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Biology unit 4 > module 3 > Flashcards

module 3 Flashcards

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1
Q

What is an ecosystem

A

Any group of living organisms and non living things occuring together, and the interrelationships between

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2
Q

Examples of large and small ecosystems

A

African grassland

Pond

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3
Q

What are the 3 components if an ecosystem

A

Habitat
Population
Community

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4
Q

What is a habitat

A

The place where an organism lives

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5
Q

What is a population

A

All if the organism of one species that live in the same place at the same time and that can breed together

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6
Q

What is a community

A

All the population of different species who live in the same place at the same time and can interact with each other

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7
Q

What is a niche

A

The role that each species plays in its ecosystem

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8
Q

It’s impossible for 2 species to occupy exactly the same niche in the same ecosystem

A

Just info

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9
Q

Why is it almost impossible to define an organisms niche

A

Cz it interacts with both living and non living things

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10
Q

Examples of biotic factors

A

Food supply
Predation
Disease

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11
Q

What are biotic factors

A

Living organism in an ecosystem that affect another living organism

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12
Q

Example so abiotic factors

A

PH
Temp
Soil type

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13
Q

What are abiotic factors

A

Effects of non living organism on living organisms in an ecosystem

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14
Q

Why do population sizes rise and fall in an ecosystem

A

Cz the community of living things in an ecosystem interact with each other and with their physical environment
Any small changes in one will affect the other

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15
Q

Example of interaction between living things and their environment

A

The nitrogen levels in soil can affect the population size of plants growing there.nitrigen fixing plants would grow successfully in nitrogen deficient soil, but they would affect their environment by increasing the soil nitrogen levels.

This change would then help other plants to grow there as well.

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16
Q

In terms of energy and ecosystems. What’s is recycled and what isn’t recycled

A

Matter e.g. In nitrogen and carbon cycles

Energy isn’t recycled it flows through the ecosystem

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17
Q

What do plants do to energy when hey capture light energy

A

Convert it to chemical energy stored in molecules such as glucose

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18
Q

What are producer. Give an examples

A

They supply chemical energy to all other organisms

Plants
Photosynthetic organisms
Algae
Some bacteria

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19
Q

What are prinary consumers
Secondary consumers
Tertiary consumers

A

Primary
Are herbivores who feed on plants

Secondary
Are carnivores who feed on herbivores

Tertiary
Are carnivores who feed on carnivorous secondary consumers

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20
Q

What are decomposers

A

Feeds on waste material or dead organisms

Bacteria fungi and some animals

21
Q

What does a food chain show

A

How energy is transferred from one living organism to another

22
Q

What is a trophic level

A

The level at which an organism feeds in a food chain

23
Q

2 reasons why energy is lost at the next trophic level

A

Living organisms need energy to carry out life processes. Respiration releases energy from organic molecules like glucose. Some of this energy is eventually converted to heat

Energy remains stored on dead organisms and ware material which is then only available for decomposer such as fungi and bacteria. They cannot be digested by consumers

24
Q

What does it mean when the organisms in a food chain are about the same size

A

They’ll be fewer consumers at the higher levels.

25
Q

3 ways of measuring efficiency of energy transfer

A

pyramids of biomass
pyramids of energy
productivity

26
Q

talk about pyramids of biomass

A

area of the bars is proportional to the dry mass of all organisms at that trophic level

27
Q

how would you calculate dry mass

A

put organisms in an oven at 80 degrees celcius until all the water in them has evaporated

or measure the wet mass of the organisms and calculate the dry mass on the basis of previously published data

28
Q

talk about pyramids of energy

A

burning the organism in a colorimeter and working out how much heat energy is released per gram - this is calculated from the temperature rise of a known mass of water

29
Q

what is the problem with pyramids of biomass

A

different species release different amounts of energy per unit mass

30
Q

what is the problem with pyramids of energy

A

only take a snapshot of an ecosystem at one moment in time

because pop size varies over time, it can give a distorted idea of the efficiency of energy transfer

31
Q

what is productivity

A

the rate at which energy flows through each trophic level

32
Q

talk about productivity (3 points)

A

gives an idea of amount of energy available at each trophic level, per unit area, at a given time. usually measure in kilojoules or megajoules of energy per square metre per year

at the base of the food chain, productivity of plants is called primary productivity

gross primary productivity is the rate at which plants convert light energy into chemical energy
the remaining energy (because some was lost due to respiration etc) is called the net primary productivity

33
Q

talk about gross primary productivity and net primary productivity

A

gross primary productivity is the rate at which plants convert light energy into chemical energy
the remaining energy (because some was lost due to respiration etc) is called the net primary productivity

34
Q

What is succession

A

A directional change in a community of organisms over time

35
Q

What ideas help explain why directional change in a community happens

A

Any change in a community of organisms can cause a change in their habitat

Any change in a habitat can also cause a change in the make up of a community

36
Q

What’s the process called when development of a community arises from bare ground

A

Primary succession

37
Q

How does prinary succession occur

A

Algae and lichens begin to live on the bare rock. This is the pioneer community

Erosion of the Rock and a build up of dead and rotten organisms produces enough soil for larger plants like mosses and ferns to grow. These succeed/replace the algae and lichens

Larger plants repkace/succeed smaller plants until a final, stable community is reached. This is called a climax community (woodland communities in the uk)

38
Q

What is a pioneer community

A

The algae or lichens that first inhabit bare rock

39
Q

What are climax communities

A

The final stages of the primary succession

40
Q

4 stages of succession on sand dunes

A

Pioneer plants colonise the sand just above the high water mark. These can tolerate salt water sprat, lack of fresh water and unstable sand

Windblown sand builds up around the base of these plants forming a mini sand dune

As plants due and decay nutrients accumulate in this mini dune so the dune gets bigger. Plants like sea Sandwood and sea couch grass colonise it.this helps stabilise the sand cz of the underground stems

With more stability and nutrients, plants like sea purge and marram grass start to grow. Marram grass helps trap mor wind

Other plants colonise the sand as sand and nutrients build up. Bacteria convert nitrogen intro nitrates more species colonise the dunes. This stabilises them further

41
Q

How do bacteria and fungi feed

Si what are they described as

A

Saprotrophically

Saprotrophic

42
Q

How do saprotrophically feed on stuff

A

Secrete enzymes onto dead and waste material

These enzymes digest the ma trial into small molecules, which are then absorbed into the organisms body

The molecules are then stored or repaired to release energy

43
Q

What would happen if cm bacteria and fungi didn’t break down dead organisms

A

Energy and valuable nutrients would remind trapped within the dead organisms

44
Q

Why do living things need nitrogen

A

To make proteins and nucleic acids

45
Q

Why do plants need a fixed nitrogen supply

A

Because it’s very unreactive so plants can’t use it directly

46
Q

2 examples of fixed nitrogen

A

Ammonium ions nh4+

Nitrate ions no3-

47
Q

3 ways nitrogen fixation can occur

A

Lightning strikes
Haber process
Nitrogen fixing bacteria

48
Q

Example of nitrogen fixing bacteria

A

Rhizobium

Biology unit 4 (2 decks)

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