Energy And Ecosystems Flashcards
Why is so much of the Sun’s energy lost?
- 90% is reflected back into space by clouds or absorbed by the atmosphere
- Not all wavelengths of light can be absorbed
- Light may not fall on the chlorophyll molecule
- Photosynthesis may be impacted by a limiting factor
Netproduction=?
Gross production-Respiratory losses
Why is only 20% of energy available from prey converted?
- Not all of the organism is eaten
- Lots is lost in faeces
- Some energy is lost in excretion
- Some energy losses from respiration and movement
Read over ecological pyramids p70
Done!
Read over agricultural ecosystems p73
Done!
What is a pest?
An organism that competes with humans got food or space, or is a danger to health
What are the characteristics of an effective pesticide?
- Specific
- Biodegradable but chemically stable so it has a long shelf-life
- Cost-effective
- Not accumulate so it does not build up in food chains
What are the differences between biological controls and chemical pesticides?
Biological
• Very specific
• Once introduced, control organism reproduces itself
• Pests do not become resistant
Chemical
• Have some effect on non-target species
• Must be reapplied making them expensive
• Pests develop genetic resistance so new pesticides must be developed
What does integrated control of pests involve?
- Choosing animal or plant varieties to suit the area
- Managing the environment to provide suitable habitats
- Regularly checking for signs of pests so early action can be taken
- Removing pests mechanically
- Using pesticides as a last resort
Read p80 domestic livestock.
Done!
How much of the Sub’s energy is converted by plants?
1-3%
