Topic 9: ecosystems, relationships,food security and more Flashcards
What factors affect food security?
- New pests and pathogens affecting farming
- Increasing human population
- Changing diets in developed countries –scarce food resources transported around world
- Environmental changes affect food production
- new pathogens/pests
What is a detritivor?
an animal which feeds on dead organic material, especially plant detritus
What is a decomposer?
Decomposers are organisms that break down dead or decaying organisms
What 3 factors affect the rate of decay?
- Heat
- Oxygen
- Water
How do people prevent Food from decaying or rotting?
Preservation by:
- canning(heated and sealed killin’ bacteria)
- cooling or chilling
- drying (removes water so bacteria cant survive)
- salt/sugar(removes water)
- Adding vinegar(changes PH so reactions cant occur)
How does adding salt or sugar preserve food?
removes water via osmosis
Why does adding vinegar preserve food?
Changes PH so reactions cant occur
Why is compost useful for gardeners?
It has been decayed into a form easier for plants to absorb the nutrients
What is the equation for rate of decomposition?
mass lost/number of days
can use triangle
What is potable water?
Water that is safe to drink and free from dirt, pathogens and harmful bacteria
What Is the carbon cycle?
All animals and living things contain carbon and the carbon is passed about in a cycle. Animals that respire also give carbon to the atmosphere by respiration and to the ground when they die. Plants that photosynthesise take in carbon from the air. This Is basically the carbon cycle.
What is the nitrogen cycle?
1) Nitrogen gas is converted to nitrate compounds by nitrogen-fixing bacteria in soil or root nodules.
2) Plants absorb nitrates from the soil and use these to build up proteins. The plant may be eaten by an animal.
3) Dead plant broken down by decomposers. This results in nitrogen being returned to the soil as ammonia.
4) denitrifying bacteria in the soil break down nitrates and return nitrogen to the air.
What is a carbon sink?
Carbon sinks absorb carbon dioxide from the atmosphere.
What is a carbon source?
Carbon sources release carbon dioxide into the atmosphere.
How do people protect biodiversity?
There are conservation methods:
- legal protection stopping hunting
- artificial ecosystems
- educating
- zoos and seedbanks
Equation for efficiency
Efficiency = energy used for growth(output) /energy supplied (input) x100
What is eutrophication and effect?
excessive richness of nutrients in a lake, due to run-off fertiliser, which causes a dense growth of plant life which blocks of sunlight and increases amount of bacteria which starves the lake of oxygen so fish die.
How do we measure the level of pollution in an area?
we use an indicator species such as lichen.
Polluted water can be determined by the type of larvae.
What is the equation for working out population size?
no. in sample (inside quadrat) x totals size of area/total size in sample(inside quadrat)
What is an example of a mutualistic relationship?
The hermit crab and an anemone which protects the crab and the hermit crab move to areas rich in nutrients
What is an example of a parasitic relationship?
cordyceps fungi spreads its spores onto insects and causes them to move up to a high area so the spores can grow out of the ant and have lots of light
How do you calculate the percentage of wasted energy?(efficiency)
energy lost/energy gained x 100
How to calculate species abundance
population of species/total population
What do nitrifying bacteria do?
turn ammonium in the soil into nitrates
What do denitrifying bacteria do?
Turns ammonium in the soil into nitrogen gas
What do nitrogen fixing bacteria do?
absorb nitrogen gas and turn it into nitrates in the soil
