In GCSE Science, students will learn about the transfer of energy and biomass in food chains. This is the first of three quizzes on that topic and it looks specifically at the transfer of chemical energy as biomass and how each stage of the food chain sees the transfer of less energy from one organism to another.
Apart from the extremophiles (some of whom get their energy from chemicals and heat coming from deep-sea hydrothermal vents), animals are solar powered! How come? The answer is food chains. Food chains are concerned with the transfer of chemical energy as biomass to the top predator. They always begin with plants or algae and end with a carnivore and they can be combined into food webs. A food web describes the feeding relationships within a community of plants and animals.
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A food chain can be represented as a pyramid of biomass (mass of living material) by drawing a pyramid style of histogram. Each trophic (feeding) level is drawn to the same scale. The lowest level of the food chain normally has the highest biomass whilst the top predator has the lowest biomass. The reason for this is that energy and materials are lost at each stage of the food chain. Let's consider a simple 3 step food chain to see how this works.
The start of a food chain are the plants or algae living in the community. They absorb the Sun's energy and use it for photosynthesis. During photosynthesis, some of the food (glucose) they produce is used to release energy in the process of respiration and some is used to form the biomass of the plant.
Herbivores eat the plants or algae. Some of the energy from what they eat is used immediately for respiration and therefore lost from the food chain. Some is stored in the body or used by the body for growth, repair or both, this keeps the biomass in the food chain. The herbivores excrete waste material which lessens the amount of biomass in the system.
Next in the food chain is a predator. This hunts and eats the herbivores. As it hunts, a lot of the energy from its previous successful kill is used up and lost from the food chain. More is lost as the predator excretes its wastes. Only a proportion of the energy from eating the prey remains in the predator.
OK, let's see what you know about energy and food chains now...
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1.
|
In a food chain what is meant by the word producer? |
|
[ ] |
An animal that produces a lot of waste material |
[ ] |
A plant or animal that makes energy |
[ ] |
A plant or algae |
[ ] |
An insect |
|
|
2.
|
What is the source of energy for most food chains? |
|
[ ] |
The Moon |
[ ] |
The Sun |
[ ] |
Chlorophyll |
[ ] |
Chromosomes |
|
|
3.
|
During photosynthesis, which of the following is the energy transfer? |
|
[ ] |
Light to sound |
[ ] |
Light to kinetic |
[ ] |
Light to chemical |
[ ] |
Light to heat |
|
|
4.
|
Other than light, what else is required for photosynthesis? |
|
[ ] |
Water and oxygen |
[ ] |
Water and carbon dioxide |
[ ] |
Water, oxygen and chlorophyll |
[ ] |
Water, carbon dioxide and chlorophyll |
|
|
5.
|
In a food chain, what does the arrow represent? |
|
[ ] |
The environment |
[ ] |
A change in biomass |
[ ] |
An increase in numbers of animals |
[ ] |
The flow of energy |
|
|
6.
|
How much of the Sun's energy produces biomass in plants? |
|
[ ] |
All of it |
[ ] |
Most of it |
[ ] |
Some of it |
[ ] |
Very little of it |
|
|
7.
|
In one year, the Sun supplies 4 x 106kJ to a particular habitat, 15kJ reaches the top predator. What percentage of the Sun's energy is transferred to the predator? Try working it out rather than trying to guess. |
|
[ ] |
0.0375% |
[ ] |
0.00375% |
[ ] |
0.000375% |
[ ] |
0.00000375% |
|
|
8.
|
Students investigated a food chain in a garden. The students found 650 aphids feeding on one rose plant. Five ladybirds were feeding on the aphids. Which of the following statements about the biomass of the ladybirds is true? |
|
[ ] |
The biomass of the ladybirds is greater than the biomass of the aphids |
[ ] |
The biomass of the ladybirds is less than the biomass of the rose plant |
[ ] |
The biomass of the ladybirds is more than the biomass of the rose plant |
[ ] |
The biomass of the ladybirds is the same as the biomass of the aphids |
|
|
9.
