1 markWhich of the following is a correct example of a population?
All the animals in a forest.
All the goldfish in a pond.
All the species of animals in Europe.
All the people born in Scotland over a 150-year period.
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1 markThe diagram below illustrates part of the carbon cycle.
Which process is shown by the arrow labelled Y?
Photosynthesis
Feeding
Respiration
Combustion
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1 markA food chain is shown below.
tree ➔ small insects ➔ small birds ➔ birds of prey
One of the pyramids of number below represents this food chain.
Which one would be correct?
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1 markWhich of the processes below is carried out by bacteria in the roots of leguminous plants?
Nitrogen fixation
Decomposition
Nitrification
Denitrification
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1 markWhich of the following diagrams show a pyramid of biomass for a forest?
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1 markWhich of the following is an example of a community?
All the populations of all species in a forest.
All the goldfish in a pond.
All the wheat and corn in a field.
All the plants in a forest.
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1 markThe graphs below show how the number of carnivores change over a period of time in a habitat.
At point X the herbivores in the habitat are removed.
Which graph correctly shows the effect of this on the number of carnivores?
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1 markThe graph shows how the world population of humans has increased from 1650 until the year 2000.
Which stage in this sigmoidal population curve is shown by point X?
Stationary phase
Lag phase
Exponential (log) phase
Death phase
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1 markWhich statement gives the best explanation for why most food chains have no more than five trophic levels?
Because 20% of the energy is transferred at each level and after 5 levels, all the energy is used up (5 × 20% = 100%).
The numbers of organisms are insufficient because the top predator has to have a count of 1 in a pyramid of numbers.
The biomass transferred from a consumer to the next-level consumer is too little.
There is a large amount of energy loss at each level so insufficient energy can be passed up to the sixth trophic level.
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1 markLook at the information about a food chain.
| Organism | Number | Biomass / kg |
| Oak tree | 1 | 400,000 |
| Aphids | 9,000 | 900 |
| Predatory midges | 120 | 45 |
What is the percentage biomass of the aphids transferred to the midges?
0.05 %
1.3 %
5%
0.225 %
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1 markA scientist grew some bacterial cells in ideal growth conditions.
Each bacterial cell can reproduce itself once in a 30 minute period.
For an initial population of 10 bacterial cells, how many cells will be present in the population after 8 hours of cell reproduction? You can assume that 10% of the bacterial cells die in the final few minutes before the end of the growth period.
655 360 cells
589 824 cells
144 cells
65 536 cells
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1 markThe image below shows a pyramid of biomass for a food chain in a rainforest ecosystem.
What would be an appropriate pyramid of numbers for this food chain?
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1 markThe graph below shows the growth of the human population globally since 1630.
Which of the following options represents the longest time period taken for the population of humans to double?
100 years
200 years
300 years
400 years
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1 markThe image shows a food web.
Which organism, from the food web, feeds on the greatest variety of organisms?
Whelks
Crabs
Limpets
Mussels
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1 markThe diagram below shows part of the nitrogen cycle.
Which letter would represent denitrification?
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1 markWhich letter shows the path of the energy from the sun?
chemical energy in sugars → stored in plants → trapped in chlorophyll
trapped in chlorophyll → chemical energy in sugars → stored in plants
stored in plants → chemical energy in sugars → trapped in chlorophyll
stored in plants → trapped in chlorophyll → chemical energy in sugars
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