Chapter 5, Problem 1LTB

Add labels to the figure that follows, which illustrates the product and reactants of photosynthesis and the relationship between its light reactions and light-independent reactions.

Summary Introduction

To label:

The given figure, which illustrates the product and reactants of photosynthesis and the relation between its light reaction and light-independent reactions.

Introduction:

Photosynthesis is a phenomenon that changes solar energy to chemical energy needed by all living organisms. Photosynthesis occurs in chloroplasts that found in the green part mainly in leaves of the plants.

Explanation of Solution

Photosynthesis can be broken down into two steps - light reaction and light-independent reaction.

Light reaction - Light reaction occurs when there is sunlight. Sunlight hits the chlorophyll molecule in the thylakoid membranes that excites electrons. These electrons are captured and passed through an electron transport chain that generates the energy-carrying molecules ATP. The electrons then transfer to the molecule NADPH. The electrons removed from chlorophyll in this way are replaced by those from water, which decompose to release them, a reaction that produces oxygen as a waste product.

Light-independent reaction - The ATP and the electrons in NADPH are utilized in the synthesis of sugar from CO₂ in the second major step of photosynthesis called light-independent reactions. It occurs mainly in the stroma of the chloroplast and is sometimes referred to as the Calvin cycle.

The following labeled figure shows the products and reactants and the relation between its light-independent reaction and light reaction.

Fig:

The process of photosynthesis.

Conclusion

Thus, photosynthesis happens in two steps - light reaction and light-independent reaction.