Discuss the role of genes and chromosomes in determining individual and shared character features of the members of a species.

Outline the process of speciation.

Describe, using one example, how homologous structures provide evidence for evolution.

Genes
a. mutation changes genes/causes genetic differences 

b. genes can have more than one allele/multiple alleles
OR
alleles are different forms/versions of a gene 

c. different alleles «of a gene» give different characters
OR
variation in alleles between individuals 

d. eye colour/other example of «alleles of» a gene affecting a character 

e. alleles may be dominant or recessive
OR
dominant alleles determine trait even if recessive allele is present 

f. both alleles influence the characteristic with codominance
OR
reference to polygenic inheritance 

g. all members of a species are genetically similar/have shared genes
OR
certain genes expressed in all members of a species 

h. reference to epigenetics/methylation/acetylation / not all genes are expressed «in an individual» 

i. genes are inherited from parents/passed on to offspring/passed from generation to generation

Chromosomes

j. same locus/same position of genes
OR
same sequence of genes/same genes on each chromosome «in a species» 

k. same number of chromosomes «in a species»/all humans have 46 chromosomes/differences in chromosome number between species 

l. some individuals have an extra chromosome/Down syndrome/other example of aneuploidy
OR
polyploidy divides a species/creates a new species 

m. X and Y/sex chromosomes determine the sex/gender of an individual 

n. meiosis/independent assortment/fertilization/sexual reproduction give new combinations «of chromosomes/genes»

a. speciation is the splitting of a species «into two species» 

b. reproductive isolation/lack of interbreeding 

c. isolation due to geography/«reproductive» behavior/«reproductive» timing 

d. polyploidy can cause isolation 

e. gene pools separated 

f. differences in/disruptive selection cause traits/gene pools to change/diverge 

g. gradualism / speciation/changes accumulating over long periods 

h. punctuated equilibrium / speciation/changes over a short time period

a. similar structure but different function «in homologous structures» 

b. pentadactyl limbs/limb with five digits/toes / other example 

c. similar bone structure/example of similarity of bones «in pentadactyl limbs» but different uses/functions 

d. two examples of use of pentadactyl limb by a vertebrate group 

e. suggests a common ancestor «and evolutionary divergence» 

f. process called adaptive radiation