Plants as food:
Plants can carry out photosynthesis. In the process of photosynthesis, plants convert the energy in light to s stored chemical form. They absorb carbon dioxide from the air and make carbohydrates. Most plants store energy as the carbohydrate starch. They also absorb minerals, such as nitrate, from the soil, and manufacture a range of other biological molecules. Herbivores are animals that make use of the biological molecules when they eat and digest plants.
Humans are omnivores. This means that we eat both plants and animals. We gain our nutrition both directly from plants and also indirectly by eating herbivorous animals. The human food chain tends to be short. By making the food chain more efficient, we can increase food production.
How can we make food production more efficient?
In plants it is possible to:
· improve the growth rate of crops
· increases the size of yield from each plant
· reduces losses of crops due to diseases and pests
· make harvesting easier by standardising plant size
· improve plant response to fertilisers
In animals it is possible to:
· improve the rate of growth
· increase productivity
· increases resistance to disease
(Where humans select the individual organisms that are allowed to breed according to chosen characteristics)
Charles Darwin was aware that people often breed animals with desirable traits and that, over time, such breeding exaggerated small differences. He recognised this as artificial selection. He described artificial selection as the intentional breeding of certain traits, or combinations of traits, in contrast to the process of natural selection. The purpose of artificial selection is to increase the benefit to humans.
There are three stages to selective breeding:
· artificial selection
· inbreeding or line breeding
In practice this means selecting a pair of animals or plants that display the characteristics you want. That pair is allowed to reproduce. The offspring produced are sorted carefully to select those with the best combination…