CHAPTER 7

Question 1

What is gas exchange?

Answer 1

Diffusion of gas from an area of higher concentration to an area of lower concentration.

Question 2

Where does gas exchange occur?

Answer 2

Over a gas exchange surface

Question 3

What is a gas exchange surface?

Answer 3

A boundary between the outside and the inside of an environment of an organism.

Question 4

What do organisms need to diffuse across gas exchange surfaces?

Answer 4

Oxygen and carbon dioxide.

Question 5

What helps to increase the rate of diffusion in gas exchange surfaces?

Answer 5

1. Large surface area
2. They’re thin which provides a short diffusion pathway across the gas exchange surface.
3. By maintaining a steep concentration gradient of gases across the exchange surfaces

Question 6

How does gas exchange work in single celled organisms?

Answer 6

They absorb and release gases by diffusion through their cell surface membranes. They have thin surfaces and short diffusion pathways so they don’t need a special gas exchange system.

Question 7

What is a single celled organism?

Answer 7

An organism consisting of one cell eg bacteria, protist and yeast.

Question 8

Why are gills important in fish?

Answer 8

Because they provide oxygen to the fish.

Question 9

How does oxygen enter the fish?

Answer 9

Through water and passes through the gills.

Question 10

What are gill filaments?

Answer 10

Gill filaments are made of lots of thin plates which give a large surface area for exchange of gases and so increase the rate of diffusion.

Question 11

Why is gas exchange important?

Answer 11

It allows the body to replenish oxygen and eliminate the carbon dioxide.

Question 12

What is lamellae?

Answer 12

Tiny structures that cover the gill and gives it a large surface area. They have lots of blood capillaries and a thin surface layer of cells to speed up diffusion

Question 13

Where does blood flow through in a fish?

Answer 13

The lamaella

Question 14

What is the counter-current system?

Answer 14

This occurs in the gills of fish and this means that water with a high oxygen concentration will flow next to blood with a lower concentration of oxygen this means that a steep concentration is maintained between water and blood. This means as much oxygen as possible diffuses from the water into the blood.

Question 15

What is needed and produced in photosynthesis?

Answer 15

CO2 is needed, O2 is produced.

Question 16

What is a dicotyledonous plant?

Answer 16

A plant that has seeds with two parts.

Question 17

What is a mesophyll cell?

Answer 17

Tissue found in the interior of the leaf

Question 18

Where does gas exchange take place in dicotyledonous plants?

Answer 18

In the surface of the mesophyll cells in the leaf.

Question 19

How are mesophyll cells adapted for their function?

Answer 19

They have a large surface area.

Question 20

How do gases move in dicotyledonous plants?

Answer 20

Gases move in and out through special pores mainly in the lower epidermis called stomata.

Question 21

How do gases move in and out of plants?

Answer 21

Through special pores in the epidermis (mostly the lower epidermis) called the stomata.