Question

11. Define photosynthesis and write its chemical reaction
12. Differentiate between: Respiration and photosynthesis​

Answer 1

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Photosynthesis is the process by which plants, some bacteria, and some protistans use the energy from sunlight to produce sugar, which cellular respiration converts into ATP, the "fuel" used by all living things.

The photosynthesis equation is as follows: 6CO2 + 6H20 + (energy) → C6H12O6 + 6O2 Carbon dioxide + water + energy from light produces glucose and oxygen.

The main difference between photosynthesis and cellular respiration is that photosynthesis is an anabolic process, where the synthesis of organic compounds occurs, storing energy whereas cellular respiration is a catabolic process, where the stored organic compounds are utilized, producing energy.

Answer 2

Answer:

11. The process by which green plants and some other organisms use sunlight to synthesize nutrients from carbon dioxide and water. Photosynthesis in plants generally involves the green pigment chlorophyll and generates oxygen as a by-product.

The chemical reaction for representing the chemical reaction of photosynthesis is

6CO

2

+6H

2

O→C

6

H

12

O

6

+6O

2

Sunlight energy

In photosynthesis reaction, energy is transferred from the light reaction step to dark reaction step by ATP. Photosynthesis is divided into two sets of reactions: the light-dependent (light) reactions and the light-independent (dark) reactions. As their names imply, the first set depends directly on light, whereas the second set does not. Nevertheless, even the dark reactions will cease if the plants are deprived of light for too long because they rely on the products of the light reactions. The light reactions, which convert the energy in light into chemical energy, take place within the thylakoid membranes of the chloroplasts, whereas the dark reactions, which use that chemical energy to fix CO2 into organic molecules, take place in the stroma of the chloroplast. In the light reactions, the energy of light is used to split water, stripping a pair of electrons from it (and causing the two hydrogens to be lost), thus generating molecular oxygen. The energy in light is transferred to these electrons and is then used to generate adenosine triphosphate (ATP) and the electron carrier NADPH. These two products carry the energy and electrons generated in the light reactions to the stroma, where they are used by the dark reactions to synthesise sugars from CO2.

The process of photosynthesis is commonly written as: 6CO2 + 6H2O → C6H12O6 + 6O2. This means that the reactants, six carbon dioxide molecules and six water molecules, are converted by light energy captured by chlorophyll (implied by the arrow) into a sugar molecule and six oxygen molecules, the products.

12. The main difference between photosynthesis and cellular respiration is that photosynthesis is an anabolic process, where the synthesis of organic compounds occurs, storing energy whereas cellular respiration is a catabolic process, where the stored organic compounds are utilized, producing energy

Photosynthesis Respiration

It takes place only in the presence of sunlight. It continues throughout day and night, in sun and darkness.

It occurs only in the green cells of the plant. It occurs in all the cells of an organism.

It is an endothermic reaction as it absorbs sunlight. It is an exothermic reaction, as it gives out energy.

It utilises carbon dioxide and water. It evolves carbon dioxide and water.

It builds up complex compounds such as carbohydrates from simple inorganic compounds. So, it is an anabolic process. It breaks complex substances into simple substances. So, it is a catbolic process.

It converts light energy into chemical energy. It releases potential or chemical energy which is used variously in the body.

Carbon dioxide and water are raw materials for photosynthesis. Sugars and oxygen are raw materials for respiration.

It produces ATP by harvesting light energy. It forms ATP from energy liberated during oxidation of food.

Hydrogen of water is used in the synthesis of NADPH. Hydrogen of food is used in the formation of NADP, NADPH and FADH

2

.

ATP and NADPH are used in the synthesis of organic compounds. ATP and reduced coenzymes are made available to cells for various metabolic activities.