Question

Pigment system II is concerned with (a) Photolysis of water (b) Reduction of \(\mathrm{CO}_{2}\) (c) Flowering (d) None of these

Short answer

(a) Photolysis of Water

Step-by-step solution

Understand the Photosynthesis process

In photosynthesis two types of pigment systems are present: Pigment system I (PS I) and Pigment system II (PS II). They are different in terms of their reaction center chlorophyll, the kind of light they absorb, and their function in the photosynthesis process.

Recognize Pigment System II Function

Pigment system II absorbs light with a wavelength of 680 nm (P680) and is particularly responsible for the photolysis of water, also known as 'water-splitting', in the process of photosynthesis. The light absorbed by PS II is utilized in 'water-splitting' which results in the release of oxygen, protons, and electrons.

Match the function with the options

We look at the options given. (a) Photolysis of water- This is correct as explained in step 2. (b) Reduction of CO2- This is not the function of PS II, it is the role of PS I. (c) Flowering- This is not directly linked to photosynthesis. (d) None of these- This option is incorrect as one of the provided options is accurate (option a). Thus the correct answer is the function that aligns with the role of PS II, which is Photolysis of Water.

Key concepts

Photolysis of Water

Photolysis of water is a critical step in the process of photosynthesis. This is where water molecules are split into oxygen, protons, and electrons. It occurs in the thylakoid membranes of chloroplasts. This process is driven by light energy and is crucial for providing the electrons required for the synthesis of ATP and NADPH.
This splitting of water is also important because it releases oxygen as a by-product, which is essential for most life forms on Earth. The photolysis of water happens in Pigment System II (PS II), which absorbs light to power this reaction. The light energy is absorbed by chlorophyll P680, making it the first step in the sequence that leads to chemical energy formation.

• Occurs in chloroplasts
• Releases oxygen into the atmosphere
• Supplies electrons for energy synthesis

Photosynthesis

Photosynthesis is the remarkable process by which green plants, algae, and some bacteria convert light energy into chemical energy. This process takes place in the chloroplasts, where light energy is used to transform carbon dioxide and water into glucose and oxygen.

There are two main parts of photosynthesis: the light-dependent reactions and the Calvin cycle (light-independent reactions). In the light-dependent reactions, light energy is captured by chlorophyll and used to split water molecules, resulting in the release of oxygen. These reactions occur in the thylakoid membranes and produce ATP and NADPH, which are utilized in the Calvin cycle to convert CO2 into glucose.

• Occurs in chloroplasts of green plants
• Includes light-dependent reactions and the Calvin cycle
• Essential for producing oxygen and glucose

Chlorophyll P680

Chlorophyll P680 is a special type of chlorophyll that plays a pivotal role in photosynthesis. Found in Pigment System II (PS II), it is named for its optimal absorption of light at a wavelength of 680 nanometers.

This molecule is the primary pigment responsible for capturing light energy, which it then converts into a form of energy used to power the photolysis of water. The excited electrons from P680 are transferred to an electron transport chain, ultimately leading to the production of ATP and NADPH.

• Absorbs light at 680 nm
• Essential for water splitting
• Initiates electron transport chain