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Biology > Ecology > Flashcards

Ecology Flashcards

0
Q

What problem is caused when fertilisers enter rivers and lakes?

A

Eutrophication

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1
Q

Give an advantage and disadvantage of intensive farming methods

A

Advantage - boosts food production

Disadvantage - destruction of habitats, pollution, reduction in diversity

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2
Q

What is intercropping?

A

The practice of growing two or more crops in the same field at the same time. This uses space efficiently, and makes maximum use of the soil nutrients.

Intercropping also encourages diversity

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3
Q

Explain how planting hedgerows helps to minimise negative effects of agriculture on ecosystems

A

Hedgerows increase the number of habitats available for colonisation and thus species diversity

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4
Q

Explain how planting trees helps to minimise the negative effects if agriculture on ecosystem

A

Trees act as wind shields and also prevent soil erosion

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5
Q

Explain how planting the legumes helps to minimise the negative effects of agriculture on ecosystems

A

Legumes naturally restore nitrates to the soil

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6
Q

Instead of chemical pesticides, what alternative method farmers can use to get rid of pests?

A

Biological control

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7
Q

List three different categories of pesticide

A

Herbicides, fungicides, and insecticides

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8
Q

Give two advantages of chemical control

A

It is often very effective at completely eradicating the pest species

It is relatively fast compared to biological control

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9
Q

Give three disadvantages of chemical control

A

It may be toxic to non-target organisms

It may be non-biodegradable and persist in the environment

It may bioaccumulate in living organisms

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10
Q

What is meant by biological control?

A

The use of a parasite or predator to control the number of pests (e.g. Aphids are controlled by the use of ladybirds)

Biological control also includes breeding pest-resistant crops

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11
Q

Give three advantages of biological control

A

It is very specific

Pests do not usually become resistant to biological control

It does not pollute the environment

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12
Q

Give three disadvantages of biological control

A

It is relatively slow compared to chemical control

Pests are never completely eliminated, so there is always some damage to crops

The control organism may become a pest in its own right

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13
Q

What is pollution?

A

A change in the abiotic or biotic characteristics of the environment as a result of human activities which introduce harmful substances into the atmosphere and water supplies

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14
Q

Name two gases that contribute to the production of acid rain

A

Sulphur dioxide and nitrogen oxides

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15
Q

Name two gases that contribute to the greenhouse effect

A

Carbon dioxide and methane

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16
Q

Explain how the greenhouse effects may lead to global warming

A

The ‘greenhouse gases’ prevent some of the sun’s radiation heat from leaving the atmosphere. As the concentration of these gases increases, more heat is trapped in the atmosphere, leading to an increase in the average temperature of the earth - global warming

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17
Q

Suggest one environmental consequence of global warming

A

Melting of the polar ice caps, leading to rising sea levels and flooding

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18
Q

What is eutrophication?

A

The decrease in biodiversity resulting from the pollution of a river or lake.

The pollutants stimulate the growth of algae in the water, which eventually die leading to an increase in the respiration of aerobic decomposers (e.g. bacteria)

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19
Q

Suggest two possible causes of eutrophication

A

Fertilisers and sewage entering rivers or lakes

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20
Q

Outline how eutrophication leads to reduced species diversity in a river or lake

A

The algal bloom caused by eutrophication and the subsequent increase in aerobic respiration by the the decomposing bacteria results in an increased biochemical oxygen demand and subsequent reduction in oxygen concentration in the water.

Consequently, many aquatic organisms, such as fish, die due to a lack of oxygen, reducing species diversity in the river or lake

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21
Q

What is succession?

A

The process by which plant communities gradually develop on bare land.

The end point of succession is the development of a stable climax community

22
Q

What is primary succession?

A

Primary succession occurs on land where there is no soil and no living organisms, such as created by volcanic eruption

23
Q

What is secondary succession?

A

Secondary succession occurs when most of the living organisms in an area have been destroyed but the soil and some living organisms remain.

E.g. Woodland that has been destroyed by fire

24
Q

Describe how quadrats are used to investigate ecosystems

A

Quadrats are used to sample areas of plant cover and can be point or area quadrats of different sizes. They provide information about percentage cover, species richness and diversity

25
Q

Describe how transects are used to investigate ecosystems

A

Transects are used to survey an area and are useful in investigating trends, such as the distribution of organisms on a rocky shore

They may be along a single line or in a belt of land

26
Q

Define carrying capacity

A

Maximum population that can be maintained over a time in a particular habitat

27
Q

Define intraspecific competition

A

Competition between individuals of the same species

28
Q

Define interspecific competition

A

Competition between individuals of different species

29
Q

What is meant by the term diversity?

A

A measure of the number of different species present in an ecosystem

30
Q

Outline the distinguishing features of an ecosystem with low diversity

A

Low diversity is common in extreme ecosystems such as deserts, tundra and salt marshes.

In these areas, plant and animal populations are mainly affected by abiotic factors and the diversity index is low

31
Q

Outline the distinguishing features of an ecosystem with high diversity

A

High diversity is common in ecosystems that are usually mature, natural (not created by human activity) and have environmental conditions that are not too hostile.

