Which Best Describes The Nature Of Photosynthesis?

Question- Which Best Describes The Nature Of Photosynthesis?

The correct answer is 'Option D - it is an energy-storing process.'

Photosynthesis is the process by which certain organisms and green plants use sunshine to produce food from water and carbon dioxide. Photosynthesis is an energy-storing process because it stores sunlight energy in the form of glucose molecule bonds.

But do you know how it happens?

Let’s delve deeper.

Every living organism on Earth is made up of a number of cells. Each cell is powered by chemical energy found primarily in carbohydrate molecules (food), most of which are generated by one process: photosynthesis. Photosynthesis is the process by which certain organisms transform solar energy (sunlight) into chemical energy that is then used to construct carbohydrate molecules. When a creature breaks down food, the energy necessary for holding those molecules together is released. Cells subsequently utilize this energy to do activities, such as breathing.

Types of plants

Photoautotrophs

Only plants, algae, and a species of bacteria known as cyanobacteria are capable of photosynthesis. Photoautotrophs are organisms that use light to produce their own food.

Heterotrophs

Animals, fungi, and the majority of bacteria are classified as heterotrophs since they must rely on sugars that are generated by photosynthetic organisms for energy.

Chemoautotrophs

A third fascinating type of bacteria, known as chemoautotrophs, produce sugars by collecting energy from inorganic chemical molecules rather than using sunlight's energy.

Importance of photosynthesis

Photosynthesis is crucial for more than just harnessing the energy of the sun. A lizard sunning itself can use the sun's energy to warm itself on a cold day. Photosynthesis is necessary because it evolved to store the energy found in sunlight as high-energy electrons in the carbon-carbon bonds of carbohydrate molecules. These carbohydrates provide the energy needed by heterotrophs to power ATP production through respiration. As a result, photosynthesis provides energy to 99% ecosystem of the earth.

The energy flow occurs as follows:

When a powerful predator, such as a wolf, hunts a deer, the wolf is at the finish line of an energy path. It began with nuclear reactions on the sun's surface and progressed through light, photosynthesis, flora, deer, and finally, wolf.

Method of photosynthesis

Photosynthesis is an intricate procedure that necessitates the use of sunlight, low-energy carbon dioxide, and water as substrates. When the reaction is complete, oxygen is released and glyceraldehyde-3-phosphate (GA3P) is generated. It is a simple, high-energy carbohydrate molecule that can be converted into glucose, sucrose, or any of hundreds of other sugar molecules. These sugar molecules transport the energetic carbon and energy required by all living organisms to survive.

Below is the chemical equation for photosynthesis:

Carbon dioxide + water ----- sugar + oxygen

Two Parts of Photosynthesis

Photosynthesis is divided into two stages: light-dependent processes and light-independent reactions.

Sunlight energy is absorbed by chlorophyll and transformed into stored chemical energy in light-dependent processes.

The chemical energy captured during the light-dependent reactions initiates the formation of sugar molecules from carbon dioxide in the light-independent reactions.

As a result, even though light is not used as a reactant in the light-independent reactions, they need the outcomes of the reactions that depend on light to function.

Light dependant reactions

Photosynthetic pigments (organized into photosystems) are used in light-dependent reactions to transform light energy into chemical energy (particularly ATP and NADPH).

These reactions take place within specialized membrane discs called thylakoids within the chloroplast and require three steps:

Photosystems are excited by light energy.
ATP production via an electron transport chain
Reduction of NADP+ and water photolysis

Overview of light-dependent reaction

The light reaction occurs in the grana sections of chloroplast, while the dark reaction occurs in the stoma regions. It's also called the primary photochemical reaction, Hill's reaction, or Arnon's cycle. A light-dependent reaction happens in the chloroplast's thylakoid section. It involves four major stages:

Light energy absorption
Water molecule breaking
Oxygen release
The creation of energy-carrying molecules ATP and NADPH

Photosystems are functional units comprising chlorophyll-a (reaction center) and accessory pigments. Pigments inside photosystems are organized into various light-harvesting complexes (LHC). LHC is made up of hundreds of pigment molecules coupled to proteins.

Photosystems are divided into two categories: Photosystem I (PSI) and Photosystem II (PSII). PSI and PSI! Absorb most light energy at 700 and 680 nm wavelengths, respectively. PSI and PSII's response centres are P700 and Pox), respectively. Photosystems are critical components of light processes. Resonance energy transfer is the process through which energy is transferred in photosystems.

There are two types of phosphorylation reactions in the light reaction: cyclic and non-cyclic phosphorylation.

The production of ATP molecules alone is the outcome of cyclic phosphorylation.
NADPH and ATP molecules are formed as a result of non-cyclic phosphorylation.

The light reaction converts light energy into chemical energy by creating ATP and NADPH. It also causes water molecule breaking and the release of oxygen as a by-product. The dark reaction / Calvin cycle, the second step of photosynthesis, uses the ATP and NADPH created by the light reaction.

Light Independent Reactions

The chemical energy obtained from light-dependent processes is used by light-independent reactions to build organic compounds. The light-independent processes take place in the chloroplast's fluid-filled area known as the stroma.

The Calvin cycle is a collection of light-independent reactions that consists of three major steps:

Ribulose bisphosphate carboxylation
Glycerate-3-phosphate reduction
Ribulose bisphosphate regeneration

Overview of light-independent reactions

Step 1: Carbon Fixation

Carbon fixation occurs in the stroma of chloroplasts. Along with carbon dioxide, several components that aid in the process are present. Ribulose bisphosphate carboxylase (RuBisCO) and Ribulose bisphosphate (RuBP) are two of them.

One molecule of RuBP reacts with CO2 during the fixation stage. As a result, 2-phosphoglyceric acid (3-PGA) molecules are generated. Each 3-PGA has one phosphate and three carbons. Despite of producing new bonds, the number of carbon atoms remains constant during the reaction.

Step 2: Glycerate-3-Phosphate Reduction

NADPH and ATP are utilized to convert 6 molecules of 3-PGA. G3P- glyceraldehyde 3-phosphate is formed from 3-PGA. G3P is the 3-phospho derivative of glyceraldehyde and is an aldotriose phosphate. Because 3-PGA gains electrons, it is a reduction reaction.

Step 3: RuBP regeneration

A molecule of G3P enters the cytoplasm from the Calvin cycle at this stage to synthesize other chemicals required by plants.

Now that you understand the photosynthesis methods, it is an energy-storing process. In this process, the energy is stored by plants and then transferred to the entire ecosystem.

Frequently Asked Questions-

Q.1: What happens when the photosynthesis process occurs?

Ans: Photosynthesis includes the exchange of carbon dioxide for oxygen.

Q.2: What gas plays an important role in photosynthesis?

Ans: A gas named carbon dioxide plays an important role in photosynthesis. Here CO2 and water are combined with sunlight to convert into glucose and oxygen.

Q.3: What exactly is photosynthesis?

Ans: Photosynthesis is the process by which plants produce glucose from carbon dioxide and water in the presence of sunshine and the green pigment chlorophyll.

Q.4: What is the difference between light and dark reactions?

Ans: The light reaction is a light-dependent process that includes light absorption, hydrolysis, oxygen release, and the synthesis of ATP and NADPH.

The dark reaction is also known as the carbon-fixing process. It is a light-independent mechanism that produces sugar molecules from carbon dioxide and water molecules.