Variation

emilyorr97
Mind Map by , created over 5 years ago

Summary of the chapter on variation in the AQA AS Biology textbook

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emilyorr97
Created by emilyorr97 over 5 years ago
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Variation
1 Sampling
1.1 Large sample size
1.1.1 More reliable data
1.1.2 smaller probability of chance occurring and influencing the results
1.2 Data analysis
1.2.1 statistical tests to determine the extent to which chance may affect the data
1.3 Chance
1.3.1 pure chance that the individuals are not representative
1.4 Sampling bias
1.4.1 random sampling is the best way to prevent sampling bias
1.4.2 unrepresentative choices either deliberately or unwittingly
2 Genetic factors
2.1 Mutations
2.1.1 sudden changes in the genes may be passed on to offspring
2.2 Meiosis
2.2.1 mixes genetic material before fertilisation so all gametes are different
2.3 Fusion of gametes
2.3.1 offspring inherit some characteristics from each parent, therefore are different
2.3.2 which gametes fuse is a random process, further adding to the variety of offspring that two parents produce
3 Environmental influences
3.1 affect the way that the organism's genes are expressed
4 Classification of characteristics
4.1 Due to genetic factors
4.1.1 a few distinct forms - no intermediate types
4.2 Due to environmental influences
4.2.1 form a continuum. e.g. height and weight
4.2.2 can be plotted on a normal distribution curve (bell-shaped)
5 Normal distribution
5.1 Mean
5.1.1 measurement at the maximum height of the curve
5.2 Standard deviation
5.2.1 measure of the width of the curve
6 Types of variation
6.1 IntERspecific variation
6.1.1 the difference between species - a giraffe isn't the same as a sloth
6.2 IntRAspecific variation
6.2.1 the difference within a species - no two humans are the same

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