6a. EXCHANGE

Question 1

Name some substances that are exchanged

Answer 1

Oxygen, carbon dioxide, nutrients, excretory products

Question 2

Describe the surface area to volume ratio of smaller organisms

Answer 2

Smaller organisms have higher surface area:volume ratio

Question 3

Describe the surface area to volume ratio of larger organisms

Answer 3

Larger organisms have smaller surface area:volume ratio

Question 4

How does surface area : volume ratio affect rate of heat exchange?

Answer 4

As surface area : volume ratio decreases, rate of heat exchange also decreases

Question 5

State why smaller animals have high metabolic rate

Answer 5

Smaller animals lose heat at a faster rate so therefore they need a high metabolic rate in order to generate enough heat to stay warm.

Question 6

List the four features gas exchange surfaces that increase the rate of gas exchange

Answer 6

Large surface area, thin walls, a transport system, and ventilated

Question 7

Why do exchange surfaces have a large surface area?

Answer 7

To increase the rate of gas exchange

Question 8

Why do exchange surfaces have a thin epithelium? (one cell thick)

Answer 8

To minimise the diffusion distance

Question 9

Why are exchange surfaces surrounded by lots of capillaries?

Answer 9

To maintain the concentration gradients

Question 10

Why are exchange surfaces ventilated?

Answer 10

To maintain the diffusion gradients

Question 11

State the equation that links diffusion, surface area, length of diffusion pathway and difference in concentration

Answer 11

Diffusion ∞ surface area x difference in concentration / length of diffusion path

Question 12

State the formula to calculate volume of a sphere

Answer 12

V = 4/3πr3

Question 13

State the formula to calculate volume of a cylinder

Answer 13

V = πr2h

Question 14

Describe how single-celled organisms exchange gases

Answer 14

Single-celled organisms exchange gases by diffusion through their outer surface which is covered by a cell surface membrane.

Question 15

Name the different parts of an insect’s gas exchange system

Answer 15

Spiracles, trachae, trachioles

Question 16

Describe the function of spiracles

Answer 16

The pores on the insect’s surface which allow air to diffuse in and out of the trachaea

Question 17

Describe how air is moved in and out of the spiracles

Answer 17

Abdominal pumping

Question 18

Why do smaller insects not need to abdominal pump?

Answer 18

As their small surface area : volume allows a shorter diffusion distance to tissues.

Question 19

Describe the structure of the trachaea and tracheoles

Answer 19

Trachaea are tubes that divide into smaller tubes called tracheoles, which are highly branched with thin walls

Question 20

Why are tracheoles highly branched with thin walls?

Answer 20

To provide a short diffusion distance to any body cell

Question 21

Why is respiration important in the gas exchange system of insects?

Answer 21

It maintains the diffusion gradients between the inside of the tracheoles and the air

Question 22

What are the end of the tracheoles filled with?

Answer 22

Tracheal fluid.

Question 23

When insects respire anaerobically, what is produced?

Answer 23

Lactate (lactic acid).

Question 24

What effect does the presence of lactate have on insect muscle cells?

Answer 24

Lactate is soluble in water so lowers the water potential of muscle cells.

Question 25

What is the effect of the reduction of the water potential of the muscle cells?

Answer 25

Fluid moves into the muscle cells from the tracheoles by osmosis.

Question 26

What happens as the tracheal fluid is drawn into the muscle cells?

Answer 26

This draws more air into the tracheoles, increasing the rate of diffusion

Question 27

How is water lost from an insect's exchange system?

Answer 27

Evaporation

Question 28

What is the purpose of the tiny hairs around the spiracles?

Answer 28

They reduce evaporation.

Question 29

How does an insect control water loss from it's exchange system?

Answer 29

It opens and closes its spiracles

Question 30

Describe the structure of fish gills.

Answer 30

Each gill has many gill filaments extending from a gill arch. Along the gill filaments, at right angles to them, are gill lamellae.

Question 31

Why does each gill have many gill filaments?

Answer 31

To increase the surface area.

Question 32

What is the function of the lamellae?

Answer 32

To increase the surface area.

Question 33

Describe the features of fish gills that increase the rate of exchange

Answer 33

Large surface area, thin walls, a transport system, and ventilated

Question 34

How do fish ventilate their gills?

Answer 34

Buccal pumping

Question 35

During buccal pumping, the fish will lower the floor of their mouths. Why does this draw water into the mouth?

Answer 35

It increases the volume and decreases the pressure inside the mouth.

Question 36

During buccal pumping, the fish will raise the floor of their mouths. Why does this force water over the gills?

Answer 36

It decreases the volume and increases the pressure inside the mouth.

Question 37

Why are a fish's gill filament and lamellae surrounded by many capillaries?

Answer 37

The circulation maintains the concentration gradients

Question 38

What is the counter-current system?

