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A2 Biology > Energy and ecosystems > Flashcards

Energy and ecosystems Flashcards

1
Q

What are producers?

A

Photosynthetic organisms that manufacture organic substances using light, water and carbon dioxide. Green plants are producers

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2
Q

What are consumers?

A

Organisms that obtain their energy by feeding on other organisms, rather than using the energy of sunlight directly. Animals are consumers

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3
Q

What are decomposers?

A

Organisms, usually fungi or bacteria, that break down the complex material of dead producers and consumers into simple components again and release minerals and elements in a form plants can absorb. They contribute to recycling. Sometimes organisms such as earth worms do this, and they are known as detritivores

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4
Q

What does a food chain describe?

A

A feeding relationship in which the producers are eaten by primary consumers, which are in turn eaten by secondary consumers, which are then eaten by tertiary consumers

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5
Q

What is a trophic level?

A

Each stage of a food chain

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6
Q

What is a food web and what does it show?

A

Lots of food chains in an ecosystem and how they over lap

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7
Q

What is an ecosystem?

A

All the organisms living in a particular area and all the non-living (abiotic) conditions

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8
Q

What is the source of energy for ecosystems?

A

The sun

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9
Q

What percentage do plants convert the sun’s energy into organic matter?

A

1-3 %

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10
Q

What is gross production?

A

Total quantity of energy that plants in a community convert to organic matter

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11
Q

What is net production and the equation for calculating it?

A

The rate at which plants store energy

net production = gross production - respiratory losses

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12
Q

What are the reasons for the low percentage of energy transferred at each stage?

A
  • Some of the organism is not eaten
  • Some parts are eaten but aren’t digested and is lost in faeces
  • Some energy is lost in excretory materials e.g. urine
  • Some energy losses occur as heat from respiration and directly from the body to the environment. High in mammals and birds due to their high body temperature
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13
Q

What does the inefficiency of energy transfer between trophic levels explain?

A
  • Why most food chains have 4 or 5 trophic levels as there is insufficient energy to support a breeding population at higher trophic levels
  • Biomass is less at higher levels
  • Total amount of energy stored is less at each trophic level
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14
Q

What is energy available usually measured as?

A

kJ m -2 year -1

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15
Q

What is the calculation for working out energy transfer?

A

energy available after transfer
_______________________
energy available before transfer X 100

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16
Q

What is biomass?

A

The total mass of a living organism in a specific area at any given time. Usually measured as dry mass because amount of water un an organism varies.

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17
Q

What is an agricultural ecosystem?

A

Domesticated animals and plants used to produce food for humans

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18
Q

What is productivity?

A

Rate at which something is produced

19
Q

What two main factors affect net productivity in agricultural ecosystems?

A
  • Efficiency of the crop at photosynthesising

- Area of ground covered by leaves of the crop

20
Q

What is a natural ecosystem?

A

An ecosystem unchanged by human activity

21
Q

What does intensive farming involve?

A

Changing an ecosystem by controlling the biotic or abiotic conditions to make it more favourable for the crops/livestock so they have greater net productivity

22
Q

How is a agricultural ecosystem maintained?

A

By preventing it’s climax community developing

23
Q

What additional energy input is used in agricultural ecosystems?

A
  • Food: what people on the farm eat

- Fossil fuels: fuel to plough, harvest , transportation etc.

24
Q

Which type of ecosystem is productivity fairly low?

A

Natural

25
Q

What are pests?

A

Organisms that competes with humans for food or space, or could be a danger to health

26
Q

What are pesticides?

A

Chemicals that attract and then kill pests

27
Q

What should an effective pesticide be?

A
  • Specific to the organism it wants to kill
  • Harmless to humans and other organisms
  • Biodegradable so it breaks down into harmless substances in the soil
  • Cost effective
  • Not accumulate
28
Q

What is biological control?

A

Using organisms that are either predators or parasites of the pest organism. The aim is to control the pest and not to eradicate it. Ideally the control agent and the pest should exist in balance with one another

29
Q

What are the advantages of biological control?

A
  • Very specific
  • Pests do not become resistant
  • Once introduced the control organism reproduces itself
30
Q

What are the disadvantages of biological control?

A
  • Don’t act as quickly so there is often a time lag
  • Control may itself become a pest
  • Less cost effective
  • May kill other non-pest species
31
Q

What are the advantages of using pesticides?

A
  • Increase productivity

- Destroys harmful pests

32
Q

What are the disadvantages of using pesticides?

A
  • Expensive as they have to be re applied
  • Pests may become resistant
  • May kill other non-pest species
  • Harmful affects on humans if applied to crops
33
Q

What are integrated pest-control systems?

A

They aim to integrate all forms of pest control ( chemical and biological) rather than just relying on one type.

34
Q

What does integrated pest-control involve?

A
  • Managing the environment near crops to provide habitats for natural predators
  • Regular monitoring of crops for signs of pests so early action can be taken
  • Using biological agents if necessary and available
  • Using pesticides as a last control if pest populations become out of control
35
Q

What are the advantages of using an integrated pest-control system?

A
  • combined effect reduces pest numbers even more, increasing productivity further
  • can reduce costs
  • reduce the environmental impact if less pesticides are used
36
Q

What is meant by intensive rearing of livestock?

A

Controlling the conditions of where the livestock live, so more of their energy is used for growth and les is used for other activities. The efficiency of energy conversion is increased so more biomass is produced and productivity increases.

37
Q

How does “factory farming” increase the energy conversion rate?

A
  • Restricted movement less energy is used for muscle contraction
  • Warm environment to reduce heat loss
  • Controlled feeding so animals receive the optimum amount and type of food for maximum growth with no wastage
  • Exclude predators
38
Q

What other methods can be used to increase the energy conversion rate?

A

Selective breeding and using growth hormones.

39
Q

What are the main features of intensive rearing?

A
  • Efficient energy conversion
  • low cost
  • quality of food
  • use of space
  • safety
  • disease
  • drugs: anti-biotic resistance
  • animal welfare
  • pollution
  • reduced genetic diversity from selective breeding
  • use of fossil fuels and increase c02 release into atmosphere
40
Q

What are fertilisers?

A

Chemicals that provide crops with minerals needed for growth

41
Q

What are the two types of fertilisers?

A

Natural and artificial

42
Q

What are natural fertilisers?

A

Organic matter e.g. manure

43
Q

What are artificial fertilisers?

A

Inorganic chemicals

44
Q

What are the disadvantages of using fertilisers?

A
  • May be washed into rivers and ponds, killing fish and plant life because of eutrophication
  • Changes the balance of nutrients in the soil
  • Difficult to make it cost effective, have to get just the right amount without harming anything

A2 Biology (12 decks)

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