When fertiliser runoff enriches water, causing algal blooms that block light; the resulting decomposing bacteria use up dissolved oxygen, reducing biodiversity.

A species that is native to a particular area.

What is the purpose of fish farms?

To raise large numbers of fish in a small space to provide food (protein) for humans, reducing the pressure of overfishing wild fish.

Give two methods used to maximise yield in fish farms.

Any two of: selective breeding for fast growth; using nets and cages to prevent interspecific predation; grouping fish by age and size to limit intraspecific predation; controlling water quality; feeding high-protein pellets; preventing disease with antibiotics or pesticides.

Why are fish grouped by age and size in fish farms?

To limit intraspecific predation (larger fish of the same species eating smaller ones), which increases the yield.

Give two ways fish farms can harm biodiversity.

Any two of: predators being attracted and caught in nets; diseases spreading quickly to other species in the water; escaped fish affecting native species; eutrophication.

How can a non-indigenous species reduce biodiversity through competition?

It may outcompete native species for food, water or space, possibly eradicating one or more indigenous species (e.g. grey squirrels outcompeting red squirrels).

How can introducing a non-indigenous species spread disease?

It may bring new diseases that are deadly to indigenous species; e.g. grey squirrels carry the parapox virus, which is fatal to red squirrels.

Outline the steps of eutrophication.

Fertiliser runoff causes algal blooms that block sunlight, so water plants and algae die. Decomposing bacteria then increase in number and use up the dissolved oxygen, so aquatic organisms such as fish and insects may be unable to survive.

How can a non-indigenous species disrupt a food chain?

It provides a new food source or a new predator, disrupting the balance and affecting the populations of other organisms (e.g. cane toads poisoning predators in Australia).

Positive human actions — such as protected areas, breeding programmes, seed banks and reforestation — that help maintain or recover biodiversity.

Why does maintaining biodiversity help keep an ecosystem stable?

Because of interdependence, the loss of one species has knock-on effects on others; maintaining biodiversity avoids disruption that could lead to the loss of species.

How can a loss of biodiversity affect the human food supply?

Some farming methods threaten certain populations (e.g. overfishing reducing fish stocks), which could affect the future availability of that species as food.

How can a loss of biodiversity affect medicine?

Some medicines are extracted from plants that may be at risk of extinction due to human activities such as deforestation.

Give two economic benefits of maintaining biodiversity.

Conservation efforts and ecotourism provide jobs to support local populations, and ecotourism provides economic support for future conservation efforts.

Why is protecting peatlands and wetlands important for climate change?

They store lots of carbon, so preventing disruption to them reduces the amount of carbon released back into the atmosphere as carbon dioxide.

Name three methods used to conserve species directly.

Protected/conservation areas, breeding programmes (often in zoos), and seed banks.

How does reforestation help biodiversity?

Replanting large areas with a variety of tree species rebuilds biodiversity, provides important habitats, and helps maintain the global carbon balance by removing carbon dioxide for photosynthesis.

Give one conflicting pressure that makes maintaining biodiversity difficult.

Any of: the cost of conservation programmes; protecting food security (land needed for farming); or the development of society (land needed for housing and agriculture for a growing population).

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Human Influences on the Environment (Edexcel GCSE Combined Science: Biology): Flashcards

Exam code: 1SC0

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FrontHuman Impact on Biodiversity
Eutrophication

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Cards in this collection (23)

Eutrophication
When fertiliser runoff enriches water, causing algal blooms that block light; the resulting decomposing bacteria use up dissolved oxygen, reducing biodiversity.
Indigenous species
A species that is native to a particular area.
What is the purpose of fish farms?
To raise large numbers of fish in a small space to provide food (protein) for humans, reducing the pressure of overfishing wild fish.
Give two methods used to maximise yield in fish farms.
Any two of: selective breeding for fast growth; using nets and cages to prevent interspecific predation; grouping fish by age and size to limit intraspecific predation; controlling water quality; feeding high-protein pellets; preventing disease with antibiotics or pesticides.
Why are fish grouped by age and size in fish farms?
To limit intraspecific predation (larger fish of the same species eating smaller ones), which increases the yield.
Give two ways fish farms can harm biodiversity.
Any two of: predators being attracted and caught in nets; diseases spreading quickly to other species in the water; escaped fish affecting native species; eutrophication.
How can a non-indigenous species reduce biodiversity through competition?
It may outcompete native species for food, water or space, possibly eradicating one or more indigenous species (e.g. grey squirrels outcompeting red squirrels).
How can introducing a non-indigenous species spread disease?
It may bring new diseases that are deadly to indigenous species; e.g. grey squirrels carry the parapox virus, which is fatal to red squirrels.
Outline the steps of eutrophication.
Fertiliser runoff causes algal blooms that block sunlight, so water plants and algae die.
Decomposing bacteria then increase in number and use up the dissolved oxygen, so aquatic organisms such as fish and insects may be unable to survive.
How can a non-indigenous species disrupt a food chain?
It provides a new food source or a new predator, disrupting the balance and affecting the populations of other organisms (e.g. cane toads poisoning predators in Australia).
An species is one which is native to a particular area.
indigenous
In eutrophication, decomposing bacteria use up the dissolved in the water, so fish and insects may be unable to survive.
oxygen
Conservation
Positive human actions — such as protected areas, breeding programmes, seed banks and reforestation — that help maintain or recover biodiversity.
Why does maintaining biodiversity help keep an ecosystem stable?
Because of interdependence, the loss of one species has knock-on effects on others; maintaining biodiversity avoids disruption that could lead to the loss of species.
How can a loss of biodiversity affect the human food supply?
Some farming methods threaten certain populations (e.g. overfishing reducing fish stocks), which could affect the future availability of that species as food.
How can a loss of biodiversity affect medicine?
Some medicines are extracted from plants that may be at risk of extinction due to human activities such as deforestation.
Give two economic benefits of maintaining biodiversity.
Conservation efforts and ecotourism provide jobs to support local populations, and ecotourism provides economic support for future conservation efforts.
Why is protecting peatlands and wetlands important for climate change?
They store lots of carbon, so preventing disruption to them reduces the amount of carbon released back into the atmosphere as carbon dioxide.
Name three methods used to conserve species directly.
Protected/conservation areas, breeding programmes (often in zoos), and seed banks.
How does reforestation help biodiversity?
Replanting large areas with a variety of tree species rebuilds biodiversity, provides important habitats, and helps maintain the global carbon balance by removing carbon dioxide for photosynthesis.
Give one conflicting pressure that makes maintaining biodiversity difficult.
Any of: the cost of conservation programmes; protecting food security (land needed for farming); or the development of society (land needed for housing and agriculture for a growing population).
Storing seeds of plant species for many years to future-proof them is done using seed .
banks
is the conscious replanting of forest to counteract the negative impact of deforestation.
Reforestation

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