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HL Biology > Topic 4 Test Revision > Flashcards

Topic 4 Test Revision Flashcards

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1
Q

What is a species?

A

A group of organisms that can interbreed to produce fertile offspring.

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2
Q

What is a population?

A

A group of organisms that live in the same area at the same time.

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3
Q

What is a community?

A

A group of populations living and interacting with each other in an area.

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4
Q

Members of a species may be?

A

Reproductively isolated in separate populations.

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5
Q

What is a habitat?

A

The environment in which a species normally lives, the location of an organism.

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6
Q

What is an ecosystem?

A

A community and its abiotic environment.

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7
Q

Ecosystems have the capability of?

A

Being sustainable over a long period of time.

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8
Q

What is ecology?

A

The study of relationships between living organisms (biotic component) and organisms and their environment (abiotic component)

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9
Q

What is an autotroph?

A

An organism that synthesises its own organic molecules from simple inorganic molecules - ie. photosynthesis.

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10
Q

What is a heteretroph?

A

An organism that obtains organic molecules by feeding on other organisms.

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11
Q

What mode of nutrition are consumers, detritivores and saprotrophs?

A

Heterotrophs

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12
Q

What is a consumer?

A

An organism that ingests other organic matter that is living or recently killed.

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13
Q

What is a detritivore?

A

An organism that ingests non-living organic matter. They digest internally.

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14
Q

What is a saprotroph?

A

Saprotrophs are organisms that live on or in non-living organic matter secreting digestive enzymes into it and absorbing the products of digestion. Saprotrophs use external digestion. eg. mushrooms

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15
Q

What are two major components of ecology?

A

The study of energy and nutrients within biotic and abiotic components of the environment.

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16
Q

What are examples of autotrophs?

A

Plants, algae and even certain types of bacteria.

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17
Q

What are examples of heterotrophs?

A

Animals, mushrooms and certain types of bacteria.

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18
Q

What is the initial source of energy for the vast majority of communities?

A

The sun.

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19
Q

What does respiration result in?

A

Whereas photosynthesis and chemosynthesis allow the formation of molecules essential for energy storage, respiration results in the decomposition of these molecules so that the stored energy may be released and utilized by the organism involved.

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20
Q

What direction does energy flow through ecosystems?

A

Light energy – producers – primary consumers – secondary consumers. All biotic components of the ecosystem eventually become utilized by decomposers.

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21
Q

What does most of the energy flow in an ecosystem get lost as?

A

Heat.

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22
Q

What are food chains?

A

Diagrams that represent the flow of energy through an ecosystem.

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23
Q

What are food webs?

A

Food webs are diagrams made up of multiple food chains interconnected by common organisms.

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24
Q

What are trophic levels?

A

The various feeding levels of a food chain. This includes producers, consumers, and decomposers.

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25
Q

How efficient are energy transformations between trophic levels?

A

10% efficient. - 90% of the original energy is usually lost. This energy loss may be in the form of heat, it may be in the parts of organisms that are not eaten, or it may be lost as indigestible material.

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26
Q

What do pyramids of energy represent?

A

The flow of energy from one trophic level to the next in a community. The units are per unit area per unit time, for example, kilojoules per square meter per year.

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27
Q

While energy enters and leaves an ecosystem, nutrients are?

A

Recycled.

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28
Q

What are examples of nutrient cycling?

A

The carbon cycle, the water cycle, the nitrogen cycle.

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29
Q

Nutrient cycling allows ecosystems to…

A

Be sustainable over a long period of time, but they rely on energy.

30
Q

What is the greenhouse effect?

A

The retaining of heat in the Earth’s atmosphere is a result of the ability of greenhouse gases to absorb longwave radiation. This is a naturally occurring phenomena called the greenhouse effect.

31
Q

What nutrient cycle plays a major role in the greenhouse effect?

A

The carbon cycle.

32
Q

What does the carbon cycle represent?

A

The carbon cycle represents the interaction of living organisms and the biosphere through the processes of photosynthesis, cell respiration, fossilization and combustion.

33
Q

What does photosynthesis result in?

A

Photosynthesis results in the fixation of carbon dioxide from the atmosphere.

34
Q

What does combustion result in?

A

Combustion results in the release of and accumulation of more carbon dioxide in the atmosphere.

35
Q

What does respiration result in?

A

Respiration results in the release of carbon dioxide and accumulation in the atmosphere.

36
Q

What relation do decomposers, detritivores and saprotrophs have to the carbon cycle?

A

Decomposers break down the dead organisms and return the carbon in their bodies to the atmosphere as carbon dioxide by respiration.

37
Q

What are other greenhouse gases that contribute to the greenhouse effect?

A

Methane, nitrous oxide, sulphur oxide.

38
Q

What do methanogenic archaeans do?

A

Produce methane from organic matter in anaerobic conditions.

39
Q

Where does methane diffuse and accumulate?

A

Diffuses into the atmosphere and accumulates in the ground.

40
Q

What happens to methane in the atmosphere?

A

It is oxidised into carbon dioxide and water.

41
Q

What is peat?

A

Peat is partially decomposed organic matter in anaerobic conditions in waterlogged soils.

42
Q

What do greenhouse gases trap?

A

Longwave radiation from the sun - radiation after it has bounced off the earth (heat). The longwave radiation comes from the short wavelengths of the sun’s rays that can easily pass through the atmosphere.

43
Q

What does the trapping of longwave radiation cause?

A

Causes the earth to be warmer, thought to be a major contributor to global warming today.

44
Q

What are the effects of global warming on the Arctic ecosystems?

A

Increased rates of decomposition of detritus previously trapped in permafrost, expansion of the range of habitats available to temperate species, loss of ice habitat, changes in the distribution of prey species affecting trophic levels, and increased success of pest species, including pathogens.

