A.S Biology Unit 2 Variation Examination Style Questions

xizuhupo's version from 2016-04-28 16:46


Question Answer
Explain how data from studies of identical twins and non-identical twins could provide further evidence about the genetic control of intelligenceidentical twins have same genotype; compare identical and non-identical twins in same environment; if genetic effect is greater, there will be more similarity between identical twins than non-identical twins; the sample should be large; use a statistical test;
If concordance (whether both twin have the condition) in genetically identical twins is 85% and in genetically non-identical twins it is 35%, what does this suggest about the relative effects of environmental and genetic factors on the development of the disease?Larger genetic component.
When collecting the data on concordance of diabetes in genetically identical and non-identical twins, suggest two factors which should be taken into account.number of cases studied; age of twins
If you know the lengths of seeds collected from three stores of different ages, and within each store the seeds showed a range of different lengths, give two causes of this variation and an explanation for each length controlled by many genes/polygenes; e ach gene may have different alleles/idea of additive effects; environmental factors/or named factor; how a named factor may affect growth of seeds
Give two possible causes of variation in the length of salmon.1. Random fusion of gametes. 2.Mutation
When comparing variation in size between two groups of organisms, it is often considered more useful to compare standard deviations rather than ranges. Explain why. range can be influenced by one extreme value; standard deviation shows the spread about mean; range only shows highest and lowest values/extremes; SD allows statistical use; tests whether or not differences are significant; A range just gives the spread of data. SD gives more idea about the range of values either side of the mean.
If there is a bar chart that shows you that the number of spots of a certain species of ladybird varies, what does the graph suggest about the genetic control of spot number in this species?polygenic/several genes involved/multiple alleles; due to a combination of genes
If, on the barchart of the ladybird spots, there is one tall bars in the middle surrounded by bars decreasing in height on either side, what evidence is there that variation in the number of spots is normally distributed?The graph is symmetrical and there is an even distribution around the middle.
Describe how discontinous variation differs from continuous variation in terms of genetic controlDiscontinuous is controlled by one gene versus many/polygenic for continuous variation
Describe how discontinuous variation differs from continuous variation in terms of the effect of the for discontinuous versus significant for continuous
Describe how discontinuous variation differs from continuous variation in terms of the range of phenotypeslimited/few for discontinuous versus wide/many for continuous
Genetically identical twins often show slight differences in their appearances at birth. Suggest one way in which these differences may have been causednamed difference in environmental factor during pregnancy, e.g. nutrient supply