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Biology > 4.2 Energy Flow > Flashcards

4.2 Energy Flow Flashcards

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1
Q

Energy source

What is the source of energy for all green plants and some bacteria?

A

Sunlight, utilized in the process of photosynthesis.

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2
Q

Energy source

How do photoautotrophs convert light energy into chemical energy?

A

Through the process of photosynthesis, where light energy is used to make organic compounds from inorganic sources.

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3
Q

Energy source

What do heterotrophs derive their chemical energy from?

A

Organic compounds produced by photoautotrophs, which are ingested and broken down through cell respiration to produce ATP.

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4
Q

Energy source

What are photoautotrophs?

A

All green plants, and some bacteria.

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5
Q

Energy flow

How does energy enter most ecosystems?

A

As sunlight, which is converted into chemical energy by producers through photosynthesis.

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6
Q

Energy flow

Where is chemical energy stored in ecosystems?

A

In carbon compounds, specifically organic molecules produced by producers during photosynthesis.

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7
Q

Energy flow

How is energy transferred to heterotrophs in ecosystems?

A

Through feeding, as heterotrophs consume organic compounds produced by producers.

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8
Q

Trophic Levels

What are the trophic levels?

A

Level 1: Producer
Level 2: Primary consumer
Level 3: Secondary consumer
Level 4: Tertiary consumer

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9
Q

Trophic levels

What is a trophic level?

A

The position an organism occupies within a feeding sequence.

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10
Q

Trophic levels

What do primary consumers feed on?

A

Producers, occupying the second trophic level in a feeding sequence.

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11
Q

Food chain

What does a food chain illustrate?

A

The linear feeding relationships between species in a community.

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12
Q

Food chain

What do arrows in a food chain represent?

A

The transfer of energy and matter as one organism is eaten by another (arrows point in direction of energy flow).

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13
Q

Energy loss

How is energy stored in organic molecules released?

A

Through cell respiration, which produces ATP.

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14
Q

Energy loss

What is ATP used for?

A

To fuel metabolic reactions necessary for growth and homeostasis.

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15
Q

Energy loss

What is a by-product of the chemical reactions involved in cell respiration?

A

Heat, also known as thermal energy, which is released from the organism.

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16
Q

Energy loss

Some of the chemical energy is lost by:

A

Being excreted as part of the organism’s faeces
Remaining unconsumed as the uneaten portions of the food

17
Q

Energy loss

What are some forms into which the chemical energy produced by an organism can be converted?

A

Kinetic energy (e.g. during muscular contractions)
Electrical energy (e.g. during the transmission of nerve impulses)
Light energy (e.g. producing bioluminescence)

18
Q

Energy loss

What type of reactions are involved in releasing thermal energy (heat) as a by-product?

A

Exothermic reactions.
Living organisms cannot turn this heat into other forms of usable energy.
This heat energy is released from the organism and is lost from the ecosystem (unlike nutrients, which are recycled).

19
Q

Energy Efficiency

What happens to most of the energy in living organisms during energy transformations?

A

It is lost to the organism, either used in respiration, released as heat, excreted in feces, or remains unconsumed.

20
Q

Energy Efficiency

What is biomass?

A

The total mass of a group of organisms, consisting of the carbon compounds contained in their cells and tissues.

21
Q

Energy Efficiency

Is the energy transformation process in living organisms 100% efficient?

A
  • Most of the energy is lost to the organism – either used in respiration, released as heat, excreted in faeces or unconsumed
  • Typically energy transformations are ~10% efficient, with about 90% of available energy lost between trophic levels
  • The amount of energy transferred depends on how efficiently organisms can capture and use energy (usually between 5 – 20%)
22
Q

Energy efficiency

Why is the number of potential trophic levels are limited?

A

Higher trophic levels receive less energy / biomass from feeding and so need to eat larger quantities to obtain sufficient amounts
Because higher trophic levels need to eat more, they expend more energy (and biomass) hunting for food
If the energy required to hunt food exceeds the energy available from the food eaten, the trophic level becomes unviable

23
Q

Pyramids of energy

What is a pyramid of energy?

A

A graphical representation of the amount of energy at each trophic level of a food chain.

24
Q

Pyramids of energy

How are pyramids of energy expressed?

A

They are expressed in units of energy per area per time.

25
Q

Pyramids of energy

Why will pyramids of energy never appear inverted?

A

Because some of the energy stored in one source is always lost upon transfer.

26
Q

Pyramids of energy

What is the general rule for the size of each level in a pyramid of energy?

A

Each level should be roughly one-tenth of the size of the preceding level, reflecting the approximately 10% efficiency of energy transformations.

27
Q

Ecological productivity

How is production typically expressed?

A

It is usually expressed in units of mass per area per time

28
Q

Primary Production

What does primary production describies?

A

The production of chemical energy in organic compounds by producers.

29
Q

Primary production

What is the main source of energy in primary production?

A

The main source of energy for primary production is sunlight, but a fraction may be driven by chemosynthesis by lithotrophs

30
Q

Primary producton

How is primary production categorised?

A

Gross primary production (GPP) is the amount of chemical energy as biomass that a producer creates in a given length of time
Net primary production (NPP) is the amount of chemical energy that is not consumed by respiration (NPP = GPP – respiration)

31
Q

Secondary Production

What does secondary production describe?

A

Secondary production describes the generation of biomass by heterotrophic organisms (consumers)

31
Q

Secondary production

What drives the generation of biomass in ecosystems?

A

The transfer of organic compounds between trophic levels via feeding.

31
Q

Food webs

Why are food web is more representative of actual feeding pathways within an ecosystem?``

A

Organisms can have more than one food source
Organisms can have more than one predator

32
Q

Food webs

What are food webs?

A

A diagram that shows how food chains are linked together into more complex feeding relationships.

33
Q

Ecological Pyramids

What do ecological pyramids show?

A

The relative amounts of a specific component at the different trophic levels of an ecosystem.

34
Q

Ecological Pyramids

What are the three main types of ecological pyramids?

A

Pyramid of Numbers
Pyramid of Biomass
Pyramid of Energy

35
Q

Ecological Pyramids

Pyramid of Numbers

A

Shows the relative number of organisms at each stage of a food chain.
These are usually shaped like pyramids, as higher trophic levels cannot be sustained if there are more predators than prey
However, the shape may be distorted if a food source is disproportionately large in size / biomass compared to the feeder

36
Q

Ecological Pyramids

Pyramid of Biomass

A

A pyramid of biomass shows the total mass of organisms at each stage of a food chain

These pyramids are almost always upright in shape, as biomass diminishes along food chains as CO2 and waste is released

37
Q

Ecological Pyramids

Pyramid of Energy

A

A pyramid of energy shows the amount of energy trapped per area in a given time period at each stage of a food chain

These pyramids are always upright in shape, as energy is lost along food chains (either used in respiration or lost as heat)
Each level in the pyramid will be roughly one tenth the size of the preceding level as energy transformations are ~10% efficient

Biology (34 decks)

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