CH 8 - Photosynthesis

The energy used by most living cells comes ultimately from the _____

Sun

Light energy is captured by:

Plants, algae, and some bacteria

Does anoxygenic photosynthesis produce or not produce oxygen?

It does not produce oxygen

Does oxygenic photosynthesis produce or not produce oxygen?

It does produce oxygen

How many sets of reactions does photosynthesis involve?

Photosynthesis involves two interrelated sets of chemical reactions

What occurs during light-dependent reactions?

• Use energy in sunlight to make ATP and NADPH

• Oxidize water to provide electrons and produce O₂

What occurs during carbon fixation?

• Use ATP and NADPH to power the synthesis of organic molecules from CO₂ in the air

• Sometimes called light-independent reactions

What are the two sets of reactions in photosynthesis?

Light-dependent reactions and carbon fixation

What is the equation for photosynthesis?

6CO₂ + 12H₂O + Light → C₆H₆O₆ + 6H₂O + 6O₂

This equation (6CO₂ + 12H₂O + Light → C₆H₆O₆ + 6H₂O + 6O₂) is the reverse of what reaction?

The reaction for respiration

What occurs during the reaction for respiration?

Glucose is oxidized to CO₂ using O₂ as an electron acceptor

What part of the plant is the primary site of photosynthesis?

Leaves

Leaves have a thick layer of photosynthetic cells called _____

Mesophyll

Mesophyll cells contain what organelles?

Chloroplasts

The inner membrane of the chloroplast is organized into flattened structures called _____, which are stacked into columns called _____

Thylakoid disks, grana

The thylakoid membrane is the internal membrane of what organelle?

Chloroplasts

“A continuous phospholipid bilayer organized into flattened sacs” describes what structure?

Thylakoid membrane

When the thylakoid membrane is stacked to form grana, this forms three compartments:

1. The thylakoid membrane itself that contains the enzymes to make ATP and photosynthetic pigments that capture light

2. The space inside the thylakoid membrane called thylakoid space

3. The compartment outside the thylakoid membrane called stroma

When a photon strikes a molecule, its energy is either:

• Lost as heat

• Absorbed by the electrons of the molecule 

“Range and efficiency of photons a molecule is capable of absorbing” describes the _____

Absorption spectrum

What are the two general types of pigments in photosynthesis?

Chlorophyll (chlorophylls) and carotene (carotenoids)

Chlorophylls preferentially absorb _____ and _____ light

Violet-blue, red

We perceive reflected photons as what color?

Green

What is the main pigment in plants and cyanobacteria?

Chlorophyll a

What is the only pigment that can act directly to convert light energy to chemical energy?

Chlorophyll a

What pigment acts as an accessory pigment, or secondary light-absorbing pigment, to complement and add to the light-absorption of chlorophyll a?

Chlorophyll b

Light is captured by photosynthesis, each of which consists of two components:

1. Antenna complex

2. Reaction center

Description and function of antenna complex:

• Hundreds of accessory pigment molecules

• Gather photons and feed the captured light energy to the reaction center

Description and function of reaction center:

• 1 or more chlorophyll a molecules in a matrix of proteins

• Passes excited electrons out of the photosystem