Biology, asked by MirsanaNazrin, 1 month ago

define light phase and dark phase ​

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Answered by rishabku16
1

Answer:

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Explanation:

Photosynthesis is the process of conversion of light energy into chemical energy which can then be utilized by living organisms. It is a rather complex process which is carried out through various stages.

Photosynthesis comprises two phases:

The first phase is the photochemical phase or light-dependent process. This phase is commonly known as the light reaction.

The second phase is the biosynthetic phase of the dark reaction of photosynthesis. This phase is the light-independent process.

The whole process of photosynthesis takes place within the chloroplast.

As stated above, photosynthesis occurs in two phases – light reaction and dark reaction.

Light Reaction

The light reaction is a light-dependent process which includes a series of events such as light absorption, hydrolysis, the release of oxygen, formation of ATP and NADPH.

The light reaction of photosynthesis initiates only when it is supplied with light energy.

The photosystem is the arrangement of pigments, including chlorophyll within thylakoids.

There are two photosystems in plants:

Photosystem I (PS-I)

Photosystem II (PS-II)

Photosystem I absorbs light at a wavelength of 700 nm, whereas Photosystem II absorbs light at a wavelength of 680 nm.

The light reaction occurs in the thylakoids of the chloroplast. When the light hits, chlorophyll a get excited to higher energy state followed by a series of reactions. This energy is converted into energy molecules ATP and NADPH by using PS I and PS II. Also, hydrolysis occurs and releases oxygen.

Light Reaction

Dark Reaction

It takes place only in the presence of light.

It can take place in the presence or absence of sunlight.

It is a photochemical phase.

It is a biochemical phase.

It takes place in the grana of the chloroplast.

It takes place in the stroma of the chloroplast.

NADP utilizes H+ ions to form NADPH.

The hydrogen of NADPH combines with CO2.

The end products are ATP and NADPH.

Glucose is the end product. ATP and NADPH help in the formation of glucose.

The water molecules split into hydrogen and oxygen.

Glucose is produced. Co2 is utilized in the dark reaction.

Photolysis occurs in PS-II.

Photolysis does not occur.

Answered by krishna9242
2

Answer:

Dark phase

The dark stage of photosynthesis is an intricate process where NADPH and ATP are used to produce carbohydrate molecules (or sugars). Unlike the light phase, it can happen in light or darkness.

Light phase

The light phase is the first phase of photosynthesis, when light is absorbed by complexes made up of chlorophylls and proteins called photosystems (located in the chloroplast). During this phase, solar energy is converted into chemical energy.

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