Asexual and sexual reproduction Cambridge IGCSE Co-ordinated Sciences (Double Award) revision
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In plain words
There are two ways to make new living things. One parent can simply copy itself: quick, but every copy is the same. Or two parents can each contribute half the instructions, which is slower but gives offspring that are all a little different.
Three things to know
- Asexual reproduction needs one parent and produces offspring that are genetically identical to it (clones). Examples: bacteria dividing, strawberry runners, potato tubers.
- Sexual reproduction involves the fusion of the nuclei of two sex cells (gametes) to form a zygote. The offspring are genetically different from each other and from their parents.
- Gametes are haploid (half the usual number of chromosomes). When they fuse, the zygote is diploid (the full number). Asexual reproduction is fast and needs no mate, but gives no variation; sexual reproduction gives variation, which helps a species survive change.
Tips and tricks
- Fertilisation is the fusion of the nuclei of the gametes. Use those words.
- Variation is the big advantage of sexual reproduction: if conditions change or a disease arrives, some offspring may survive.
It lands in your notebook with its questions as flashcards.
Asexual and sexual reproduction: 5 questions and answers
These are the quiz’s questions. Do the quiz first, then come back here for the ones that got you.
How many parents are needed for asexual reproduction?
A single parent copies itself.
What are the offspring of asexual reproduction like?
They are clones.
What is formed when two gametes fuse?
The zygote divides to form an embryo.
What is an advantage of sexual reproduction?
Variation helps a species survive changes.
A human gamete has 23 chromosomes. How many does a zygote have?
Two haploid gametes make one diploid zygote.
Quiz
5 questions
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Worksheet
3 questions, 6 marks. Write your answers on paper, then check them.
Asexual and sexual reproduction
Cambridge IGCSE Co-ordinated Sciences (Double Award) 0654 · 6 marks · papermunch.org
Name ______________________________ Date ______________
State two differences between asexual and sexual reproduction.[2]
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Asexual reproduction involves one parent and produces genetically identical offspring; sexual reproduction involves the fusion of two gametes (usually from two parents) and produces genetically different offspring.
State what is meant by fertilisation.[2]
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The fusion of the nuclei of two gametes (to form a zygote).
Give one advantage and one disadvantage of asexual reproduction for a plant.[2]
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Advantage: it is quick, or only one parent is needed, or a well-adapted plant makes identical copies. Disadvantage: no variation, so a disease or a change in conditions could kill them all.
Answers: Asexual and sexual reproduction
- 1. Asexual reproduction involves one parent and produces genetically identical offspring; sexual reproduction involves the fusion of two gametes (usually from two parents) and produces genetically different offspring.
- 2. The fusion of the nuclei of two gametes (to form a zygote).
- 3. Advantage: it is quick, or only one parent is needed, or a well-adapted plant makes identical copies. Disadvantage: no variation, so a disease or a change in conditions could kill them all.