome for translation into proteins.

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Watch more educational videos and past questions: https://youtube.com/@allcbts

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Final Thoughts

These 10 questions cover essential topics like:

• Cell biology
• Genetics
• Molecular biology
• Inheritance

Mastering them gives you a major edge in your JUPEB, WAEC, NECO, and JAMB Biology exams.

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