B3.1 Gas exchange in animals and plants

Question 1

What are the properties of gas-exchange surfaces?

Answer 1

• thin
• permeable
• large SA:V ratio
• moist

Question 2

What is ventilation?

Answer 2

moving air in and out of lungs

Question 3

What is surfactant?

Answer 3

substance that prevents alveoli from collapsing and provides moisture

Question 4

What happens when inhaling (5 things)?

Answer 4

• diaphragm contracts
• external intercostal muscles contract
• interior intercostal muscles relax
• volume increases
• pressure decreases
• abdominal muscles relax

Question 5

What happens when exhaling (5 things)?

Answer 5

• diaphragm relax
• external intercostal muscles relax
• interior intercostal muscles contract
• volume decreases
• pressure increases
• abdominal muscles contract

Question 6

What is ventilation rate?

Answer 6

number of inhalations/exhalations per minute

Question 7

What is tidal volume?

Answer 7

volume of air ihaled/exhaled in each breath

Question 8

What is vital capacity?

Answer 8

maximum amount of air the lungs can hold

Question 9

What is inspiratory reserve volume?

Answer 9

amount of air a person can inhale after a normal breath

Question 10

What is expiratory reserve volume?

Answer 10

amount of air a person can exhale after a normal breath

Question 11

List the anatomy of the respiratory system (5)

Answer 11

• mouth
• trachea
• bronchus
• bronchioles
• alveoli

Question 12

What is stomata?

Answer 12

openings on the bottom of a leaf for gas exchange and water loss

Question 13

List the layers of a leaf (3)

Answer 13

• upper epidermis
• mesophyll: palisade layer, spongy mesophyll
• lower epidermis

Question 14

How leaves are adapted for gas exchange?

Answer 14

thin and flat, which leads to large SA that gases can diffuse through and absorb light

Question 15

Why leaves are thin and flat?

Answer 15

increases SA so gases can diffuse through and also absorb more light

Question 16

What’s the function of waxy layer on upper epidermis in plants?

Answer 16

waterproof barrier that prevents water loss

Question 17

Where are stomata found?

Answer 17

epidermis layer

Question 18

What’s the function of spongy mesophyll and how its structure helps carry out its function?

Answer 18

it provides many air spaces, so the gasses can diffuse from one part of the leaf to another

Question 19

In which leaf layer does photosynthesis take place and how does it look?

Answer 19

in palisade mesophyll, tightly packed cells with chloroplasts

Question 20

What is transpiration?

Answer 20

loss of water from the leaves

Question 21

What’s the effect of higher temperature on transpiration?

Answer 21

more transpiration

Question 22

What’s the effect of higher humidity on transpiration?

Answer 22

less transpiration

Question 23

How plants can control water loss?

Answer 23

by closing or opening the stomata

Question 24

What are guard cells?

Answer 24

guard cells control the opening of stomata by swelling or removing water

Question 25

What is stomatal density?

Answer 25

number of stomata

Question 26

How many oxygen molecules can haemoglobin carry?

Answer 26

4 oxygen molecules

Question 27

What happens when the oxygen binds to haemoglobin?

Answer 27

it binds to heme group, causing reversible conformational change and increases the attraction for oxygen

Question 28

What is Bohr shift?

Answer 28

high carbon dioxide concentrations make haemoglobin less attracted to oxygen and give it up easier, e.g. to muscles during exercise when it is needed

Question 29

What is partial pressure?

Answer 29

pressure of one particular gas in the mixture of gases

Question 30

What happens to the oxygen dissociation curve in foetal haemoglobin and in high CO2 environment?

Answer 30

foetal: shifts left high CO2: shifts right

Question 31

Which organs initiate inspiration in mammals?

Answer 31

diaphragm and intercostal muscles

Question 32

What's the function of surfactant in alveoli?

Answer 32

- preventing alveoli from collapsing - decrease surface tension - gases dissolve in it before entering or exiting the alveoli and diffusing into or out of the blood

Question 33

Describe the structure of the bronchi and function of each structure

Answer 33

- cartilage for support - smooth muscle to relax and contract for control - lined with ciliated epithelium to remove particles

Question 35

How ventilation can be measured?

Answer 35

- measuring breaths - using spirometer - person breaths in and out into a spirometer - this is repeated for different levels and for multiple times

Question 36

What are endothelial cells?

Answer 36

they cover the inner surface of the blood vessel

Question 37

What are epithelial cells?

Answer 37

they cover inner surface of the internal organs and outer surface of the human body

Question 38

Describe route of oxygen from alveolus to blood

Answer 38

- across type I pneumocyte - acrfoss endothelium of blood capillary