Module 3 - Exchange Surfaces

Question 1

Suggest why goblet cells have a large number of mitochondria

Answer 1

To provide lots of energy

Question 2

Suggest the role of golgi apparatus in the function of goblet cells

Answer 2

Golgi apparatus packages protein and allows mucus to be secreted

Question 3

Sjogren’s syndrome is a rare condition that can reduce the production of mucus.
Suggest how the upper respiratory tract of a person with Sjogren’s syndrome might be affected

Answer 3

They may be coughing to attempt to remove the mucus

Question 4

Why do large multicellular animals have a specialised exchange surface

Answer 4

They have a large surface area to volume ratio, therefore simple diffusion cannot be used to meet the body’s metabolic demands, and nutrients as it is a long path and will be too slow.

Question 5

State the roles of cartilage and elastic fibres in mammalian gas exchange

Answer 5

Cartilage - stops the trachea from collapsing

Elastic fibres - recoil of alveoli

Question 6

Bony fish and insects have different gas exchange systems. Both can be observed by dissection.
Describe how you would carry out the dissection to display maximum detail of either gas exchange system

Answer 6

Fish - remove the operculum and observe the gills

Insects - cut open the exoskeleton and observe the tracheae

Question 7

Describe how the trachea of a mammal is different from the trachea in an insect

Answer 7

Mammals have just one trachea , insects have multiple tracheae
Mammals trachea have smooth muscle, goblet cells. Individual insect tracheae do not.

Question 8

What does surfactant do in the alveoli

Answer 8

It reduces the cohesive action between water molecules.

It prevents alveoli from collapsing.

Question 9

Alveoli are located in the lungs of mammals.

Explain how alveoli are adapted for efficient gas exchange (6)

Answer 9

Alveoli have thin wall, one cell thick, so diffusion can occur rapidly, as shorter diffusion path

Larger number of alveoli so larger volumes of gas exchanged/higher rate of diffusion

Alveoli is well ventilated as oxygen is constantly replenished and CO2 is constantly removed. So maintains the concentration gradient.

Alveoli have elastic fibres which stretch and recoil. Stretching increases surface area and recoil helps force air out.

Question 10

Describe and explain how one feature of the lungs provides an efficient gas exchange surface

Answer 10

Large surface area for maximum diffusion.

Squamous epithelium cells provide a short diffusion rate

Question 11

What do the abbreviations FEV1 and PEFR stand for?

Answer 11

FEV1 - Forced Expiratory Volume

PEFR - Peak Expiratory Flow Rate

Question 12

The walls of the alveoli consist of squamous epithelial cells.
How does the structure of these cells differ from the epithelial cells lining bronchioles?

Answer 12

They do not have cilia and have fewer mitochondria

Question 13

Bronchiole walls contain smooth muscle and elastic fibres.

Describe the role of each of these tissues

Answer 13

Smooth Muscle - Controls lumen size

Elastic fibres - Allow stretch and recoil

Question 14

Outline the process of gaseous exchange in the alveoli of mammalian lungs

Answer 14

Gases move by diffusion down a concentration gradient
Oxygen diffuses from alveoli into blood
Carbon Dioxide diffuses from blood into alveoli

Question 15

State the correct term for the definition

A group of organs working together to perform an essential function

Answer 15

Organ System

Question 16

Many teachers use models to demonstrate and explain breathing and lung function in mammals.
When the rubber sheet is pulled down the balloons expand.
Explain why the balloons expand

Answer 16

Volume inside the jar increases and the pressure inside the jar decreases, lower than atmospheric pressure so air is forced into the balloons causing it to expand.

Question 17

Explain how the structure of the lungs provides humans with an efficient gaseous exchange

Answer 17

There are many alveoli which provide a large surface area
Squamous epithelial cells are thin so shorter diffusion path
Capillary wall is only one cell thick
Thin walls for gasses to diffuse quicker
Dense capillary network around alveoli

Question 18

Bony fish absorb dissolved oxygen from the water using gills. Water is passed through the buccal cavity and over the gill lamellae. The oxygen saturation of the blood a water changes as the water passes over the gills.

