16.2

Sexual reproduction

Cambridge IGCSE Biology (0610)  · Unit 16: Reproduction  · 10 flashcards

Sexual reproduction is topic 16.2 in the Cambridge IGCSE Biology (0610) syllabus , positioned in Unit 16 — Reproduction , alongside Asexual reproduction, Sexual reproduction in plants and Sexual reproduction in humans.  In one line: Sexual reproduction is a process involving the fusion of the nuclei of two gametes (sex cells) to form a zygote. This results in offspring that are genetically different from each other.

This topic is examined in Paper 1 (multiple-choice) and Papers 3/4 (theory), plus Paper 5 or Paper 6 (practical / alternative to practical). Past papers from 2022 to 2025 record 1 explicit question on this topic — though the concept underpins many adjacent topics, so it is tested far more often than that figure suggests.

The deck below contains 10 flashcards — 2 definitions, 2 key concepts, 1 process card and 5 application cards — covering the precise wording mark schemes reward.  Use the 2 definition cards to lock down command-word answers (define, state), then move on to the concept and application cards to handle explain, describe and compare questions.

Key definition

Sexual reproduction

Sexual reproduction is a process involving the fusion of the nuclei of two gametes (sex cells) to form a zygote. This results in offspring that are genetically different from each other.

Example: human reproduction, where sperm and egg fuse.

What the Cambridge 0610 syllabus says

Official 2026-2028 spec

These are the exact learning objectives Cambridge sets for this topic. Match the command word (Describe, Explain, State, etc.) in your answer to score full marks.

  1. Describe Describe sexual reproduction as a process involving the fusion of the nuclei of two gametes to form a zygote and the production of offspring that are genetically different from each other
  2. Describe Describe fertilisation as the fusion of the nuclei of gametes
  3. State State that nuclei of gametes are haploid and that the nucleus of a zygote is diploid Supplement
  4. Discuss Discuss the advantages and disadvantages of sexual reproduction: (a) to a population of a species in the wild (b) to crop production Supplement
Definition Flip

Define sexual reproduction.

Answer Flip

Sexual reproduction is a process involving the fusion of the nuclei of two gametes (sex cells) to form a zygote. This results in offspring that are genetically different from each other.

Example: human reproduction, where sperm and egg fuse.
Definition Flip

Describe fertilisation.

Answer Flip

Fertilisation is the fusion of the nuclei of two gametes, such as the sperm and egg in animals or pollen and ovule in plants, to form a zygote. This restores the diploid number of chromosomes.

Example: Pollination in flowering plants.
Key Concept Flip

What is the ploidy of gametes and zygotes?

Answer Flip

Gametes (e.g., sperm and egg) are haploid, meaning they have half the number of chromosomes of a normal cell. A zygote, formed from the fusion of two gametes, is diploid, containing the full set of chromosomes.

Example: Human gametes have 23 chromosomes, zygote has 46.
Key Concept Flip

What is the main genetic consequence of sexual reproduction?

Answer Flip

Sexual reproduction produces offspring that are genetically different from each other and from their parents due to the mixing of genes from two parents. This leads to variation within a population.

Example: Siblings look different due to unique gene combinations.
Key Concept Flip

What is a key advantage of sexual reproduction for a species in the wild?

Answer Flip

A significant advantage is increased genetic variation within the population. This variation allows a species to adapt more effectively to changing environmental conditions, increasing their chances of survival.

Example: Resistance to a new disease.
Key Concept Flip

What is a disadvantage of sexual reproduction for a species in the wild?

Answer Flip

A disadvantage is the need to find a mate, which can be difficult and time-consuming, especially when population densities are low. Also, only half of an individual's genes are passed on to each offspring.

Example: Peacock mating displays can attract predators.
Key Concept Flip

What is an advantage of sexual reproduction in crop production?

Answer Flip

Sexual reproduction allows for the creation of new varieties of crops with desirable traits, such as disease resistance or higher yield, through selective breeding. This enhances agricultural productivity.

Example: Creating new strains of wheat.
Key Concept Flip

What is a disadvantage of sexual reproduction in crop production?

Answer Flip

Sexual reproduction can result in offspring with unpredictable traits, making it challenging to maintain consistent crop quality and characteristics. It is also a slower process compared to asexual propagation.

Example: Offspring of a hybrid plant may not be as productive.
Key Concept Flip

Describe the formation of a zygote.

Answer Flip

A zygote is formed when a sperm cell and an egg cell fuse together during fertilisation. The sperm's nucleus merges with the egg's nucleus, combining their genetic material to create a single diploid cell.

Example: The zygote implants in the uterus wall during pregnancy.
Key Concept Flip

How does sexual reproduction contribute to evolution?

Answer Flip

Sexual reproduction generates genetic variation through processes like crossing over during meiosis and the random assortment of chromosomes. This variation provides the raw material for natural selection, driving evolutionary change.

Example: Insecticide resistance evolving in insects.

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16.1 Asexual reproduction 16.3 Sexual reproduction in plants

Key Questions: Sexual reproduction

Define sexual reproduction.

Sexual reproduction is a process involving the fusion of the nuclei of two gametes (sex cells) to form a zygote. This results in offspring that are genetically different from each other.

Example: human reproduction, where sperm and egg fuse.
Describe fertilisation.

Fertilisation is the fusion of the nuclei of two gametes, such as the sperm and egg in animals or pollen and ovule in plants, to form a zygote. This restores the diploid number of chromosomes.

Example: Pollination in flowering plants.

Tips to avoid common mistakes in Sexual reproduction

More topics in Unit 16 — Reproduction

Sexual reproduction sits alongside these Biology decks in the same syllabus unit. Each uses the same spaced-repetition system, so progress in one informs the next.

16.1 Asexual reproduction

10 flashcards
16.3 Sexual reproduction in plants

12 flashcards
16.4 Sexual reproduction in humans

12 flashcards
16.5 Sex hormones in humans

10 flashcards
16.6 Sexually transmitted infections

9 flashcards

Cambridge syllabus keywords to use in your answers

These are the official Cambridge 0610 terms tagged to this section. Mark schemes credit responses that use the exact term — weave them into your answers verbatim rather than paraphrasing.

sexual reproduction gamete fertilisation zygote variation meiosis haploid diploid

Key terms covered in this Sexual reproduction deck

Every term below is defined in the flashcards above. Use the list as a quick recall test before your exam — if you can't define one of these in your own words, flip back to that card.

Sexual reproduction
Describe fertilisation

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How to study this Sexual reproduction deck

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