|
Students measured the biomass of a community living in leaf litter under the trees in the school conservation area. They found woodlice feeding on the leaves, ground beetles feeding on the woodlice and centipedes feeding on the beetles. Each student weighed the leaves in their sample and the other organisms and put their results together with the rest of the class. Which of the following could represent the class results in order of the food chain starting from the leaves? |
|
[ ] |
25g, 35g, 38g, 40g |
[ ] |
1kg, 550g, 38g, 750g |
[ ] |
482g, 98g, 67g, 80g |
[ ] |
800g, 45g, 3g, 0.0005g |
|
|
10.
|
For every 200kJ a gazelle gets from eating, 125kJ are excreted and 65kJ are used in respiration so how much of the original energy would be passed on to a lion that caught and ate it? |
|
[ ] |
5% |
[ ] |
10% |
[ ] |
15% |
[ ] |
20% |
|
|
1.
|
In a food chain what is meant by the word producer? |
|
[ ] |
An animal that produces a lot of waste material |
[ ] |
A plant or animal that makes energy |
[x] |
A plant or algae |
[ ] |
An insect |
|
|
2.
|
What is the source of energy for most food chains? |
|
[ ] |
The Moon |
[x] |
The Sun |
[ ] |
Chlorophyll |
[ ] |
Chromosomes |
|
|
3.
|
During photosynthesis, which of the following is the energy transfer? |
|
[ ] |
Light to sound |
[ ] |
Light to kinetic |
[x] |
Light to chemical |
[ ] |
Light to heat |
|
|
4.
|
Other than light, what else is required for photosynthesis? |
|
[ ] |
Water and oxygen |
[ ] |
Water and carbon dioxide |
[ ] |
Water, oxygen and chlorophyll |
[x] |
Water, carbon dioxide and chlorophyll |
|
|
5.
|
In a food chain, what does the arrow represent? |
|
[ ] |
The environment |
[ ] |
A change in biomass |
[ ] |
An increase in numbers of animals |
[x] |
The flow of energy |
|
|
6.
|
How much of the Sun's energy produces biomass in plants? |
|
[ ] |
All of it |
[ ] |
Most of it |
[ ] |
Some of it |
[x] |
Very little of it |
|
|
7.
|
In one year, the Sun supplies 4 x 106kJ to a particular habitat, 15kJ reaches the top predator. What percentage of the Sun's energy is transferred to the predator? Try working it out rather than trying to guess. |
|
[ ] |
0.0375% |
[ ] |
0.00375% |
[x] |
0.000375% |
[ ] |
0.00000375% |
|
|
8.
|
Students investigated a food chain in a garden. The students found 650 aphids feeding on one rose plant. Five ladybirds were feeding on the aphids. Which of the following statements about the biomass of the ladybirds is true? |
|
[ ] |
The biomass of the ladybirds is greater than the biomass of the aphids |
[x] |
The biomass of the ladybirds is less than the biomass of the rose plant |
[ ] |
The biomass of the ladybirds is more than the biomass of the rose plant |
[ ] |
The biomass of the ladybirds is the same as the biomass of the aphids |
|
|
9.
|
Students measured the biomass of a community living in leaf litter under the trees in the school conservation area. They found woodlice feeding on the leaves, ground beetles feeding on the woodlice and centipedes feeding on the beetles. Each student weighed the leaves in their sample and the other organisms and put their results together with the rest of the class. Which of the following could represent the class results in order of the food chain starting from the leaves? |
|
[ ] |
25g, 35g, 38g, 40g |
[ ] |
1kg, 550g, 38g, 750g |
[ ] |
482g, 98g, 67g, 80g |
[x] |
800g, 45g, 3g, 0.0005g |
|
|
10.
|
For every 200kJ a gazelle gets from eating, 125kJ are excreted and 65kJ are used in respiration so how much of the original energy would be passed on to a lion that caught and ate it? |
|
[x] |
5% |
[ ] |
10% |
[ ] |
15% |
[ ] |
20% |
|
|