Define the term ecosystem.
An ecosystem includes all of the living things interacting with each other, and also with their non-living environment.
Give an Example of an Abiotic factor
Abiotic factors are the non living components of an ecosystem so things such as the soil pH, light levels, wind speed, water content etc.
Define a 'Community'
A group of organisms or a population of different species occupying a particular area.
Name a producer on this food web
Name a secondary consumer on this food web.
snake or lizard
What are the mising labels on the water cycle? Starting with the arrows up from the sea to the sun and working clockwise.
Evaporation, Condensation, precipitation.
What is a detritovore?
An organism that eats detritus (decaying matter).
What is a saprophyte?
A fungus or plant which feeds on detritus by secreting enzymes which help digest the detritus.
Name a process which locks carbon away.
Photosynthesis or sedimentation
Name a process which adds carbon to the carbon cycle
Respiration or Combustion
What does 'biodiverse' mean?
An area with a large number of different species living there.
What is a pesticide?
A chemical which kills pests, used in farming methods.
What is a herbicide?
A chemical used in agriculture which kills weeds.
What can cause algal blooms in lakes and result in Eutrophication?
Name a gas responsible for causing acid rain.
Sulpher or nitrogen oxides.
What produces sulphur dioxide responsible for acid rain?
Cars and factories.
Name an effect of acid rain on the environment.
Limestone buildings and grave stones worn away, trees die, lakes too acidic for fish to survive.
Name a fossil fuel
natural gas, coal, oil.
What effect does the action of destroying peat bogs have on the gases in the atmosphere?
Increases the amount of carbon dioxide.
Describe one effect of deforestation on the environment.
disruption of food chains
Name a gas responsible for Global warming.
Carbon dioxide, Methane.
Biodiversity can be reduced by these things:
What are Trophic Levels?
They are the feeding levels within a food chain.
What is a top or 'Apex' predator?
A predator that has no predators of its own.
Where is trophic level one found on a pyramid of biomass?
At the bottom.
Approximately how much biomass is transferred from one trophic level to another?
How is the energy lost at each trophic level?
Movement, Respiration, Senses, Growth, Excretion, Nutrition
Why is most energy lost between the transfer from producer to consumer?
Much of the plant material (cellulose) is indigestible and is simply excreted.
Calculate the missing respiration value.
Calculate the efficiency for this diagram.
Only 4 kJ of the original energy available to the bullock is available to the next stage, which might be humans. The efficiency of this energy transfer is:
efficiency = 4⁄100 × 100 = 4%
Give two possible negative effects of the decrease in forest cover on ecosystems.
any two from:
• decreased biodiversity
• loss of habitats
• increased carbon dioxide (concentration)
• global warming
Define three biotic factors which affect an ecosystem.
Any three from
availability of food • new predators arriving • new pathogens • one species outcompeting another so the numbers are no longer sufficient to breed.
What are 'extremophiles'?
Some organisms live in environments that are very extreme, such as at high temperature, pressure, or salt concentration.
Bacteria living in deep sea vents are extremophiles.
What are the conditions needed for rapid decay?
Heat, Moisture and Oxygen.
Which gas is produced in anaerobic decay?
How does a biogas generator work?
They canbe used to produce methane gas as a fuel.
Why has large scale deforestation in tropical areas occured?
Large-scale deforestation in tropical areas has occurred to:
provide land for cattle and rice fields
grow crops for biofuels
What is 'food security'?
Food security is having enough food to feed a population.
Decsribe 2 factors which are affecting food security.
2 answers from here:
Biological factors which are threatening food security include:
the increasing birth rate has threatened food security in some countries
• changing diets in developed countries means scarce food resources are transported around the world
• new pests and pathogens that affect farming
• environmental changes that affect food production, such as widespread famine occurring in some countries if rains fail
• the cost of agricultural inputs
• conflicts that have arisen in some parts of the world which affect the availability of water or food.
Describe one way in which the efficency of cattle farming could be improved.
The efficiency of food production can be improved by restricting energy transfer from food animals to the environment.
This can be done by limiting their movement and by controlling the temperature of their surroundings
Describe two methods which maintain fish stocks at sustainable levels.
Control of net size and the introduction of fishing quotas play important roles in conservation of fish stocks at a sustainable level.
What is the name of the fungus used to produce mycoprotein?
The fungus Fusarium is useful for producing mycoprotein