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A Level AQA Biology > Energy and Ecosystems > Flashcards

Energy and Ecosystems Flashcards

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1
Q

What is a key term to describe ecosystems and what is meant by it?

A

Dynamic - the abundance and distribution of organisms are controlled by biotic (living) and abiotic (non-living) factors.

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2
Q

What is meant by the term population?

A

All the organisms of a single species in a habitat.

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3
Q

What is meant by the term community?

A

All the organisms of all the species in a habitat.

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4
Q

What is meant by the term habitat?

A

The place where an organism lives.

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5
Q

What is meant by the term niche?

A

The role of a species in an ecosystem.

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6
Q

What is meant by the term trophic level?

A

Each stage of the food chain.

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7
Q

What is meant by Gross Primary Productivity (GPP)?

A

Total amount of energy made by producers (per unit area per unit time).

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8
Q

What are respiratory losses?

A

The energy used by organism for respiration.

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9
Q

What is net primary production?

A

The amount of chemical energy a producer store as biomass (per unit area per unit time).

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10
Q

What is the energy transfer efficiency between the sun and the producer?

A

Around 2%.

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11
Q

Why is the energy transfer efficiency so low between the sun and the producer?

A
  • Wrong wavelength of light.
  • Light strikes a non-photosynthetic region.
  • Light reflected.
  • Lost as heat.
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12
Q

What is the energy transfer efficiency between the producer and primary consumer?

A

Around 10%.

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13
Q

Why is the energy transfer efficiency between the producer and primary consumer low?

A
  • Respiratory losses.
  • Lost as heat.
  • Not all the plant is eaten.
  • Some food is not digested.
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14
Q

What is the energy transfer efficiency between the primary and secondary consumer?

A

Around 10.15%.

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15
Q

Why is the energy transfer efficiency between the primary and secondary consumer low?

A
  • Respiratory losses.
  • Lost as heat.
  • Not all the animal is eaten.
  • Some of the food not digested.
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16
Q

For what organisms is energy transfer efficiency especially low for?

A
  • Old animals(stopped growing) - homeotherms/endotherms (warm blooded).
  • Herbivores (more faeces).
17
Q

How can we increase the efficiency of plant crops?

A
  • Shorten food web (reduce competition so the plant has more energy to create biomass).
  • Fertilisers (prevent growth being limited by lack of nutrients).
  • Artificially select organism with a high yield.
18
Q

What can be used to reduce competition for plants?

A
  • Herbicides - kills weeds.
  • Fungicides - Reduce fungal infections.
  • insecticides - chemical control of pets.
19
Q

How can we increase the efficiency of animals/livestock?

A
  • Reduce respiratory loss (restrict movement and keep warm during winter).
  • Slaughter animals while young.
  • Keep predators away.
  • Controlled diet.
  • Artificially select organisms with a high yield.
20
Q

How would you dry biomass before measuring it?

A
  • A sample of biomass is warmed on a scale until the mass remains constant.
  • Temperature must be low to avoid loss of biomass/CO2.
21
Q

Why do we dry biomass before we measure it?

A

The amount of water in a sample can vary a lot so dry biomass gives a more representative sample.

22
Q

Why is mass of carbon a good indicator of biomass?

A
  • Organisms are made from organic compounds.

- Carbon is usually about 50% of the dry biomass.

23
Q

What is calorimetry?

A

Used to estimate the amount of energy stored in dry biomass.

24
Q

How do we calculate energy stored in biomass?

A
  • Burn a sample of biomass completely.
  • Heat a known volume of water.
  • Measure the temperature change of water.
  • Calculate energy released.
25
Q

What is the nitrogen cycle?

A

Ammonium ions - (nitrification) -Nitrite - (Nitrification) - Nitrate - (denitrification) - Nitrogen gas - (nitrogen fixation) - Plants - (saprobiontic nutrition) - Decomposers - (Ammonification) - Ammonium ions.

26
Q

What is the phosphorus cycle?

A

(PHOSPHORUS TRANSFERRED AT EACH STAGE).

  • Plants are decomposed or eaten by animals.
  • Animals produce faeces and eventually die - both are decomposed.
  • Decomposers enter the soil.
  • Weathering and erosion of rocks also enters soil.
  • soil then enters lakes, rivers and oceans.
  • water then used by plants and cycle starts all over again.
27
Q

How do microorganisms play a vital role in recycling nutrients?

A

They breakdown large organic compounds into small inorganic (soluble) compounds. These can be stored by producers.

28
Q

What are Saprobionts?

A

Type of decomposers that digest their food by saprobiontic nutrition.

29
Q

What is saprobiontic nutrition?

A

Digestion of dead organic matter by extracellular enzymes. These products are absorbed.

30
Q

What is Mycorrhizae?

A

A fungi that grow in a mutualistic relationship with plant roots.

31
Q

What do natural fertilisers contain?

A

nitrogen and phosphorus in organic compounds.

32
Q

What are benefits of natural fertilisers?

A
  • Aerate soil.
  • Less Leaching.
  • Contain a wide range of elements.
  • Consume less energy.
33
Q

What are the negatives of natural fertilisers?

A
  • Still need breaking down by saprobionts.

- Slow release of nitrogen and phosphorus.

34
Q

What are artificial fertilisers?

A

Inorganic chemical compounds that contain nitrogen and phosphorus (water soluble).

35
Q

What is leaching?

A

When soluble compounds are washed off land by rain.

36
Q

When is leaching more common?

A

In artificial fertilisers.

37
Q

What is eutrophication?

A
  • Nitrate/phophorus ions leach into fresh water.
  • Algal bloom.
  • Blocks out the light.
  • Plants can’t photosynthesise and therefore dies.
  • Saprobionts breakdown dead plants.
  • Respire anaerobically so use up oxygen.
  • Fish, etc die.
38
Q

What happens when you harvest crops/livestock?

A
  • Removes nitrogen and phosphorus from their cycle.
  • Soil becomes depleted.
  • Add fertilisers to replace nitrogen and phosphorus (too much fertilisers can be harmful).

A Level AQA Biology (10 decks)

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