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Biology Unit 3 > 3.5 Population > Flashcards

3.5 Population Flashcards

1
Q

What is ecology?

A

Study of how living organisms interact with each other and with their environment.

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2
Q

Abiotic factors

A

Non-living components (light, temperature)

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3
Q

Biotic factors

A

Living components (predators, disease)

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4
Q

Reproductive rate

A

To which organisms enter the eco system- make sure to apply it to the question.

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5
Q

Define ecosystem

A

The community of biotic and abiotic components of an area and their interactions.

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6
Q

Define community

A

All of the populations of different species living together in a habitat.

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7
Q

What is a habitat?

A

The region where an organism normally lives.

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8
Q

What is population?

A

All organisms of the same species living with one another in a habitat at the same time.

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9
Q

What is a niche?

A

Describes how an organism fits into an ecosystem and its role in that environment.

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10
Q

What do population numbers depend on?

A

Birth and death rate, immigration and emmigration.

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11
Q

What is birth rate?

A

The number of offspring born per thousand of population per year.

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12
Q

What is death rate?

A

The number of deaths per thousand of population per year.

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13
Q

What is immigration?

A

The number of individuals entering a region per thousand of population per year.

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14
Q

What is emigration?

A

The number of individuals leaving a region per thousand of population per year.

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15
Q

What are the phases of population growth?

A

Lag phase- period of slow population growth
Log phase- period of rapid exponential population growth in which birth rate exceeds death rate
Stationary phase- period of stability in which population numbers generally remain constant.

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16
Q

What is carrying capacity?

A

The average size of a population that can be supported by an ecosystem over extended periods of time. This varies depending on biotic and abiotic factors.

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17
Q

What is density dependent factors?

A

Factors whose effects on population size differ with population density such as competition, predation and disease.

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18
Q

What is density independent factors?

A

Factors whos effects on population size remain the same regardless of population density such as climate.

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19
Q

What is abundance?

A

The number of individuals per species in a specific area at any given time.

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20
Q

What is distribution?

A

The spread of living organisms in an ecosystem.

21
Q

What is sampling?

A

Selecting a group of individuals that will represent the whole target of population and allows us to measure the distribution and abundance of organisms.

22
Q

What are two sampling methods?

A

Quadrats- Square frames placed at random in an area
Transects- Line of belt that runs across an area.

23
Q

What is random sampling?

A

A sampling technique used to avoid bias.

24
Q

What is systematic sampling?

A

Sampling technique used to determine the abundance and distribution of organisms along an area at periodic intervals.

25
Q

What is a trophic level?

A

The position that an organism holds in a food chain, food web, pyramid of number of pyramid of biomass.

26
Q

Why is some energy lost at each trophic level?

A

Respiration, lost as heat.

27
Q

What is gross primary productivity?

A

The rate of chemical energy fixture during photosynthesis by all producers in an ecosystem.

28
Q

What is net primary productivity?

A

The amount of chemical energy that is available to heterotrophs in an ecosystem.

29
Q

What is meant by primary succession?

A

Where an area previously devoid of life is colonised by pioneer species.

30
Q

What is a pioneer species?

A

Species that can survive in hostile environments and colonise bare rock or sand such as lichens.

31
Q

Summaries the process of primary succession.

A

Pioneer species colonise the area, die and decompose which adds nutrients the ground which allows more complex organisms to survive.

32
Q

What is secondary succession?

A

A type of succession in which a habitat is re-colonised after a disturbance such as natural disaster.

33
Q

What are organisms that play an important role in decay?

A

Dentrivores which feed on dead organic matter and saprotrophs which feed by extracellular digestion.

34
Q

How do saprotrophs feed by extracellular digestion?

A

They release enzymes which catalyse the breakdown of dead plant and animal material into simpler organic matter.

35
Q

What is the carbon cycle?

A

The cycle through which carbon moves between living organisms and the environment, involving respiration, photosynthesis and combustion.

36
Q

What are the stages of the carbon cycle?

A

Photosynthesising plants remove carbon dioxide from the atmosphere. Eating passes carbon compound along a food chain. Respiration in plants and animals return carbon dioxide to the atmosphere. Organisms die and decompose and saprotrophs break down dead material and release carbon dioxide by respiration. Combustion of material releases carbon dioxide.

37
Q

What is the nitrogen cycle?

A

The cycle through which nitrogen moves between living organisms and the environment involving ammonification, nitrification, nitrogen fixing and dentrification.

38
Q

How do plant roots take up nitrogen?

A

Taken up by active transport and facilitated diffusion as ammonium and nitrate ions.

39
Q

What are the four types of bacteria involved in the nitrogen cycle?

A

Nitrogen fixing bacteria
Nitrifying bacteria
Denitrifying bacteria
Decomposers

40
Q

What is ammonification?

A

The product of ammonium compounds when decomposers feed on organic nitrogen containing molecules.

41
Q

What is nitrification?

A

The conversion of atmospheric nitrogen gas into ammonia by nitrogen fixing bacteria in the soil or root nodules of legumes.

42
Q

What are examples of nitrifying bacterias?

A

Azotobacter and rhizobium.

43
Q

What is nitrogen fixation?

A

Conversion of ammonium ions to nitrate ions by nitrifying bacteria where ammonium ions are oxidised into nitrite ions which are oxides into nitrate ions.

44
Q

What are two types of nitrifying bacteria’s?

A

Nitrosomas which oxidise ammonium compounds into nitrites and nitrobacter which oxidises nitrites into nitrates.

45
Q

What is denitrifying bacteria?

A

Anaerobic microorganisms found in waterlogged soils responsible for reduction of nitrate ions to nitrogen gas.

46
Q

How does the nitrogen cycle help the economy?

A

It maximises plant growth and crop yield, increasing food production.

47
Q

What is an artificial fertiliser?

A

Ammonium nitrate.

48
Q

What is eutrophication?

A

The process by which pollution by nitrogen containing fertilisers results in algal blooms and subsequent oxygen level reductions in bodies of water.

Biology Unit 3 (8 decks)

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