Biology · AQA Paper 2
Variation and Evolution
Why individuals in a population differ and how that variation drives change: the causes of variation and the part played by mutations, evolution by natural selection and the formation of new species, selective breeding of plants and animals, genetic engineering, and (for separate Biology only) cloning. Matches AQA topics 4.6.2.1 to 4.6.2.5. Every lesson is for both Combined Science and separate Biology except the two lessons on cloning, which are for separate Biology only; the Higher tier steps of genetic engineering are marked.
Lessons
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1
Variation
No two individuals are exactly the same, not even identical twins. This lesson is for both Combined Science and separate Biology. It covers the causes of…
8 terms -
2
Evolution and Natural Selection
How did the huge variety of life on Earth come about? This lesson is for both Combined Science and separate Biology. It explains evolution as a change in the…
8 terms -
3
Selective Breeding
Humans have been shaping the plants and animals around them for thousands of years. This lesson is for both Combined Science and separate Biology. It explains…
8 terms -
4
Genetic Engineering
Genetic engineering moves a gene from one organism into another to give it a new characteristic. This lesson is for both Combined Science and separate Biology…
8 terms -
5
Cloning Plants
This lesson is for separate Biology only: Combined Science students do not need it. It covers tissue culture and cuttings as ways of cloning plants, and the…
8 terms -
6
Cloning Animals
This lesson is for separate Biology only: Combined Science students do not need it. It covers embryo transplants and adult cell cloning, Dolly the sheep, and…
8 terms -
Knowledge organiser
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Key terms in this chapter
All 48, gathered from every lesson.
- Variation
- The differences in the characteristics of individuals in a population.
- Population
- All the organisms of one species living in the same area.
- Genetic variation
- Variation caused by differences in the genes individuals inherit.
- Environmental variation
- Variation caused by the conditions in which an individual has developed.
- Mutation
- A change in the base sequence of DNA.
- Variant
- A different version of a gene, which arose from a mutation.
- Phenotype
- The characteristics of an organism that result from its genes and the environment.
- Modal class
- The group with the highest frequency.
- Evolution
- A change in the inherited characteristics of a population over time, through natural selection.
- Natural selection
- The process in which individuals best suited to their environment survive and breed, passing on their alleles.
- Selection pressure
- A factor in the environment, such as predators or disease, that affects which individuals survive.
- Adaptation
- A feature that helps an organism survive in its environment.
- Species
- A group of organisms that can interbreed to produce fertile offspring.
- Population
- All the organisms of one species living in the same area.
- Camouflage
- Colouring that makes an organism hard for predators to see.
- Allele
- A different form of a gene that can be passed on to offspring.
- Selective breeding
- The process by which humans breed plants and animals for particular genetic characteristics.
- Artificial selection
- Another name for selective breeding, in which humans choose which individuals reproduce.
- Domesticated
- Bred by humans to be kept as farm animals or pets.
- Inbreeding
- Breeding closely related individuals, which reduces variation and increases the chance of inherited defects.
- Desired characteristic
- The feature, such as high milk yield, that the breeder wants to produce.
- Yield
- The amount of a product, such as milk or grain, obtained from an animal or plant.
- Disease resistance
- The ability to avoid becoming ill when exposed to a pathogen.
- Allele
- A different form of a gene.
- Genetic engineering
- Modifying the genome of an organism by introducing a gene from another organism to give a desired characteristic.
- Genetically modified (GM)
- Having had its genes changed by genetic engineering.
- GM crop
- A crop plant that has had a gene added, for example for insect or herbicide resistance.
- Herbicide
- A chemical that kills weeds.
- Vector
- A carrier, such as a plasmid or virus, that transfers a gene into a cell (Higher tier).
- Plasmid
- A small ring of DNA in bacteria that can be used as a vector (Higher tier).
- Insulin
- A hormone made in the pancreas that controls blood glucose.
- Yield
- The amount of a crop produced from an area of land.
- Cloning
- Producing genetically identical copies of an organism.
- Clone
- An organism that is genetically identical to its parent.
- Tissue culture
- Growing identical new plants from small groups of cells on agar jelly.
- Cutting
- A piece of stem cut from a plant and planted to grow into a new plant identical to the parent.
- Agar jelly
- A sterile jelly containing nutrients, used to grow cells and microorganisms.
- Plantlet
- A very small young plant grown in tissue culture.
- Rooting powder
- A powder containing plant hormones that helps cuttings to grow roots.
- Aseptic
- Free from microorganisms.
- Cloning
- Producing genetically identical copies of an organism.
- Embryo transplant
- Splitting an early embryo into identical embryos and transplanting them into host mothers.
- Adult cell cloning
- Producing a clone by putting the nucleus of an adult body cell into an egg cell with its nucleus removed.
- Host mother
- A female animal into whose womb an embryo is placed to develop.
- Unfertilised egg
- An egg cell that has not been joined by a sperm cell.
- Specialised
- Adapted to do a particular job.
- Donor
- The adult animal that provides the nucleus for cloning.
- Embryo
- A ball of cells in the early stage of development.