Question

Which of the following is the main function of the light-dependent reactions of photosynthesis?

Answer 1

A. to produce ATP and NADPH for the light-independent reactions Remember, the purpose of photosynthesis is to provide energy for the plant to perform other chemical reactions during the process of growing. So now, let's take a look at the possible answers and see why they do or do not make sense. A. to produce ATP and NADPH for the light-independent reactions * Both of these are nice high energy compounds produced directly by photosynthesis. Unless we see a better option later, this looks like a good choice. B. to convert carbon dioxide into water * Does this provide energy to the plant? No it does not. So this is a bad choice. C. to release oxygen into the atmosphere * This is a happy side effect of the process for us mammals, but it's not the main purpose of photosynthesis and in fact doesn't provide energy to the plant. So wrong choice. D. to break down glucose into pyruvic acid * This does produce energy. But doesn't require light. So it has nothing to do with photosynthesis. Wrong choice.

Answer 2

The light-dependent phase of photosynthesis helps in the conversion of light energy into NADPH and ATP which in turn is utilized by the plant to produce glucose through light-independent reactions.

Further Explanation:

Photosynthesis starts with the absorption of light or solar energy by the plant pigments called chlorophyll. The activated chlorophyll molecule helps in the electron transfer from one acceptor to another forming a chain.

The first phase of photosynthesis the light-dependent reaction in which the absorbed light is utilized to produce molecules carrying energy that is used in the second phase to form carbohydrates by reducing carbon dioxide. The first phase occurs in the grana region of the chloroplast and involves the transport of electrons through photosystem II (PS II) followed by photosystem I (PS I). The energy gained by the chlorophyll molecule is transferred to PS II in the form of electrons. These electrons are passed on further through series of electron transporter or carrier from PS II to PS I. In photosystem I, finally, the electron is gained by NADP+ to form NADPH.

As the electrons are passed through the electron transport chain, energy is released which helps in the pumping of protons (H+ ions) into the lumen from the stroma through the thylakoid membrane. A proton gradient is developed which allows the movement of protons back to the stroma which in turn results in the formation of ATP through membrane-bound ATP synthase.  

The dark reaction or the light-independent reaction happens in the stroma and utilizes the products formed during light-dependent phase.During dark reaction, the carbon dioxide (CO2) is incorporated into the plants to form carbohydrates which involve the utilization of NADPH and ATP. This occurs through Calvin cycle in which Ribulose bisphosphate (RuBP) and CO2 combine together to form phosphoglycerate. This is followed by conversion of phosphoglycerate into two triose phosphate molecules which requires ATP. Some of the triose phosphates are recycled back into RuBP while some are used for glucose production.

Learn more:

1. Learn more about cellular respiration brainly.com/question/543244

2. Learn more about protein by cell organelle brainly.com/question/5923583

3. Learn more about cell cycle brainly.com/question/1600165

Answer Details:

Grade: High School

Subject: Biology

Chapter: Photosynthesis

Keywords:

Photosynthesis, light-dependent reacts, light-independent reactions, dark reactions, chlorophyll, grana, stroma. Proton gradient, Calvin cycle, glucose, carbohydrates, PS I, PS II, electron transport chain, ATP, ATP synthase, NADPH.