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A2 Biology Unit 4 > Energy transfer and energy loss > Flashcards

Energy transfer and energy loss Flashcards

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1
Q

What are reasons for which a lot of available energy is never taken in by organisms?

A

Plants can’t use all the light energy that reaches their leaves (e.g wrong wavelength).
Some parts of food, e.g roots or bones, aren’t eaten by organisms.
Some parts of food are indigestible so pass through organisms and come out as waste, e.g faeces.

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2
Q

What is gross productivity?

A

The available energy that is absorbed by the body.

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3
Q

What is net productivity?

A

The amount of energy that’s available to the next trophic level.

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4
Q

Net productivity

A

= gross productivity - respiratory loss

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5
Q

Efficiency of energy transfer =

A

net productivity of trophic level/ net productivity of previous trophic level x 100

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6
Q

What is the main route by which energy enters an ecosystem?

A

Photosynthesis

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7
Q

Name the type of diagram that shows lots of food chains in an ecosystem and how they overlap.

A

Food web

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8
Q

What is the name given to the amount of energy taken in by an organism?

A

Gross productivity

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9
Q

What is respiratory loss?

A

Energy lost to the environment when organisms use energy produced for movement or body heat.

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10
Q

What do pyramids of numbers show?

A

The number of organisms in each trophic level.

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11
Q

What do pyramids of biomass show?

A

The amount of biomass in each trophic level.

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12
Q

What is a natural ecosystem?

A

An ecosystem that hasn’t been changed by human activity.

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13
Q

What is the energy input of a natural ecosystem?

A

The amount of sunlight captured by the producers in the ecosystem.

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14
Q

What is intensive farming?

A

Involves changing an ecosystem by controlling the biotic or abiotic conditions.

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15
Q

What different ways can intensive farming methods increase productivity?

A

They can increase the efficiency of energy conversion- more energy is used for growth and less on other activities e.g recovering from disease or movement.
They can remove growth limiting factors.
They can increase energy input.

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16
Q

In what 3 ways can pests be killed?

A

Using chemical pesticides.
Using biological agents.
Using integrated systems.

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17
Q

What are herbicides?

A

Chemical pesticides that kill weeds that compete with agricultural crops for energy.
Reducing competition means crops receive more energy, so they grow faster and become larger, increasing productivity.

18
Q

What are fungicides?

A

Chemical pesticides that kill fungal infections that damage agricultural crops.
The crops use more energy for growth and less for fighting infection, so they grow faster and become larger, increasing productivity.

19
Q

What are insecticides?

A

These kill pests that eat and damage crops.

Killing pests mean less biomass is lost from crops, so they grow to be larger which means productivity is greater.

20
Q

What are some environmental issues of using chemical pesticides?

A

They may directly affect other non pest species, e.g butterflies.
They may indirectly affect other non pest species e.g poisoning secondary consumers.

21
Q

Give three examples of biological agents.

A

Natural predators.
Parasites.
Pathogenic bacteria and viruses.

22
Q

What are some environmental issues of using biological agents?

A

Natural predators introduced to an ecosystem may become a pest species themselves.
Biological agents can affect other non pest species.

23
Q

What are some economic issues of using chemical pesticides?

A

They can be expensive and so may not be profitable for farmers.

24
Q

What are integrated systems?

A

Use both chemical and biological.

25
Q

What are fertilisers?

A

Chemicals that provide crops with minerals needed for growth, reducing that as a limiting factor as growth is limited when there isn’t enough minerals and fertilisers replace lost minerals.

26
Q

What are the two different types of fertiliser?

A

Natural and artificial fertilisers.

27
Q

What are some environmental issues of using fertilisers?

A

Eutrophication- the killing of plants and fish as the fertiliser is washed into rivers and ponds.
Changes the balance of nutrients in the soil- too much of a particular nutrient can cause crops and other plants to die.

28
Q

Whats the difference between natural and artificial fertilisers?

A

Natural- organic matter.

Artificial- inorganic matter.

29
Q

Gross productivity =

A

net productivity + respiratory loss

30
Q

Respiratory loss =

A

gross productivity – net productivity

31
Q

Intensive farming increases productivity by:

A

Restricting movement so less energy used in muscle contraction. This lowers respiratory loss
Keeping the environment warm to reduce heat loss
Feeding animal’s higher energy food so more energy is available for growth. Also less indigestible material
Slaughtering animals before they reach adulthood because young animals use more energy for growth
Exclusion of predators

32
Q

Why is chemical control used?

A

Herbicides kill weeds that compete with agricultural crops for resources such as space, water and light.
Fungicides kill fungal infections which damage crops -> less energy wasted fighting infections.
Insecticides kill pests that eat and damage crops -> less biomass lost.

33
Q

Pros and cons of biological control.

A
  • Very specific
  • The control organism would reproduce so you don’t need to reapply, but there would be a lag time
  • Pests do not become resistant
  • The control organism could become a pest itself
  • Pest will not be completely eradicated because it is a food source for the biological agent
34
Q

Pros and cons of chemical control

A
  • Bioaccumulation
  • May affect non-pest species
  • Have to reapplied so are expensive
  • Pests can become resistant
35
Q

What are integrated systems?

A

Integrated systems use biological and chemical control mechanisms. This reduces the environmental impact as less pesticide is used.

36
Q

Why is ploughing good?

A

Aeration

Aids nitrification

37
Q

Why is crop rotation good?

A

Restore fertility of soil- enhance nutrient quality.
Adds diversity.
Certain pests at certain times.

38
Q

Units for gross productivity

A

KJm-2Yr-1

39
Q

Why does climate change increase soil salinity?

A

Evaporation
Salt less diluted in soil, increase salt conc
Also heard about sea levels rising, and deposit salts

40
Q

Why plant growth is lower at higher salt salinity?

A

Low WP in soil,
Water moves out of roots via osmosis or less absorbed for photsyn
Less photo means less proteins, carbs etc.
Less growth

41
Q

Why does gross productivity decrease as succession occurs?

A

Taller trees, dense leaves in canopy,
Less light to producers on forest floor
Less energy conversion (gross prod)
Less energy for all organisms in food chain that eat producers.

A2 Biology Unit 4 (12 decks)

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