In photosynthesis, which chemicals are needed for the light-dependent reaction? Tick (/) one box - AQA - A-Level Biology - Question 7 - 2019 - Paper 2

During photolysis, water molecules are split into oxygen, protons, and electrons when light energy is absorbed by chlorophyll. This process provides the electrons needed for the electron transport chain and releases oxygen as a byproduct.

The student marked the origin with a pencil to avoid ink mixing with the pigments during chromatography. Ink could dissolve in the solvent and interfere with the results by moving with the solvent front.

The student placed the chromatography paper in a solvent. The solvent travels up the paper, carrying the pigments with it at varying rates. Each pigment's distinct mobility allows for separation based on their differing affinities for the paper and the solvent.

To calculate the Rf value of pigment C, measure the distance pigment C has moved from the origin and the distance the solvent front has moved. If pigment C moved 4 cm and the solvent front moved 10 cm, the Rf value would be:

$R_f = \frac{4 \text{ cm}}{10 \text{ cm}} = 0.4$

Having different coloured pigments in leaves allows plants to absorb a broader spectrum of light wavelengths. This enhances photosynthesis efficiency, as various pigments can capture light energy at different wavelengths, optimizing energy production. For example, chlorophyll primarily absorbs red and blue light, while carotenoids capture light in the green-yellow range, providing additional energy for the plant.