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biology 2022 paper 2 > Paper 2: Topic 7 Ecology - Organisation of an ecosystem > Flashcards

Paper 2: Topic 7 Ecology - Organisation of an ecosystem Flashcards

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1
Q

Define the term food web

A
  • A representation of the feeding relationships within the community
  • It shows the flow of energy and biomass between organisms

HINT: do not say it “shows who eats who”

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2
Q

Define the term food web

A

A series of interconnected food chains

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3
Q

Define the term producer

A
  • An organism at the start of a food chain
  • They have the ability to make glucose by photosynthesis using energy from the sun
  • E.g. plants, algae
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4
Q

Define the term trophic level

A

The feeding level of an organism within the food chain

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5
Q

Define the term biomass

A

The mass of the living material that makes up an organism

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6
Q

Define the term consumer

A

An organism that eat other organisms

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7
Q

Define the term herbivore

A

A primary consumer that feeds ONLY plants

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8
Q

Define the term carnivore

A

A consumer that feeds ONLY on animals

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9
Q

Define the term omnivore

A

A consumer that feeds on BOTH animals and plants

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10
Q

Define the term detritivore

A

An animal that feeds on dead animal, algal and plant material e.g. worms, beetles

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11
Q

Define the term predator

A

A consumer that hunts and kills another animal to obtain its food

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12
Q

Define the term prey

A

An organism that is hunted, killed and eaten by another animal

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13
Q

Describe the pattern between predators and prey in a stable community

A
  • In a stable community the numbers of predators and prey rise and fall in cycles.
  • The levels of both populations oscillates (fluctuates) in cycles
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14
Q

Describe the relationship between predators and prey in a stable community

A
  • The population of any species is determined by the availability of food
  • If the population size of the prey increases the population size of the predators will increase (a little time afterwards)
  • The increase in the population size of the predators will cause a decrease in the population size of the prey
  • If the population size of the prey decreases the population size of the predators will decrease (a little time afterwards)
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15
Q

State the term to describe a trend line that constantly fluctuates (goes up and down)

A

Oscillates

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16
Q

Explain why predator-prey cycles are always a little out of phase with each other

A
  • It takes a period of time for the population to respond to changes in the other population
  • E.g. it takes time for the foxes to reproduce if more rabbits become available
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17
Q

Place the following organisms in the correct sequence in a food chain:

Primary consumer

Producer

Tertiary consumer

Secondary consumer

A

Producer → Primary consumer → Secondary consumer → Tertiary consumer

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18
Q

Predator prey graph

A
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19
Q

Food chains

A
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20
Q

State the name of the piece of apparatus that s often used to study organisms in their habitats

A

Quadrat

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21
Q

State 2 methods that can be used to study organisms in their environment

A
  1. Quadrats
  2. Transects
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22
Q

Describe how to use a quadrat to study the distribution of small organisms

A
  1. Lie a 10m tape measure along the environmental gradient to be studied e.g. from the base of a tree out of the canopy
  2. Use a calculator to generate 10 random numbers
  3. Convert the random numbers to positions along the 10m tape measure e.g. 720 = 7m20
  4. Place the left hand corner of a 1m x 1m (1m2) quadrat at the first position on the tape measure
  5. Count all the organisms within the quadrat
  6. Repeat for each of the 10 positions
  7. Calculate the mean number of organisms per m2
  8. Repeat the above steps in the second sample site e.g. environment from a different species of tree
  9. Compare the two means (one from each sample site)
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23
Q

Describe how to calculate a mean

Remember: Maths will count for a minimum of 10% of the marks of each paper

A

Add all the data in the sample together then divide the total by the number of pieces of data

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24
Q

Describe how to determine the mode

Remember: Maths will count for a minimum of 10% of the marks of each paper

A

Identify the number that appears the most frequently in the data set

25
Q

Describe how to determine the median

Remember: Maths will count for a minimum of 10% of the marks of each paper

A

Arrange all the data in ascending order of size

Count the number of pieces of data

Divide the number of pieces of data by 2

Then count along the ascending order of numbers until you reach this point

26
Q

State how the distribution of organisms across an area can be studied

A

Setting up a transect and using quadrats along the line

27
Q

Describe how quadrats can be placed along a transect to prevent bias

A
  • Use random numbers to decide where to place the quadrat

OR

  • Place quadrats at specified intervals e.g. every 2m along the tape measure
28
Q

Describe how to estimate the percentage cover of organisms in a quadrat

A
  • Use a grid quadrat (a frame divided into smaller squares)
  • Count the number of squares covered by the first organism
  • Convert this to a percentage:
    • (Number of squares covered by the organism divided by total number of squares ) multiplied by 100
  • Repeat for all other organisms
29
Q

State 3 environmental changes that can affect the distribution of organisms

A
  1. Availability of water
  2. Temperature
  3. Composition of atmospheric gases (carbon dioxide, oxygen)
30
Q

Explain how the availability of water can affect the distribution of organisms

A

The distribution of some animals e.g. wildebeasts, elephants, lions, camels varies in the wet and dry seasons

31
Q

Explain how temperature can affect the distribution of organisms

A

The distribution of some animals e.g. birds varies in winter and summer

32
Q

Explain how changes in the composition of atmospheric gases can affect the distribution of organisms

A

The distribution of lichens changes with changes in air quality e.g. some species of lichen can not grow in areas with high sulphur dioxide found in industrial areas

33
Q

Explain what causes changes in the environment

A
  1. Seasonal changes
  2. Geographic factors
  3. Human interaction with the environment
34
Q

