Exchanging substances

Question 1

What is the primary function of the lungs?

Answer 1

To transfer oxygen to the blood and to remove waste carbon dioxide from it.

Question 2

What are the tiny air sacs in the lungs called?

Answer 2

Alveoli.

Question 3

What is the surface area of alveoli in humans?

Answer 3

About 75 m².

Question 4

What are the four special features of alveoli that aid gas exchange?

Answer 4

• An enormous surface area
• A moist lining for dissolving gases
• Very thin walls
• A good blood supply.

Question 5

What are villi?

Answer 5

Tiny projections that cover the inside of the small intestine.

Question 6

How do villi assist in digestion?

Answer 6

They increase the surface area for quicker absorption of digested food into the blood.

Question 7

What is a key structural feature of villi?

Answer 7

A single layer of surface cells.

Question 8

What aids in the absorption of digested food in the small intestine?

Answer 8

A very good blood supply.

Question 9

How does digested food move into the blood?

Answer 9

By diffusion and by active transport.

Question 10

True or False: Alveoli have a thick wall for gas exchange.

Answer 10

False.

Question 11

Fill in the blank: The lungs remove _______ from the blood.

Answer 11

carbon dioxide.

Question 12

What diffuses into the air spaces within the leaf?

Answer 12

Carbon dioxide

Carbon dioxide is essential for photosynthesis, which occurs in the leaf cells.

Question 13

What are the small holes on the underside of the leaf called?

Answer 13

Stomata

Stomata allow for the exchange of gases, including carbon dioxide and oxygen.

Question 14

What gas is produced during photosynthesis and diffuses out through the stomata?

Answer 14

Oxygen

Oxygen is a byproduct of photosynthesis and is released into the atmosphere.

Question 15

What do guard cells control?

Answer 15

The size of the stomata

Guard cells regulate water loss and gas exchange in plants.

Question 16

What happens if guard cells are not functioning properly?

Answer 16

The plant would soon wilt

Guard cells are crucial for maintaining water balance in plants.

Question 17

What shape increases the area of the exchange surface in leaves?

Answer 17

Flattened shape

A flattened leaf maximizes the surface area for gas exchange.

Question 18

What do the air spaces inside the leaf do?

Answer 18

Increase the area of the exchange surface

More air spaces allow for greater diffusion of carbon dioxide into cells.

Question 19

What is the gas exchange surface in fish?

Answer 19

Gills

Gills facilitate the exchange of gases between water and blood.

Question 20

How does water enter the fish?

Answer 20

Through its mouth

Water flows over the gills for gas exchange.

Question 21

What are the thin plates in the gills called?

Answer 21

Gill filaments

Gill filaments provide a large surface area for gas exchange.

Question 22

What structures cover the gill filaments to increase surface area?

Answer 22

Lamellae

Lamellae further enhance the efficiency of gas exchange in gills.

Question 23

What do lamellae contain to speed up diffusion?

Answer 23

Lots of blood capillaries

Capillaries increase the efficiency of gas exchange by transporting gases quickly.

Question 24

What is the direction of blood flow through the lamellae?

Answer 24

One direction

This ensures a concentration gradient for efficient gas exchange.

Question 25

What direction does water flow over the gills?

Answer 25

Opposite direction to blood flow ## Footnote This maintains a concentration gradient between oxygen in water and blood.

Question 26

True or False: The concentration of oxygen in the water is lower than in the blood.

Answer 26

False ## Footnote The concentration of oxygen in water is always higher than in the blood.

Question 27

Fill in the blank: Water vapor _______ from the cells inside the leaf.

Answer 27

Evaporates ## Footnote Evaporation of water vapor helps maintain gas exchange.