Pearson Edexcel · GCSE · Biology
Course version: 1BI0 · Version from Sept 2016
Describe how specialised cells are adapted to their function, including: a…
Full specification wording
Topic 1 – Key concepts in biology: 1.2 Describe how specialised cells are adapted to their function, including: a sperm cells – acrosome, haploid nucleus, mitochondria and tail b egg cells – nutrients in the cytoplasm, haploid nucleus and changes in the cell membrane after fertilisation c ciliated epithelial cells
A specialised cell has features that help it do one job well, and you must name the feature and say how it helps.
Checked against the Pearson Edexcel 1BI0 specification (opens in a new tab) on .
- Point 2 of 17
Study notes
From the checked teaching notes for this specification point.
The idea
A specialised cell has features that help it do one job well, and you must name the feature and say how it helps. A sperm cell has an acrosome containing enzymes to digest the egg's membrane, a haploid nucleus carrying one set of chromosomes, many mitochondria releasing energy for swimming, and a tail that moves it towards the egg. An egg cell has nutrients in the cytoplasm to supply the early embryo, a haploid nucleus so that fusion restores the diploid number, and its cell membrane changes after fertilisation so that no further sperm can enter. Ciliated epithelial cells line surfaces such as the airways; tiny hair-like cilia beat to move mucus, and with it trapped dust and microbes, away from the lungs. Always connect the adaptation to the function rather than describing the cell in general.
What earns the marks
- Sperm acrosome: contains enzymes that digest the egg cell membrane so the sperm can penetrate and fertilise it.
- Sperm haploid nucleus: carries a single set of chromosomes so fusion with the egg restores the diploid number.
- Sperm mitochondria: release energy for the tail to beat and move the sperm.
- Sperm tail: a flagellum-like structure that propels the sperm towards the egg.
- Egg cell: nutrients stored in the cytoplasm supply the developing embryo before implantation.
- Egg cell haploid nucleus: contains one set of chromosomes, combining with the sperm nucleus at fertilisation.
- Egg cell membrane change after fertilisation: the membrane alters so that no further sperm can enter, preventing polyspermy.
- Ciliated epithelial cells: cilia on the surface beat to move mucus and trapped particles along a surface such as the airways.
Common mistakes and how to put them right
Saying the sperm nucleus is diploid.
Put it right: It is haploid, carrying one set of chromosomes.
Describing the acrosome as providing energy.
Put it right: The acrosome contains enzymes to digest the egg membrane, while mitochondria supply energy.
Ignoring the change in the egg cell membrane after fertilisation.
Put it right: State that it prevents further sperm entering.
Describing cilia as moving the cell itself.
Put it right: Cilia beat to move mucus and trapped particles along the surface.
Exam tips
- For each cell, name the adaptation and then state the function it performs, using a linking phrase such as 'so that' or 'which allows'.
- Use the correct terms 'haploid' and 'diploid' and apply them to the right nucleus.
- When asked about ciliated epithelial cells, mention both the cilia and what they move.
Try the lesson
The start of the Topic 1 – Key concepts in biology: 1.2 Describe how specialised cells are adapted to their function, including: a sperm cells – acrosome, haploid nucleus, mitochondria and tail b egg cells – nutrients in the cytoplasm, haploid nucleus and changes in the cell membrane after fertilisation c ciliated epithelial cells lesson, made from checked teaching notes for this specification point.
Have a go first
Which part of a sperm cell provides the energy needed for it to swim towards an egg?
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