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Figure 16 shows a photomicrograph of two stomata in a leaf - Edexcel - GCSE Biology - Question 9 - 2023 - Paper 2
Question 9
Figure 16 shows a photomicrograph of two stomata in a leaf. (a) (i) The length of one guard cell in this image is 6 mm. Convert the length of this guard cell into m... show full transcript
Worked Solution & Example Answer:Figure 16 shows a photomicrograph of two stomata in a leaf - Edexcel - GCSE Biology - Question 9 - 2023 - Paper 2
Step 1
Step 2
Calculate the actual size of the guard cell.
Answer
To find the actual size of the guard cell, divide the length measured in the image by the magnification factor:
ext{Actual size} = rac{ ext{Measured size}}{ ext{Magnification}}
Substituting the values:
ext{Actual size} = rac{6 ext{ mm}}{150} = 0.04 ext{ mm}
To express this in standard form:
The actual size of the guard cell is 4 x 10^(-2) mm.
Step 3
Explain the role of denitrifying bacteria in the nitrogen cycle.
Answer
Denitrifying bacteria play a crucial role in the nitrogen cycle by converting nitrates (NO₃⁻) in the soil back into nitrogen gas (N₂), which is released into the atmosphere. This process, known as denitrification, helps to:
- Reduce Soil Nutrient Levels: By removing excess nitrates from the soil, they can help prevent the accumulation of nutrients that can lead to pollution.
- Maintain Nitrogen Balance: Denitrification helps to maintain the balance of nitrogen in the ecosystem, making it available again for other organisms.
- Support Plant Life: By cycling nitrogen back into the atmosphere, denitrifying bacteria enable plants to access nitrogen in forms they can use, thereby supporting overall ecosystem health.