Monitoring & Maintaining the Environment (OCR GCSE Combined Science A (Gateway): Biology): Flashcards
Exam code: J250
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Define abundance.
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Cards in this collection (54)
Define abundance.
The number of organisms of a particular species in a habitat.
Define distribution.
The geographical spread of a species — where in a habitat it is found.
Why do ecologists sample rather than count every organism?
A habitat is far too large to count completely, so a well-chosen sample is scaled up to estimate the whole population.
Why must sampling be random?
To avoid bias. Choosing where to sample would give an unrepresentative result.
How can quadrat positions be chosen randomly?
By using a random number generator to pick coordinates within the marked-out study area.
Define quadrat.
A square frame placed on the ground, within which the organisms present are recorded.
Give three things a quadrat can be used to record.
The number of individuals of one species.
Species richness — how many different species are present.
Percentage cover of a species.
When is percentage cover used instead of counting individuals?
When individual plants are hard to count, such as grass or moss.
Define transect.
A line along which quadrats are placed at set intervals, to study how distribution changes across a habitat.
When would you use a transect rather than random quadrats?
When conditions change gradually across the area, such as from a shoreline inland.
Why is capture-recapture used for animals rather than quadrats?
Animals move about, so they could easily be missed or counted twice.
Describe the capture-recapture method.
Capture a sample, mark the animals and release them.
After time for them to mix back in, capture a second sample and count how many are marked.
Write the capture-recapture equation.
population = (first sample × second sample) ÷ number marked in the second sample
54 snails are marked; of 48 recaptured, 9 are marked. Estimate the population.
(54 × 48) ÷ 9 = 288 snails
Give two conditions for capture-recapture to give a valid estimate.
The marking must not harm the animals or make them easier for predators to see.
Enough time must be allowed for them to mix back into the population.
What is a pooter used for?
A hand-held suction device for capturing small invertebrates such as flies and spiders.
What is a sweep net used for?
Sweeping through vegetation to catch the invertebrates living there.
What is an identification key?
A series of yes/no questions that leads you step by step to the identity of an organism.
Name two abiotic factors measured during fieldwork, and how.
Light intensity, using a light meter.
Soil pH, using a pH probe or indicator solution.
A key that offers only two possible answers at each step is called a ＿＿＿＿＿＿＿＿ key.
A key that offers only two possible answers at each step is called a dichotomous key.
True or False?
Sampling gives the exact size of a population.
False.
It gives an estimate, which is reliable only if the sampling was properly random.
What is the largest biotic factor affecting other species on Earth?
Human impact.
Why is human impact on ecosystems increasing?
The human population is growing rapidly, and people expect a higher standard of living, which uses more resources.
Name three human uses of land that threaten biodiversity.
Farming, building homes and businesses, and quarrying for minerals.
Waste disposal also takes up land.
How does taking land for farming reduce biodiversity?
Habitats are destroyed, so the species that lived there lose their food and shelter.
How does hunting threaten biodiversity?
It can reduce a population faster than it can breed, and may drive a species to extinction.
Define conservation.
Protecting species and habitats so that humans can use natural resources without harming biodiversity.
Give three conservation measures that protect biodiversity.
Protecting habitats by law.
Creating protected areas such as national parks and reserves.
Using zoos and botanical gardens as a safe store of species.
Why is conservation not the same as leaving an area untouched?
Conservation allows humans to live alongside other species and use resources, rather than excluding people entirely.
Give three ways humans depend on other species.
Photosynthetic organisms produce the oxygen we respire.
Pollinators such as bees pollinate our food crops.
Many plants provide medicines.
Why is maintaining biodiversity in humans' own interest?
Humans depend on other species through interdependence, so a falling biodiversity threatens our own survival.
Give an example of a positive human interaction with an ecosystem.
Conservation schemes that protect a species or restore a habitat, reversing a fall in biodiversity.
Why are raw materials being used up a concern?
Many cannot be replaced, so alternatives must be found before they run out.
Creating national parks and nature reserves protects habitats and is an example of ＿＿＿＿＿＿＿＿.
Creating national parks and nature reserves protects habitats and is an example of conservation.
The main driver of increasing human impact on ecosystems is the growing human ＿＿＿＿＿＿＿＿.
The main driver of increasing human impact on ecosystems is the growing human population.
True or False?
All human interactions with ecosystems are negative.
False.
Conservation and habitat protection are positive interactions that increase biodiversity.
True or False?
Humans could survive without other species.
False.
We depend on other species for oxygen, food crops and medicines.
Define biodiversity.
The variety of different species living in an area.
Give three benefits of maintaining biodiversity.
It maintains the human food supply.
It keeps food chains and webs intact.
It provides materials such as timber and medicines.
What is meant by local biodiversity?
The biodiversity within a small geographical area, such as a national park or a single country.
Give one advantage of working on biodiversity at a local level.
A government can pass laws within its own borders, so protection can be made a legal requirement.
How can small local schemes add up to something bigger?
If enough form, they can join into corridors of protected land linking habitats together.
Define ecotourism.
Tourism that lets people visit wild landscapes and species while supporting rather than harming biodiversity.
Give an example of ecotourism.
Whale-watching trips, or tours of biodiversity-friendly farms.
How does ecotourism help maintain biodiversity?
It gives local people an income that depends on protecting wildlife rather than exploiting it.
Give one drawback of ecotourism.
Too many visitors would themselves damage the habitat they came to see.
Why is a global approach to biodiversity needed as well as a local one?
Many species cross country borders, such as migrating birds and whales, so one country acting alone is not enough.
Why is it difficult to gain agreement on global conservation schemes?
Governments must co-operate, but conflicts between countries and differing cultural priorities get in the way.
Why is monitoring conservation schemes a challenge?
International agreements are often not legally binding, so it is hard to check they are being followed or to enforce them.
Give one objection local people may raise to a biodiversity scheme.
The land could be used for housing or growing food, and restrictions on fishing or hunting can reduce their income.
What can happen if one species is removed from a food chain?
The whole food chain can collapse, whichever level the species occupied.
Tourism that attracts visitors to wild landscapes without damaging them is called ＿＿＿＿＿＿＿＿.
Tourism that attracts visitors to wild landscapes without damaging them is called ecotourism.
True or False?
Global conservation agreements are legally binding on all countries.
False.
Many are not legally binding, which is why they are hard to monitor and enforce.
True or False?
A fall in biodiversity is sustainable in the long term.
False.
As conditions change, low biodiversity leaves ecosystems unable to adapt — so it is unsustainable.
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