Chapter 8: Photosynthesis

Question 1

What is carried out by oxygenic photosynthesis?

Answer 1

Cyanobacteria, 7 group of algae, all land plants

Question 2

Photosynthesis is divided into

Answer 2

Light-dependent reaction and carbon fixation reactions

Question 3

What is light-dependent reaction?

Answer 3

it is captures energy from sunlight

make ATP and reduce NADP+ to NADPH

Question 4

What is carbon fixation reactions?

Answer 4

Use ATP and NADPH to synthesize organic molecules from CO2

Question 5

Where is photosynthesis happen?

Answer 5

it takes place in chloroplasts

Question 6

What is thylakoid membrane?

Answer 6

Internal membrane arranged in flattened sacs

Contains chlorophy ll and other pigments

Question 7

What is grana?

Answer 7

Stacks of thylokoid membranes

Question 8

what is stroma?

Answer 8

Semiliquid substance surrounding thylakoid membrane

Question 9

Named several scientists who led to the discovery of how photosynthesis works

Answer 9

Jan Baptista Van Helmont (1580-1644)
Joseph Priestly (1733-1804)
Jan Ingen-Housz (1730-1799)
F.F. Blackman (1866-1947)

Question 10

What is photon?

Answer 10

• A particle of light
• Acts as a discrete bundle of energy
• Energy content of a photon is inversely proportional to the wavelength of the light

Question 11

What is photoelectric effect?

Answer 11

Removal of an electron from a molecule by light

Occurs when photons transfer energy to electrons

Question 12

What is pigments?

Answer 12

• Molecules that absorb visible light

- Each pigment has a characteristic absorption spectrum, the range and efficiency of photons it is capable of absorbing.

Question 13

What is chlorophyll a?

Answer 13

• Primary pigment in plants and cyanobacteria

- Absorbs violet-blue and red light

Question 14

What is chlorophyll b?

Answer 14

Secondary pigment absorbing light wavelengths that chlorophyll a doesn’t absorb

Question 15

What is the structure of pigments?

Answer 15

• PORPHYRIN RING: Complex ring structure with alternating double and single bonds
• Magnesium ion at the center of the ring
• Photons excite electrons in the ring
• Electrons are shuttled away from the ring
• ACCESSORY pigments: secondary pigments absorbing light wavelengths other than those absorbed by chlorophyll a
• increase the range of light wavelengths that can be used in photosynthesis
• include: chlorophyll b, carotenoids, phycobiloproteins
• carotenoids also acts as antioxidants

Question 16

A photosystem consists of:

Answer 16

Antenna complex of hundreds of accessory pigments molecules and reaction center of one or more chlorophyll a molecules

Question 17

Where is the energy transferred?

Answer 17

Energy of electrons is transferred through the antenna complex to the reaction center

Question 18

Photosystem organization

Answer 18

• At the reaction center, the energy from the antenna complex is transferred to chlorophyll a.
• This energy causes an electron from chlorophyll to become excited
• The excited electron is transferred from chlorophyll a to an electron acceptor
• Water donates an electron to chlorophyll a to replace the excited electron

Question 19

Listed 4 stages are occurred in light-dependent reactions

Answer 19

1. Primary photoevent- a photon of light is captured by a pigment molecule
2. Charge separation- energy in transferred to the reaction center, an excited electron is transferred to an acceptor molecule
3. Electron transport- electrons move through carriers to reduce NADP+
4. Chemiosmosis- Produces ATP

Question 20

In sulfur bacteria, what is the only one can used for Cyclic Photo phosphorylation?

Answer 20

Photosystem

1. An electron joins a proton to produce hydrogen
2. An electron is reduced to chlorophyll – This process drives the chemiosmotic synthesis of ATP

Question 21

What are the two linked photosystems are used in noncyclic phosphorylation?

Answer 21

1. Photosystem l: Reaction center pigment (P700) with a peak absorption at 700nm
2. Photosystem ll: Reaction center pigment (P680) has a peak absorption at 680 nm