What is fertilisation?
Reveal answer
Fusion of male and female gamete nuclei → zygote.
Key words: nuclei · zygote
4(a) REPRODUCTION · RECALL
4.2 Fertilisation and the zygote
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What is a zygote?
Reveal answer
The diploid cell formed at fertilisation.
Key words: diploid
Why are gametes haploid?
Reveal answer
Two haploid → diploid zygote → chromosome number constant.
Key words: haploid
Where does fertilisation happen in humans?
Reveal answer
In the oviduct.
Key words: oviduct
What do sperm acrosome enzymes do?
Reveal answer
Digest the egg's outer layer.
Key words: digest
What happens to a zygote?
Reveal answer
Divides by mitosis → embryo.
Key words: mitosis
What is meant by the term haploid?
Reveal answer
Containing one complete set of chromosomes.
Key words: haploid
What is meant by the term diploid?
Reveal answer
Containing two complete sets of chromosomes.
Key words: diploid
What is meant by the term fertilisation?
Reveal answer
Fusion of nuclei of male and female gametes.
Key words: fertilisation
What is meant by the term zygote?
Reveal answer
Diploid cell formed at fertilisation.
Key words: zygote
From gametes to embryo: for Male gamete, give the chromosome state and the main event.
Reveal answer
Chromosome state: Haploid. Main event: Carries one paternal set.
Key words: Male gamete
From gametes to embryo: for Female gamete, give the chromosome state and the main event.
Reveal answer
Chromosome state: Haploid. Main event: Carries one maternal set.
Key words: Female gamete
From gametes to embryo: for Fertilisation, give the chromosome state and the main event.
Reveal answer
Chromosome state: Two haploid nuclei fuse. Main event: Diploid number is restored.
Key words: Fertilisation
From gametes to embryo: for Zygote, give the chromosome state and the main event.
Reveal answer
Chromosome state: Diploid. Main event: First cell of the new organism.
Key words: Zygote
From gametes to embryo: for Embryo, give the chromosome state and the main event.
Reveal answer
Chromosome state: Diploid cells. Main event: Mitosis, growth and differentiation.
Key words: Embryo
True or false, and why? “Fertilisation is when gametes meet.”
Reveal answer
False. It specifically requires fusion of their nuclei.
True or false, and why? “A zygote is already a multicellular embryo.”
Reveal answer
False. It is the single cell that divides to produce the embryo.
True or false, and why? “Gametes have no chromosome pairs because they have no chromosomes.”
Reveal answer
False. They have one chromosome from each homologous pair.