Chapter 7

Front 1

In most land plants, photosynthesis occurs in cells of the __________ of the leaves, because these cells contain the largest numbers of chloroplasts.

Back 1

mesophyll

Front 2

Light energy is initially captured by "photosystems" within thylakoid membranes. Photosystems are organized arrays of

Back 2

chlorophyll molecules,
proteins,
pigment molecules such as carotenoids

Front 3

Why is carbon dioxide a key molecule in the light-independent reactions of photosynthesis?

Back 3

Carbon dioxide, together with water, is the raw material for the synthesis of sugars, which are the key products of the light-independent reactions.

Front 4

What is photorespiration?

Back 4

the process that prevents sugar production in C3 plants when CO2 levels are low and O2 levels are high.

Front 5

In the light-dependent reactions of photosynthesis, ATP is produced by chemiosmosis. Describe this process.

Back 5

As high-energy electrons move from carrier to carrier in the electron transport system of the thylakoid membrane, some of the energy is captured to pump hydrogen ions across it.

Front 6

A lovely tree called the flowering plum has beautiful pink flowers in spring and deep-purple leaves in summer. What types of pigments are plentiful in this plant? Can photosynthesis occur in these purple leaves? Explain your answer.

Back 6

The leaves probably contain a high amount of phycocyanins and carotenoids and less chlorophyll than do plants with green leaves. They can still perform photosynthesis, because photosynthesis can occur to some extent at all wavelengths of light.

Front 7

Take a deep breath and slowly exhale. The oxygen in that breath is being used by your mitochondria in reactions that produce ATP from sugars and other food molecules you ate. Where did that oxygen come from originally?

Back 7

The oxygen in the air is produced by the splitting of water during the light-dependent reactions of photosynthesis

Front 8

A scientist studying photosynthesis illuminated a culture of algae with bright visible light. She then turned out the light and simultaneously began to bubble radioactive CO2 gas into the culture. After 30 minutes, she stopped the reaction and measured the amount of radioactivity inside the cells. What did she find? Explain your answer.

Back 8

There was radioactivity in the cells, because the CO2 is used to synthesize sugar, even in the dark.

Front 9

During photosynthesis, electrons are continuously lost from the reaction center of photosystem II. What source is used to replace these electrons?

Back 9

water

Front 10

The term carbon fixation refers to __________.

Back 10

the incorporation of atmospheric carbon dioxide into a larger organic molecule

Front 11

You have just discovered a new plant with red-orange leaves. What wavelengths of visible light are NOT being absorbed by this pigment?

Back 11

red and orange

Front 12

In the light-dependent reactions of photosynthesis the difference in hydrogen ion concentration across the thylakoid membrane is used to generate __________.

Back 12

ATP

Front 13

____________________ converts the energy of sunlight into chemical energy

Back 13

Photosynthesis

Front 14

____________________ are organisms that can produce their own food in their cells

Back 14

Autotrophs

Front 15

Photosynthesis takes place within ____________________.

Back 15

Choroplasts

Front 16

Where do the light-independent, carbon-fixing reactions occur?

Back 16

In the chloroplast stroma

Front 17

The role of accessory pigments is to

Back 17

capture additional light energy and transfer it to the chlorophyll reaction centers

Front 18

Where do the light-dependent reactions of photosynthesis occur?

Back 18

within the thylakoid membranes of the chloroplast