5.3 Energy & Ecosystems Flashcards

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1
Q

How do plants use sugars from photosynthesis?

A

Primarily as respiratory substrates
Synthesise other biological molecules

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2
Q

What is biomass?

A

Total dry mass of tissue or mass of carbon measured over a given time in a specific area or volume

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3
Q

Suggest units for biomass.

A

Sampled area = gm⁻²
Sampled volume = gm⁻³

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4
Q

How can the chemical energy store in dry biomass be estimated?

A

Using calorimetry

energy released = specific heat capacity of water x water volume x temperature increase of water

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5
Q

Why is bomb calorimetry preferable to simple calorimetry?

A

Reduces heat loss to surroundings

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6
Q

How could a student ensure that all water had been removed from a sample before weighing?

A

Heat the sample and reweigh it until the mass reading is constant

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7
Q

Define Gross Primary Production (GPP).

A

Total chemical energy in plant biomass within a given volume or area

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8
Q

Define Net Primary Productivity (NPP).

A

Total chemical energy available for plant growth, plant reproduction and energy transfer to other trophic levels after respiratory losses

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9
Q

Give the mathematical relationship between GPP & NPP.

A

NPP = GPP - R

R represents respiratory losses

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10
Q

Why is most of the Sun’s energy not converted to organic matter?

A

Most solar energy absorbed by atmosphere or reflected by clouds
Photosynthetic pigments cannot absorb some light wavelengths
Not all light falls directly on chlorophyll
Energy lost as heat during respiration/photosynthesis

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11
Q

How can the net production of consumers be calculated?

A

N = I - (F + R)

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12
Q

What does I represent in N = I - (F + R)?

A

Chemical energy from food

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13
Q

What does F represent in N = I - (F + R)?

A

Energy lost as faeces/urine

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14
Q

What does R represent in N = I - (F + R)?

A

Respiratory losses

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15
Q

Why does biomass decrease along a food chain?

A

Energy lost in urine/faeces
Some of organism not consumed
Energy lost as heat to surroundings

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16
Q

Define primary productivity.

A

Rate of primary production
Biomass in specific area over a given time period

17
Q

Define secondary productivity.

A

Rate of secondary production
Biomass in specific area over a given time period

18
Q

Outline common farming practices used to increase efficiency of energy transfer.

A

Exclusion of predators
Aritificial heating
Restriction of movement
Feeding is controlled at optimum

19
Q

How does exclusion of predators increase the efficiency of energy transfer?

A

No energy lost to other organisms in food web

20
Q

How does aritifical heating increase the efficiency of energy transfer?

A

Reduce energy lost to maintain constant body temperature

21
Q

Give a general equation for % energy efficiency.

A

(energy converted to a useful form/total energy supplied) x 100

22
Q

Explain why the length of food chains is limited.

A

Energy is lost at each trophic level
Insufficient energy to support higher trophic level

23
Q

What is a pyramid of biomass?

A

Diagram that shows the biomass at each trophic level

24
Q

Why is a pyramid of biomass preferable to a pyramid of numbers?

A

Shape of pyramid of numbers may be skewed since a small number of producers can support many consumers