In these ecosystems, populations are mostly affected by biotic factors, and so the diversity index is high

32
Q

What is meant by the term population?

A

A population is a group of individuals of the same species occupying a certain area

33
Q

Distinguish between population size and population density

A

Population size refers to the total number of individuals present in a given area

Population density is a measure of the number of individual organisms per unit area

34
Q

Explain what are density-dependant factors

A

Density-dependant factors are factors limiting the size of a population whose effects are proportional to the density of the population

These factors tend to be biotic, for example, food supply (for both predators and prey) and infectious disease

35
Q

Explain what are density-Independant factors

A

Density-Independant factors are factors limiting the size of a population.

These factors tend to be abiotic, for example, temperature and water availability

36
Q

What is a pyramid of biomass?

A

A pyramid of biomass shows the mass of organisms at each tropic level in a food chain

37
Q

What are the two main factors that contribute to the destruction of natural habitats?

A

Expansion of human population

Over-exploitation of resources (e.g. Deforestation)

38
Q

What are measures that have been put in place to promote habitat conservation in the UK?

A

National Parks

Sites of Specific Scientific Interest (SSSIs)

Environmentally Sensitive Areas (ESAs)

Wildlife Reserves

39
Q

Name two environments in which species can be conserved outside their natural habitats

A

Zoos and botanical gardens

40
Q

What is conservation?

A

The protection and maintainable of natural resources

41
Q

List the key resources required for human life

A

Food water

Land

Other species

Minerals and other raw materials

Energy

42
Q

Define tropisms

A

Growth movement in response to a stimulus e.g. Light

43
Q

Define taxis

A

A type of response to directional stimulus seen in motile developmental stages of lower plants (e.g. moss)

Moving to/away from a stimulus

44
Q

Define nastic movements

A

‘Rapid’ response - e.g. Flower closing when touched

45
Q

Explain why plants need to respond to their environment in terms of the need to avoid predation and abiotic stress

A

Plants respond to external stimuli as well as biotic and abiotic components of the environment to help the plant avoid stress, being eaten, and survive long enough to reproduce.

These responses are coordinated by hormones

46
Q

Explain how plant responses to environmental changes are co-ordinated by hormones, with reference to responding to changes in light direction

A

The presence of auxin promotes the active transport of hydrogen ions through the ATPase enzyme, into the cell wall.

This decreases the pH and allows optimum conditions for the wall loosening enzymes to work.

These enzymes break bonds within the cellulose, so the walls become less rigid and can expand as the cells take in water.

A shoot bends towards a light source because auxin in transported to the tip o the shoot to the cells in the shade, allowing the cells to take up more water and elongate.

Because the cells elongate more on the shaded side than the side in the light, the shoot bends towards the light source

47
Q

Evaluate the experimental evidence for the role of auxins in the control of apical dominance

A

Apical dominance is when the growing apical bud at the tip of the shoot inhibits the growth of the lateral buds further down the shoot

Auxins are produced in the tip of the main shoot. They inhibit the growth of side shoots

When the tip of the main shoot is removed, or an auxin transport inhibitor is applied below the apex of the main shoot, the side shoots grow.

This shows that auxin is produced in the apex of the main shoot and transported to lateral buds to inhibit their growth.

When there are low concentrations of auxin in the side shoots, their growth is not inhibited, and so they can grow.

This is also shown where, as the plant grows taller, the lateral buds at the bottom of the plants start to grow larger - they are further away from the main shoot, so there is a lower concentration of auxin and their growth is less inhibited

48
Q

Evaluate the experimental evidence for the role of gibberellin in the control of stem elongation

A

If genetically dwarf plants are treated with Gibberellic acid, the stems elongate considerably

49
Q

Outline the role of hormones in leaf loss in deciduous plants

A

Cytokinins stop the leaves of deciduous trees senescing by making sure that the leaves act as a sink for phloem transport, so the leave is guaranteed a good supply of nutrients

If cytokinin production drops, the supply of nutrients dwindles and senescence begins

Senescence causes auxin production at the tip of the leaf to drop

This makes the cells in the abscission zone more sensitive to ethene

A drop in auxin concentration causes an increase in ethene production

This increases production of cellulase, which digests the walls of the cells in the abscission zone, eventually separating the petiole from the stem

50
Q

Describe how plant hormones are used commercially

A

Synthetic auxins are used as growth stimulants when root cuttings are taken

A synthetic auxin is used as a selective weed killer

A form of abscisic acid what is not readily broken down by plants is used as an anti-transpirant as it closes stomata

51
Q

What are plant growth substances?

A

Substances produced by the plant in response to stimuli

They move through the plant and bind to specific receptors on target cells

52
Q

What are the five types of plant growth substance?

A

Auxins - associated with cell enlargement and differentiation

Gibberellins - also associated with cell enlargement and
differentiation

Cytokinins - associated with cell division

Abscisic acid - usually associated with dormancy, as with buds

Ethene - often associated with ageing (senescence)

Biology (13 decks)

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