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Biology External 2024 > Unit 3 Topic 2 > Flashcards

Unit 3 Topic 2 Flashcards

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1
Q

What is an individual?

A

A single organism

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2
Q

What is a population?

A

A group of organisms of the same species living in a defined geographical area

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3
Q

What is a community?

A

A group or association of populations of two or more different species occupying the same geographical area at the same time

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4
Q

What is an ecosystem?

A

A community of living organisms (plants, animals and microbes) in a particular area

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5
Q

What is a biome?

A

A biome is a distinct geographical region with specific climate, vegetation, and animal life

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6
Q

What is the biosphere?

A

The biosphere is made up of the parts of Earth where life exists—all ecosystems.

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7
Q

What is photosynthesis?

A

Photosynthesis is the process by which green plants and certain other organisms transform light energy into chemical energy.

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8
Q

What are autotrophs?

A

An autotroph is an organism that can convert abiotic sources of energy into energy stored in organic compounds, which can be used by other organisms.

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9
Q

What are heterotrophs?

A

A heterotroph is an organism that cannot produce its own food, instead taking nutrition from other sources of organic carbon, mainly plant or animal matter.

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10
Q

What is biomass?

A

Biomass is the total amount (dry weight) of biologicalmatter of a group of organismsin a givenarea

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11
Q

What is a trophic level?

A

An organism’s level in the food chain of an ecosystem based on feeding relationships.

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12
Q

How is energy being transferred to autotrophs lost?

A

Energy is lost through radiation, reflection and absorption. Only a small amount of light falling on a plant is captured and used inphotosynthesis to produce glucose

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13
Q

What is Gross primary productivity

A

The rate at which solar energy is used to fix carbon into organicmolecules

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14
Q

What is Net primary productivity

A

Subtracts the energy used in metabolism from the GPP

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15
Q

How much energy in one trophic level is actually incorporated into the tissues of the next trophic level?

A

10%

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16
Q

Where does the rest of the energy (90%) in the transfer between trophic levels go?

A

Transformed by the metabolism into heat energy and lost to the surroundings OR
remains as chemical energy in both the uneaten portion of the organism and its body waste.

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17
Q

What is a biomass pyramid?

A

A biomass pyramid shows the amount of energy stored in biomass of autotrophs and subsequent heterotrophs. A healthy balanced ecosystem must have a stable pyramid, with decreasing mass of organisms from bottom to top.

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18
Q

What is an energy flow diagram?

A

Energy flow diagrams are used to display the transfer of energy from the sun through the trophic levels of an ecosystem.

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19
Q

What is biochemical cycling?

A

The process wherebuilding blocks of living things arerecycled throughecosystems

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20
Q

What would happen without biochemical cycling?

A

Without cycling of nutrients,molecules would eventually all betrapped in the dead bodies andwaste material of once-living things

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21
Q

What are the steps of the water cycle?

A

Evaporationfrom oceans and fresh water
Condensation in clouds
Precipitation as rainfall/snow
Release from organisms through transpiration and respiration
Run off from land into waterways

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22
Q

Why is carbon/the carbon cycle important?

A

Carbon is a key element in organic molecules that makes up ahigh proportion of living organisms

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23
Q

How does Carbon enter the ecosystem?

A

Carbon enters the ecosystem through:
Combustion of fossil fuels
Respiration of plants/animals
Death and decay of living organisms
Coming out of solution in water
Volcanic activity

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24
Q

How is Carbon taken up?

A

Carbon is taken up by:
Photosynthesis in plants
Dissolving in water and forming carbonates
Formation of fossil fuels
Incorporation as biomass

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25
Q

What is the role of Carbon?

A

Contributes to changes in global weather patterns

Absorbs heat and insulates the earth by preventing heat from leaving, leading to increased atmospheric temperatures

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26
Q

What is the nitrogenic relationship between plants and animals?

A

Plants take up nitrogen products from the soil to produce proteins
Animals consume plants and animals and obtain nitrogen compounds

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27
Q

What is Nitrogen Fixation?

A

Nitrogen gas (N₂) in the atmosphere is converted into ammonia (NH₃) by nitrogen-fixing bacteria, such as Rhizobium, found in root nodules of leguminous plants. This process can also occur through lightning and industrial methods like the Haber process.

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28
Q

What is Nitrification?

A

Ammonia is oxidized to nitrites (NO₂⁻) by bacteria such as Nitrosomonas, and then nitrites are further oxidized to nitrates (NO₃⁻) by Nitrobacter. These nitrates are usable by plants. Under normal conditions nitrates are converted to protein in the plant at about the same rates as they are absorbed into the root system.

29
Q

What is Ammonification?

A

Decomposers break down organic matter from dead organisms and waste products, converting nitrogen compounds back into ammonia, which re-enters the soil.

30
Q

What is Denitrification?

A

Under anaerobic conditions, denitrifying bacteria convert nitrates back into nitrogen gas, releasing it into the atmosphere and completing the cycle.

31
Q

What is an ecological niche?

A

Ecological niche is the role and space that an organism fills in an ecosystem, including all its interactions with the biotic and abiotic factors of its environment. An example is predation, as a Tiger plays the role of a predator and keeps the population of prey down.

32
Q

What are the 3 types of competition?

A

Interspecific competition
Organisms of different species compete for thesame resources

Intraspecific competition
Different individuals of the same speciescompete for resources

Competitive exclusion
One species successfully utilizes a resource atthe exclusion of another – they cannot bothuse the resource

33
Q

What is the competitive exclusion principle?

A

This principle states that twospecies requiring the sameresources can occupy the same habitat but cannot exist in thesame niche. Species can only coexist if theyhave different requirements

34
Q

What is a species fundamental niche?

