These questions follow a flowering plant from pollen arrival through fertilisation, fruit and seed formation, dispersal and germination. Put each event in order, then connect a structure or condition to the job it performs.
Build the sequence
After pollen lands on a stigma, the grain stays there while a pollen tube grows down through the solid tissue of the female stalk. A nucleus travels through the tube and joins an ovule nucleus within the chamber at the flower's base. That joining is fertilisation. Afterward, each fertilised ovule develops into a seed, while the surrounding chamber develops into a fruit. In biology, a dry pod or a winged case can be a fruit even though it is not sweet.
| Stage or clue | Method to apply |
|---|---|
| Pollen has reached a stigma | Next trace tube growth through the female stalk towards an ovule. |
| Ovule after fertilisation | Follow it into a seed; follow the enclosing chamber into a fruit. |
| Light body, wing or parachute of hairs | Infer wind dispersal because the structure slows falling or catches moving air. |
| Juicy fruit or external hooks | Infer animal dispersal through eating or attachment to fur. |
| A seed beginning growth | Check for water, an air supply, and suitable warmth, then trace energy to respiration of the internal food store. |
Dispersal places offspring away from the parent, reducing competition for light, water, mineral ions and space. Match the carrier to the adaptation rather than relying on the fruit's appearance alone. During germination, water activates the seed, warmth allows its chemical reactions to proceed, and air supplies the gas used in respiration to release stored energy. The young root emerges before the shoot, helping with anchorage and water uptake. Light is usually unnecessary for germination; it becomes important after leaves appear and photosynthesis begins.
Avoid these sequence mistakes
| Tempting idea | How to reject it |
|---|---|
| Calling pollen arrival fertilisation | Arrival is pollination. Fertilisation requires the later joining of two nuclei inside an ovule. |
| Swapping what the ovule and its enclosing chamber become | Track inside and outside: each ovule becomes a seed, while the chamber around it becomes the fruit. |
| Adding light, soil or mineral ions to the germination requirements | A seed can begin underground using supplies already inside it. The immediate external needs are water, an air supply, and suitable warmth. |
| Sending the shoot out first because it needs light | Early growth uses the seed's stored reserves. The young root emerges first; leaves and light matter later. |
| Treating soil minerals as fuel for a buried seedling | Respiration releases energy from the food store inside the seed. Roots take up water and ions, not ready-made food. |
Try it
Why is it an advantage to a plant that its seeds are carried away from the place where they were made?
- So the seeds can find fresh soil that holds more food for the seedlings to live on
- So the seeds are warmed enough by the open ground to be able to germinate
- So the seedlings do not compete with the parent for light, water and space
- So the seeds can then be pollinated by a different plant of the same kind
Why does a seed buried in dark soil still need oxygen in order to germinate?
- It respires, and respiration releases stored energy
- It needs oxygen for photosynthesis while it is underground
- It uses oxygen to soften and split its seed coat
- It does not need any oxygen while it is in the dark