45
Q

How would the changes in the Arctic affect the whole planet?

A

Rising oceans, increased carbon dioxide release into the atmosphere, altered food chains and webs in the Arctic and associated areas, increased world pathogens, and extreme weather events.

46
Q

How is coal formed?

A

When peat (partially decomposed matter) is buried under sediments and becomes compressed and heated over time.

47
Q

How are oil and gas formed?

A

When partially decomposed matter at the bottom of seas and lakes is compressed, heated and undergoes chemical changes. Methane forms a large part of the natural gas created.

48
Q

What forms does carbon dioxide take in aquatic ecosystems?

A

Dissolved carbon dioxide and hydrogen carbonate ions. Can be absorbed by aquatic autotrophs like phytoplankton.

49
Q

What is the biggest carbon sink?

A

The ocean - carbon dioxide is absorbed from the atmosphere by bodies of water.

50
Q

What are decomposers?

A

Organisms that break down carbon compounds in dead organic matter and release elements such as nitrogen into the ecosystem so that they can be used again by other organisms.

51
Q

What is a food chain?

A

A sequence of organisms, each of which feeds on the previous one.

52
Q

How many organisms are there usually in a food chain?

A

Between 2 and 5.

53
Q

What is ATP and what is it used for?

A

The energy supplied for activities like

  • synthesising large molecules like DNA, RNA, proteins
  • Pumping molecules or ions across membranes by active transport
  • Moving things around inside the cell (chromosomes or vesicles)
54
Q

How is ATP produced?

A

Through cell respiration

55
Q

How does cell respiration release heat?

A

In the process of cell respiration, carbon compounds such as carbohydrates and lipids are oxidised. These oxidation reactions are exothermic and the energy released is used in endothermic reactions to make ATP. However, not all the energy from the oxidisation of carbon compounds in cell respiration is transferred to ATP. The rest is converted to heat.

56
Q

How is heat lost from ecosystems?

A

Heat passes from hotter to cooler bodies, so the heat produced in living organisms will all eventually leave the ecosystem. All energy released from cell respiration is eventually lost from an ecosystem.

57
Q

How is CO2 present in water?

A
  • Can remain as dissolved gas
  • Can combine with water to form carbonic acid
  • Carbonic acid can dissociate to form hydrogen and hydrogen carbonate ions (H and HCO3)
58
Q

What else is released from cell respiration?

A

Carbon dioxide is a byproduct of aerobic respiration and therefore diffuses out of organisms into surrounding water or atmosphere.
- saprotrophs and animal cells release CO2 as a byproduct of respiration

59
Q

How is methane formed?

A

From archaeans that produce methane from carbon dioxide, hydrogen and acetate in many anaerobic environments. This methane diffuses into the atmosphere.

60
Q

How is limestone formed?

A

From animals that have hard parts composed of calcium carbonate (molluscs, corals that produce exoskeletons by secreting CaCO3) that, in neutral or alkaline conditions, form on the sea bed and form limestone rock.

61
Q

How is water vapour formed?

A

By evaporation from oceans and transpiration from plants.

62
Q

How does water vapour contribute to the greenhouse effect?

A

Retains heat even after it condenses to form droplets of liquid water in clouds. It absorbs heat energy and radiates it back to the earth’s surface, it also reflects energy back. This explains why it is colder at night in areas with clear skies than with cloud cover.

63
Q

What are the two factors that determine the warming impact of a greenhouse gas?

A
  • how readily the gas absorbs longwave radiation

- the concentration of the gas in the atmosphere

64
Q

Why does methane have a lesser impact on global warming?

A

Methane causes much more warming per molecule than CO2 but has a much lower concentration in the atmosphere.

65
Q

What does the concentration of a greenhouse gas depend on?

A

The rate at which it is released into the atmosphere and how long it stays there. Water vapour rapidly enters the atmosphere but stays 9 days on average, while methane remains for 12 years.

66
Q

What happens to some of the short wavelength radiation that comes from the sun before it reaches the earth’s surface?

A

It is absorbed by the ozone as UV light. 25-30 per cent is absorbed like this, meaning 70-75 per cent reaches the earth’s surface and is converted to heat.

67
Q

What happens after the earth’s surface absorbs short-wavelength- radiation?

A

It is re-emitted as longer-wavelength radiation. 70-85% of this is absorbed by greenhouse gases in the atmosphere, the rest is emitted back to space. Some of the radiation captured is re-emitted to the earth’s surface, creating the greenhouse effect.

68
Q

What does an increase in greenhouse gases tend to cause?

A

Higher global average temperatures and increased intense heat waves.

69
Q

What other aspects of climate do higher global temperatures cause?

A
  • increased evaporation of water from oceans and therefore increased periods of rain
  • higher ocean temperatures cause tropical storms and hurricanes to be more frequent
70
Q

What is the effect of increased CO2 emissions on coral reefs?

A

Corals use CaCO3 to form their exoskeletons. To do so, they need to absorb carbonate ions, a key component of CaCO3, from seawater. Dissolved CO2 lowers the concentration of carbonate ions because when CO2 reacts with water, it forms carbonic acid (H2CO3-). This dissociates into hydrogen and hydrogen carbonate ions. Hydrogen ions react with dissolved carbonate ions and reduce their concentration, making it more difficult for corals to absorb them and build their exoskeletons.

71
Q

Why are food chains limited to 2-5 members?

A

Because of losses of energy through trophic levels, after a few stages in a food chain, the amount of energy remaining would not be enough to support another trophic level.

72
Q

What is ADH?

A

ADH controls reabsorption of water in the

collecting duct.

HL Biology (12 decks)

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