Inheritance and Selection 27/11/2018 Inheritance and Selection W Richards Worthing High School

Variation 27/11/2018 Variation is a name given to differences in a species, e.g. dogs: Variation is due to each animal having different GENETIC INFORMATION in their cells.

Where is this information stored? 27/11/2018 Genetic information is stored by genes which are arranged on chromosomes: Section of a chromosome: Genes for eye colour Genes for blood group: Genes for hair colour Different species have different numbers of chromosomes. Humans have 46 (23 pairs) in every cell.

Environmental differences 27/11/2018 Clearly, not all differences are due to just our genes… Variation due to inheritance only Variation due to environment only Variation due to a bit of both

Sexual reproduction 27/11/2018 Sexual reproduction involves two organisms of the same species. Each organism produces a GAMETE. For example, in animals the gametes are the egg and the sperm: When the sperm penetrates the egg the egg is fertilised and cells start to reproduce to form a new individual:

Sexual reproduction In plants, the gametes are the egg and pollen: 27/11/2018 In plants, the gametes are the egg and pollen: Fertilisation Any type of sexual reproduction helps a species to become more varied because the offspring inherit characteristics from both parents.

Selective breeding Friesian Jersey Hereford 27/11/2018 I raise cows. Each type of cow is good at a certain job. The Friesian cow produces large quantities of milk, the Jersey cow produces very nice milk and the Hereford cow produces lot of beef. Friesian Jersey If, for example, I want lots of milk I would only breed Friesian cows with each other – this is SELECTIVE BREEDING. Hereford

Words – clones, damp, independent, roots, identical Asexual reproduction 27/11/2018 Plants can reproduce ASEXUALLY. The offspring are genetically ________ to the parent plant and are called _________. Two examples: 1) This spider plant has grown a rooting side branch (“stolon”) which will eventually become __________. 2) A gardener has taken cuttings of this plant (which probably has good characteristics) and is growing them in a ____ atmosphere until the ____ develop. Words – clones, damp, independent, roots, identical

Cloning 27/11/2018 1) Cloning plants: 2) Cloning sheep: