photosynthesis

• What is the process of photosynthesis primarily about?

  Transformation of light energy to chemical energy
• What is the significance of the chemical energy produced in photosynthesis?

  It supplies most of the chemical energy needed for life processes in ecosystems
• What is the word equation for photosynthesis?

  Carbon dioxide + Water → Glucose + Oxygen
• What role does light energy play in photosynthesis?

  It is needed to split a water molecule in a process called photolysis
• What happens to oxygen produced during photosynthesis?

  It diffuses out of photosynthesizing cells
• Which organisms were the first to perform photosynthesis?

  Cyanobacteria
• How do algae and plants perform photosynthesis?

  They use chloroplasts
• What is a by-product of photosynthesis?

  Oxygen
• How does oxygen exit the plant during photosynthesis?

  It diffuses out through stomata
• What are pigments in plants responsible for?

  Absorbing light
• Why do pigments appear different colors to us?


  Because they absorb specific wavelengths of light
• What happens to pigments that absorb all wavelengths of light?

  They appear black
• What are the main photosynthetic pigments?

  Chlorophylls
• Why do chlorophyll pigments appear green?

  Because they reflect green light and absorb red and blue light
• What does an absorption spectrum show?

  The percentage of light absorbed at each wavelength by a pigment
• What is the range of wavelengths shown on an absorption spectrum?

  400 to 700 nanometers
• How do absorption and action spectra relate to each other?

  They look similar because photosynthesis occurs at wavelengths absorbed by pigments
• What are the effects of varying concentrations of carbon dioxide, light intensity, or temperature on the rate of photosynthesis?


  • Increasing light intensity increases the rate of photosynthesis until another factor limits it.
  • Increasing carbon dioxide concentration increases the rate until another factor limits it.
  • Increasing temperature increases the rate until enzymes begin to denature.
• What is the relationship between light intensity and photosynthesis at low levels?

  Light intensity is a limiting factor
• What happens to the rate of photosynthesis at high light intensity?

  Further increases have no effect on the rate
• How does temperature affect the rate of photosynthesis?

  Increases in temperature give molecules more kinetic energy, increasing the rate
• What occurs as temperature approaches the optimum for photosynthesis?

  The rate of photosynthesis increases more slowly and eventually peaks
• What happens to enzymes at temperatures above the optimum?

  They begin to denature, causing a rapid decrease in the rate of photosynthesis
• What are the key components of carbon dioxide enrichment experiments?

  • Conducted in high light intensity and warm temperatures
  • CO₂ levels are varied while temperature and light are kept constant
  • Increasing CO₂ levels can enhance rates of photosynthesis and plant growth
• What was the carbon dioxide concentration before the industrial revolution?

  About 270 ppm