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GCSE OCR Biology > B4.1 Ecosystems > Flashcards

B4.1 Ecosystems Flashcards

1
Q

What is an ecosystem made up of?

A

All the living organisms and physical conditions in an area

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2
Q

Define community.

A

The organisms within the ecosystem

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3
Q

Define habitat.

A

Where organisms live

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4
Q

Define population?

A

The total number of organisms of each species

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5
Q

What are organisms grouped into? What is their role?

A
  • Producers - organisms that make their own food by photosynthesis. They include all plants and algae
  • Consumers - organisms that cannot make their own food. They have to eat other organisms to gain energy.All animals are consumers.
  • Decomposers - a special group of consumers. They gain their energy by feeding on dead or decaying material.
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6
Q

What can glucose be converted into?

A

Carbohydrates, fats and proteins which are used as energy stores and for growth and repair.

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7
Q

Define biomass?

A

The dry mass of all of the living organisms in an area

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8
Q

What does a food chain show?

A

The transfer of biomass and energy transfer from one organism to the next.

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9
Q

Define food web.

A

A series of interlinked food chains.

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10
Q

Define omnivore.

A

Animals which eat both animals and plants

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11
Q

Define carnivore.

A

an organism that mostly eats meat, or the flesh of animals

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12
Q

Define herbivore.

A

an animal that mainly eats plants.

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13
Q

Define biotic factors.

A

The living factors of an ecosystem

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14
Q

Define abiotic factors

A

The non living factors of an ecosystem e.g rainfall or temperature

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15
Q

What do organisms compete for?

A

Food - space - mates

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16
Q

How does temperature affect communities

A

Temperature has its greatest effect on the enzymes that control metabolic reactions. Plants develop more rapidly in warmer temperatures.

SIDE NOTE: Warm blooded animals are less affected by their external environment

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17
Q

How does light intensity affect communities?

A

Light is required for photosynthesis. In general the greater the light availability the greater the success of a plant.

SIDE NOTE: in areas of low light plants often have larger leaves

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18
Q

How does moisture levels affect communities?

A

A lack of water leads to death in most plants and animals.
A lack of water causes most plants to wilt because water is required to keep their cells turgid, keeping plants upright.
Water is used in photosythesis

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19
Q

How does soil pH affect communities?

A

The pH of soil affects the biological activity in the soil and the availability of certain minerals.
Some plants grow better in acidic soils such as farms.
Some plants grow better in alkaline soils such as cucumbers and cauliflower

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20
Q

What is used to measure the following abiotic factors:

Light intensity
Availability of moisture
pH
Temperature

A

Light meter
Humidity sensor
pH probe
thermometer

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21
Q

What do plants need to survive?

A

Light
Water
Carbon dioxide
Minerals
Space

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22
Q

What do animals need to survive?

A

Food
Water
Mates
Space
Shelter

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23
Q

What is interdependence?

A

How different organisms depend on each other within a community.

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24
Q

What are the three main types of interdependence?