Describe the way oxygen is transferred in the blood at the gills

Answer 18

Blood and water flow in a countercurrent system with a constant concentration gradient between them

Question 19

Describe how the structures of the insect tracheal system and fish gills provide large surface area for gas exchange

Answer 19

Insect tracheal system has many branched tracheae

Fish have many filaments

Question 20

Which of the muscles in the mammalian ventilation system contract to force air out of the lungs

Answer 20

Internal intercostal muscle

Question 21

What structural features are present in 
Trachea 
Bronchi 
Bronchioles 
Alveoli

Answer 21

Trachea - cartilage, goblet cells elastic fibres

Bronchi - cartilage, goblet cells, elastic fibres

Bronchioles - elastic fibres

Alveoli - elastic fibres

Question 22

Compare and contrast between normal expiration and forced expiration (6)

Answer 22

Normal expiration is a passive process, the diaphragm moves up, external intercostal muscle relax, ribs move down and in, elastic fibres recoiled and the volume of thorax reduced.

In forced expiration is an active process, it requires energy, the internal intercostal muscles contract and the ribs pulled down hard.

Question 23

Name a piece of apparatus that may be used to monitor lung function and outline how a vital capacity measurement may be taken using this apparatus.

Answer 23

spirometer
Vital capacity can be taken by one deep breath in and one full expiration. The height of peak to trough of the trace shows vital capacity.

Question 24

Explain the meaning of the term tidal volume

Answer 24

Volume of air inhaled/exhaled in one breath during regular breathing

Question 25

Suggest how the teacher may use a glass jar and rubber sheets to demonstrate tidal volume

Answer 25

Move the rubber sheet up and down

Question 26

Explain the meaning of the term vital capacity

Answer 26

Maximum volume of air inhaled and exhaled in one breath

Question 27

Show how gills are adapted for efficient gas exchange

Answer 27

The lamellae provide large surface area
Short distance between blood and water
Blood maintains diffusion gradient

Question 28

Why can expiration be a passive process?

Answer 28

It does not use muscle contraction, muscle relaxes

Question 29

Some chemicals act as allergens. If these allergens are inhaled, they can cause breathing problems. Allergens cause the smooth muscle in the walls of the airway to contract.

Suggest the effects that this muscle contraction has on ventilation

Answer 29

Harder to exhale
Harder to inhale
More air remains in the lungs

Question 30

what is the function of smooth muscle cells in gaseous exchange system

Answer 30

Reduces diameter of airway

Question 31

What is the function of squamous epithelial cells in the gaseous exchange system

Answer 31

Provide short diffusion distance

Question 32

Explain why using standard deviation would increase the confidence in any conclusion made

Answer 32

Standard deviation is the spread of data around the mean. Reduces the effect of an anomaly.

Question 33

What is the formula for tidal volume

when ventilation rate and breathing rate is given

Answer 33

Tidal volume = ventilation rate (cm^3) / breathing rate

Question 34

CPF can affect lung function in dogs. CPF can reduce the tidal volume of a dog’s lungs. Explain how the high occurrence of CPF in West Highland Terriers could have been a result of artificial selection

Answer 34

Inbreeding reduces genetic diversity

Question 35

Explain how DNA sequencing could help scientists understand how a dogs genes affect its probability of developing CPF

Answer 35

Compare genomes of dog breeds

Identify dogs that carry the allele for CPF.

Question 36

Explain why a booster vaccination is needed

Answer 36

Produce more memory cells as they may have reduced in number

Question 37

Asthma is a condition in which the bronchioles become reduced in diameter
Suggest how diameter might become reduced

Answer 37

Contraction of smooth muscle

Extra mucus production

Question 38

Explain why it is difficult to expel air from the lungs if the bronchioles become reduced in diameter

Answer 38

Exhalation is passive so reduced diameter means force may be needed - breathing harder

Question 39

Which muscle contracts to force air out of the lungs

Answer 39

Internal intercostal muscle

Question 40

Explain how grasshopper pumps air in and out of its body

Answer 40

Gasses, O2 and CO2 are dissolved in trachea fluid and is diffused through trachéales.
The changes in volume of its body by rhythmic abdominal movements

Question 41

Explain why a parallel flow gas exchange system would be less efficient than a counter current gas exchange system

Answer 41

In a parallel flow system, the oxygen concentration gradient between the water and the blood decreases with distance along gill plate, which will mean that the rate of oxygen diffusion will also decrease.

Less oxygen diffuses into the blood than with a counter current system, where the concentration gradient is maintained.

Question 42

Explain how the concentration gradients of oxygen and carbon dioxide are maintained between the alveoli and the blood in a healthy person.

Answer 42

Alveoli surrounded by rich capillary network which means blood constantly takes O2 and brings CO2

Question 43

Emphysema is a lung disease that leads to the breakdown of the alveoli walls.
Suggest why a person with emphysema would have difficulty expelling air from the lungs.

Answer 43

Break down of the alveoli walls would mean less elastic fibres from the alveoli.
Harder for lungs to recoil and expel air