Photosynthesis

• What is the primary location where photosynthesis occurs in plant cells?

  Chloroplasts
• What are the main steps involved in the conversion of light energy to chemical energy during photosynthesis?

  1. Absorption of light by pigments
  2. Water splitting (photolysis)
  3. Electron transport chain
  4. Formation of ATP and NADPH
  5. Calvin cycle for glucose production
• Which pigments primarily absorb light energy during photosynthesis?

  Chlorophyll
• What wavelengths of light do chlorophyll pigments primarily absorb?

  Blue and red wavelengths
• What is the process called that splits water molecules during photosynthesis?

  Photolysis
• What are the products of water splitting during photolysis?

  Oxygen, protons, and electrons
• What is the role of the electron transport chain in photosynthesis?

  To transfer excited electrons and create a proton gradient
• How is ATP produced during photosynthesis?

  By using the energy from the proton gradient through ATP synthase
• What is the Calvin cycle's primary function in photosynthesis?

  To convert carbon dioxide into glucose
• What is the source of carbon dioxide for the Calvin cycle?

  The atmosphere
• What enzyme is responsible for fixing carbon dioxide in the Calvin cycle?

  RuBisCO
• What happens to the 3-PGA molecules during the reduction phase of the Calvin cycle?

  They are phosphorylated by ATP and reduced by NADPH to form G3P
• How many G3P molecules are needed to form one glucose molecule?

  Two G3P molecules
• From where does the hydrogen needed for glucose formation come during photosynthesis?

  From water molecules
• What is the overall word equation for photosynthesis?

  Light + Carbon Dioxide + Water → Glucose + Oxygen
• Why is oxygen produced during photosynthesis?

  As a by-product of water splitting in the light-dependent reactions
• How does the process of photolysis contribute to oxygen production?

  It splits water molecules, releasing oxygen gas as a by-product
• What role does water play in the light-dependent reactions of photosynthesis?

  It acts as an electron donor
• What are the two main methods for separating and identifying photosynthetic pigments?

  1. Paper Chromatography
  2. Thin-Layer Chromatography (TLC)
• How is the Rf value calculated?

  Rf = Distance traveled by the pigment / Distance traveled by the solvent front
• What is the purpose of calculating Rf values in chromatography?

  To help identify pigments based on their movement
• What types of light do chlorophyll a and b absorb?

  Chlorophyll a absorbs blue-violet and red light; chlorophyll b absorbs blue and red-orange light
• What is the significance of absorption spectra in photosynthesis?

  They show how much light is absorbed at different wavelengths by pigments
• How do photosynthetic pigments initiate the process of photosynthesis?

  By absorbing light energy and exciting electrons
• What does chlorophyll a primarily absorb?

  Blue-violet and red light
• What light does chlorophyll b absorb?

  Blue and red-orange light
• What do carotenoids absorb and reflect?

  Absorb blue-green light and reflect yellow, orange, and red hues
• What is an absorption spectrum?

  • A unique representation of light absorption by a pigment at different wavelengths
  • Plotted with wavelength on the x-axis and absorbance on the y-axis
• How does light absorption initiate photosynthesis?

  It excites electrons within pigments, converting light energy into chemical energy
• How can photosynthetic pigments be separated and identified?

  • Using chromatography techniques
  • Rf values are calculated for identification
• Why do photosynthetic pigments absorb only specific wavelengths of light?

  Due to their molecular structure and energy levels of electrons
• What determines the specific wavelengths absorbed by chlorophyll and carotenoids?

  The specific arrangement of atoms and bonds in the pigments
• How do electrons get excited within a pigment molecule?

  A photon with appropriate energy strikes the pigment and is absorbed
• What happens to an excited electron in a pigment molecule?

  It can be transferred to an electron transport chain or return to its original state
• What are the key features of an absorption spectrum?

  • Wavelengths on the X-axis (in nanometers)
  • Absorbance on the Y-axis
  • Characteristic peaks for effective absorption wavelengths
• How does chlorophyll a's absorption spectrum appear?

  Strong absorption in blue and red regions, less in green
• What factors significantly affect the rate of photosynthesis?

  Carbon dioxide concentration, light intensity, and temperature
• How does increasing CO2 concentration affect photosynthesis?

  It generally increases the rate until limited by other factors
• What happens to the rate of photosynthesis at low light intensities?

  The rate increases proportionally with light intensity
• What occurs at very high light intensities?

  They can damage chlorophyll and reduce the rate of photosynthesis