5B - Farming practices and production Flashcards
What do food chains and webs show?
How energy is transferred through an ecosystem/between organisms.
What do food chains look like/show?
Show simple lines of energy transfer. Each of the stages in a food chain is called a trophic level.
What is each of the stages in a food chain called?
A trophic level.
What do food webs look like/show?
Lots of food chains in an ecosystem and how they overlap.
What are parts of food chains/webs that aren’t shown?
Decomposers.
What do decomposers do?
Break down dead or undigested material, allowing nutrients to be recycled.
Give an example of a decomposer
Fungi
What do most farming practices aim to do?
Increase the amount of energy that is available for human consumption - increasing the efficiency of energy transfer.
How can farming practices increase the amount of energy that is available for human composition?
1) The energy lost to other organisms, e.g. pests, can be reduced.
2) The energy lost through respiration can be reduced.
What does simplifying food webs do?
Reduces energy loss to other organisms.
What does simplifying food webs mean needs to happen?
Getting rid of pests.
What methods of pest control can farmers use to get rid of pests to simplify food webs?
1) Use chemical pesticides.
2) Use biological agents.
3) Use integrated methods that combine both chemical and biological methods.
In what 2 ways can farming practices increase the efficiency of energy transfer?
- Simplifying food webs reduces energy loss to other organisms.
- Reducing respiratory losses means energy is transferred more efficiently.
How can farmers reduce pest numbers using chemical pesticides?
- Insecticides kill insect pests that eat and damage crops. killing insect pests means less biomass is lost from crops, so they grow to be larger, which mean NPP is greater.
- Herbicides kill weeds (unwanted plant species). Killing weeds can remove direct competition with the crop for energy from the sun. It can also remove the preferred habitat or food source of the insect pests, helping to further reduce their numbers and simplify the food web.
How can biological agents reduce the number of pests, so less crops lose energy and biomass, increasing the efficiency of energy transfer to humans?
- Parasites live in or lay eggs on pest insect. Parasites either kill the insect or reduce its ability to function, e.g. some wasp species lay their eggs inside caterpillars - the eggs hatch and kill the caterpillars.
- Pathogenic (disease-causing) bacteria and viruses are used to kill pests, e.g. the bacterium Bacillus thuringiensis produces a toxin that kills a wide range of caterpillars.
