Photosynthesis

Question 1

chloroplasts

Answer 1

• have outer membrane, inner membrane, and inter membrane space
• inter membrane is not important

Question 2

thylakoid membranes

Answer 2

• 3rd membrane system
• stack of interconnected discs (stack called granum)
• lamellae connect the granum

Question 3

electromagnetic spectrum

Answer 3

• Visible light- between 400-740 nm
• Smaller wavelengths are more energetic
• x rays- smaller- can penetrate through soft tissue

Question 4

chlorophyll

Answer 4

• major pigment arranged in a particular way to absorb light
• look green, embedded in membranes
• 2 major types, a and b
• structure: porphyrin ring- with Mg inside, hydrophobic tail (important for anchoring into membrane)
• R group can be methyl or aldehyde (A or B)

Question 5

absorption spectrum (chlorophyll A and B)

Answer 5

• A absorbs blue, orange/yellow
• B absorbs blue and orange
  NEITHER absorb green–> plants reflect green

Question 6

photosystem

Answer 6

• cluster of chlorophyll and proteins found in thylakoids
• Photon of light hits- absorbs energy of light, passed around through complex in a way that directs energy through what is called reaction center
• Putting energy onto electrons and boosted energy levels

Question 7

antenna complex

Answer 7

• part of a photosystem, containing an array of chlorophyll molecules and accessory pigments, that receives energy from light and directs the energy to a central reaction center during photosynthesis

Question 8

NADPH

Answer 8

• An electron carrier involved in photosynthesis. Light drives electrons from chlorophyll to NADP+, forming NADPH, which provides the high-energy electrons for the reduction of carbon dioxide to sugar in the Calvin cycle

Question 9

Z diagram

Answer 9

• A representation of the path of excited electrons through the photosystems, acceptors, and donors
• oxygen comes out (waste)

Question 10

photosystem (1 and 2)

Answer 10

• contain chlorophyll

- absorb light energy during the light-dependent reactions

Question 11

Carbon Fixation (Calvin Cycle)

Answer 11

• during photosynthesis
• forms sugar and other organic compounds
• Requires ATP
• need CO2, ATP, NADPH
• product:glucose, ADP+, NADP+
• Location: stroma

Question 12

autotroph

Answer 12

• an organism that makes its own food

Question 13

light reactions (calvin cycle)

Answer 13

• the first of two major stages in photosynthesis (preceding the Calvin cycle)
• occur on the thylakoid membranes or on membranes of certain prokaryotes
• convert solar energy to the chemical energy of ATP and NADPH, releasing oxygen in the process
• light absorbed in PS2–> e- in pigment is boosted in energy level and transferred to acceptor next to PS1–> e- passed to PS1–> PS1 absorbs light and boosts an e- and passes excited e- to protein pump–> electron flows through pump–> electron put on NADP+ e- acceptor to make NADPH (stores reducing power)

Question 14

dark reactions (calvin cycle)

Answer 14

• Second step of photosynthesis where chemical energy is used to make sugar (Glucose)
• reactions of photosynthesis in which energy from ATP and NADPH is used to build high-energy compounds such as sugars

Question 15

heterotroph

Answer 15

• an organism deriving its nutritional requirements from complex organic substances.

Question 16

cyclic photosphorolation

Answer 16

• electrons break this pattern and instead loop back to the first part of the electron transport chain, repeatedly cycling through PSI instead of ending up in NADPH

Question 17

C3 photosynthesis

Answer 17

• the most common form of photosynthesis in which atmospheric CO2 is used to form 3-phosphoglycerate, a three-carbon sugar

Question 18

bundle sheath cells

Answer 18

• in C4 plants, a type of photosynthetic cell arranged into tightly packed sheaths around the veins of a leaf

Question 19

CAM plants

Answer 19

• plants close their stomata during the day, collect CO2 at night, and store the CO2 in the form of acids until it is needed during the day for photosynthesis
• cacti, pineapples, bromeliads

Question 20

C4 cycle/ Hatch Slack Cycle

Answer 20

• an alternative form of carbon fixation that some plants use, particularly in hot weather, to increase the concentration of CO2 available for the Calvin cycle reactions
• takes place in the bundle sheath cells, not mesophyll

Question 21

Rubisco

Answer 21

• enzyme in C3 plants that first captures CO2 to begin the Calvin cycle

Question 22

Engelmann’s experiment

Answer 22

• strip of green algae under light reflected through a prism, creating a visible light spectrum
• Then put oxygen-using bacteria into the mix and they congregated where photosynthesis was most active (violet/blue and red light)

Question 23

Endosymbiont Hypothesis in plants

Answer 23

• Believe that chloroplasts have also come from endosymbiotic pathway
• Some ate up photosynthetic bacterium and then had ability to make ATP with mitochondria and glucose with chloroplasts

Question 24

History of O2 in atmosphere

Answer 24

• Early earth atmosphere- no or very little O2 in the atmosphere
• Eventually water splitting photosynthesis evolved and O2 released
• After a while- became much more efficient and huge numbers of organisms with photosynthesis–> oxygen levels went up to about 20%
• -> caused many organisms to die out (b/c O2 steals e-, organisms poisoned)