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IB DP Biology Mock Exam HL Paper 1A Set 5 - 2025 Syllabus

IB DP Biology Mock Exam HL Paper 1A Set 5

Prepare for the IB DP Biology Exam with our comprehensive IB DP Biology Exam Mock Exam HL Paper 1A Set 5. Test your knowledge and understanding of key concepts with challenging questions covering all essential topics. Identify areas for improvement and boost your confidence for the real exam

IB DP Biology Mock Tests -All Sets

Question 

Which property of water helps aquatic habitats maintain stable temperatures throughout the year?

A. High specific heat capacity because covalent bonding restricts molecular motion
B. Low specific heat capacity because covalent bonding restricts molecular motion
C. Low specific heat capacity because hydrogen bonding restricts molecular motion
D. High specific heat capacity because hydrogen bonding restricts molecular motion

▶️ Answer/Explanation
Water has a high specific heat capacity due to extensive hydrogen bonding between molecules. These bonds absorb and release heat slowly, preventing rapid temperature changes in aquatic ecosystems.
✅ Answer: (D) High specific heat capacity because hydrogen bonding restricts molecular motion

Question 

Which diagram(s) below best represent the process of semi-conservative DNA replication?

A. X only
B. Y only
C. Z only
D. X and Y only
▶️ Answer/Explanation

In semi-conservative replication, each new DNA molecule contains one original strand and one newly synthesized strand.

Only diagram Y shows this pattern correctly.

✅ Correct Answer: B

Question 

The table shows the concentrations of potassium and sodium ions found inside and outside human cells.

IonsIntracellularExtracellular
Potassium1354
Sodium10145

What process best explains how these ion concentrations are maintained?

A.  Active transport using a protein pump
B.  Facilitated diffusion using a vesicle
C.  Simple diffusion using a protein channel
D.  Osmosis using an aquaporin
▶️ Answer/Explanation
Human cells maintain high intracellular K⁺ and high extracellular Na⁺ using the sodium–potassium pump, which actively transports ions against their concentration gradients using ATP.
✅ Answer: (A)
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