A

A theoretical potential use of resources

35
Q

What is a realized niche?

A

The actual use of resources when considering competition

36
Q

What is a keystone species?

A

A keystone species is a species that plays acritical role in maintaining the structure andfunctioning of their ecosystem

37
Q

What happens to an ecosystem when a keystone species is removed/

A

When a keystone species is removed from anecosystem, the ecosystem becomes much lessstable and its structure changes

38
Q

What is carrying capacity?

A

Carrying capacity is the size of thepopulation that can be supportedindefinitely on the availableresources and services of thatecosystem

39
Q

What are limiting factors?

A

Any factor that limits the size of a population is calleda limiting factor

40
Q

What is the limiting factor of population density?

A

The limiting factor of a population’s size, density orgrowth is the resource that a population requires, butwhich is present in such small quantities that itnegatively impacts the population’s growth

41
Q

What are density dependent factors?

A

Density-dependent factors influence population size and density, where themagnitude of their effects depend on theexisting population density (generally biotic)

42
Q

What are density independent factors?

A

Density-independent factorsimpact a population regardless ofthe population size or density (generally abiotic)

43
Q

What are some examples of biotic limiting factors?

A

Competition for resources (food,water, shelter, mates)
Predation
Disease & parasites (spread faster with a bigger density)

44
Q

What are some examples of abiotic limiting factors?

A

Space
Availability of nutrients and water
Pollution
Natural disasters (bushfire, cyclone, flood, drought)
Extreme climatic events (drought, cyclones, global temperature change)

45
Q

What is a tolerance range?

A

A particularrange of conditions in which a speciescan survive. For each abiotic factor there isan ideal range that isfavorablefor the growth,development and survival ofthe species

46
Q

What affects the size of a population?

A

Natality (births / germination)
Mortality (deaths)
Immigration (organisms moving in from anotherpopulation)
Emigration (organisms moving out of a population)

47
Q

When do populations decrease?

A

When the combined rates of deathand emigration are greater than the combined rates birth andimmigration

48
Q

What does exponential (J curve) population growth indicate?

A

Birth rate remains higher than mortality rate. Usually observed with an influx of r-strategists, and occurs only for a short period of time.

49
Q

What does logistic population growth indicate?

A

Initial exponential growth flattens due to density-dependent factors. Usually occurs with k-strategists, and if remains balanced can occur for long periods of time.

50
Q

What are the different types of ecosystem changes?

A

Regular change - day/night cycles, changing seasons and lunar cycles

Irregular change –e.g.flood, fire, earthquake or tsunami

Short term change – day/night

Long term change – seasonal, whole ecosystem change

Successional change refers to changes occurring in an entireecosystem

51
Q

What is ecosystem succession?

A

Succession is the sequence of change in an ecosystem, where one kind of community isreplaced by another more complex one

52
Q

What is a sere?

A

A ‘sere’ refers to successive communities in changing ecosystems (e.g.one sere replacesanother). Each sere replaces the previous one until finally a stable community, the climaxcommunity, is formed.

53
Q

What is the pioneer community?

A

A pioneer community is the first community to inhabit a previouslyuninhabited area. This area is harsh, very exposed and lacks nutrients and water

54
Q

Why are organisms in pioneer communities special?

A

Organisms in pioneer communities have features that make themwell suited to harsh conditions where other organisms cannot survive

55
Q

What are features of organisms in pioneer communities?

A

Ability to perform nitrogen-fixation

These plants often have symbiotic relationshipswith soil bacteria that fix nitrogen from air, which isfundamental for protein synthesis

Ability to photosynthesise efficiently

Shade intolerant

Pioneer species often feature rapid seed or sporegermination and growth (r-selected species)

56
Q

What is the climax community?

A

The climax communityis the final stage ofecosystemdevelopment in anarea
The community iscomplex and stable (logistic growth curve). Will often feature slower seedgermination and growth (k-selected species

57
Q

What is primary succession?

A

Primary succession involves the initial colonization of a previously uncolonized area

58
Q

What is secondary succession?

A

Secondary succession occurs when a previously colonized area has been disturbed and recolonized

59
Q

If you find a fossil shaped like amodern fish in a layer of rock, what can you infer?

A

You can infer that theenvironment at the time wasaquatic

60
Q

If you find many fossilised teethwith adaptations for eatinggrass, what ca you hypothesize?

A

You can hypothesisethat the area was a grasslandat one time

61
Q

What ecological change can human activities cause?

A

Land clearing
Rising carbon dioxide
Introduction of new species
Spread of disease
Over-fishing and hunting
Genetic modification and selective breeding
Planting of monocultures
Nutrient cycling

62
Q

What is overexploitation?

A

Overexploitation involves harvesting a resource at an unsustainable rate
Continued overexploitation can lead to the destruction of the resource

63
Q

What has caused the clearing of forested ecosystems, and thus habitats?

A

Urban development

64
Q

What are monocultures?

A

Monoculture involves planting of a singlespecies as a crop (e.g.pine plantations). These feature very low biodiversity andsimplified species interactions (e.g.foodwebs)

65
Q

What can monocultures result in?

A

Reduced soil quality, overuse of chemicals, pollution to groundwater, overuse of water and fossil fuel energy

66
Q

What is pollution?

A

Pollution involves contamination of the environment insome way

67
Q

What is the pollution hypothesis?

A

It is hypothesized that this will cause the surface of theEarth to increase in temperature over the nextcenturies

68
Q

What is spatial change/prediction?

A

Spatial = changes in the area

69
Q

What is temporal change/prediction?

A

Temporal = changes over time

Biology External 2024 (2 decks)

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