| Criteria | Marks |
|---|
| Provides similarity and differences in the ways genetic variation can arise in offspring derived from asexual reproduction and sexual reproduction; differentiates between mitosis in asexual reproduction and meiosis in sexual reproduction; demonstrates a comprehensive understanding of the sources of variation in the offspring of sexual reproduction | 6 |
| Provides a similarity and difference(s) in the ways genetic variation can arise in offspring derived from asexual reproduction and sexual reproduction; differentiates between mitosis in asexual reproduction and meiosis in sexual reproduction; demonstrates a clear understanding of the sources of variation in the offspring of sexual reproduction | 5 |
| Provides a similarity and/or differences in the ways genetic variation can arise in offspring derived from asexual reproduction and sexual reproduction; outlines processes in meiosis that contribute to variation in sexual reproduction | 4 |
| Provides a similarity and/or difference(s) about genetic variation in offspring derived from asexual reproduction and sexual reproduction | 3 |
| Provides some information about the variation in offspring derived from asexual reproduction and/or sexual reproduction | 2 |
| Provides some relevant information | 1 |
Sample answer:
Mutation during DNA replication is a source of genetic variation that can arise in offspring of both asexual reproduction and sexual reproduction.
Asexual reproduction is achieved by cells of one organism dividing by mitosis and differentiating into a new organism with the same genetic code as the parent. The most likely cause of genetic variation among the offspring would be mutations that occur due to environmental factors or miscopying of the chromosomes during mitosis.
Variation in the offspring resulting from sexual reproduction also can be due to mutations during DNA replication. However, sexual reproduction leads to much more genetic variation in offspring due to the production of gametes by meiosis. Random assignment of chromosomes of each homologous pair to the gametes and the possible recombination of alleles from crossing over of genetic material between homologous pairs of chromosomes lead to each gamete having a unique set of alleles. In addition, the chance that any one gamete from one individual has of combining with another gamete from a second individual at fertilisation leads to infinite variation in the offspring of sexual reproduction.