Problem 2 - Biology

Question

In photolysis, some of the energy captured by chlorophyll is used to split (a) \(\mathrm{CO}_{2}\) (b) ATP (c) NADPH (d) \(\mathrm{H}_{2} \mathrm{O}\) (e) both b and \(\mathrm{c}\)

Step-by-Step Solution

Answer

The correct answer is (d) \(\mathrm{H}_{2}\ \mathrm{O}\).

Step 1: Understand Photolysis

Photolysis is a process where light energy is used to split molecules. This is part of the light-dependent reactions in photosynthesis.

Step 2: Determine the Molecule Split by Photolysis

In the process of photolysis within photosynthesis, water (\(\mathrm{H}_{2}\ \mathrm{O}\)) molecules are split using the energy captured by chlorophyll. This releases oxygen and produces protons and electrons.

Step 3: Review the Options

The options provided are different molecules or processes. Option (d), \(\mathrm{H}_{2}\ \mathrm{O}\), is the molecule that is actually split during photolysis. None of the other options directly involve the splitting of molecules during photolysis.

Key Concepts

Chlorophyll

Chlorophyll is a green pigment found in the chloroplasts of plants, algae, and some bacteria. It plays a crucial role in photosynthesis, the process by which plants convert light energy into chemical energy.
Chlorophyll's main function is to absorb light, most efficiently in the blue and red wavelengths, and use this energy to drive the synthesis of organic compounds. It includes two main types: Chlorophyll a and Chlorophyll b, both essential for capturing solar energy.
The absorbed light energy is crucial for photolysis, as it energizes the electrons, facilitating the breakdown of water molecules. This process not only provides the necessary electrons for energy transfer but also releases oxygen as a byproduct, crucial for life on Earth.

Light-Dependent Reactions

Light-dependent reactions occur in the thylakoid membranes of the chloroplasts, being the first stage of photosynthesis. These reactions are contingent on the presence of light, hence the name.
During these reactions, the energy from absorbed light excites chlorophyll electrons, which then pass through a series of proteins known as the electron transport chain. This process converts the light energy into chemical energy in the form of ATP and NADPH, which are then used in the next stage of photosynthesis.

• Primary Function: Convert solar energy into chemical energy.
• Main Products: ATP and NADPH.
• Byproducts: Oxygen gas released from the splitting of water.

The splitting of water, or photolysis, provides the electrons necessary to replace those lost by chlorophyll and also produces protons used for the creation of the proton gradient, facilitating ATP synthesis.

Photosynthesis

Photosynthesis is a vital process that enables plants, algae, and some bacteria to convert light energy, usually from the sun, into chemical energy stored in glucose molecules.
This process occurs mainly in the leaves where chloroplasts are abundant. Photosynthesis consists of two main stages: light-dependent reactions and the Calvin cycle.
In the light-dependent reactions, captured light energy is used to produce ATP and NADPH. The Calvin cycle, occurring in the stroma of chloroplasts, utilizes these compounds to convert carbon dioxide into glucose through a series of enzyme-assisted chemical reactions.

• Importance: Photosynthesis provides the oxygen we breathe and is the foundation of the food chain.
• Efficiency: While energy conversion is essential, only about 4-6% of the sun's energy is effectively converted by plants.
• Impact: Reduces carbon dioxide in the atmosphere, mitigating global warming effects.

Understanding this process is crucial for appreciating how life is sustained on Earth, highlighting the interdependence between different organisms and the environment.