Do you remember the topic of plants in I/GCSE Biology
- This is controlled by plant genes. The way in which living organisms respond to changes in day length.
- For example:
- deciduous trees as they lose their leaves in winter as the days become shorter.
- The plants use the change in day length to help them grow or flower at the right time. Responses to changing day length are called photoperiodism.
- Plants can tell when it is spring from winter as the days get longer. As a result, their seeds sense this and germinate even if the plant has already died.
- Some plants grow throughout winter but grow faster in lengthening days as a response. In autumn, the days get shorter and the plants stop growing to prepare for winter.
- Plant species are often synchronised when releasing their pollen as it is an important stage for creating the next generation.
- For example
- millions of crop plants harmonise their life cycles to produce grains at the same time.
- Plants can be attacked by insects or pathogens. If this happens to crops, crop yield can be severely reduced as the plants are eaten, which will increase the price of the crop in the long run.
- As a result, plants can produce chemicals to protect the plant when they are attacked by pathogens. This can be done in different ways:
- Attract parasites to kill the insects.
- Put the insect off (doesn’t taste nice)
- Attract predators to attack the insects eating the plants.
- Although the plant may have to use a lot of energy to make the chemicals it is worth it.
- Milkweed plant produces a toxic chemical that stops insects from eating due to the taste.
- Corn plant, when attacked by caterpillars produces a chemical that attracts a parasitic wasp. The wasp lays eggs in the skin of the caterpillar. When the larvae hatch they eat the caterpillar from the inside out, preventing further attack.
- Wheat seedlings produce a chemical when attacked by insects which attract aphids that eat the insects.
- Young lupin leaves produce poisonous chemicals called alkaloids. These make the leaves poisonous to insect pests or larger herbivores that might want to eat them.
- Potatoes are often attacked by a fungus-like organism called potato blight that destroys their leaves, thereby killing the plant. Some varieties of potato produce chemicals that kill it.
Plants are a key source of food for people. If pathogens destroy a crop our food supply is at risk. An example of this is the famine caused by potato blight in Ireland in 1845 and 1846 that killed over 1 million people.
And we're done with this topic! Well Done!
Drafted by Alyssa (Biology)
- "Deciduous trees", https://i2.wp.com/arbor-experts.com/wp-content/uploads/blog-leaves-winter.jpg?fit=1280%2C500&ssl=1
- "What Is Photoperiodism?", https://cdn1.byjus.com/wp-content/uploads/2019/01/Photoperiodism-Vernalisation-And-Seed-Dormancy-1.jpg
- "Figure 1 from Prospects of herbivore", https://d3i71xaburhd42.cloudfront.net/70c820287cffd673adc61cfeb04de827e67210cc/2-Figure1-1.png
- "Alisa Huffaker", https://biology.ucsd.edu/_images/research/faculty-research-images/ahuffaker_fig_3.jpg