IB Biology HL A4.1 Evolution and Speciation Questions

a. mutations generate variation/generate new traits;

b. mutations are changes to base/nucleotide sequence (of DNA/genes);

c. new alleles are formed by mutation;

d. meiosis/sexual reproduction generates new combinations of genes/alleles;

e. natural selection;

f. better adapted (individuals) have higher chance of survival;

g. better adapted (individuals) (tend to) produce more offspring/more likely to reach reproductive age;

h. heritability / traits/genes passed on (to offspring) / offspring inherit genes/alleles of their parents;

i. directional selection causes change in traits;

j. environmental change/environmental pressure causes selection of advantageous mutations/new traits;

k. antibiotic resistance/melanism in moths/other evidence-based example of development of new traits;

I. development of new traits over time is evolution;

Marking guidance:

Reject examples of speciation for mpk.

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max

a. polyploidy is having more than two sets of (homologous) chromosomes;

b. triploids have three sets of chromosomes/tetraploids have four sets of chromosomes;

c. polyploid/tetraploid cells generated from diploid cells by DNA replication without cytokinesis/non-disjunction (of all bivalents) during meiosis;

d. tetraploids produce diploid/2n gametes;

e. fusion of diploid and haploid gametes results in triploids;

f. triploids are sterile/no gametes produced because pairing of homologous chromosomes/meiosis fails;

g. diploids and tetraploids are reproductively isolated / tetraploids cannot interbreed with the diploid parent species / diploids and tetraploids only produce infertile offspring when they cross;

h. polyploids/tetraploids are therefore a different/new species (according to the biological species definition);

Marking guidance:

Reject polyspermy as the
origin of polyploid cells

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max