3.7.3 Evolution may lead to speciation

Question 1

Describe allopatric speciation (5)

Answer 1

1.      Geographical isolation;
2.      Reproductive separation/isolation OR No gene flow OR Gene pools remain separate; Accept no interbreeding but must be a separate idea from mp5 which relates to definition of a species. Reject no inbreeding.
3.    Different selection pressures;
4.    Variation due to mutations; 5     
5.     Different allele/s passed on/selected OR Change in frequency of allele/s;
6.      Eventually different species cannot (inter)breed to produce fertile offspring;

Question 2

Why does speciation take a

long time? (3)

Answer 2

1. Initially one/few animals with favourable mutation/allele;
2. Individuals with (favourable) mutation/allele will have more offspring;
3. Takes many generations for (favourable) mutation/allele to become the most common allele (of this gene);

Question 3

explain Natural Selection in Resistant Strains (5)

Answer 3

1. Some individuals in population naturally resistant/not killed by pesticide/antibiotic;
2. Due to mutation;
3. These survive when pesticide/antibiotic applied/non-resistant ones are killed;
4. To reproduce and pass on allele/gene (for resistance);
5. Increase in frequency of allele for resistance;

Question 4

Describe sympatric speciation (4)

Answer 4

1.      Not geographically isolated;
2.   mutation   causes reproductive isolation
3. Gene pools kept separate/no gene flow;
4.      Different allele/s passed on / selected OR Change in frequency of allele/s
5.      Cannot breed/mate to produce fertile offspring;

Question 5

Define community (1)

Answer 5

All / group of species / all / group of populations / all the organisms;