OCR A level Biology Module 3 UPDATED
ACTUAL Questions and CORRECT Answers
Why can't fish breathe in and out via ventilation? - CORRECT ANSWER -Water is denser and has a lower oxygen
content than air, so requires too much energy to be efficiently moved by a 2-way ventilation system
What is an exchange surface? - CORRECT ANSWER -A specialised area that is adapted to maximise rate of
diffusion of molecules to cross from one side of the surface to the other
Do prokaryotes need specialised exchange surfaces? - CORRECT ANSWER -No - they are small enough to get the
resources they need via osmosis, diffusion etc (large enough SA:V ratio)
Why do larger, eukaryotic organisms need specialised exchange surfaces? - CORRECT ANSWER -Because they
have greater metabolic demand so they need more resources and have smaller SA:V ratios so cannot get all of these
resources via simple diffusion, osmosis etc. , as the substances need to travel further to get to our internal cells
The need for specialised exchange surfaces - CORRECT ANSWER -Surface area to volume ratio (SA:V),
metabolic activity and demand, distinction between single-celled and multicellular organisms
What are 4 things all good exchange surfaces should have/be? - CORRECT ANSWER -1. Large surface area
2. Thin e.g alveoli
3. Good ventilation e.g gills/alveolus
4. Good blood supply
How does having a large surface area aid exchange surfaces? - CORRECT ANSWER -Allows more substances to
travel across at a time, increasing exchange rate, overcomes limitations of SA:V ratio in larger organisms
How does being thin aid exchange surfaces? - CORRECT ANSWER -Allows substances to travel across them
more quickly as distance to travel is shorter, increasing exchange rate,
How does having a good blood supply aid exchange surfaces? - CORRECT ANSWER -steep concentration
gradient is maintained by bringing/taking away substances quickly
How does having good ventilation aid exchange surfaces? - CORRECT ANSWER -a steep concentration gradient
is maintained
Why can a single-celled organism only reach a certain size? - CORRECT ANSWER -Because any larger and it's
SA:V ratio would be too small for it to support its metabolism when only transporting materials via diffusion, osmosis
etc.
Why do mammals need excellent exchange surfaces? - CORRECT ANSWER -Because they have large
metabolisms, need to take in reagents for metabolic reactions e.g oxygen and glucose, excretion of waste products from
these reactions e.g carbon dioxide
What is the biological name for the mouth? - CORRECT ANSWER -The buccal cavity
What is the purpose of the nasal cavity? - CORRECT ANSWER -Increases the temperature and moisture content of
inhaled air. contains ciliated epithelium, mucus-secreting (presence of goblet cells) lining also traps pathogens and
irritants
What is the membrane on the surface of the lungs called? - CORRECT ANSWER -Pleural Membrane
What are the muscles between the ribs called? - CORRECT ANSWER -Intercostal muscles
What is the sequence of airways that air passes down? - CORRECT ANSWER -Mouth/Nostril--->Buccal/nasal
cavity--->Trachea--->Bronchus--->Bronchioles--->Alveoli
What parts of the mammalian respiratory system contain cartilage? - CORRECT ANSWER -trachea
, bronchi
What parts of the mammalian respiratory system contain smooth muscle? - CORRECT ANSWER -trachea
bronchi
bronchioles
alveoli
What parts of the mammalian respiratory system contain elastic fibres? - CORRECT ANSWER -trachea
bronchi
bronchioles
alveoli
What parts of the mammalian respiratory system contain collagen? - CORRECT ANSWER -trachea
bronchi
bronchioles
alveoli
What parts of the mammalian respiratory system contain ciliated epithelium? - CORRECT ANSWER -trachea
bronchi
bronchioles
What parts of the mammalian respiratory system contain goblet cells? - CORRECT ANSWER -trachea
bronchi
Why does the trachea have c-shaped rings of cartilage? - CORRECT ANSWER -To prevent it from collapsing due
to pressure changes in the lungs
What two types of cells is the trachea lined by? - CORRECT ANSWER -Goblet to secrete mucus to trap pathogens
and bacteria
Ciliated Epithelial cells
What is the purpose of goblet cells? - CORRECT ANSWER -They secrete mucus, which traps dust and microbes
What is the purpose of ciliated epithelial cells? - CORRECT ANSWER -They are adjoining to goblet cells, and use
their cilia to sweep mucus and whatever is trapped within it out into the throat and away from the alveoli
What is the purpose of smooth muscle ? - CORRECT ANSWER -Bronchoconstriction, help the lumen to constrict
or dilate
What is the structure of the bronchi? - CORRECT ANSWER -Similar to the trachea and with rings of cartilage,
thinner and narrower
What is the purpose of smooth muscle cells contained in the walls of the bronchioles? - CORRECT ANSWER -To
allow them to dilate and constrict (bronchoconstriction), regulate flow of air
What are the walls of alveoli made up of? - CORRECT ANSWER -Squamous epithelial cells (one cell thick), some
collagen and elastic fibres made from elastin, surfactant on the inner walls
What is the purpose of the elastic tissues in alveoli? - CORRECT ANSWER -They allow the alveoli to stretch
when air enters, and recoil in order to help force air out, prevents alveoli from bursting
What is the purpose of elastic fibres in the gaseous exchange system ? - CORRECT ANSWER -Allow components
to stretch and recoil, adapting to the volume of air passing through, prevents bursting
Where is lung surfactant found? - CORRECT ANSWER -Coating the inside of alveoli
What are the 2 purposes of lung surfactant? - CORRECT ANSWER -Prevent the alveoli from collapsing and help
