LEFT CLICK OR PRESS SPACE BAR TO ADVANCE, PRESS P BUTTON TO GO BACK, PRESS ESC BUTTON TO END LEFT CLICK OR PRESS SPACE BAR TO ADVANCE, PRESS P BUTTON TO GO BACK, PRESS ESC BUTTON TO END COMPUTER PRESENTATIONS FOR KS3 SCIENCE - BIOLOGY ©2003, STEVE PARKER COMPUTER PRESENTATIONS FOR KS3 SCIENCE - BIOLOGY ©2003, STEVE PARKER

1 1 KS3 SCIENCE - BIOLOGY KS3 SCIENCE - BIOLOGY Genetic Variation Genetic Variation

VARIATION 2 2

3 3 Different species look very different, but members of the same species also vary Different species look very different, but members of the same species also vary

VARIATION 4 4 Different species look very different, but members of the same species also vary Different species look very different, but members of the same species also vary Characteristics like height, weight and the colour of eyes or hair differ from one person to another Characteristics like height, weight and the colour of eyes or hair differ from one person to another

VARIATION 5 5 Some characteristics have Continuous Variation - you can see gradual differences, e.g. in people’s height Some characteristics have Continuous Variation - you can see gradual differences, e.g. in people’s height Men’s Height (cms) Number of Men

VARIATION 6 6 But some characteristics are Discontinuous - they are one thing or another, e.g. eye colour But some characteristics are Discontinuous - they are one thing or another, e.g. eye colour

INHERITED VARIATION 7 7

8 8 Inherited Variation is due to differences in the Genetic make-up of individuals Inherited Variation is due to differences in the Genetic make-up of individuals The Nucleus contains Chromosomes - humans have 23 pairs, or 46 of them The Nucleus contains Chromosomes - humans have 23 pairs, or 46 of them

INHERITED VARIATION 9 9 Genes are information for making the animal - the information is in chemicals on the chromosomes Genes are information for making the animal - the information is in chemicals on the chromosomes

Baby has 46 Chromosomes INHERITED VARIATION 10 Egg and Sperm cells have half the usual number of chromosomes, so that when they join together the baby has the right number Egg and Sperm cells have half the usual number of chromosomes, so that when they join together the baby has the right number 23 of Mum’s Chromosomes 23 of Dad’s Chromosomes

INHERITED VARIATION 11 So the child has some of mum’s characteristics and some of dad’s So the child has some of mum’s characteristics and some of dad’s 23 of Mum’s Chromosomes 23 of Dad’s Chromosomes

ENVIRONMENTAL VARIATION 12

ENVIRONMENTAL VARIATION 13 Many characteristics are affected by an individual’s environment Many characteristics are affected by an individual’s environment For example, some people won’t eat much and become very thin For example, some people won’t eat much and become very thin

ENVIRONMENTAL VARIATION 14 A lot of characteristics depend on both genetic and environmental factors, but these four are NOT affected by the environment: A lot of characteristics depend on both genetic and environmental factors, but these four are NOT affected by the environment:  Blood Group  Eye Colour  Inherited Disease  Albinism  Blood Group  Eye Colour  Inherited Disease  Albinism

VARIATION IN PLANTS 15

VARIATION IN PLANTS 16 Plants also inherit characteristics through their genes, e.g. some specimens are taller than others Plants also inherit characteristics through their genes, e.g. some specimens are taller than others

VARIATION IN PLANTS 17 And the environment also affects them, e.g. sunshine, temperature, soil conditions and moisture And the environment also affects them, e.g. sunshine, temperature, soil conditions and moisture This is why skilled gardeners can grow bigger, stronger plants This is why skilled gardeners can grow bigger, stronger plants

SELECTIVE BREEDING 18

SELECTIVE BREEDING 19 By breeding from specimens who have the best characteristics it is possible to get high yield crops, fast race horses or cute dogs By breeding from specimens who have the best characteristics it is possible to get high yield crops, fast race horses or cute dogs