Photosynthesis (Study guide and practice questions)

Stomata allow for gas exchange, bringing ____ into the chloroplast and sending
out___.
a. H2O; O2
b. CO2; H2O
c. CO2; O2
d. O2; CO

c. CO2; O2

The light dependent reaction of photosynthesis occurs in the
a. Cytoplasm
b. Chloroplast thylakoid membrane
c. Chloroplast stroma
d. Mitochondria

b. Chloroplast thylakoid membrane

The light dependent reaction of photosynthesis
a. Uses light energy to synthesize ATP and reduce NADP+ to NADPH
b. Uses light energy to fix CO2 to Ribulose 1,5 bisphosphate
c. Uses light energy to hydrolyze ATP and oxidize NADPH to NADP+
d. Uses light energy to reduce O2 to H2O

a. Uses light energy to synthesize ATP and reduce NADP⁺ to NADPH

Which is true regarding chloroplasts?
a. The pH of the stroma is lower than the pH of the thylakoid lumen
b. The pH of the thylakoid lumen is lower than the pH of the stroma
c. The pH of the thylakoid lumen is equal to the pH of the stroma
d. None of the above

b. The pH of the thylakoid lumen is lower than the pH of the stroma

Chlorophyll is an essential molecule for______.
a. Carbon fixation
b. Creating a proton gradient
c. Reduction of NADP+
d. Absorbing light energy

d. Absorbing light energy

During the Calvin cycle, a molecule of BPG with a high energy bond
a. Is hydrolyzed to synthesize ATP
b. Is formed through hydrolysis of ATP to ADP
c. Reduces NADP+ to NADPH
d. Is formed by rubisco

b. Is formed through hydrolysis of ATP to ADP

Hydrogen ions are pushed across a membrane to create a proton gradient during
the___.
a. Split of water to create O2 and H+ in photosystem II
b. Split of water to create O2 and H+ in photosystem I
c. Light independent reaction
d. Synthesis of sucrose

a. Split of water to create O2 and H+ in photosystem II

Describe how photosynthesis is the reverse of respiration

• Using solar energy to reduce CO2 to C6H12O6 Figure 5-9

• Phototrophs: organisms that convert solar energy to chemical energy
  

Photosynthesis is composed to 2 reactions. What are they?

• light-dependent and a light-independent reaction

• Light reaction: generates ATP and reduced NAPD+ to NADPH. Occurs on the thylakoid

• Dark reaction: Carbon fixation. Occurs in the stroma

Describe how a photosystem works to collect energy and excite electrons

• Light-dependent reaction: uses light energy to synthesize ATP and reduce NADP+ to NADPH

• Chlorophyll: pigment that absorbs light energy

• Photosystems: located in thylakoid membrane to collect and transfer light energy

What are the major products of the Photosystem II and Photosystem I?

• Proton gradient

• Reduction of NADP+ to NADPH

Describe the three stages of the light independent reaction (Calvin cycle)

Three stages:
Phase 1: CO2 added to ribulose 1,5 bisphosphate
Phase 2: ATP is used to generate BPG. BPG is then reduced to
Glyceraldehyde 3 phosphate, used for biosynthesis
Phase 3: ATP is used to regenerate ribulose 1,5 bisphosphate

Chloroplasts

The sites of photosynthesis

Thylakoid/thylakoid membrane/thylakoid lumen

The membrane-bound structures within chloroplasts where the light-dependent reactions of photosynthesis occur, containing chlorophyll and electron transport chains.

Stroma

The fluid-filled space surrounding the thylakoids in chloroplasts, where the light-independent reactions (Calvin cycle) take place.

Stromata

Allows gas exchange (Co2 → O2)

NAD+

Used in respiration

NADP+

Used in photosynthesis. Has a phosphate on the 2” carbon of ribose. Reduced in the same way as NAD+

Light dependent reaction

Generates ATP and reduces NAPD+ to NADPH.

Occurs on the thylakoid membrane

Uses light energy to synthesize ATP and reduce NADP+ to NADPH

Light independent reaction

Carbon fixation

Occurs in the stroma

Chlorophyll

Pigment that absorbs light energy

Photosystems

Located in thylakoid membrane to collect and transfer light energy

Photosystems contain?

• Chlorophyll

• Chlorophyll binding proteins

• Proteins that stabilizes electron transfer

• Protein catalyze redox reactions

Antenna pigments

Chlorophyll molecules that collect light energy and pass along to neighboring chlorophyll molecules through resonance energy transfer.

Reaction Center

A pair of chlorophyll a molecule at the center of antenna pigments-catalyze the conversion of solar energy into chemical energy.

Photosystem II (P680)

Favorable reduction reactions push H+ into lumen. (photoexcitation)

Photosystem I (P700)

Plays a crucial role in the light-dependent reactions of photosynthesis, facilitating the reduction of NADP+ to NADPH.

Calvin Cycle

Phase 1- CO2 added to ribulose 1,5 biphosphate

Phase 2- ATP is used to generate BPG, BPG is then reduced to Glyceraldehyde 3 phosphate, used for biosynthesis

Phase 3- ATP is used to regenerate ribulose 1,5 biphosphate

Rubisco

Catalyzes carboxylation of ribulose 1,5-bisphophate

The purpose of pigment is

Collect energy from light, which is passed to a special pair at the reaction
center

Light energy is required for water to serve as an electron donor because

Oxygen readily accepts electrons and therefore requires a large energy input
before donating electrons

• Photosystem I

Light energy is used to reduce NADP+ to NADPH

• Rubisco

Catalyzes carbon fixation

• CO2

Enters through stomata

• 1,5 Biphosphate

regenerated during the Calvin cycle

• Photosystem II

Water split into H+ and O2, releasing electrons

• BPG

ATP is used to synthesize

Glyceraldehyde 3 phosphate

Used to synthesize sugars