prevent water loss
ACTUAL Questions and CORRECT Answers
Why can't fish breathe in and out via ventilation? - CORRECT ANSWER -Water is denser and has a lower oxygen
content than air, so requires too much energy to be efficiently moved by a 2-way ventilation system
What is an exchange surface? - CORRECT ANSWER -A specialised area that is adapted to maximise rate of
diffusion of molecules to cross from one side of the surface to the other
Do prokaryotes need specialised exchange surfaces? - CORRECT ANSWER -No - they are small enough to get the
resources they need via osmosis, diffusion etc (large enough SA:V ratio)
Why do larger, eukaryotic organisms need specialised exchange surfaces? - CORRECT ANSWER -Because they
have greater metabolic demand so they need more resources and have smaller SA:V ratios so cannot get all of these
resources via simple diffusion, osmosis etc. , as the substances need to travel further to get to our internal cells
The need for specialised exchange surfaces - CORRECT ANSWER -Surface area to volume ratio (SA:V),
metabolic activity and demand, distinction between single-celled and multicellular organisms
What are 4 things all good exchange surfaces should have/be? - CORRECT ANSWER -1. Large surface area
2. Thin e.g alveoli
3. Good ventilation e.g gills/alveolus
4. Good blood supply
How does having a large surface area aid exchange surfaces? - CORRECT ANSWER -Allows more substances to
travel across at a time, increasing exchange rate, overcomes limitations of SA:V ratio in larger organisms
How does being thin aid exchange surfaces? - CORRECT ANSWER -Allows substances to travel across them
more quickly as distance to travel is shorter, increasing exchange rate,
How does having a good blood supply aid exchange surfaces? - CORRECT ANSWER -steep concentration
gradient is maintained by bringing/taking away substances quickly
How does having good ventilation aid exchange surfaces? - CORRECT ANSWER -a steep concentration gradient
is maintained
Why can a single-celled organism only reach a certain size? - CORRECT ANSWER -Because any larger and it's
SA:V ratio would be too small for it to support its metabolism when only transporting materials via diffusion, osmosis
etc.
Why do mammals need excellent exchange surfaces? - CORRECT ANSWER -Because they have large
metabolisms, need to take in reagents for metabolic reactions e.g oxygen and glucose, excretion of waste products from
these reactions e.g carbon dioxide
What is the biological name for the mouth? - CORRECT ANSWER -The buccal cavity
What is the purpose of the nasal cavity? - CORRECT ANSWER -Increases the temperature and moisture content of
inhaled air. contains ciliated epithelium, mucus-secreting (presence of goblet cells) lining also traps pathogens and
irritants
What is the membrane on the surface of the lungs called? - CORRECT ANSWER -Pleural Membrane
What are the muscles between the ribs called? - CORRECT ANSWER -Intercostal muscles
What is the sequence of airways that air passes down? - CORRECT ANSWER -Mouth/Nostril--->Buccal/nasal
cavity--->Trachea--->Bronchus--->Bronchioles--->Alveoli
What parts of the mammalian respiratory system contain cartilage? - CORRECT ANSWER -trachea
, bronchi
What parts of the mammalian respiratory system contain smooth muscle? - CORRECT ANSWER -trachea
bronchi
bronchioles
alveoli
What parts of the mammalian respiratory system contain elastic fibres? - CORRECT ANSWER -trachea
bronchi
bronchioles
alveoli
What parts of the mammalian respiratory system contain collagen? - CORRECT ANSWER -trachea
bronchi
bronchioles
alveoli
What parts of the mammalian respiratory system contain ciliated epithelium? - CORRECT ANSWER -trachea
bronchi
bronchioles
What parts of the mammalian respiratory system contain goblet cells? - CORRECT ANSWER -trachea
bronchi
Why does the trachea have c-shaped rings of cartilage? - CORRECT ANSWER -To prevent it from collapsing due
to pressure changes in the lungs
What two types of cells is the trachea lined by? - CORRECT ANSWER -Goblet to secrete mucus to trap pathogens
and bacteria
Ciliated Epithelial cells
What is the purpose of goblet cells? - CORRECT ANSWER -They secrete mucus, which traps dust and microbes
What is the purpose of ciliated epithelial cells? - CORRECT ANSWER -They are adjoining to goblet cells, and use
their cilia to sweep mucus and whatever is trapped within it out into the throat and away from the alveoli
What is the purpose of smooth muscle ? - CORRECT ANSWER -Bronchoconstriction, help the lumen to constrict
or dilate
What is the structure of the bronchi? - CORRECT ANSWER -Similar to the trachea and with rings of cartilage,
thinner and narrower
What is the purpose of smooth muscle cells contained in the walls of the bronchioles? - CORRECT ANSWER -To
allow them to dilate and constrict (bronchoconstriction), regulate flow of air
What are the walls of alveoli made up of? - CORRECT ANSWER -Squamous epithelial cells (one cell thick), some
collagen and elastic fibres made from elastin, surfactant on the inner walls
What is the purpose of the elastic tissues in alveoli? - CORRECT ANSWER -They allow the alveoli to stretch
when air enters, and recoil in order to help force air out, prevents alveoli from bursting
What is the purpose of elastic fibres in the gaseous exchange system ? - CORRECT ANSWER -Allow components
to stretch and recoil, adapting to the volume of air passing through, prevents bursting
Where is lung surfactant found? - CORRECT ANSWER -Coating the inside of alveoli
What are the 2 purposes of lung surfactant? - CORRECT ANSWER -Prevent the alveoli from collapsing and help
prevent water loss
