Ch 10-Photosynthesis

Question 1

Explain the significance of photosynthesis to other living organisms

Answer 1

Photosynthesis is important to lving organismas because it is the number one source of oxygen in the atosphere. without photosynthesis, the carbon cycle could not occur, oxygen-requiring life would not survive and plants would die.

Question 2

Describe the main structures involved in photosynthesis

Answer 2

Chloroplast

• found mainly in cells of mesophyll-interior tissue of the leaf
• outer and inner membrane
• stroma
• thylakoids
• grana or granum

Thylakoids

• internal compartment-thylakoid space-surrounded by thylakoid membranes
• chlorophyll resides in thylakoid membrane
• Stroma

Question 3

Identify the substrates and products of photosynthesis

Answer 3

Substates

• Sunlight
• carbon dioxide
• water

Products

• Oxygen
• glucose

Question 4

Explain how plant absorb energy from sunlight

Answer 4

light energy the process of photosynthesis when pigments absorb the light. In plants, pigment molecules absorb only visible light for photosynthesis. The Visible light seen by humans as white light actually exists in a rainbow of colors.

Question 5

Describe how and where photosynthesis takes place within a plant

Answer 5

Takes place in the mesophyll of the leaves, inside the chloroplasts. Chloroplasts contain disc-shaped structures called thylakoids, which ccontain the pigment chlorophyll. Chlorophyll absorbs certain portions of the visible spectrum and catures energy from sunlight.

Question 6

List different photosynthetic pigments and describe their roles

Answer 6

• CHLOROPHYLL a
  
  • key light-capturing pigment
• CHLOROPHYLL b
  
  • accessory pigment
• Carotenoids
  
  • accessory pigment

Question 7

Describe photosystems

Answer 7

are complex arrangments of chlorophyll a with pigments, including clorophyll b, xanthophylls and carotenoids, which capture light energy to energize an electron removed from a water molecule. in plants, photosystems are located in the thykaloid membrane with in the chloroplast.

Question 8

Describe different types of electron flow during light dependent reaction.

Answer 8

• Linear electron flow
  
  • Primary pathway
  • Involves both photosystems
  • produces atp, nadph, and oxygen
• Cyclic electron flow
  
  • involves only ps1
  • produces only atp
  • no oxygen releaseed
  • found in purple sulfur bacteria

Question 9

Describe the Calvin cycle

Answer 9

• Carbon fixation
  
  • catalyzed by rubisco
• Reduction
• Regeneration of CO2 acceptor (RuBP)

Question 10

Define Carbon Fixation

Answer 10

The process by which photosynthetic organisms such as plants turn inorganis carbon into organic compounds

Question 11

Explain Photorespiration

Answer 11

a respiratory process in many higher plants by which they take up oxygen in the light and give out some carbon dioxide, contrary to the general pattern of photosynthesis

Question 12

Describe alternative mechanism of carbon fixation with examples

Answer 12

• C3 plants
  
  • example- most of the plants
• C4 plants
  
  • Minimize photorespiration by incorporating CO2 into 4-Carbon compounds, Catalyzed by enzyme PEP carboxylase
    
    • ex-sugarcane
• CAM plants (Crassulacean acid metabolism)
  
  • Open stroma at night, incorporate CO2 into organic acids, stored in vacuoles
    
    • ex- pineapple, succulent plants