Photosynthesis in Plants

Answer is option A i.e. "a and b only"
Light between 400-700 nm wavelength constitute the photosynthetically active radiation (PAR). Maximum absorption of light by chlorophyll a occurs in red and blue regions of the absorption spectrum. So that, the rate of photosynthesis is maximum in red and blue light of the visible spectrum.

Photosynthesis is an anabolic process, which helps in forming ATP, where it is called as energy currency. During the light reaction photophosphorylation takes place producing ATP and $NADPH _2$ which is used as energy source for dark reaction.

A) Along with ATP, ${ NADPH } _{ 2 }$ is also produced.
B) Along with ${ NADPH } _{ 2 }$, ATP is also produced.

The CF0-CF1 complex is the ATP synthase enzyme found in the thylakoid membrane of chloroplasts, responsible for synthesizing ATP during the light reactions.

The Calvin cycle consists of: 1. Carboxylation (CO2 + RuBP), 2. Reduction (using ATP/NADPH to form sugar), and 3. Regeneration (reforming RuBP). The sequence is 3, 1, 2.

Carboxylation of the dark reaction (Calvin cycle) does not directly involve ATP synthesis or consumption. The enzyme RuBisCO catalyzes CO2 fixation with RuBP without ATP. Both reduction and regeneration phases consume ATP, and cyclic photophosphorylation produces ATP.

Oxygen-producing photosynthesis (oxygenic photosynthesis, found in cyanobacteria, algae, and plants) relies on a non-cyclic electron transport chain that requires both Photosystem I and Photosystem II working in series. Non-oxygen producing organisms (like some bacteria) typically use anoxygenic photosynthesis with only a single photosystem.

The light-dependent reactions of photosynthesis, involving electron transport chains and photophosphorylation, take place across the thylakoid membrane where photosystems and ATP synthase complexes are embedded.

Photolysishappens in the thylakoids, producing H+ ions inside the thylakoid membrane., a gradient of hydrogen ions will form across the membrane, ATP synthase take the advantage of this gradient, by allowing hydrogen ions to leak out of the membrane capturing their energy and phosphorylating ADP into ATP, while another statement is correct for mitochondria.

NADH and FADH$ _{2}$ transfer their electrons to molecules near the beginning of the transport chain. As electrons are passed down the chain, they move from a higher to a lower energy level, releasing energy. Some of the energy is used to pump H$^{+}$ ions, moving them out of the matrix and into the intermembrane space. The energy released in these reactions is captured as a proton gradient, which is then used to make ATP in a process called chemiosmosis. Together, the electron transport chain and chemiosmosis make up oxidative phosphorylation. 

The Hill reaction is defined as the photoreduction of an electron acceptor by the hydrogens of water, with the evolution of oxygen. In vivo, or in the organism the final electron acceptor is NADP⁺. We can measure the rate of the Hill reaction in isolated chloroplasts. first demonstrated by Robert Hill in 1939, in which illuminated chloroplasts evolve oxygen when incubated in the presence of an artificial electron acceptor (e.g. Ferricyanide). The reaction is a property of photosystem II. 

During photosynthesis, carbon dioxide is fixed to form carbohydrate by the dark reaction. The water molecules are broken down during the light reaction and release oxygen. Thus, the two process helps to maintain the balance of oxygen and carbon dioxide in the atmosphere.

• Like animals, plants also respire all the time because their cells need energy, to stay alive, but plants can only photosynthesize when they are in the light. Photosynthesis happens in the chloroplasts of plant cells. 
• It produces glucose for use by the plant, and oxygen as a waste product. Respiration uses oxygen and produces carbon dioxide and water as a waste product.