BRAINCAKEGenes, inheritance and selection
Revision notes for Genes, inheritance and selection in OCR Combined Science A (J250). Every lesson in BrainCake comes with R.E.C.I.P.E. recall steps, a quick check and spaced reviews.
- Key genetics termsA gamete is a sex cell: a sperm cell in males and an egg cell in females.
- The genomeThe genome of an organism is all of its genetic material.
- Genome, environment and phenotypeThe phenotype of an organism is its observable characteristics.
- Mutations and variantsA mutation is a random change in the base sequence of DNA.
- Haploid and diploidA cell that contains a single set of chromosomes is called haploid.
- Meiosis and gametesMeiosis is the type of cell division that makes gametes.
- Single gene inheritanceSome features are controlled by just one gene.
- Predicting single gene crossesA Punnett square is a grid that shows every possible way the alleles from two parents can combine.
- Sex determination in humansHuman body cells have 23 pairs of chromosomes.
- Features controlled by many genesThe single gene crosses you have met are useful, but they are the exception.
- Genetic variation within a populationA population is a group of organisms of the same species living in the same area.
- Classification and developments in biologyClassification means sorting living things into groups.
- Natural selection and mutationA mutation is a random change in the base sequence of the DNA of a gene.
- Evolution and the formation of new speciesEvolution is a change in the inherited characteristics of a population over time, through the process of natural selection.
- Evidence for evolutionFossils are the remains or traces of organisms from many years ago, found preserved in rocks.