Photosynthesis

• identify the important components of photosynthesis and their specific roles

• explain what happens during the light reaction phase of photosynthesis

• discuss how sugar is formed during the dark reaction of photosynthesis

PHOTOSYNTHESIS - takes place in the cells of leaves within structures called chloroplasts. The leaves, which are considered as the plants' food factories, contain cells whose shapes and arrangements are well adapted to perform the photosynthetic function efficiently.

WHAT TO DO!

Make a poster that represents your understanding of photosynthesis. Together with the poster, you are to write a short essay that explains how your poster relates to the concept of photosynthesis and the connection to your daily life activities/experiences.

TWO TYPES of PROCESSES THAT OCCURS DURING PHOTOSYNTHESIS

What is Light Reaction

Light reaction is the first stage of photosynthesis, which produces ATP and NADPH by trapping the energy of sunlight by pigments called chlorophyll. Light reaction occurs in the thylakoid membrane of chloroplasts. Since light reaction depends on sunlight, it only occurs in the presence of sunlight.

What is Dark Reaction

Dark reaction is the second stage of photosynthesis, which produces glucose from the energy of ATP and NADPH produced in the light reaction. It occurs in the stroma of the chloroplast.

Difference Between Light and Dark Reaction

Occurs in

Light Reaction: Light reaction occurs in the thylakoid membrane of the chloroplast.

Dark Reaction: Dark reaction occurs in the stroma of the chloroplast.

Light

Light Reaction: Light reaction depends on the sunlight.

Dark Reaction: Dark reaction is independent of sunlight.

Pigments

Light Reaction: Chlorophylls are the pigments involved in the light reaction.

Dark Reaction: No pigments are involved in the dark reaction.

Oxygen/Carbon dioxide

Light Reaction: Oxygen is liberated during the light reaction.

Dark Reaction: Carbon dioxide is fixed during the dark reaction.

Results

Light Reaction: ATP and NADPH are produced during the light reaction.

Dark Reaction: Glucose is produced by using the energy from ATP and NADPH, produced in the light reaction.

Conclusion:

Light reaction and dark reaction are the two steps of reactions involved in photosynthesis. Light reaction occurs in the thylakoid membrane of chloroplasts. The energy of sunlight is trapped by chlorophylls, and the trapped energy is used in the production of ATP and NADPH. These ATP and NADPH are used in the production of glucose in the dark reaction. The dark reaction occurs in the stroma of chloroplast with the involvement of enzymes. It occurs in two ways, C3 cycle and C4 cycle. C4 cycle is more efficient than C3 cycle. The main difference between light and dark reaction is their contribution to photosynthesis.

CELLULAR RESPIRATION

TASK TO DO!

Make a poster that shows how much you rely on plants and plant products every day. List 5 ways that you depend on plants.