14. Ecosystems Flashcards

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1
Q

What is a ommunity

A

All the organisms/ populations present in an habitat

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2
Q

What is a population

A

All the individuals of one species in a habitat

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3
Q

What is an ecosystem

A

consists of the community and the non-living / abiotic components of the environment

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4
Q

What is an ecosystem made up of

A

· Abiotic factors are non-living factors.
· Biotic factors are due to the interactions of organisms in an area.

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5
Q

What resources to plants and animals compete for

A

· Plants compete for Light, water, minerals
· Animals compete for food, territory, mates, breeding sites

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6
Q

What are the types of competition

A

Interspecific
Intraspecific

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7
Q

What is interspecific competition

A

Competition between different species
· An organism’s role in its ecosystem is known as its niche
· No two species can occupy the same niche as there would be too much interspecific competition for the same resources.
· The more similar the niches of two competitors, the greater the competition will be between them.
· The effect of this competition is likely to cause some species to disappear from the area as they are competitively excluded by stronger competitors.

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8
Q

What is intraspecific competition

A

Occurs between individuals of the same species for the same resource

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9
Q

What is a predator

A

an organism that hunts, kills and eats another, the prey.

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10
Q

How does the number of predators affect the number of prey

A

The overall effect is that both populations will fluctuate but only within narrow limits
Each species preventing the other increasing beyond the size that the environment will support

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11
Q

What is carrying capacity

A

The maximum size that a population can remain sustainable in a particular habitat

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12
Q

Why can population size vary

A

· the effect of abiotic factors
· interactions between organisms

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13
Q

What is energy flow

A

-Energy flows only once through an ecosystem and is eventually lost as heat. Nutrients are continually recycled.
· Energy and nutrients pass through ecosystems from autotrophs to heterotrophs

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14
Q

What is an autotroph

A

the primary producers

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15
Q

What is a heterotroph

A

· Primary consumers, i.e. herbivores, which feed exclusively on plants.
· Secondary consumers, i.e. carnivores, which eat herbivores.
· Tertiary consumers i.e. carnivores that eat other carnivores.
Each feeding role is called a trophic level

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16
Q

What is a food chain

A

Energy flows through the ecosystem from one trophic level to the next.
A series of trophic levels is a food chain.

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17
Q

What is a food web

A

food chains can interconnect to produce a food web.

18
Q

What are saprobionts

A

organisms that digest the dead remains and waste products (detritus) of every type of organism, releasing inorganic molecules and ions.
They secrete enzymes onto the detritus (extracellular digestion) and absorb the products of digestion.

19
Q

Why cant all light energy be used for photosynthesis

A

· Some of the light does not fall on photosynthetic parts of the plant and even if it does it may not strike chlorophyll.
· Some of the light is not of an appropriate wavelength to be used in photosynthesis.
· Some of the light is reflected or transmitted through the leaf.

20
Q

Why is only a small amount of light energy used i photosynthesisi converted into chemical energy

A

· Energy is lost during the inefficient reactions of photosynthesis.
· There may be other limiting factors of photosynthesis. For example CO2 concentrations.
· Most of the sugars synthesised by plants are used by the plant for respiration.
· The rest are used to make other biological molecules which form the biomass of the plant.

21
Q

What is biomass

A

the mass of organic material in an organism / ecosystem
can be measured in terms of mass of carbon, or dry mass of tissue, per given area.

22
Q

Why is it important to use dry biomass

A

as the amount of water in any living organism varies over time

23
Q

What is calorimetry

A

chemical energy store in dry biomass can be estimated using a bomb calorimeter
Dry material is burnt in oxygen.
Energy given off heats up the water in the calorimeter.
Rise in temperature can be used to calculate the energy (in calories) that was contained in the material.

24
Q

What is the function of a stirrer in a calorimeter

A

Distributes the heat evenly throughout the water

25
Q

How can a caloimeter be modified to reduce heat loss

A

Cover in insulating material / have a layer of air in the wall of container

26
Q

How is NPP calculated

A

NPP = GPP - Respiration
NPP is the chemical energy store store in plant biomass after respiratory losses to the environment
GPP = GPP is the chemical energy store in plant biomass, in a given area or volume.

27
Q

How do you calculate the efficiency of energy transfer

A

Energy transfer = energy available after transfer / energy available before transfer x 100

28
Q

What are losses due to whith the transfer of energy to and between concumers

A

· Some of the food taken in is not digested, it lost in faeces.
· Some is lost due to excretion of metabolic waste products (e.g. urea)
· Some energy remains in parts of the organism that are not consumed e.g. roots or bones/teeth
In all the above cases the energy is passed on to saprobionts.
· Most of the energy is lost due to consumer respiration.
· Eventually all energy lost is transferred to the environment as heat.

29
Q

What is net production and how is it calculaed

A

the production of biomass that is available to other consumer
N = I – (F + R)
I= ingested food
F= Feaces
R = respitory loses

30
Q

What is the efficiency of energy transfer from producers to primary consumers

A

(5-10% efficiency). Herbivores eat plant material which is difficult to digest, therefore they lose a lot of energy in faeces.

31
Q

What is the efficiency of energy transfer from Consumer to consumer

A

(10-20% efficiency) Carnivores are very efficient at digesting protein. They can absorb a greater proportion of the food they ingest.

32
Q

What is the efficiency of energy transfer in endotherms

A

organisms that maintain a constant body temperature. The efficiency is lower when energy is transferred to mammals or birds. They require more energy to maintain a constant body temperature. These organisms lose a lot of energy as heat.

33
Q

What is the efficiency of energy transfer in Older organisms

A

Efficiency is often lower

34
Q

How do farmers increase production by increasing the efficiency of energy transfer

A

· Reducing respiratory losses within a human food chain.
· Simplifying food webs to reduce energy losses to non-human food chains e.g. the use of pesticides to prevent crops being eaten by pests.

35
Q

how do you would reduce the respiratory losses in cattle farming.

A
  1. Slaughtered when still growing so more energy transferred to biomass
  2. Feed on controlled dietso higher proportion of (digested) food absorbed/lower proportion lost in faeces
  3. Movement restricted so less respiratory loss
  4. Kept inside so less heat loss / no predators.
  5. Genetically selected for high productivity
36
Q

What is succession

A

The way in which the different species of organisms which make up a community change over a period of time.

37
Q

What are the events of succession

A

-Hostile environment – colonised by pioneer species (Lichens)
-Abiotic environment of habitat changed by pioneer species (By adding more nitrates to soil)
-Changed environment becomes more suitable to support new species (Moss and ferns)
-Establishment of new plant species increases the species diversity as various groups of animals enter the habitat; the early colonisers are replaced by new species
-Changes in the abiotic factors result in a less hostile environment and an increase in biodiversity
-A climax community develops (woodland)

38
Q

Where does primary succesion occur

A

takes place on bare rock or sand, on which no community has previously been established.

39
Q

Where does secondary succession occur

A

This takes place in an area that has been previously colonised, but has been disturbed

40
Q

What is concervation

A

Conservation is concerned with managing biological diversity and ecosystems. An individual species can only survive if it has a suitable habitat in which to live, so many conservation projects involve management of succession.

41
Q

How is the countryside being conserved

A

managed by grazing and controlled burning, so deflecting the natural succession process and preventing a climax community from developing.
The aim is to ensure there are a variety of different types of habitat in the UK.