GCSEScienceAQACombined Science: SynergyLife & Environmental SciencesRevision NotesExplaining ChangeInheritanceSex Determination In Humans

Sex Determination In Humans (AQA GCSE Combined Science: Synergy: Life & Environmental Sciences): Revision Note

Exam code: 8465

Ruth Brindle

Written by: Ruth Brindle

Reviewed by: Lára Marie McIvor

Updated on

Human Chromosomes

  • Ordinary human body cells contain 23 pairs of chromosomes

  • 22 pairs control characteristics only, but one of the pairs carries the genes that determine sex

  • In females, the sex chromosomes are the same (XX)

  • In males, the sex chromosomes are different (XY)

 

Sex chromosomes, IGCSE & GCSE Biology revision notes

Sperm cells determine the sex of offspring

Determining sex

  • The inheritance of sex can be shown using a genetic diagram (known as a Punnett square), with the X and Y chromosomes taking the place of the alleles usually written in the boxes

 

Inheritance of sex, IGCSE & GCSE Biology revision notes

Punnett square showing the inheritance of sex

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Author
Reviewer
Ruth Brindle

Author: Ruth Brindle

Expertise: Biology Content Creator

Ruth graduated from Sheffield University with a degree in Biology and went on to teach Science in London whilst also completing an MA in innovation in Education. With 10 years of teaching experience across the 3 key science disciplines, Ruth decided to set up a tutoring business to support students in her local area. Ruth has worked with several exam boards and loves to use her experience to produce educational materials which make the mark schemes accessible to all students.

Lára Marie McIvor

Reviewer: Lára Marie McIvor

Expertise: Biology, Psychology & Sociology Subject Lead

Lára graduated from Oxford University in Biological Sciences and has now been a science tutor working in the UK for several years. Lára has a particular interest in the area of infectious disease and epidemiology, and enjoys creating original educational materials that develop confidence and facilitate learning.