Populations, Evolutions & Genetics Random Retrieval

Which of the following does NOT stop succession?

What is it called when succession is stopped artificially?

What is humus?

What is lichen made out of ?

At which stage will abiotic factors be most hostile?

What is the biological meaning of succession?

What type of speciation is caused by reproductive Isolation, but without a physical barrier between two populations?

What type of variation is show in the graph?

Which type of selection is when the number of individuals with a particular characteristic, increase around an extreme or outlier value?

Natural Selection is when organisms which are better adapted are more likely to survive and pass on their genes. Factors which affect the chance of survival are called selection pressures. These can be positive ( advantageous) or negative ( disadvantageous). Which of these is a negative selection pressure?

Which of these is a source of variation?

Tay Sachs is a recessive disease which leads to the build up of certain lipids which eventually become toxic. The Cajun community in the USA has an incidence of about 1 in every 3,500 births. What is the allele frequency of the normal healthy genes?

In peppered moths, having light coloured wings is dominant. In Sheffield (an industrial northern town in the UK) a sample of moths was taken. The numbers collected were 73 light coloured , and 326 dark coloured. What proportion of all alleles are for the dark one?

The Hardy Weinberg principle only applies to a population that is or has____.

Which statistical test would we use to see if the observed phenotypes are different from the expected phenotypes?

This gene interaction once again alters the phenotype ratio. Which type of Epistatic allele will produce a ratio of 9:3:4?

What term describes when a characteristic is controlled by more than one gene, and the expression of one gene will effect the expression of others?

Being colour blind is a sex-linked disorder. What is the probability of an unaffected male having a colour- blind child with a heterozygous female?

How can you tell from a pedigree (family tree) that a trait is sex linked?

What is the best definition of a 'dominant allele'?