GCSE Biology- Ecosystems & the Environment
4.6
Producer Ø Plants and photosynthetic bacteria
Ø Autotrophs = make their own food
Ø Plants are photoautotrophic = used energy from the sun to make their own
food via the process of photosynthesis
Ø Some bacteria are chemotrophic = use inorganic chemical to make food
Primary Ø Get energy by feeding on producers à primarily herbivores
consumer
Secondary and Ø Feed on primary consumers
tertiary Ø Carnivores that get their energy by feeding on other animals
producers
Decomposers Ø Feed on dead and decomposing animals/ organic matter
e.g. dead animal, undigested parts of plant and animal matter in faeces
4.9 NOTE! A food chain doesn’t normally extend beyond a terFary consumer, because
energy is lost from the chain at each trophic level, so there wouldn’t be enough energy to
support another organism aKer the terFary consumer – only about 10% of the energy is
passed on at each trophic level
Energy can be lost from food chains because:
ü Some plant material can’t be digested by animals, so it is left in their faeces
ü Some animals aren’t eaten whole or some animal parts like feather, bones can’t be eaten
ü Movement of animals, so some energy is “wasted” for movement instead of growth
ü Some energy is used to generate heat for the body
Endotherms – animals that actively generate their own heat/ regulate their body temperature
Ectotherms – rely on the environment to keep a constant temp e.g. lizards that bask under the
sun in the morning or hide under a rock because they don’t want to get too hot
4.7
Food web: a network of interconnected food chains. It shows the transfer of energy
throughout an ecosystem (an ecosystem is made up of mulFple food chains)
Q: Why is it important that food chains are interconnected in nature?
This is because this way animals have more than 1 food sources, so they won’t become
exFnct should one of those food sources ceases to exist
4.6
Producer Ø Plants and photosynthetic bacteria
Ø Autotrophs = make their own food
Ø Plants are photoautotrophic = used energy from the sun to make their own
food via the process of photosynthesis
Ø Some bacteria are chemotrophic = use inorganic chemical to make food
Primary Ø Get energy by feeding on producers à primarily herbivores
consumer
Secondary and Ø Feed on primary consumers
tertiary Ø Carnivores that get their energy by feeding on other animals
producers
Decomposers Ø Feed on dead and decomposing animals/ organic matter
e.g. dead animal, undigested parts of plant and animal matter in faeces
4.9 NOTE! A food chain doesn’t normally extend beyond a terFary consumer, because
energy is lost from the chain at each trophic level, so there wouldn’t be enough energy to
support another organism aKer the terFary consumer – only about 10% of the energy is
passed on at each trophic level
Energy can be lost from food chains because:
ü Some plant material can’t be digested by animals, so it is left in their faeces
ü Some animals aren’t eaten whole or some animal parts like feather, bones can’t be eaten
ü Movement of animals, so some energy is “wasted” for movement instead of growth
ü Some energy is used to generate heat for the body
Endotherms – animals that actively generate their own heat/ regulate their body temperature
Ectotherms – rely on the environment to keep a constant temp e.g. lizards that bask under the
sun in the morning or hide under a rock because they don’t want to get too hot
4.7
Food web: a network of interconnected food chains. It shows the transfer of energy
throughout an ecosystem (an ecosystem is made up of mulFple food chains)
Q: Why is it important that food chains are interconnected in nature?
This is because this way animals have more than 1 food sources, so they won’t become
exFnct should one of those food sources ceases to exist
