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A Level Biology > Ecosystems > Flashcards

Ecosystems Flashcards

1
Q

Define an ecosystem?

A

All the living organisms that interact with one another in a defined area

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2
Q

Two factors that affect an ecosystem?

A

Abiotic and Biotic

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3
Q

Examples of biotic factors?

A

Competition, disease, food availability, territory

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4
Q

Examples of abiotic factors?

A

Light intensity, temperature, water availability, oxygen availability, soil mineral concentration

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5
Q

What produces the most energy for ecosystems?

A

The Sun

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6
Q

What is a trophic level?

A

Each stage in the food chain

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7
Q

The first trophic level is called what?

A

A producer

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8
Q

What is a producer?

A

An organism that converts light energy into chemical energy by the process of photosynthesis

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9
Q

What is a consumer?

A

Organisms that obtain their energy by feeding on other organisms

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10
Q

Why don’t food chains have more than 4 trophic levels?

A

Not sufficient biomass and stored energy left to support any further organisms

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11
Q

What is biomass?

A

The mass of living material present in a particular place of an organism

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12
Q

How do you calculate biomass?

A

Net production of biomass = gross production (initial energy) subtracted by the respiratory loss

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13
Q

What is the measurement for biomass?

A

gm-2yr-1
(grams per meter squared per year)

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14
Q

In a food chain diagram where are the producers always placed?

A

At the bottom of the pyramid

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15
Q

How much of biomass is consumed by an organism passed onto the next trophic level?

A

10 percent !!

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16
Q

Equation for the efficiency of trophic levels?

A

energy available after transfer/ energy available before transfer x 100

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17
Q

Where does the biomass go once entered into an organism?

A

The environment, lost in urine/excretion, movement, respiration

18
Q

The unit for the efficiency of energy transfers between trophic levels?

A

kJm-2year-1

19
Q

How much sun energy is captured by organic material?

A

1-3 percent

20
Q

Why do organisms capture so little sun radiation?

A

Most hits the Earth and bounces back by clouds, dust and the atmospher

21
Q

Ways that humans can manipulate biomass through an ecosystem?

A

Reducing competition by feeding them, using pesticides or fertilizers, destruction of habitat eg:deforestation, routine antibiotic application or heating

22
Q

Name and describe what a scavenger is?

A

An organism that breaks/opens up the carcass. An example is hyenas or vultures

23
Q

What is a decomposer?

A

An organism that feeds on and breaks down dead plant or animal matter by external digestion

24
Q

An example of a decomposer?

A

Fungi or bacteria

25
Q

Detritivores are what?

A

Break down organic material by internal digestion, increases the SA for the decomposers

26
Q

Examples of detritivores?

A

Woodlice, maggots, worms

27
Q

Conditions needed for decomposition?

A

Optimum temperature for digestive enzymes, high oxygen availability, moist water availability

28
Q

Examples of habitats with no decomposition?

A

Mountains, volcanoes, amber, peat bogs

29
Q

How much of the atmosphere is nitrogen?

A

78%

30
Q

Why is nitrogen essential?

A

Essential element for making amino acids and proteins

31
Q

Why is the nitrogen cycle needed?

A

The nitrogen in the atmosphere cannot be taken up by plants. It needs to be combined with other elements such as oxygen and hydrogen

32
Q

4 processes involved in the nitrogen cycle?

A

Nitrogen fixation, Ammonification, Nitrification and Denitrification

33
Q

What is involved in nitrogen fixation?

A

Bacteria such as Rhizobium and Azotobacter combine Nitrogen with Hydrogen to make Ammonia

34
Q

Where is Rhizobium found?

A

In the root nodules of leguminous plants, the bacteria has a mutualistic relationship with the plants

35
Q

Describe ammonification?

A

Its the process of decomposers converting nitrogen-containing compounds into ammonium ions

36
Q

Nitrification?

A

The ammonium ions from ammonification are converted into NITRITES and then become NITRATES used in plants

37
Q

What is the name of the bacteria involved in nitrification?

A

Nitrosomonas

38
Q

When and why does denitrification occur?

A

In the absence of oxygen (anaerobic conditions) Denitrifying bacteria uses the nitrates as a source of energy for respiration and nitrogen gas is released

39
Q

What is succession?

A

The process in an ecosystem where abiotic factors change, causing the biotic factors to change

40
Q

Primary succession?

A

Occurs in a newly found area of land, bare rock, no soil or organic matter

41
Q

Secondary succession?

A

In areas of land where soil is present but has no plant or animal species (the bare earth after a forest fire)

42
Q

Examples of primary succession occuring?

A

Volcano eruptions, sand blown by the wind, glaciers retreating

A Level Biology (15 decks)

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