Photosynthesis Quiz

Site of Photosynthesis

• Photosynthesis occurs mainly in the leaves of green plants.
• Mesophyll cells, located within leaves, harbor chloroplasts which facilitate photosynthesis.
• Optimal temperature range for photosynthesis activity is between 120-40°C.

Chloroplast Structure

• Composed of an outer membrane and an inner membrane.
• The inter-membrane space is present between the two membranes.
• Grana, stacks of thylakoids, are essential for light-dependent reactions.
• Stroma, the fluid surrounding the thylakoids, is where the light-independent reactions occur.

Types of Pigments

• Chlorophyll a (Chla) - bright blue-green, serves as the chief pigment in photosynthesis.
• Chlorophyll b (Chlb) - yellow-green, functions as an accessory pigment to broaden light absorption.
• Xanthophyll - yellow pigment, also an accessory pigment.
• Carotenoids - yellow-orange pigments, serve as additional accessory pigments.

Photosystems

• Two types of photosystems are crucial for capturing light energy during photosynthesis.
• Photosystem I (PS-I)
  • The reaction center is designated as P700.
  • Light harvesting complex (LHC) acts as an antenna to gather light.
  • Absorbs maximum light at a wavelength of 700nm.
• Photosystem II (PS-II)
  • The reaction center is referred to as P680.
  • Contains hundreds of pigments and proteins.
  • Absorbs maximum light at a wavelength of 680nm.

Steps in Light-Dependent Reactions

• Initial step involves the absorption of light energy.
• Water molecules are split, resulting in the release of oxygen.
• During these reactions, ATP and NADPH are produced, essential for subsequent processes.

Photophosphorylation Types

• Non-cyclic photophosphorylation
  • Responsible for ATP formation during light-dependent reactions.
• Cyclic photophosphorylation
  • Produces ATP in light-independent reactions, operating in a cycle.