20.3

Pollution

12 flashcards to master Pollution

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Key Concept Flip

How do untreated sewage and excess fertiliser impact aquatic ecosystems?

Answer Flip

Untreated sewage introduces pathogens and organic matter, increasing decomposers and decreasing oxygen. Excess fertilizer leads to algal blooms, which die and decompose, similarly depleting oxygen levels and harming aquatic life such as fish and invertebrates.

Key Concept Flip

What are the negative effects of non-biodegradable plastics in aquatic ecosystems?

Answer Flip

Non-biodegradable plastics persist for long periods, entangling marine life like turtles and seabirds, causing injury or death. They also break down into microplastics, ingested by organisms and potentially disrupting food chains, affecting species like zooplankton and fish.

Key Concept Flip

What are the negative effects of non-biodegradable plastics in terrestrial ecosystems?

Answer Flip

In terrestrial environments, plastics can contaminate soil, hindering plant growth by preventing water and nutrient absorption. Animals may ingest plastic, leading to blockages or toxicity within their digestive systems. An example would be earthworms and badgers.

Key Concept Flip

What are the main sources of methane as an air pollutant?

Answer Flip

Methane is released from sources like livestock farming (

Example: cattle digestion), decomposition in landfills, and natural gas leaks. These sources contribute significantly to atmospheric methane concentrations. Rice paddy fields also contribute to methane emmisions.
Key Concept Flip

What are the main sources of carbon dioxide as an air pollutant?

Answer Flip

Carbon dioxide primarily originates from the burning of fossil fuels (coal, oil, and natural gas) in power plants, vehicles, and industrial processes. Deforestation, through burning of trees, is also a major contributor.

Key Concept Flip

How do methane and carbon dioxide contribute to the enhanced greenhouse effect?

Answer Flip

Methane and carbon dioxide are greenhouse gases that trap heat in the Earth's atmosphere. Increased concentrations prevent heat from escaping into space, leading to a rise in global temperatures. This effect is particularly important for plants which require specific conditions.

Key Concept Flip

What is the link between the enhanced greenhouse effect and climate change?

Answer Flip

The enhanced greenhouse effect, caused by increased levels of greenhouse gases like carbon dioxide and methane, leads to climate change. This results in rising sea levels, altered weather patterns (

Example: more frequent extreme weather events), and disruptions to ecosystems.
Definition Flip

What is eutrophication?

Answer Flip

Eutrophication is the enrichment of an ecosystem with chemical nutrients, typically compounds containing nitrogen or phosphorus. It often results from runoff of fertilizers from agricultural land. This enrichment then leads to a cascade of ecological effects.

Key Concept Flip

Explain the first step of eutrophication: increased availability of nitrate and other ions.

Answer Flip

The process begins with increased levels of nutrients, such as nitrates and phosphates, entering a water body. These nutrients come from sources like agricultural runoff (fertilizers) or sewage.

Example: rainwater can wash excess nitrate into lakes.
Key Concept Flip

Explain the second step of eutrophication: increased growth of producers.

Answer Flip

The increased availability of nutrients fuels rapid growth of aquatic producers like algae and phytoplankton. This rapid growth is termed an algal bloom and can cause the water to become murky.

Example: *Chlamydomonas* reproduces rapidly.
Key Concept Flip

Explain the third step of eutrophication: increased decomposition after death of producers.

Answer Flip

Following the algal bloom, the algae die and sink to the bottom of the water body. Decomposers, such as bacteria and fungi, break down the dead organic matter.

Example: *Aspergillus* bacteria perform aerobic respiration.
Key Concept Flip

Explain the final step of eutrophication: reduction in dissolved oxygen and death of organisms.

Answer Flip

Decomposers consume large amounts of dissolved oxygen during aerobic respiration. This reduces the oxygen available for other aquatic organisms, leading to their death. Fish (

Example: trout), invertebrates, and other oxygen-dependent species will die.

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20.2 Habitat destruction 20.4 Conservation

Key Questions: Pollution

What is eutrophication?

Eutrophication is the enrichment of an ecosystem with chemical nutrients, typically compounds containing nitrogen or phosphorus. It often results from runoff of fertilizers from agricultural land. This enrichment then leads to a cascade of ecological effects.

About Pollution (20.3)

These 12 flashcards cover everything you need to know about Pollution for your Cambridge IGCSE Biology (0610) exam. Each card is designed based on the official syllabus requirements.

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