AQA GCSE Biology - 6.1 Reproduction - Sexual & Asexual Reproduction

Sep 5, 2026

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Revision notes for AQA GCSE Biology on reproduction, focusing on sexual versus asexual reproduction and the role of cell division. Mitosis is explained as nuclear division producing genetically identical cells used for growth, repair, replacement, and asexual reproduction. Meiosis is then introduced as reduction division that forms genetically different gametes, enabling fertilisation and variation in offspring. The notes also connect fertilisation to restoring chromosome numbers and producing a zygote that develops into an embryo.

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6.1 Reproduction

6.1.1 Sexual & Asexual Reproduction

6.1.2 Meiosis

6.1.4 DNA & the Genome

Head to www.savemyexams. com for more awesome resources AQA GCSE Biology: Combined Science 6 .1 Reproduction Contents 6.1.1 Sexual & Asexual Reproduction 6.1.2 Meiosis 6.1.4 DNA & the Genome 6.1. 6 Genetic Inheritance 6.1.7 Inherited Disorders 6.1. 8 Sex Determination Page 1 of 25 © 2015 − 2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers Your notes Head to www.savemyexams. com for more awesome resources 6.1.1 Sexual & Asexual Reproduction Mitosis & Meiosis Mitosis is a type of nuclear division that gives rise to cells that are genetically identical It is used for growth, repair of damaged tissues, replacement of cells and asexual reproduction Meiosis is a type of nuclear division that gives rise to cells that are genetically diyerent It is used to produce gametes (sex cells) Sexual Reproduction Sexual reproduction is a process involving the fusion of the nuclei of two gametes (sex cells) to form a zygote (fertilised egg cell) and the production of oyspring that are genetically diyerent from eachother The gametes of animals are the sperm cells and egg cells The gametes of }owering plants are the pollen cells and egg cells Fertilisation is de|ned asthe fusion of gamete nuclei, and as each gamete comes from a diyerent parent, there is variation in the oyspring The formation of gametes involves meiosis Asexual Reproduction Asexual reproduction does not involve sex cells or fertilisation Only one parent is required so there is no fusion of gametes and no mixing of genetic information As a result, theoyspring are genetically identical to the parent and to each other (clones) Asexual reproduction is de|ned as a process resulting in genetically identical oyspring from one parent Only mitosis is involved in asexual reproduction Page 2 of 25 © 2015 − 2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers Your notes Head to www.savemyexams. com for more awesome resources 6.1.2 Meiosis Meiosis Cells in reproductive organs divide by meiosis to form gametes (sex cells) The number of chromosomes must be halved when the gametes are formed Otherwise, there would be double the number of chromosomes after they join at fertilisation in the zygote (fertilized egg) This halving occurs during meiosis, and so it is described as a reduction division in which the chromosome number is halved from diploid to haploid, resulting in genetically diyerent cells It starts with chromosomes doubling themselves as in mitosis and lining up in the centre of the cell After this has happened the cells divide twice so that only one copy of each chromosome passes to each gamete We describe gametes as being haploid – having half the normal number of chromosomes Because of this double division, meiosis produces four haploid cells Page 3 of 25 © 2015 − 2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers Your notes Head to www.savemyexams. com for more awesome resources Page 4 of 25 © 2015 − 2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers Your notes Head to www.savemyexams. com for more awesome resources The process of cell division by meiosis to produce haploid gamete cells Process Each chromosome is duplicated (makes identical copies of itself ) , forming X-shaped chromosomes First division: the chromosome pairs line up along the centre of the cell and are then pulled apart so that each new cell only has one copy of each chromosome Second division: the chromosomes line up along the centre of the cell and the arms of the chromosomes are pulled apart A total of four haploid daughter cells will be produced Importance Produces gametes eg. sperm cells and egg cells in animals, pollen grains and ovum cells in plants Increases genetic variation of oyspring Meiosis produces variation by forming new combinations of maternal and paternal c

FAQs

What is the difference between sexual and asexual reproduction?

Sexual reproduction involves fusion of nuclei from two gametes to form a zygote, producing genetically different offspring. Asexual reproduction does not involve sex cells or fertilisation and produces offspring genetically identical to the parent.

What role does mitosis play in reproduction?

Mitosis produces genetically identical cells and is used for growth and repair. In asexual reproduction, only mitosis is involved to generate genetically identical offspring.

How does meiosis lead to genetic variation?

Meiosis halves the chromosome number to form haploid gametes. Because of the way chromosomes are combined and assorted during meiosis, gametes receive new combinations of maternal and paternal chromosomes, so offspring differ from one another after fertilisation.

Sep 5, 2026

Upload by Noah