Bio Topic 11

Question 1

Describe the structure of the lungs

Answer 1

The trachea branches into two bronchi
The bronchi branch into bronchioles
These bronchioles end in alveoli which are lined with capillaries for exchange

Question 2

Adaptations alveoli to maximise gas exchange

Answer 2

1) Thin surface (short diffusion distance)
2) Good blood supply (maintains high concentration gradient for fast diffusion)
3) good ventilation with air (to ensure a steep concentration gradient)
4) large surface area (faster diffusion)
5) moist ( allows gases to dissolve before diffusing across membrane)

Question 3

What is the purpose of the cartilage in the trachea?

Answer 3

-allows trachea to expand + hold it open so air can pass through it
-provides structural strength

Question 4

What is the percentage composition of nitrogen, water vapour, oxygen and carbon dioxide in inhaled air?

Answer 4

Nitrogen 78%, Oxygen 21%, Carbon dioxide 0.04%, water vapour varies

Question 5

What is the percentage composition of nitrogen, water vapour, oxygen and carbon dioxide in exhaled air?

Answer 5

Nitrogen 79%, Oxygen 16%, Carbon dioxide 4%, water vapour saturated (as much as it can)

Question 6

State the difference in the amount of water vapour present in inhaled air vs exhaled air and why

Answer 6

Exhaled air contains more water vapour
bc alveoli lining is kept moist & it evaporates as a result of body warmth

Question 7

Why is the percentage of nitrogen in the exhaled air the same as the inhaled air?

Answer 7

The body does not absorb nitrogen from the air so all of the nitrogen that is taken in is released again

Question 8

Describe the difference in the percentage of CO2 and O2 in inhaled air and exhaled air

Answer 8

There is a lower percentage of oxygen in exhaled air as some
of the oxygen is absorbed by the body
There is a higher percentage of carbon dioxide in exhaled air as extra carbon dioxide from respiration is removed

Question 9

What chemical can be used to test for carbon dioxide?

Answer 9

Calcium hydroxide Ca(OH)2 - commonly known as limewater

Question 10

How can limewater be used to test for carbon dioxide?

Answer 10

Bubble the gas you are testing for through the limewater

Question 11

Describe the effects of physical activity on breathing rate and breathing depth

Answer 11

As physical activity increases, the
breathing rate increases and so does the breathing depth

Question 12

Explain the effects of physical activity on breathing rate and breathing depth

Answer 12

As physical activity increases, the rate of respiration also increases, producing more carbon dioxide
The brain detects the increased carbon dioxide concentration in the blood and sends signals to trigger an increase in breathing rate and depthto remove the carbon dioxide more quickly

Question 13

How do ciliated epithelial cells and goblet cells work together to remove debris and pathogens from the airways

Answer 13

-mucus is produced by goblet cells & traps bacteria, dust & particles
-the cilia beat
-and push the mucus away from the lungs into the throat
-mucus then swallowed & pathogens destroyed in acidic conditions of stomach

Question 14

What happens to the breathing system during inspiration?

Answer 14

-external i.m. + diaphram CONTRACT
-internal i.m. relax
-ribs move outwards + upwards
-volume of thorax increases
-pressure in thorax decreases

Question 15

What happens to the breathing system during expiration?

Answer 15

-external i.m. + diaphram RELAX
-internal i.m. CONTRACT
-ribs move inwards + downwards
-volume of thorax decreases
-pressure in thorax increases

Question 16

Alveoli adaptations to maximise gas exchange:

Answer 16

-large surface area: allow faster diffusion of gases
-thin surface: diffusion distances remain short
-good blood supply
-good ventilation w/ air: high diffusion gradients mantained
-moist : allow gasses to dissolve before diffusing through membrane