natural selection, evolution and speciation exam Qs pack 9

Question 1

why do scientists prefer to classify plants as varieties within the same species rather than as two separate species

Answer 1

individuals of a species can interbreed to produce fertile offspring, the hybrids can flower and produce viable seeds

Question 2

genetic diversity

Answer 2

variety of alleles in a gene pool

Question 3

explain why there is likely to be a greater genetic diversity in the hybrid plants than in either of the two separate species

Answer 3

different alleles on each of the two populations, each population is adapted to live in different environmental altitudes

Question 4

explain how two different species of plants may have evolved from a single population of an ancestral species

Answer 4

original population increasing in size and spreading into wider diversity of habitats, mutation occurs which leads to diversity in flowering times and other plant features, reproductive isolation restricts gene flow between extremes of population

Question 5

how to identify and justify which population has been interbreeding from a data table

Answer 5

whichever has the lowest heterozygosity and high number of homozygous recessives

Question 6

describe the differences between what is meant by the terms species richness and genetic diversity

Answer 6

species richness is the number of species in a habitat whilst genetic diversity is the number of alleles in one species

Question 7

suggest how this strategy of transferring individuals from one population to another could help species survive

Answer 7

this increases the gene pool, this increases potential for the species to adapt and this will increase the survival

Question 8

explain how the use of the hardy- weinberg equation allows scientists to determine whether evolution has occurred

Answer 8

identifies changes in the allele frequency over time, if allele frequency stays the same then there is no evolution, if allele frequency changes then there is evolution

Question 9

describe two conditions under which properties remain the same over many generations

Answer 9

population is large, mating is random

Question 10

explain what could occur in natural selection to bring about adaption in a species

Answer 10

selection pressure due to competition, there was a mutation in the species because of an advantageous allele. the individuals with advantageous allele survive and breed