4 (a) Plants use nitrate ions to make proteins and chlorophyll - Edexcel - GCSE Biology - Question 4 - 2018 - Paper 1

Bacteria are the primary organisms that convert nitrogen to nitrate ions during the nitrogen cycle. Specifically, certain bacteria are capable of nitrification, transforming ammonia into nitrates.

To calculate the surface area to volume ratio, divide the surface area (36,000 µm²) by the volume (288,000 µm³):

$\text{Surface Area to Volume Ratio} = \frac{36,000\, \mu m^2}{288,000\, \mu m^3} = \frac{1}{8}$

Thus, the surface area to volume ratio of the root hair cell is 1:8.

Root hair cells increase the surface area of the root, enabling the plant to absorb more water and essential minerals from the soil. This increased absorption is crucial for plant nourishment, supporting vital processes such as nutrient uptake and anchorage.

From February to June, the number of algae in the lake generally increases. This rise can be attributed to increasing temperatures and longer daylight hours, which enhance photosynthesis. As sunlight becomes more available and temperatures rise, algal growth accelerates, resulting in higher populations during these months.