Module 3.1 - Exchange and Transport

Question 1

Why do organisms need to exchange things with their environment? (2)

Answer 1

• Organisms need oxygen and glucose for metabolic activities
• Organisms need to excrete waste products

Question 2

What does the rate of exchange depend on? (1)

Answer 2

• Organism’s surface area to volume ratio (SAV)

Question 3

How to calculate SA:V? (1)

Answer 3

• Divide the surface area by the volume

Question 4

Why do single-celled organisms not need exchange surfaces? (2)

Answer 4

• Substances can diffuse across the cell surface membrane
• Diffusion rate is quick because the distance of travel is small

Question 5

Why do multicellular organisms need exchange surfaces? (4)

Answer 5

• Diffusion across the outer membrane is too slow
• Big distance between cells within the body and the outside environment
• Low surface area to volume ratio
• High metabolic rate

Question 6

Adaptation of root hair cells? (1)

Answer 6

• Large surface area which increases the rate of transport mechanisms

Question 7

Adaptations of alveolus? (6)

Answer 7

• Made of a single layer of thin, flat cells called the alveolar epithelium
• Decrease the distance for the diffusion of O2 and CO2
• Surrounded by a large capillary network
• The blood takes O2 and CO2 to and from the alveoli
• Well ventilated
• Help to maintain concentration gradients of O2 and CO2

Question 8

Adaptations of fish gills? (4)

Answer 8

• Gills are the gas exchange surface in fish
• Has a large network of capillaries
• Well ventilated - fresh water passes over them
• Help to maintain concentration gradients of O2 and CO2

Question 9

Structure of the lungs? (2)

Answer 9

• Trachea → bronchi → bronchioles → alveoli
• The ribcage, intercostal muscles and diaphragm work together to move air in and out

Question 10

Goblet cells? (2)

Answer 10

• Lines the airways
• Secrete mucus

Question 11

Mucus? (2)

Answer 11

• Traps microorganisms and dust particles in the inhaled air
• Stops them from reaching the alveoli

Question 12

Cilia? (4)

Answer 12

• Beat the mucus
• Waft the mucus upward and away from the alveoli towards the throat
• Mucus is swallowed
• Prevent lung infections

Question 13

Elastic fibres? (4)

Answer 13

• Found in the walls of the trachea, bronchi, bronchioles and alveoli
• Help the process of breathing out
• On breathing in, the lungs inflate and the elastic fibres are stretched
• The fibres recoil to help push the air out when exhaling

Question 14

Smooth muscle? (2)

Answer 14

• Found in the walls of the trachea, bronchi and bronchioles
• Allows their diameter to be controlled

Question 15

Rings of cartilage? (4)

Answer 15

• In the walls of the trachea and bronchi
• Provides support
• Strong but flexible
• Stops the trachea and bronchi collapsing when breathing and pressure drops

Question 16

Trachea? (5)

Answer 16

• Large C-shaped cartilage
• Smooth muscle
• Elastic fibres
• Goblet cells
• Ciliated epithelium

Question 17

Bronchi? (5)

Answer 17

• Smaller pieces of cartilage
• Smooth muscle
• Elastic fibres
• Goblet cells
• Ciliated epithelium

Question 18

Larger bronchiole? (4)

Answer 18

• Smooth muscle
• Elastic fibres
• Goblet cells
• Ciliated epithelium

Question 19

Smaller bronchiole? (3)

Answer 19

• Smooth muscle
• Elastic fibres
• Ciliated epithelium

Question 20

Smallest bronchiole? (2)

Answer 20

• Elastic fibres
• No cilliated epithelium

Question 21

Alveoli? (2)

Answer 21

• Elastic fibres
• No ciliated epithelium

Question 22

Inspiration? (7)

Answer 22

• External intercostal and diaphragm muscles contract
• Ribcage moves upwards and outwards
• Diaphragm flattens
• Volume of the thorax increases
• Lung pressure decreases to below atmospheric pressure
• Air flows into lungs
• Inspiration requires energy

Question 23

Expiration? (6)

Answer 23

• External intercostal and diaphragm muscles relax
• Ribcage moves downwards and inwards
• Diaphragm curves
• Volume of the thorax decreases
• Lung pressure increase to above atmospheric pressure
• Air flows out of lungs

Question 24

Forced expiration? (2)

Answer 24

• Internal intercostal muscles contract
• Ribcage is pulled down and in

Question 25

Tidal volume (TV)? (2)

Answer 25

- Volume of air in each breath - Usually about 0.4 dm³

Question 26

Vital capacity? (1)

Answer 26

- Maximum volume of air that can be breathed in or out

Question 27

Breathing rate? (1)

Answer 27

- How many breaths are taken in a minute

Question 28

Oxygen consumption/ oxygen uptake? (1)

Answer 28

- Rate at which an organism uses up oxygen

Question 29

Spirometer? (1)

Answer 29

- A machine that can give readings of tidal volume, vital capacity, breathing rate and oxygen uptake

Question 30

How does a spirometer work? (8)

Answer 30

- Spirometer has an oxygen-filled chamber with movable lid - Person breathes through tube connected to oxygen chamber - Person breathes in and out lid of chamber moves up and down - Movements recorded by pen attached to the lid writes on a rotating drum - A spirometer trace is made - Spirometer can be hooked to a motion sensor that use movements to produce electronic signals - Electron signals are picked up by a data logger - Soda lime in the tube the subject breathes into absorbs CO2

Question 31

Use of soda lime? (2)

Answer 31

- Air that's breathed out is a mixture of O2 and CO2 - CO2 is absorbed by soda lime so there's only oxygen in the chamber

Question 32

How to analyse a spirometer trace? (4)

Answer 32

- Breathing rate: number of peaks in the first minutes - Tidal volume: difference in height of the peaks - Vital capacity: difference in height of the largest peak - Oxygen consumption: gradient of the slope, should be negative

Question 33

Gill? (7)

Answer 33

- Gill filaments/ primary lamellae - thin branches - Gill filaments increase surface area for gas exchange - Gill filaments covered in gill plates/ secondary lamellae - Gill plates increase surface area even more - Gill plates have lots of blood capillaries to increase diffusion - Gill plates have thin surface layer of cells to increase diffusion - Each gill is supported by a gill arch

Question 34

Counter-current system? (5)

Answer 34

- Water enters fish through mouth and passes out through gills - Blood flows through the gill plates in one direction - Water flows over in the opposite direction - Concentration of oxygen in water is higher than in blood - Oxygen diffuses from the water into the blood

Question 35

Water entering during fish ventilation? (5)

Answer 35

- Fish opens its mouth - Floor of buccal cavity lowers - Volume of buccal cavity increases - Pressure decreases inside the cavity - Water enters cavity

Question 36

Water leaves during fish ventilation? (5)

Answer 36

- Fish closes its mouth - Floor of buccal cavity rises - Volume of buccal cavity decreases - Pressure increases inside cavity - Water leaves cavity across the gill filaments

Question 37

Role of operculum? (3)

Answer 37

- A bony flap that covers and protects the gills - Increase in pressure from water leaving gills forces operculums to open - Allows water to leave the gills

Question 38

Gas exchange in insects? (7)

Answer 38

- Insects have trachea for gas exchange - Air through spiracles - Trachea → tracheoles - Tracheoles has thin permeable walls - Tracheoles contain fluid - O2 diffuse down concentration gradient through fluid into body cells - CO2 diffuses in the opposite direction

Question 39

How do insects mechanically move air in and out? (2)

Answer 39

- Use rhythmic abdominal movements to change volume of bodies to move air through spiracles - Larger insects fly and use wing movements to pump their thoraxes