Germination 🌱
A seed contains a plant embryo, consisting of a radicle, plumule (shoot) and one or two seed leaves called cotyledons.
In I/GCSE Biology, dicotyledonous plants or dicots have two cotyledons – examples being peas or beans. Monocotyledonous plants or monocots have one, examples being orchids and irises.
Anyways the radicle grows down into the soil and the plumule grows up towards the light where it can start to photosynthesise. Once the seedling is able to photosynthesise, germination is over.
👇The conditions needed for germination are:
- Warm temperatures – for enzymes to work efficiently
- Water – for chemical reactions to take place
- Oxygen – for respiration
The food store gets used up during germination, but provides the nutrients needed to allow the radicle and plumule to grow. The food store in dicots is present in the cotyledons. Monocots have a separate food store. Dispersed seeds contain only about 10% water. This low water content restricts a seed’s metabolism, so that it can remain alive but dormant for a long time.
Asexual reproduction in plants 🌵
Asexual reproduction in plants usually involves some part of the plant growing, then breaking away from the parent before growing into a new plant. Either:
- The parent plant grows a runner. When the runner touches the ground, a new plant is produced.
- Tubers form at the ends of the branches from the main stem.
- Some plants form bulbs, bases of leaves which have become swollen in food. Buds in them can form into new plants.
In I/GCSE Biology, artificial methods of reproducing plants asexually include cutting a piece of a plant’s stem, with a few leaves attached. This is planted in a damp compost, where it will grow roots and develop into a new plant.
That's the end of the topic!
Drafted by Joey (Biology)
Reference:
https://slideplayer.com/slide/15076251/