A farmer has a small pond on their farm land. One year, most of the organisms in the pond die. The next year, the farmer decreases their use of nitrate fertilisers and fewer organisms in the pond die. Which statement explains why this will help increase the number of organisms living in the pond?

There is a decrease in dissolved oxygen due to an increase in decomposition.

There is a decrease in dissolved oxygen due to an increase in photosynthesis.

There is an increase in dissolved oxygen due to a decrease in decomposition.

There is an increase in dissolved oxygen due to a decrease in photosynthesis.

Biology

IGCSE&ALevel

CAIE

Exam No：0610_w24_qp_22 Year：2024 Question No：37

Answer:

Knowledge points:

21.3.1 State the sources and effects of pollution of land and water, e.g. rivers, lakes and the sea, by insecticides, herbicides and by nuclear fall-out

21.3.10 Discuss the causes and effects on the environment of acid rain

21.3.11 State the measures that are taken to reduce sulfur dioxide pollution and reduce the impact of acid rain

21.3.12 Explain how increases in carbon dioxide and methane concentrations in the atmosphere cause an enhanced greenhouse effect that leads to climate change

21.3.13 Describe the negative impacts of female contraceptive hormones in water courses, limited to reduced sperm count in men and feminisation of aquatic organisms

21.3.2 State the sources and effects of pollution of water (rivers, lakes and the sea) by chemical waste, discarded rubbish, untreated sewage and fertilisers

21.3.3 State the sources and effects of pollution of water (rivers, lakes and the sea) by chemical waste, discarded rubbish, untreated sewage and fertilisers

21.3.4 State the sources and effects of pollution of the air by methane and carbon dioxide, limited to the enhanced greenhouse effect and climate change

21.3.5 State the sources and effects of pollution of the air by methane and carbon dioxide, limited to the enhanced greenhouse effect and climate change

21.3.6 State the sources and effects of pollution of the air by methane and carbon dioxide, limited to the enhanced greenhouse effect and climate change

21.3.7 State the sources and effects of pollution of the air by methane and carbon dioxide, limited to the enhanced greenhouse effect and climate change

21.3.8 Explain the process of eutrophication of water in terms of: – increased availability of nitrate and other ions – increased growth of producers – increased decomposition after death of producers – increased aerobic respiration by decomposer – reduction in dissolved oxygen – death of organisms requiring dissolved oxygen in water

21.3.9 Discuss the effects of non-biodegradable plastics in the environment, in both aquatic and terrestrial ecosystems

A farmer has a small pond on their farm land. One year, most of the organisms in the pond die. The next year, the farmer decreases their use of nitrate fertilisers and fewer organisms in the pond die. Which statement explains why this will help increase the number of organisms living in the pond?

Answer:

Knowledge points:

Solution:

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