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CAIE IGCSE Biology 16.2 Sexual Reproduction

Practise sexual reproduction questions by defining gamete nuclear fusion, applying haploid/diploid chromosome numbers and evaluating variation.

Syllabus
2026–2028
Course
Biology 0610

Exam points

  • describe sexual reproduction as gamete nuclear fusion forming a zygote
  • apply haploid gametes and diploid zygotes to human chromosome-number evidence
  • evaluate genetic variation for adaptation, disease risk and crop breeding

Covered syllabus points

16.2.1—Sexual reproduction as a process16.2.2—Fertilisation as the fusion16.2.3—Nuclei of gametes are haploid and that16.2.4—Advantages and disadvantages of sexual

16.2 Sexual reproduction question 1

[Maximum number: 4]

Question (a)

(a)

A scientist investigated sexual reproduction in flowering plants.

Fig. 2.1 shows the procedure for crossing two plants of the same species.

Fig. 2.1 shows the procedure for crossing two plants of the same species.

The scientist collected the seeds and germinated them. The leaves and flowers of the offspring plants showed phenotypic variation as they were not all identical to the parent plants.

The scientist then investigated the chromosomes of all the offspring plants and found that they had exactly the same number of chromosomes as the parent plants.

[ 4 ]

Question (i)

(i)

Explain how sexual reproduction results in the variation that the scientist discovered in the offspring plants.

[ 2 ]

Question (ii)

(ii)

The chromosome number of the offspring plants is the same as the chromosome number of the parent plants in this investigation.

Explain how the chromosome number is maintained from one generation to the next.

[ 2 ]

16.2 Sexual reproduction question 2

[Maximum number: 3]

Question (a)

(a)

Meiosis and mitosis are important processes in the life cycles of organisms.
Fig. 3.1 shows the life cycles of two different organisms.
Organism 1 has a simple life cycle.
Organism 2 has a complex life cycle. It has a stage A that produces spores and a stage B that produces gametes.

In the diagrams, the haploid number of chromosomes is represented by n. The diploid number of chromosomes is represented by 2 n.
organism 1

Figure for Question (a) — CAIE IGCSE Biology

organism 2

Fig. 3.1

Fig. 3.1

[ 1 ]

Question (i)

(i)

State the name of process W shown in Fig. 3.1.

[ 1 ]

Question (b)

(b)

State the events in the life cycle diagram for organism 1 in Fig. 3.1 that would not be present in a life cycle diagram for asexual reproduction.

[ 2 ]

16.2 Sexual reproduction question 3

[Maximum number: 2]

Fig. 4.1 is a diagram of the human female reproductive system.

Fig. 4.1

Fig. 4.1

Fertilisation is the fusion of the nuclei of a male gamete and a female gamete resulting in a zygote.

State the number of chromosomes present in a human:
female gamete
zygote

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