Biology Revision Notes Essay

10384 WordsJul 17, 201242 Pages
BIOLOGY REVISION Background: Evolution in its broadest sense means change over time. Biological evolution is a change to the gene pool of a population. So, evolution refers to a lasting change to a population over generations. The theory of evolution is supported by many forms of evidence. There are inherent variations in populations and not all individuals survive to reproduce. Through the mechanism of natural selection, heritable changes may occur in populations over many generations. plan, choose equipment or resources and perform a first-hand investigation to model natural selection * Plan a first-hand investigation to model natural selection. You need an investigation design that will allow valid and reliable data to be collected. A simple but useful investigation that you might use is 'Stick-bird': Within a hypothetical population of 'worms' (toothpicks) that inhabit a predominantly green-coloured environment (green grass), there are two colour variations; cream and green. The worms are food for a predator known as a 'stick-bird' (students). Possible hypothesis: In a predominantly green coloured environment, green worms have a greater chance of survival and therefore reproduction due to their ability to blend in with the background. Stick bird Toothpicks are mixed and scattered randomly over a measured grassed area. Stick birds (students) are later brought to that area and remain outside a 'fence'. They are told to prey on the 'worms' in the field (collect as many toothpicks as they can) in a given time. After 3 minutes, the 'stick-birds' are driven from the field by the 'farmer' (teacher). They escape back to the classroom Tally and compare the numbers of green and cream toothpicks recovered. Calculate percentages recovered of each colour. Consider the numbers of toothpicks and students that will be needed for valid and reliable data

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