3.1 - Exchange and Transport

Question 1

What substances need to be exchanged between an organism and their environment?

Answer 1

• Glucose - in
• Oxygen - in
• Urea - out
• Carbon dioxide - out

Question 2

What makes an efficient exchange

Question 3

Factors of an efficient exchange system?

Answer 3

• Large Surface Area
• Thin
• Good Blood Supply/Ventilation

Question 4

Function of Goblet Cells and where are they found?

Answer 4

• Line airways
• Secrete mucus which traps microorganisms and dust particles which stops them from reaching alveoli

Question 5

Function and location of Cilia

Answer 5

• Surface of cells lining airways
• Beat mucus which moves trapped microorganisms and dust away from the alveoli and towards the throat to be swallowed
• This prevents lung infections

Question 6

Function and location of Elastic Fibres

Answer 6

• Walls of the trachea, bronchi, bronchioles and alveoli
• During inspiration, the lungs inflate and the elastic fibres are stretched
• During expiration, the elastic fibres recoil to help push the air out when exhaling

Question 7

Function and location of Smooth Muscle

Answer 7

• Walls of the trachea, bronchi and bronchioles
• Allows their diameters to be controlled
• E.g. during exercise, smooth muscle relaxes which makes the tubes wider. This means there is less resistance to airflow and air can move in and out of the lungs more easily.

Question 8

Function and location of Rings of Cartilage

Answer 8

• Walls of trachea and bronchi
• Provide structural support
• Strong but flexible
• Stops the trachea and bronchi collapsing during inspiration when the pressure drops

Question 9

What is inspiration and expiration?

Answer 9

A form of ventilation in mammals that consists of breathing in and out

Question 10

Outline inspiration

Answer 10

1. External intercostal and diaphragm muscles contract
2. Causes ribcage to move up and out and the diaphragm to flatten which increases the volume of the thorax
3. As volume of thorax increases, lung pressure decreases to below atmospheric pressure
4. Causes air to flow into the lungs
5. Active process - requires energy

Question 11

Outline expiration

Answer 11

1. External intercostal and diaphragm muscles relax
2. Ribcage moves down and in, the diaphragm becomes curved again
3. Thorax volume decreases causing the air pressure to increase above atmospheric pressure
4. Air is forced out of the lungs
5. Passive process - no energy required

During forced expiration (e.g. blowing out candles) the intercostal muscles contract to pull the ribcage down and in

Question 12

What is the tidal volume?

Answer 12

Volume of air in each breath (usually 0.4 dm³)

Question 13

What is the vital capacity?

Answer 13

Max. volume of air that can be breathed in or out

Question 14

What is the breathing rate?

Answer 14

How many breaths are taken per unit time (usually 1 min)

Question 15

What is oxygen consumption/uptake?

Answer 15

Rate at which an organism uses up oxygen

(dm³ used per minute)

Question 16

Sketch and label spirometer trace

Question 17

What is a spirometer?

Answer 17

A machine that gives readings of:

• Tidal Volume
• Vital Capacity
• Breathing Rate
• Oxygen Uptake

Question 18

What system do fish use for gas exchange?

Answer 18

Counter-Current System

Question 19

How are fish gills ventilated?

Answer 19

1. Fish opens its mouth which lowers the floor of the buccal cavity.
2. The volume of the buccal cavity increases, decreasing the pressure inside the cavity, water is then sucked into the cavity.
3. Fish closes its mouth, raising the floor of the buccal cavity again.
4. The volume inside the cavity decreases and the pressure increases, water is forced out of the cavity across the gill filaments.
5. Each gill covered by bony flap (operculum) which protects the gill. The increase in pressure causes the operculum on each side of the head to open, allowing water to leave the gills.

Question 20

What is the counter-current system in fish gas exchange?

Question 21

Outline gas exchange in fish