11. (a) (i) Name the type of nutrition exhibited by organisms that carry out photosynthesis - Leaving Cert Biology - Question 11 - 2020

The balanced chemical equation for photosynthesis is:

Stomata are tiny openings on the leaf's surface that allow for gas exchange. They enable the entry of carbon dioxide (CO₂) needed for photosynthesis and the exit of oxygen (O₂), a by-product of the process.

I would expect part B to contain the most chloroplasts. This is typically where photosynthesis predominantly occurs, as palisade mesophyll cells are packed with chlorophyll-rich chloroplasts.

Chlorophyll molecules play a crucial role in photosynthesis by absorbing light, primarily in the blue and red wavelengths. This absorbed light energy drives the reactions that convert CO₂ and water into glucose.

The particles released from chlorophyll during the light-dependent stage are electrons (e⁻). These electrons are crucial for the subsequent reactions in the photosynthesis pathway.

In pathway 2, the electrons that are released during the light-dependent reactions are utilized in the electron transport chain. These electrons are transported along a series of proteins in the thylakoid membrane, leading to the generation of ATP and NADPH. NADP⁺ accepts electrons to form NADPH, while protons (H⁺) help in creating a proton gradient that drives ATP synthesis through ATP synthase.

The 3-carbon molecule that enters the mitochondrion is Pyruvate (also referred to as Pyruvic acid).

When Pyruvate is broken down, the two products formed are Carbon Dioxide (CO₂) and Acetyl Coenzyme A (Acetyl CoA).

The series of reactions that take place are known as the Krebs Cycle (or Citric Acid Cycle). This cycle occurs within the mitochondrial matrix.

In the electron transport chain, high-energy electrons are transferred along a series of proteins embedded in the inner mitochondrial membrane. As these electrons move through the chain, they release energy, which is used to pump protons (H⁺) into the intermembrane space, creating a proton gradient. Finally, protons flow back into the mitochondrial matrix through ATP synthase, driving the conversion of ADP and inorganic phosphate (Pi) into ATP, while oxygen acts as the final electron acceptor to form water.