topic 4.2- energy flow Flashcards

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1
Q

why do most ecosystems rely on sunlight?

A

it is the initial source of energy for both autotrophs (directly) and heterotrophs (indirectly)

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2
Q

give 3 groups of autotroph that carry out photosynthesis and are therefore referred to as producers

A
  • plants
  • eukaryotic algae
  • cyanobacteria
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3
Q

how is light energy converted into chemical energy in carbon compounds?

A

by photosynthesis

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4
Q

how does chemical energy in carbon compounds flow through food chains? what then happens to it?

A

by means of feeding; energy released from carbon compounds by respiration is used in living organisms and converted to heat.

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5
Q

what is the function of cell respiration?

A

it transfers chemical energy from carbon compounds to ATP, which can be used directly for many activities.

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6
Q

what is the drawback of cell respiration?

A

not all of the energy in cell respiration is transferred to ATP. The remainder is converted to heat. Some heat is also produced when ATP is used in cell activities.

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7
Q

why is heat lost from ecosystems?

A

because living organisms cannot convert heat to other forms of energy. Heat then passes from hotter to cooler bodies, so it will eventually all be lost to the abiotic environment.

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8
Q

define biomass

A

the total mass of a group of organisms

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9
Q

what is the effect of energy losses on an ecosystem?

A

energy losses between trophic levels restrict the length of food chains and the biomass of higher trophic levels

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10
Q

give 3 reasons why the energy added to biomass by each successive trophic level is less

A
  • most of the energy in food that is digested and absorbed by organisms in a trophic level is released in respiration and lost as heat- the only energy available to organisms in the next trophic level is chemical energy in carbohydrates and other compounds that have not been used in respiration.
  • the organisms in a trophic level are not usually entirely consumed by organisms in the next trophic level- the remaining energy passes to saprotrophs/detritivores instead.
  • not all parts of food ingested by the organisms in a trophic level are digested and absorbed. some material is indigestible and egested as faces.
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11
Q

distinguish between energy flow in ecosystems and cycling of inorganic nutrients

A
  • there is a continuous but variable supply of energy in the form of sunlight
  • the supply of nutrients in an ecosystem is finite and limited
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12
Q

why does biomass in terrestrial ecosystems diminish with energy along food chains?

A

due to loss of carbon dioxide, water and other waste products (eg urea)

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