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N4 Biology > Unit 3A > Flashcards

Unit 3A Flashcards

1
Q

Habitat

A

The place where an organism is found.

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2
Q

Community

A

All the living organisms in a habitat - plants, animals and micro-organisms.

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3
Q

Ecosystem

A

Habitat + community + the interactions between them.

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4
Q

Abiotic factors

A

The non-living physical features of a habitat. eg. temperature, pH, moisture levels.

They can be measured using instruments eg. light meters, pH and temperature probes.

They affect the distribution of living organisms in a habitat.

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5
Q

Sampling techniques

A

Used to investigate the living organisms present in a habitat.

eg. pitfall traps to measure the woodlouse population, quadrats for plant species.

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6
Q

Population

A

Organisms that belong to the same species and live in the same area.

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7
Q

Pitfall trap

A

Used to estimate the population of ground-dwelling invertebrates such as woodlice.

A cup with steep sides is buried in the ground, and the entrance is disguised to deter predators.

The invertebrates are captured when they fall in and can’t escape.

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8
Q

Quadrat

A

A sampling square used to estimate abundance of organisms that don’t move eg. plants.

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9
Q

Transect

A

A line crossing a habitat from one set of conditions to another eg. light to shade or down a slope.

Quadrat samples and measurements of abiotic factors are taken at regular intervals along the line.

This shows how distribution of organisms changes across the habitat.

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10
Q

Abundance

A

How many organisms there are in a sample area.

It can be measured using a quadrat, by counting how many squares each species appears in.

eg if it is found in 7/25 squares, the abundance is 7 (regardless of how many individual organisms there are)

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11
Q

Interdependence

A

Describes how the members of a community depend on each other.

Examples include food, shelter, pollination, seed dispersal, nutrient cycling and exchange of gases.

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12
Q

Pollination

A

Transfer of the male gamete (pollen) to the stigma of another flower, so that it can be fertilised.

Insect pollinated flowers depend on insects to transfer the pollen.

Insects gain nectar and pollen as a food reward.

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13
Q

Seed dispersal

A

Seeds are contained inside fruits (modified ovary walls) that are used to spread the seeds.

When birds eat berries they gain food, and they spread the seeds of the plant.

When burrs hook onto animal fur, the plant is depending on the animal to spread its seeds.

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14
Q

Shelter

A

Animals can provide shelter for other animals eg. anemones/clown fish.

Plants provide shelter, habitats and building materials for animals and birds eg. swans nest in reeds, birds nest in trees.

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15
Q

Decomposers

A

Bacteria and fungi.

Essential for nutrient cycling, as they break down dead material and return nitrates to the soil.

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16
Q

Gas exchange

A

Plants absorb carbon dioxide for photosynthesis and release oxygen, which is used for respiration by both animals and plants.

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17
Q

Biotic factors

A

Interactions between different species in a habitat.

Interactions include food availability, predation, disease and competition.

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18
Q

Food availability

A

Determines the abundance (number) and distribution of species.

Food is scarce in some habitats, and population numbers are low eg. Arctic

Food is abundant in others, eg. mudflats, supporting large numbers of organisms.

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19
Q

Predation

A

Predators hunt prey animals for food.

Predators and prey are interdependent, with the numbers of predators affecting the number of prey, and vice versa.

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20
Q

Disease

A

Can affect the number of individuals in a population.

Diseases caused by bacteria, fungi and viruses spread rapidly in over crowded conditions.

If large numbers of organisms are killed by a disease it can affect the balance of food webs. eg myxomatosis in rabbits.

21
Q

Competition

A

Animals of the same species compete for food, territory and mates.

Organisms of different species compete for the same resource, eg. trees compete for light.

22
Q

Niche

A

An organisms exact role in an ecosystem.

It describes how it survives, what it eats and how it interacts with the habitat and other organisms.

2 species cannot occupy exactly the same niche - the stronger species will drive the weaker one out.

23
Q

Food chains and webs

A

Show feeding relationships between members of a community of organisms.

The arrows represent energy flow.

Removal of species can affect the balance of a food web.

24
Q

Producers

A

Plants that make their own food molecules using photosynthesis.

25
Q

Consumers

A

Eat other organisms to obtain food molecules.

Herbivores (primary consumers) eat plants.

Carnivores eat other animals, omnivores eat both plants and animals.

Carnivores and omnivores can be secondary or tertiary consumers, as they eat herbivores.

26
Q

Invasive species

A

An organism that is introduced into an ecosystem where it is not normally found.

It has no natural predators in its new habitat and can outcompete native wildlife.

eg. rhododendron and mink in Scotland.

