Practise Abiotic factors. 11 exam-style questions on this subtopic, at up to four difficulty levels, with full mark schemes and a progress tracker. Free, no account needed.
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The oxygen level in water is an abiotic factor for aquatic animals. Why do aquatic animals need oxygen?
For aerobic respiration
Sample questions
Written for this site in the style of AQA exam questions. They are not taken from real past papers.
Question 1Easy5 marks
Abiotic factors are non-living factors that can affect a community.
(a) Which two of the following are abiotic factors? Tick (✓) two boxes.[2]
Availability of food
Light intensity
New pathogens
Soil pH
Predators
(b) Give two other abiotic factors that can affect a community.[2]
(c) The oxygen level in water is an abiotic factor for aquatic animals. Why do aquatic animals need oxygen?[1]
Show the answer and mark scheme
(a)Answer: Light intensity; Soil pH
(b)
temperature
moisture level / amount of water
soil mineral content
wind intensity / direction
carbon dioxide level (for plants)
oxygen level (for aquatic animals)
(c)Answer: For aerobic respiration
for (aerobic) respiration
Question 2Medium6 marks
A factory releases warm water into a river. Scientists measured the water temperature and the concentration of dissolved oxygen at different distances downstream from the factory. They also counted the mayfly nymphs in samples taken from the river bed. {table} shows the results.
[object Object]
(a) Describe the relationship between the concentration of dissolved oxygen and the number of mayfly nymphs.[1]
(b) Mayfly nymphs need water with a high concentration of dissolved oxygen. Use {table} to explain the distribution of mayfly nymphs in the river.[3]
(c) The scientists took several samples at each distance and calculated a mean. Give one reason why.[1]
(d) Suggest one other abiotic factor the scientists should measure before concluding that oxygen concentration affects the distribution of mayfly nymphs.[1]
Show the answer and mark scheme
(a)
as the concentration of dissolved oxygen increases, the number of mayfly nymphs increases / positive correlation
(b)
the water is warmest near the factory
warmer water contains less dissolved oxygen
near the factory, nymphs cannot get enough oxygen for (aerobic) respiration, so few survive
further downstream the water is cooler and contains more oxygen, so more nymphs survive
(c)
to reduce the effect of an unusual sample / anomaly / so the result is more representative / accurate
(d)
pH
speed of water flow
concentration of pollutants / chemicals from the factory
light intensity
type of river bed
Question 3Hard6 marks
A shallow pond contains algae, pondweed, frogs, fish and many insects. During a long, hot, dry summer, the water level fell to half its normal depth and the water temperature rose.
Explain how the changes in abiotic factors during the summer could affect the community of organisms in the pond.[6]
Show the answer and mark scheme
higher temperature means that less oxygen can dissolve in the water
higher temperature increases the rate of respiration of the animals (enzymes work faster), so they need more oxygen
at night there is no photosynthesis, so oxygen levels may fall very low and fish and other animals may die
more light and warmth may cause rapid growth of algae, which shade the pondweed so it photosynthesises less and dies
dead algae and plants are decayed by bacteria, which use oxygen in respiration
the falling water level reduces the habitat; shallow areas dry out, killing frog spawn, tadpoles or insect larvae
animals are more crowded, so there is more competition for food, space and oxygen
only species that can tolerate warm water with little oxygen survive, so biodiversity falls and food chains are affected
Marked with levels of response: the full level descriptors are in the app.