What is the total mass of carbon released into the atmosphere from respiration per year?
60 billion tonnes
148 billion tonnes
150 billion tonnes
140 billion tonnes
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Syllabus Edition
First teaching 2023
First exams 2025
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Tool 3: Mathematics
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Tool 3: Mathematics
What is the total mass of carbon released into the atmosphere from respiration per year?
60 billion tonnes
148 billion tonnes
150 billion tonnes
140 billion tonnes
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With reference to the International System of Units, which is the correct unit and symbol for the amount of substance?
kilogram, kg
gram, g
mole, mol
mass, m
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A pipette shows a scale with graduations every 0.1 cm3.
What is the uncertainty associated with readings from this pipette?
0.15 cm3
0.01 cm3
0.05 cm3
0.5 cm3
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The electron micrograph shows the organelles in a leaf cell. A student uses their ruler to measure the length of the scale bar, which they find to be 1.5 cm.
What is the magnification of the micrograph?
×7000
×7.5
×3000
×300
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A chi-squared test was carried out to test for association between species A and species B. The results of the chi-squared test are given below.
Results of chi-squared test:
Chi-squared value | 5.89 |
Degrees of freedom | 1 |
Critical values table:
Degrees of freedom | Probability level | |||
0.1 | 0.05 | 0.01 | 0.001 | |
1 | 2.71 | 3.84 | 6.64 | 10.83 |
2 | 4.60 | 5.99 | 9.21 | 13.82 |
What can be concluded from the chi-squared test for association carried out to test for association between species A and species B?
There is no significant association between species A and species B
Species A competes with species B for resources
There is a statistically significant association between species A and species B at the 5% probability level
There is a statistically significant association between species A and species B at the 1% probability level
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Which of the statements relating to deforestation in the Amazon rainforest is correct?
Only a small area of rainforest is needed to sustain the cycle of transpiration and rainfall that maintains the ecosystem.
A region of rainforest with an area of 4 100 000 km2 was reduced to an area of 3 855 000 km2 over a ten year period, resulting in a percentage decrease of 6 %.
Scientists know the area of rainforest that needs to be maintained in order to avoid passing a tipping point in rainforest stability.
The Amazon rainforest will be able to recover even if deforestation continues until the stability tipping point is reached.
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