bk2 ch7.3

Question 1

L_____ are the main location at which photosynthesis takes place.

Answer 1

leaves

Question 2

Leaves are usually broad and

flat, allowing maximum exposure to the…

Answer 2

sunlight

Question 3

The upper and lower surfaces of the leaf are bound

by a one-cell-thick layer called the e_____, which is t_____ allowing l_____ to reach the lower c_____ l_____

Answer 3

epidermis, transparent, light, cell layers

Question 4

The epidermis is covered with a waxy

waterproof c_____.

Answer 4

cuticle

Question 5

What is the purpose of the cuticle?

Answer 5

It reduces water loss from the leaf and protects it from both freezing in cold weather and invasion by fungi and bacteria. It does not, however, allow gases to pass through it.

Question 6

Gases enter the leaf through small openings called…

Answer 6

stomata

Question 7

The size of these stomata is regulated by special cells called g_____ c_____.

Answer 7

guard cells

Question 8

There are two main layers of cells within the leaf.
• The upper layer contains the p_____ c_____,
• The lower m_____ c_____

Answer 8

palisade cells, mesophyll cells

Question 9

The c_____ in leaves absorbs sunlight, but not all colours are equally absorbed. The leaves look green because…

Answer 9

chlorophyll, they reflect green light.

Question 10

Why do plants change colour prior to losing leaves?

Answer 10

Prior to losing leaves the plant breaks down chlorophyll and stores some of its components, leaving the red, orange or yellow accessory pigments behind.

Question 11

Plants in water face special problems because…

Answer 11

water absorbs light

Question 12

Why are most aquatic plants are therefore

found in the surface layers?

Answer 12

Light’s more available, because water absorbs light