Germination

In the syllabus and the exam

Germination is tested as the final stage of the seed dispersal and reproduction sequence in flowering plants, and the topic is examined both conceptually and practically, since candidates are often asked to design or interpret an experiment investigating the conditions a seed needs to germinate. Candidates must know that three conditions are generally required for germination: water, oxygen, and a suitable temperature, and that light is not required by most seeds, a point that is frequently tested by asking candidates to identify which of several listed conditions is not necessary. The process itself begins when the seed absorbs water, activating enzymes that break down stored food reserves such as starch into simpler soluble substances, which are then transported to the growing embryo to fuel cell division and elongation as the radicle and plumule emerge. Paper 3-style practical questions commonly involve setting up several test tubes or containers with seeds under different conditions as a controlled experiment to identify which factor affects germination. A common error is including light as a necessary condition for germination, or confusing germination with pollination and fertilisation, which are earlier, separate stages of the plant reproductive cycle occurring before a seed even forms. Candidates should also be able to explain why a germinating seed initially loses dry mass before it can photosynthesise for itself, since stored food reserves are broken down and used up for respiration and growth before the first true leaves emerge and begin producing new food.

Example

Describing the process, a candidate writes: 'Germination begins when a seed absorbs water, causing enzymes to become active and break down stored food, which is then used to provide energy for the growth of the embryo's root and shoot.'

Related terms

MeristemMitosisCell differentiation

Source:SRC-DSKP-EN