U5T8 – Biomass, Gross and Net Primary Productivity

Biomass, Gross and Net Primary Productivity

1 / 15

Which of the following is NOT an accurate way of measuring biomass?

The mass of organically bound carbon

The dry mass of tissue

2 / 15

What would be the most appropriate units for measuring biomass?

kJ m^-2

Kg m^-2

3 / 15

Which would be the most accurate method of sampling dry biomass?

Burning the sample in a calorimeter in the presence of oxygen.

Taking the mass of the sample, then drying in an oven at a very low temperature, until the mass remains constant.

Taking the mass of the sample, then drying in an oven at a very high temperature, until the mass remains constant.

4 / 15

What does GPP stand for?

Gross Primary Productivity

General Primary Productivity

Gross Photosynthetic Productivity

5 / 15

What does GPP represent in a given area?

The amount of chemical energy produced, minus respiratory losses.

The total amount of carbon fixed by photosynthesis.

The total amount of chemical energy produced from light energy.

6 / 15

What is the formula for NPP?

NPP = GPP - R

NPP = GPP + R

NPP = R - GPP

7 / 15

Suggest the most appropriate units for primary productivity.

KJ m^-2yr^-1

Kg m^-2

KJ m^-2yr¹

8 / 15

In the formula for the calculation of NPP, what does the 'R' stand for?

Respiration Rate

Respiratory loss

Renal Excretion

9 / 15

In a woodland, 8,150 kJ m^-2yr^-1 is lost as heat from respiration. The gross primary productivity of the wood is15,000 kJ m^-2yr^-1. What is the net primary productivity of the woodland?

6.85 x 10 ⁵ kJ m^-2yr^-1

6.85 x 10 ⁴ kJ m^-2yr^-1

6.85 x 10 ³ kJ m^-2yr^-1

10 / 15

The above table shows the volume and density of a fresh wood sample, then the volume and density of the same sample after it was dried. Calculate the percentage of water in the sample (water weighs 1g / ml)

35.2

22.6

16.4

11 / 15

If N = Net productivity, F = Energy in food, U = Energy lost in Faeces and Urine, R = Energy lost in Respiration. What would be the formula for Net productivity?

N = F (U + R)

N = F + (U - R)

N = F - (U + R)

12 / 15

It has been estimated that an area of 8000m² is needed to keep a cow. The productivity of grass in the UK is 18,000 kJ m^-2yr^-1

0.0833

0.0096

0.0104

13 / 15

The diagram shows a food web found in the arctic. the producers have a net productivity of 4.52 x 10 ^-3 kJ m^-2yr^-1-2yr^-1

0.9865

0.0135

0.135

14 / 15

The diagram shows an Arctic food web. The arctic fox consumes a 35% share of the primary consumers, with the Gulls and skuas consuming 65%. The arctic fox achieves a 9% energy efficiency, from the total primary consumers productivity of 6,112kJ m^-2yr^-1. What is the productivity of the arctic fox?

201.3 kJ m^-2yr^-1

550 kJ m^-2yr^-1

198.5 kJ m^-2yr^-1

15 / 15

The diagram shows an Arctic food web. Why is the energy efficiency between Forbs and Rock Ptarmigan lower than that between a Rock Ptarmigan and an Arctic Fox?

a) Because more of the body of the Ptarmigan is eaten than the Frobs.

b) Because more of the Ptarmigan is digested and absorbed (assimilated)

c) Because a Ptarmigan is bigger than a Forbs

a) and c)

b) and c)

a) and b)

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