Describe the water cycle

A
  1. Energy form the sun heats bodies of water (lakes, oceans, rivers etc)
  2. The transfer of energy from the sun to the water causes water molecule to evaporate
  3. The water vapour is carried upwards as warm air rises
  4. When the warm air reaches the cooler air higher up it condenses and forms clouds
  5. The water falls to the Earth as precipitation (rain, sleet, snow, hail)
  6. This precipitation provides fresh water for animals and plants
  7. The freshwater then drains back into the water courses again i.e. back to the lakes, oceans, rivers etc
35
Q

State the 4 key contributors/parts to the carbon cycle

A
  1. Respiration
  2. Photosynthesis
  3. Decay
  4. Combustion
36
Q

Describe how carbon is removed from the atmosphere

A

Plants and algae remove carbon dioxide from the air to use as a raw material for photosynthesis

37
Q

Explain how carbon is transferred from plants to animals

A
  • Herbivores consume plants and convert the carbon from the plant material to new proteins, lipids and carbohydrates
  • Consumers then eat animals and then convert the carbon from the herbivores/other animals to new proteins, lipids and carbohydrates
38
Q

Describe how carbon is removed from the atmosphere

A
  • All living organisms (plants, animals, fungi, decomposers) all respire and release carbon dioxide into the atmosphere
  • Combustion of fuels releases carbon dioxide to the atmosphere
  • Decay of dead organic material by micro-organisms and detritivores releases carbon dioxide to the atmosphere
39
Q

Define the term decay

A

The breakdown of dead animal and dead plant waste by micro-organisms

40
Q

State the 3 conditions for decay

A
  1. Warmth
  2. Moisture
  3. Oxygen
41
Q

Describe and explain how temperature affects the rate of decay

A

Describe:

  • As temperature increases the rate of decay increases until an optimum temperature
  • At temperatures above the optimum temperature the rate of decay decreases to zero

Explanation:

  • At very low temperatures the enzymes are inactive and the rate of decay is very low or zero
  • As temperature increases the rate of enzyme activity increases
  • The increased enzyme activity increases the breakdown of proteins, lipids and carbohydrates in the dead animal and plant material
  • At temperatures above the optimum temperature the enzymes are denatured and no breakdown of material occurs
42
Q

Describe and explain how oxygen affects the rate of decay

A

Describe:

  • In the absence of oxygen the rate of decay is zero
  • In the presence of oxygen the rate of decay increases

Explain:

  • Many micro-organisms and detritivores that break down the dead plant and animal material need oxygen to carry out aerobic respiration and live
  • However, some micro-organisms that use anaerobic decay can survive without oxygen
43
Q

Describe and explain how water availability (moisture) affects the rate of decay

A
  • Describe:*
  • The rate of decay increases in areas with greater water availability
  • Explain:*
  • Water is needed to carry out the chemical reactions that breaks down the lipids, carbohydrates and proteins in the dead animal and plant material
44
Q

Describe and explain how the number of micro-organisms affects the rate of decay

A
  • Describe:*
  • The greater the number of micro-organisms the greater the rate of decay
  • Explain:*
  • The greater the number of micro-organisms the greater the quantity of enzymes to carry out the break down of the waste animal and plant material
45
Q

State the type of decay that is used to produce biogas

A

Anaerobic decay

46
Q

State the gases that are form biogas

A
  1. Methane
  2. Carbon dioxide
47
Q

State the name of the simple apparatus used to produce biogas

A

Generator or digester

48
Q

Explain the function of a water jacket on a biogas generator

A
  • As the microbes inside the generator respire the temperature inside the generator increases because respiration is an exothermic reaction
  • The water jacket cools the contents of the generator as the temperature inside the generator increases
  • This prevents the enzymes being denatured and the micro-organisms being killed which wold stop the biogas production
49
Q

Explain the function of an air inlet on a biogas generator

A

To supply oxygen for the micro-organisms to use in aerobic respiration

50
Q

Explain the function of monitoring probes in a biogas generator

A
  • To monitor the pH, temperature and water levels in the generator
  • These can then be regulated by a computer to maintain optimum conditions for biogas production
51
Q

Explain the function of a stirrer/paddles in a biogas generator

A
  • To mix the micro-organisms with the waste material to maximise biogas production
  • To distribute the heat that is given out from the exothermic reactions in respiration
  • To mix the micro-organisms with oxygen
52
Q

Explain the function of the 2 outlet pipes on a biogas generator

A
  • One to remove the digested material
  • One to remove the biogas product
53
Q

Explain why biogas has to be used as soon as it is produced

A

It can’t be stored as a liquid (as it needs too high a pressure to convert it from gas to liquid)

54
Q

State 4 uses of biogas

A
  1. Fuel for cooking
  2. Fuel for heating
  3. Fuel for lighting
  4. Fuel to power a turbine to generate electricity
55
Q

State the 2 different types of biogas generator

A
  1. Batch generator
  2. Continuous generator
56
Q

Describe 3 key features of batch generators

A
  1. They only produce biogas in small batches
  2. The waste plant and animal material is added to the generator manually
  3. The waste products at the end of the process are cleared away each session
57
Q

Describe 3 key features of continuous generators

A
  1. The waste plant and animal material is added to the generator continually
  2. There is a steady rate of biogas production
  3. They enable large scale production of biogas
58
Q

Describe a practical that can be carried out to study the effect of temperature on the rate of decay

A

Investigate the time it takes for lipase to break down lipids in milk in the presence of phenolphthalein indicator at different temperature

59
Q

Describe the colour change observed when using phenolphthalein indicator

A

Pink to colourless when the pH changes from alkaline to acidic

biology 2022 paper 2 (6 decks)

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