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IB DP Biology Mock Exam HL Paper 1A Set 4 - 2025 Syllabus

IB DP Biology Mock Exam HL Paper 1A Set 4

Prepare for the IB DP Biology Exam with our comprehensive IB DP Biology Exam Mock Exam HL Paper 1A Set 4. 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 

Pink flowers in the four o’clock plant (Mirabilis jalapa) result from incomplete dominance between the red-flower allele and the white-flower allele. A pink-flowering plant is crossed with a white-flowering plant.

What possible flower phenotypes could appear in the offspring?

A.  White flowers only
B.  Pink and white flowers
C.  Red and white flowers
D.  Pink flowers only
▶️ Answer/Explanation
Pink plants have genotype Rw, while white plants have genotype ww. A cross of Rw × ww produces 50% Rw (pink) and 50% ww (white). Thus, offspring can be pink or white.
✅ Answer: (B)

Question 

Which statement best describes analogous structures?

A.  They are formed through divergent evolution.
B.  They share a common ancestor.
C.  They originated from different evolutionary pathways.
D.  They have identical structures but different functions.
▶️ Answer/Explanation
Analogous structures arise due to similar environmental pressures rather than shared ancestry. They perform similar functions but evolved independently from different origins.
✅ Answer: (C)

Question 

Both mutations and sexual reproduction help create variation, which natural selection acts upon. Which statements describe how this variation is produced?

I.  Mutations generate new alleles.
II.  Mutations generate new combinations of alleles.
III.  Sexual reproduction generates new alleles.
A.  I only
B.  III only
C.  II and III only
D.  I and III only
▶️ Answer/Explanation
Mutations are the only source of entirely new alleles in a population. Sexual reproduction reshuffles existing alleles but does not create new ones. Therefore, only statement I correctly describes the generation of variation.
✅ Answer: (A)
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