27
Q

Biodiversity

A

Describes how many different species are found in a particular area.

28
Q

Population size

A

Remains the same if birth rate = death rate.

Increases if birth rate is higher than death rate.

Remains stable over time in animal populations due to disease, predation and food availability.

29
Q

Human population

A

Increasing rapidly due to improvements in healthcare and food production, which reduce the death rate.

Life expectancy is increasing.

Human populations compete with other species for food, space, water and raw materials.

This results in extinctions, and a reduction in biodiversity.

30
Q

Ecological (carbon) footprint

A

A measure of the impact of humans on the Earth.

Indicates how many resources are consumed for heating, cooking, transport, manufacturing etc.

Developed areas of the world have the highest ecological footprints.

31
Q

Human impacts on biodiversity

A

Humans consume resources in huge quantities and alter the natural environment, reducing biodiversity.

Human impacts include : habitat destruction, intensive agriculture, acid rain, climate change and litter.

32
Q

Habitat destruction

A

Land can be cleared for agriculture, housing or to provide wood for fuel or building.

Removal of trees (deforestation) reduces biodiversity, as habitats are removed.

33
Q

Intensive farming

A

Huge areas of land are used to grow a single crop, reducing biodiversity.

Hedges are removed to make fields larger, pesticides are used to kill weeds and pests and fertilisers may run off the fields into rivers.

These activities also decrease biodiversity.

34
Q

Overfishing

A

Catching too many of one species of fish reduces their populations and can affect the balance of food webs, reducing biodiversity.

35
Q

Acid rain

A

Carbon dioxide and sulphur dioxide are released when fuels are burned.

They combine with water vapour in the atmosphere to form acid, which falls as rain.

Acid rain can reduce the pH of rivers and soil, affecting the species that live there and reducing biodiversity.

36
Q

Oil and chemical spills

A

Oil can escape from tankers or pipelines.

It can wash up on beaches, smothering sea creatures such as birds, and reducing biodiversity.

It is hard to clean up and lasts a long time.

Toxic chemicals may be released from factories, reducing biodiversity.

37
Q

Genetic pollution

A

Genes from GM crops may spread into the wild population, as many crops have wild relatives that they can breed with.

The effects on biodiversity are unknown, and must be closely monitored.

38
Q

Sewage

A

Untreated sewage encourages the growth of bacteria in freshwater.

Bacteria use up all the oxygen, killing species that need high oxygen levels eg. fish.

This reduces biodiversity.

39
Q

Climate change

A

Increasing carbon dioxide levels due to human activity such as burning fossil fuels and cattle farming, cause global warming, as more heat is trapped in the atmosphere.

Global warming may result in climate change which has many consequences - storms, increased rainfall leading to flooding, higher temperatures resulting in desertification, melting ice caps and sea levels rising.

This results in a loss of biodiversity.

40
Q

Litter

A

Litter is unsightly and can be hazardous.

If it washes into rivers and seas it breaks down into microplastics.

Microplastics enter food chains when they are collected by filter feeders, which are then eaten by other organisms.

Plastic pollution also affects biodiversity when organisms swallow plastics or become entangled.

41
Q

Natural hazards

A

Include forest fires, earthquakes, tsunamis (massive waves triggered by earthquakes), flooding and volcanic activity.

They are natural events that reduce biodiversity.

They can be made worse by human activity.

Forest fires are more likely as the climate gets hotter and drier, and they are often started by humans.

Tsunamis and earthquakes can result in water pollution if populated areas are affected.

42
Q

Conservation

A

The protection of natural resources and the environment.

Aims to prevent further extinction of species and to restore biodiversity.

43
Q

Nature reserves

A

Protect plants and animals in their natural environment.

Can be very large, including whole ecosystems and many species.

May cause conflict with local people, and are difficult to patrol.

44
Q

Zoos and wildlife parks

A

Protect animals in artificial environments.

Have captive breeding programmes for endangered species.

Wildlife parks are larger than zoos.

45
Q

Arguments for and against zoos.

A

For : protect endangered species and breed them to re-introduce them to the wild, used for research and to educate the public

Against : animals are confined and used as a source of entertainment, they may be bored or stressed.

46
Q

Botanical gardens

A

Protect endangered plant species by growing them away from their natural habitat.

Used to study plants and to collect seeds and specimens which may be re-introduced into the wild.

47
Q

Hunting laws

A

Make it illegal to hunt certain species for their tusks, pelts (skin + fur) or meat.

Game wardens protect the animals from poachers.

48
Q

Fishing quotas

A

Place a limit of the number of endangered fish that can be caught.

Helps to sustain natural populations, and allows fish stocks to recover.

N4 Biology (6 decks)

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