Ch. 7 homework

Approximately what wavelength of light is best absorbed by chlorophyll a, the pigment that participates directly in the light reactions?

435 nm

Which wavelength of light is best absorbed by chlorophyll b?

455 nm

Part complete Which of these equations best summarizes photosynthesis?

6 CO2 + 6 H2O → C6H12O6 + 6 O2

What two molecules are produced by the light reactions and used to power the Calvin cycle?

ATP and NADPH

What connects the two photosystems in the light reactions?

An electron transport chain

What provides the carbon atoms that are incorporated into sugar molecules in the Calvin cycle?

Carbon dioxide (CO2)

The radioactive isotope used in the Calvin experiments was ____.

Carbon-14

In which of the following organelles does photosynthesis take place?

Chloroplast

Part complete What provides electrons for the light reactions?

H20

What transports electrons from the light reactions to the Calvin cycle?

NADPH

Can you tell from these absorption spectra whether red light is effective in driving photosynthesis?

One cannot tell from this graph, but because chlorophyll a does absorb red light, we can predict that it would be effective in driving photosynthesis.

Part complete Where does the Calvin cycle occur?

Stroma

If only chlorophyll a were involved in the light reactions, would blue light (wavelength about 490 nm) be effective in driving photosynthesis?

The graph indicates that chlorophyll a absorbs very little blue light, so we can predict that blue light would not be effective.

water (ATP) ... NADPH

The light reactions of photosynthesis use _____ and produce _____.

An action spectrum plots the rate of photosynthesis at various wavelengths of visible light, and it shows that blue light with a wavelength of about 490 nm is effective in driving photosynthesis. Based on this information and the absorption spectra shown at left, what role may chlorophyll b and carotenoids play in photosynthesis?

These pigments are able to absorb more wavelengths of light (and thus more energy) than chlorophyll a alone can absorb. As part of light-harvesting complexes in photosystems, they broaden the range of light that can be used in the light reactions.

You obtain the pigments called carotenoids in your diet when you eat carrots. Why do carotenoids appear yellow and orange?

They absorb blue/green light and reflect yellow and red wavelengths of light.

What type of organism was used in Calvin's experiments?

algae

The Calvin cycle describes the conversion of ___.

carbon dioxide to carbohydrates

Paper chromatography is used to _____.

separate components in a material of interest

The light reactions take place in the _________ and the Calvin cycle takes place in the _________.

thylakoids; stroma