| Criteria | Marks |
|---|
| • Provides an assessment of the statement with relation to agreement/disagreement.<br>• Shows a thorough understanding of both internal and external fertilisation in ensuring continuity of a species.<br>• Shows clear understanding of the advantages/disadvantages of internal over external fertilisation. | 4 |
| • Shows a sound understanding of both internal and external fertilisation.<br>• Links both to ensuring continuity of a species.<br>• Outlines benefits and/or weaknesses of internal and external fertilisation. | 3 |
| • Outlines features of both internal and external fertilisation.<br>• OR identifies some features of internal and/or external fertilisation. | 2 |
| • Provides some relevant information. | 1 |
Sample answer:
For the continuity of a species, each generation must successfully reproduce to produce sufficient numbers of the next generation. A critical number of embryos must survive to gestational maturity. This is less likely with external fertilisation. Organisms that reproduce by external reproduction spend a substantial amount of energy and resources in the production and release of very large numbers of sperm and eggs. This is because each sperm and egg and the resulting embryos have limited chances of survival, not being protected by the parent for example in the open ocean. Chances of successful fertilisation are low in such vast aquatic environments. Larger numbers ensure some will be fertilised. Internal fertilisation provides a smaller safer environment for release of gametes, fertilisation and maturation of the embryos. Chances of successful fertilisation are increased and embryos are protected from predators within the body of the parent. Even after birth/egg laying parental care assists survival of the offspring.