Natural Selection L.O: To understand how natural selection can lead to evolution

Natural Selection – Match each statement to its title and put them in order. 1 All living things in a species are not the same. 2 There is not enough food or space for all of them. 3 Some individuals have features which help them survive. 4 They are more likely to have offspring. More of the next generation have the useful feature. A. Competition B. Survival C. Variation D. Reproduction

Natural Selection 1) Each species shows variation: 2)There is competition within each species for food, living space, water, mates etc 4)These survivors will pass on their better genes to their offspring who will also show this beneficial variation. Get off my land Gutted! Yum 3)The “better adapted” members of these species are more likely to survive – “Survival of the Fittest”

A smaller example… Consider the four steps of natural selection in the example of some bacteria that has become resistant to penicillin: 1)Variation – some strains of bacteria are resistant and some aren’t. 2)Competition – The non-resistant bacteria are killed by the penicillin. 3)Survival of the fittest – the resistant bacteria survive. 4)Passing on of genes – the resistant bacteria reproduce and pass on their adaptations to their offspring. Bacteria Penicillin

Natural Selection If an animal or plant has an advantage in competition against other members of its species it is more likely to survive and breed (“survival of the fittest”).

Each gene is the instruction for making one protein. Sometimes a mistake is made when the gene’s DNA is copied. The gene may code for a different protein. Mutations do happen naturally. They can also be caused by some chemicals, and ionizing radiation. Mutations Back Explain what a mutation is and how it can occur.

This bacterium is resistant to most antibiotics. A person who is a carrier of the sickle cell allele is protected from malaria. Most mutations do not help the organism. The different protein that is made cannot do its job well. But mutations are random – a very small number may help the organism survive in some environments. For example, some bacteria have mutations that make them resistant to certain antibiotics. Sickle-cell anaemia is a serious blood disease. People with two copies of the disease allele can be very ill. But people who carry just one copy of the allele have protection from malaria. This helps them to survive in countries where malaria is common. How can mutations be helpful? Back

Mutations True or False 1.A mutation is a change in the DNA 2.Mutations are useful most of the time 3.Mutations can cause cancer to develop if a mutation occurs in a gamete 4.Mutations can cause the young to die or develop abnormally if a mutation occurs within a gamete 5.All individuals which have a mutation have an advantage over other individuals, and lead to natural selection 6.The chance of a mutation can be increased by exposure to ionising radiation such as UV, X-rays and radioactive substances 7.Certain chemicals can increase the chance of a mutation

Natural Selection – The Peppered Moth

Natural Selection and the Peppered Moth 1.Cut 10 small pieces of white and 10 pieces of black paper. 2.Place them on a large piece of black paper. 3.Cover your eyes with a scarf or jumper so you can just see through (this is more realistic as predators don’t have eyesight as good as us). 4.Pick off 10 pieces of paper (the ones easiest to find). 5.Draw a table with the number of black surviving in one column and number of white in the other. Record how many black and white you have. 6.Add this number of black and white pieces of paper demonstrating reproduction. 7.Repeat until you have all of one colour. 8.Write a conclusion.

Natural selection in rats: warfarin Now put these statements in the correct order. B: A mutation in a rat’s sex cells make its offspring resistant to warfarin. A: The mutated gene is passed on and is common in the rat population. C: The number of resistant rats increases with each generation. D: Warfarin kills most rats. E: Mutations may happen when DNA is copied in the cell. G:People use warfarin to kill the rats. F:The resistant rats have a better chance of surviving and reproducing. H: The resistant rats breed and pass their features on. I: Mutations are a change in the genetic code. J: Mutations can be caused by some chemicals or ionizing radiation.

Natural selection in rats: warfarin Now put these statements in the correct order. B: A mutation in a rat’s sex cells make its offspring resistant to warfarin. A: The mutated gene is passed on and is common in the rat population. C: The number of resistant rats increases with each generation. D: Warfarin kills most rats. E: Mutations may happen when DNA is copied in the cell. G:People use warfarin to kill the rats. F:The resistant rats have a better chance of surviving and reproducing. H: The resistant rats breed and pass their features on. I: Mutations are a change in the genetic code. J: Mutations can be caused by some chemicals or ionizing radiation.