A

Predation
Mutualism
Parasitism

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25
What is predation?
The relationship between a predator and a prey species.The size of the predator population directly affects the size of the prey population
26
What is mutualism?
Where both organisms benefit from the relationship e.g bees and flowers
27
What is parasitism ?
Where only one organism (the parasite) gains from the relationship. The organism. it lives off (the host) suffers. e.g headlice and humans
28
What do pyramids of biomass show?
Show the population at each tropic level.
29
How is a pyramid of biomass structured
The producer is placed at the base, with the next tropic levels placed above.
30
What does the bar width represent in a pyramid of biomass?
The number of organisms present
31
What is the general pattern for a pyramid of biomass?
The size of the population generally increases ,but the number of organisms decreases.
32
How do you calculate biomass at each trophic level?
The average mass of each organism x Number of organisms present
33
State a disadvantage of collecting biomass data?
Biomass data is difficult to obtain as the organism needs to be killed and heated in an oven to remove any water, until a constant dry mass is obtained.
34
What are the steps to draw a pyramid of biomass?
Step 1: Decide on a sale to represent the biomass of each species Step 2: Calculate the width of each bar bye dividing each biomass by the scale factor Step 3: Use the measurements to draw each bar in the pyramid
35
How is energy transferred to producers?
Sunlight
36
How much energy do producers transfer into chemical stores?
1%
37
How much energy is transferred to each trophic level?
10%
38
How is biomass lost in organisms?
Not all of an organism is eaten Some of the biomass is used in respiration Some parts of an organism cannot be digested, such as hair and teeth Waste products produced by the body are lost through excretion. e.g urea is lost in urine
39
What is egestion?
The release of undigested substances as feces
40
What is excretion?
The removal of toxic materials, waste products of metabolism and excess substances from organisms
41
How do you calculate the efficiency of biomass transfer?
[Biomass available after the transfer (g or kg) / Biomass available before the transfer (g or kg)] X 100
42
Where do plants get their nutrients?
Soil
43
Name three molecules which are cycled through ecosystems
Carbon Nitrogen Water
44
What is carbon used for?
Fats Proteins DNA
45
Where can carbon become trapped?
Oceans and rocks
46
How much of the atmosphere is nitrogen?
80%
47
What do organisms use nitrogen for?
To make DNA and proteins.
48
How does nitrogen exist in soil?
As nitrates dissolved in water
49
Describe how nitrogen is cycled through an ecosystem.
1. Nitrogen is fixed by lightening and nitrogen-fixing bacteria 2. Denitrifying bacteria release nitrites in soil into nitrogen in the air 3. Denitrifying bacteria convert nitrates in soil into nitrites, and nitrites to ammonia 4. Nitrifying bacteria convert ammonia in soil into nitrites, and nitrites to nitrates 5. Nitrates in soil taken up by plants and combined with carbohydrates to make plant proteins. 6. Plant proteins either eaten by other animals to form animal protein or die and decompose to release ammonia into soil 7. Animals excrete ammonia and die and decompose to release ammonia into soil.
50
Where does the water cycle move from?
Through the atmosphere ,soil, rivers , lakes and oceans
51
What can excess use of nitrates lead to?
eutrophication
52
What is the carbon cycle?
The process by which carbon is cycled through the atmosphere, the Earth, plants and animals
53
How is carbon removed from the atmosphere?
Carbon dioxide is removed from the environment during photosynthesis. When animals eat plants, carbon in the plant is transferred to the animal. Some of this carbon is used to produce fats and proteins in the animals body Glucose is used in plants to grow and develop.The carbon is part of their extra biomass
54
How is carbon released back into the atmosphere?
Respiration - All living organisms respire to transfer energy from chemical stores in food. Carbon dioxide is produced and released. Decomposition - When plants and algae and animals die decomposers break down their remains, reeling carbon dioxide as they respire. Burning fossil fuels - Fossil fuels are a store of carbon. When they burn this trapped carbon is released.
55
What are some examples of fossil fuels
Coal Oil Natural gas
56
Why does the level of atmospheric carbon dioxide vary?
photosynthesis only takes place in the light, so carbon dioxide is only removed from the atmosphere in the day time Respiration is carried out throughout the day and night, releasing carbon dioxide at a relatively consistent rate.
57
What are decomposers?
micro-organisms that break down or decay dead organic material and waste at a microscopic level
58
What are saprophytes?
A plant, fungus, or microorganism that lives on dead or decaying organic matter.
59
What are detritivores?
Small animals that speed up decomposition by shredding organic material into very small pieces.
60
Name examples of Detritivores and the material they break down
earthworm - leaves woodlouse - wood maggot - animal material
61
How do bacteria and fungi break down substances in organic matter?
They release enzymes and then absorb the soluble nutrients and use them for growth and an energy store
62
How can nutrients be passed on to other organisms?
Be eaten or directly released into soil
63
What factors affect the rate of decomposition?
Warm temperatures Moist environments Aerobic conditions
64
Explain how warm temperatures affect the rate of decomposition
Enzymes work faster is higher temperatures yet not too high as to avoid denaturing which prevents decomposition occurring
65
Explain how moist environments affect the rate of decomposition
If not enough water is available, reactions within the microorganisms will slow down or be prevented. This reduces or stops the process of decomposition
66
Explain how aerobic conditions affect the rate of decomposition?
Oxygen is needed for the microorganisms to respire. Anaerobic conditions will prevent most forms of decomposition as the micro-organisms cannot survive in this environment
67
How do you calculate the rate of decay of biological material?
Change in mass (g) / Time (day)
68
Why is recycling in ecosystems necessary?
To create a continuous flow of nutrients
69
Describe how carbon is cycled through an ecosystem.
1. Carbon dioxide is fixed through photosynthesis 2. Respiration releases carbon dioxide 3. Decomposition releases carbon dioxide 4. Combustion releases carbon dioxide
70
Describe how water is cycled through an ecosystem.
1. Water evaporates from rivers and lakes and from transpiration 2. Water condenses as clouds 3. Water is returned through precipitation

GCSE OCR Biology (9 decks)

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