Answer 38

Blood flows in the opposite direction to water

Question 39

Explain why the counter-current system increases gas exchange

Answer 39

Blood is always passing water with a higher oxygen concentration, so a diffusion gradient is maintained throughout the length of the gill filaments.

Question 40

Name the different parts of the human gaseous exchange system

Answer 40

Trachea, bronchi, bronchioles, ribcage, right and left lungs, alveoli

Question 41

What is the function of the rings of cartilage around the trachea?

Answer 41

They prevent it collapsing under low pressure

Question 42

What is the trachea divided into?

Answer 42

Two bronchi

Question 43

What do the bronchi divide into?

Answer 43

Bronchioles

Question 44

What are found at the end of brionchioles?

Answer 44

Alveoli

Question 45

What is the function of the alveoli?

Answer 45

They are the site of gas exchange

Question 46

Why do alveoli contain elastic and collagen fibres?

Answer 46

To allow them to stretch and recoil

Question 47

Why do the lungs contain many alveoli?

Answer 47

To produce a large surface area

Question 48

Why is the alveolar epithelium one cell thick?

Answer 48

To provide a short diffusion pathway

Question 49

Why are the alveoli surrounded by many capillaries?

Answer 49

Circulation maintains the diffusion gradients

Question 50

Why are the capillary epithelium one cell thick?

Answer 50

To provide a short diffusion pathway

Question 51

List in the correct sequence all the structures that air passes through a human respiratory system

Answer 51

Nostril, nasal cavity, trachea, bronchi, lungs, bronchioles, alveoli.

Question 52

What is the purpose of ventilation of the lungs?

Answer 52

To maintain the diffusion gradients

Question 53

Name the two types of muscle involved in human ventilation

Answer 53

Diaphragm and intercostal muscles

Question 54

What is inspiration?

Answer 54

When air is drawn into the lungs down a pressure gradient

Question 55

Why is inspiration an active process?

Answer 55

It involves muscle contraction

Question 56

What happens to the intercostal muscles during inspiration?

Answer 56

External intercostal muscles contract and internal intercostal muscles relax. They are antagonistic.

Question 57

What happens to the ribs during inspiration?

Answer 57

They are pulled upwards and outwards

Question 58

What happens to the diaphragm during inspiration?

Answer 58

It contracts and flattens

Question 59

Describe what happens to the volume and pressure inside the thorax during inspiration that causes air to be drawn into the lungs?

Answer 59

Volume increases and pressure decreases

Question 60

What is expiration?

Answer 60

Expiration is when air is forced out of the lungs down a pressure gradient.

Question 61

Why is expiration a passive process?

Answer 61

It does not involves muscle contraction

Question 62

What happens to the intercostal muscles during expiration?

Answer 62

Internal intercostal muscles contract and external intercostal muscles relax. They are antagonistic.

Question 63

What happens to the ribs during expiration?

Answer 63

They move downwards and inwards.

Question 64

What happens to the diaphragm during expiration?

Answer 64

It relaxes (and moves up).

Question 65

Describe what happens to the volume and pressure inside the thorax during expiration that causes air to be pushed out of the lungs

Answer 65

Volume decreases and pressure increases

Question 66

Define tidal volume.

Answer 66

The volume of air in each breath.

Question 67

Define breathing / ventilation rate.

Answer 67

The number of breaths per minute.

Question 68

Define forced expiratory volume.

Answer 68

This is the maximum volume of air that can be breathed out in one second.

Question 69

Define forced vital capacity.

Answer 69

This is the maximum volume of air it is possible to breathe forcefully.

Question 70

Define PVR

Answer 70

Pulmonary Ventilation Rate: volume of air moved into lungs per minute.

Question 71

Recall the equation used to calculate PVR

Answer 71

PVR (dm3 min-1) = tidal volume dm3) × breathing rate (min-1)

Question 72

State what a spirometer is.

Answer 72

An equipment used to measure the volume of air breathed in and out.

Question 73

Name some lung diseases.

Answer 73

Asthma, Emphysema, Pulmonary Tuberculosis, fibrosis.

Question 74

Describe some risk factors for lung diseases.

Answer 74

Smoking, air pollution, genetic makeup, infections, occupation

Question 75

Describe how breathing in dust and harmful gases can decrease the rate of gas exchange

Answer 75

It can cause the epithelium to become thicker, increasing the diffusion distance

Question 76

Describe what happens during an asthma attack

Answer 76

The muscle walls of the bronchi contract and the walls of the bronchi secrete more mucus, which reduces the diameter of the airways, reducing the air flow.

Question 77

How does smoking reduce air flow to the lungs?

Answer 77

Smoking causes the airways to become inflamed and produce excess mucus. This narrows the airways.

Question 78

Smoking can cause scar tissue to form on the alveoli. What effect does this have?

Answer 78

It reduces the elasticity of the lungs, and reduces the surface area available for gas exchange.