Cell Biology Practice Questions
IB (International Baccalaureate) · IB Biology HL · 138 free MCQs with instant results and detailed explanations.
138
Total
37
Easy
70
Medium
31
Hard
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Sample Questions from Cell Biology
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Q1
Easy
What is the function of the plasma membrane in a cell?
A.
To provide structural support
B.
To control the movement of substances in and out of the cell
C.
To perform photosynthesis
D.
To synthesize proteins
Show Answer & Explanation
Correct Answer: B
The plasma membrane regulates what enters and exits the cell, maintaining homeostasis and allowing selective permeability.
Q2
Easy
Which of the following statements accurately describes prokaryotic cells?
A.
They have membrane-bound organelles.
B.
They lack a nucleus.
C.
They are always multicellular.
D.
They have linear DNA.
Show Answer & Explanation
Correct Answer: B
Prokaryotic cells do not have a defined nucleus; instead, their genetic material is located in a nucleoid region, distinguishing them from eukaryotic cells.
Q3
Easy
Which organelle is responsible for producing ATP in eukaryotic cells?
A.
Mitochondria
B.
Nucleus
C.
Endoplasmic Reticulum
D.
Golgi Apparatus
Show Answer & Explanation
Correct Answer: A
Mitochondria are known as the powerhouse of the cell because they are the primary site for ATP production through cellular respiration.
Q4
Medium
Which of the following processes occurs in the mitochondria and is crucial for ATP production?
A.
Glycolysis
B.
Photosynthesis
C.
Krebs Cycle
D.
Fermentation
Show Answer & Explanation
Correct Answer: C
The Krebs Cycle, also known as the Citric Acid Cycle, occurs in the mitochondria and is essential for ATP production through aerobic respiration, utilizing acetyl-CoA derived from carbohydrates, fats, and proteins.
Q5
Medium
What is the role of ribosomes in the cell?
A.
Energy production
B.
Protein synthesis
C.
DNA replication
D.
Cell division
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Correct Answer: B
Ribosomes are essential for protein synthesis as they facilitate the translation of messenger RNA (mRNA) into polypeptide chains, constructing proteins based on genetic instructions.
Q6
Medium
Which of the following statements best describes the structure of the phospholipid bilayer?
A.
Hydrophobic tails face outward, hydrophilic heads face inward.
B.
Hydrophilic heads face outward, hydrophobic tails face inward.
C.
Both heads and tails are hydrophobic.
D.
Both heads and tails are hydrophilic.
Show Answer & Explanation
Correct Answer: B
In the phospholipid bilayer, the hydrophilic (water-attracting) heads face outward towards the aqueous environment, while the hydrophobic (water-repelling) tails face inward, away from water, forming the bilayer structure essential for cell membranes.
Q7
Medium
Which organelle is responsible for modifying, sorting, and packaging proteins for secretion?
A.
Nucleus
B.
Golgi apparatus
C.
Endoplasmic reticulum
D.
Lysosome
Show Answer & Explanation
Correct Answer: B
The Golgi apparatus is responsible for modifying, sorting, and packaging proteins synthesized in the endoplasmic reticulum for secretion or delivery to different cellular destinations.
Q8
Hard
In eukaryotic cells, the process of protein synthesis occurs in multiple locations. Which of the following statements correctly describes the role of the endoplasmic reticulum (ER) in this process?
A.
The rough ER synthesizes lipids, while the smooth ER assembles proteins.
B.
The rough ER aids in the folding and modification of proteins, while the smooth ER is involved in lipid synthesis.
C.
Both the rough and smooth ER synthesize proteins, but only the smooth ER can transport them.
D.
The rough ER synthesizes RNA, while the smooth ER synthesizes carbohydrates.
Show Answer & Explanation
Correct Answer: B
The rough ER is studded with ribosomes, which are the sites of protein synthesis, while the smooth ER is involved in lipid synthesis and does not have ribosomes. Thus, option B accurately describes their functions.
Q9
Hard
An experiment is conducted to determine the effect of temperature on enzyme activity. A specific enzyme is observed at 30°C, 37°C, and 45°C. The enzyme shows maximum activity at 37°C, minimal activity at 30°C, and starts denaturing at 45°C. Which of the following statements best explains the observed results?
A.
Enzymes have a temperature range within which they are most active and can denature at extreme temperatures.
B.
Enzymes are equally active at low and high temperatures, but denature at a specific temperature.
C.
The enzyme is independent of temperature, and the results are coincidental.
D.
Enzymes are more active at lower temperatures due to increased substrate affinity.
Show Answer & Explanation
Correct Answer: A
Enzymes indeed have an optimal temperature range where they exhibit their highest activity. Outside this range, especially at high temperatures, enzymes can denature, losing their functional shape, which explains the results at 30°C and 45°C.
Q10
Hard
Which of the following statements most accurately describes the role of ribosomes in eukaryotic cells?
A.
Ribosomes synthesize ATP from glucose.
B.
Ribosomes are the site of protein synthesis.
C.
Ribosomes modify and package proteins.
D.
Ribosomes are responsible for lipid synthesis.
Show Answer & Explanation
Correct Answer: B
Ribosomes are the cellular structures where protein synthesis occurs, translating mRNA into polypeptide chains. This process is essential for cell function and growth, distinguishing ribosomes from other organelles that are involved in energy production or lipid synthesis.
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Cell Biology — IB (International Baccalaureate) IB Biology HL Practice Questions Online
This page contains 138 practice MCQs for the chapter Cell Biology in IB (International Baccalaureate) IB Biology HL. The questions are organized by difficulty — 37 easy, 70 medium, 31 hard — so you can choose the right level for your preparation.
Every question includes a detailed explanation to help you understand the concept, not just memorize answers. Take a timed quiz to simulate exam conditions, or practice at your own pace with no time limit.