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Biology A-level > Energy and Ecosystems > Flashcards

Energy and Ecosystems Flashcards

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1
Q

What is a producer?

A

A photosynthetic organism that manufactures organic substances using light energy

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2
Q

What is a consumer?

A

An organism which obtains its energy by feeding on other organisms

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3
Q

What is a primary consumer?

A

An organism which eats green plants

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4
Q

What is a secondary consumer?

A

An organism which eats primary consumers

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5
Q

What is a saprobiont?

A

A decomposed which breaks down complex material of dead organisms into simple ones to be reused

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6
Q

Which organisms work as sapropbionts?

A

Fungi and bacteria

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7
Q

What is a food chain?

A

A description of the relationship between producers and consumers

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8
Q

What are the stages of a food chain called?

A

Trophic levels

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9
Q

What is a food web?

A

The many chains within a habitat which are interlinked. Shows how an organism may eat or be eaten

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10
Q

What is biomass?

A

Total mass of living material in a specific area at a given time

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11
Q

Why is fresh biomass not a reliable amount?

A

Volume of water can vary

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12
Q

What is the measurement of dry biomass?

A

Dry mass per given area per given time.

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13
Q

How is biomass measured?

A

Sample is dried in an oven then weighed at regular intervals until the mass is constant

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14
Q

How is the energy stored in biomass estimated?

A

Calorimeter

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15
Q

How much energy from the sun is typically converted into organic matter?

A

1-3%

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16
Q

Most of the suns energy is not converted to biomass, why?

A
  • Light wrong wavelength
  • Light misses the chlorophyll
  • Factor other than light intensity limiting photosynthesis
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17
Q

What is gross primary production?

A

Total amount of energy converted by plants in a given area at a given time

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18
Q

What is net primary production?

A

NPP= GPP-R

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19
Q

Why is consumption so insufficient?

A

Energy is lost as:
- Not all of the organism is consumed
- Lost as faeces
- Lost in excretionary materials
- Energy is lost during respiration as heat

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20
Q

What is the net production in consumers?

A

N=i-(f+r)

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21
Q

Why is the total mass of organisms in a particular place less at higher trophic levels?

A

Inefficiency of energy transfer between organisms. Less energy is available for those at higher trophic levels

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22
Q

What is the efficiency of energy transfer?

A

Net production at a trophic level divided by the net production in the previous trophic level X 100

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23
Q

What is productivity?

A

Amount of energy available to an organism

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24
Q

Why do organisms require nitrogen?

A

For protein, nuclei acids

25
Q

In what form do plants absorb nitrogen?

A

Nitrate ions

26
Q

How are nitrate ions absorbed by plants?

A

Active transport into the roots

27
Q

How are nitrate replaced in the environment?

A

The break down of nitrogen containing compounds by decomposers

28
Q

How are nitrates replaced artificially?

A

Fertilisers

29
Q

What are the four stages of the nitrogen cycle?

A
  • Ammonification
  • Nitrification
  • Nitrogen fixation
  • Denitrification
30
Q

What happens in ammonification?

A

Ammonia in the soil is converted to ammonium ions

31
Q

What happens in nitrification?

A

Bacteria oxidise ammonium ions into nitrite ions and a different bacteria creates nitrate ions

32
Q

What happens in nitrogen fixation?

A

Nitrogen gas is converted to nitrogen containing compounds by bacteria

33
Q

Where are the nitrogen fixing bacteria found?

A

Free living or mutualistic ( in the root nodules of plants)

34
Q

What do free living nitrogen fixing bacteria fo?

A

Reduce nitrogen gas to ammonia which are used to create amino acids released when they die

35
Q

What do mutualistic bacteria do?

A

Rescue nitrogen gas into ammonia which create amino acids given to plants so they receive carbohydrates in return

36
Q

What happens in denitrification?

A

Anaerobic denitrifying bacteria convert nitrates to nitrogen gas

37
Q

What are the benefits of ploughing?>

A

Increases air space, supports aerobic respiration of bacteria

38
Q

What biological molecules contain phosphorus?

A

ATP, Phospholipids, and nuclei acids

39
Q

How is phosphorus general found in nature?

A

As phosphate ions in sedimentary rock

40
Q

How are phosphates removed from rocks

A

Weathering and erosion

41
Q

How are phosphates incorporated into the food chain?>

A

Dissolved phosphates are absorbed into plants

42
Q

How do phosphate ions find their way into animas?

A

Some animals eat plants and so ingest the phosphate containing molecules

43
Q

How are phosphate ions released from animals?

A

Excretion

44
Q

How are phosphates removed from living organisms?

A

Upon death, decomposers break down the organism, releasing soluble phosphates which flow into bodies of water

45
Q

What are mycorrhizae?

A

Mutualistic fungi’s that live on the roots of plants. Help with the uptake of nitrogen and phosphates whilst receiving carbohydrates in return.

46
Q

How do mycorrhizae aid absorption of nutrients?

A

Act as extensions of the roots, increasing surface area for absorption. Also act as a sponge to hold nutrient rich water closer to the roots

47
Q

What are the two types of fertilisers?

A

Natural and artificial

48
Q

Why aren’t fertilisers required in nature?

A

Plants that remove the mineral ions return them when they are decomposed

49
Q

Why is it important to replenish the mineral ions in the soil?

A

They will become a limiting factor in photosynthesis if too low

50
Q

Why is it important that fertilisers are given in appropriate quantities?

A

There is a limit. Past a certain point they don’t add to the effectiveness

51
Q

How do fertilisers increase productivity?

A

Mineral ions readily available

52
Q

What are the effects of nitrogen containing fertilisers?

A

Increase area of leaves therefore increasing rate of photosynthesis and crop productivity

53
Q

What are the drawbacks of nitrogen containing fertilisers? `

A

Reduced species diversity, leaching and eutrophication

54
Q

Why does the use of nitrogen rich fertilisers affect species diversity?

A

Nitrogen rich soil favours fast growing species which outcompete other species

55
Q

What is leaching?

A

Process by which nutrients are washed out of the soil

56
Q

How are minerals leached from the soil?

A

Rainwater carries dissolved nutrients deep into the soil away from plant roots. This makes it into water ways and lakes

57
Q

Why is leaching dangerous to humans?

A

If the water source is a drinking source it has been linked to stomach cancer and insufficient oxygen transport in babies. Also causes eutrophication.

58
Q

What happens in eutrophication?

A

As the nitrate ion concentration increases due to leaching, it no longer is a limiting factor so plant and algae populations will grow. As algae is at the surface, it blocks light from lower depths so light is now a limiting factor. Saprobiontic bacteria population will grow as dead organic material ceases to be a limiting factor and this bacteria requires oxygen so the oxygen concentration decreases becoming a limiting factor for aerobic organisms.

Biology A-level (22 decks)

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