Exchange & Transpor Pt1

Question 1

Small organisms have a …………….. ratio

Answer 1

High Surface area to volume

Question 2

Large organisms have a …………….. ratio

Answer 2

Low surface area to volume ratio

Question 3

Why don’t microorganisms need adaptations to maximise gas exchange?

Answer 3

Because their SA: vol ratio is high

Question 4

What are 3 specialised gas exchange surfaces?

Answer 4

• lungs in mammals
• gills in fish
• tracheoles in insects

Question 5

How is gas transported round multicellular organisms?

Answer 5

• mostly through circulatory systems

- insects don’t have blood, but a fluid called “haemolyph” which doesn’t transport oxygen, so doesn’t have a pigment

Question 6

What makes a good gas exchange surface?

Answer 6

• a large surface area
• a thin exchange surface
• a steep concentration gradient

Question 7

What’s Fick’s law?

Answer 7

(Rate of diffusion) is proportional to (surface area) x (concentration gradient) / (thickness of exchange surface)

Question 8

What happens during inhalation in mammals?

Answer 8

1. the external intercostal muscles contract
2. the rib cage moves up and out
3. the diaphragm contracts and flattens
4. this increases the volume of the thorax
5. this lowers the pressure in the thorax
6. air is forced in from a higher pressure outside to a lower pressure inside the lungs

Question 9

What happens during exhalation in mammals?

Answer 9

1. the external intercostal muscles relax
2. the rib cage moves down and in
3. the diaphragm relaxes and returns to its dome shape
4. this decreases the volume of the thorax
5. this increases the pressure in the thorax
6. air is forced out by a higher pressure inside the lungs

Question 10

What happens during forced exhalation in mammals?

Answer 10

1. The internal intercostal muscles contract
2. This forces the rib cage down and in
3. The diaphragm relaxes and returns to its dome shape
4. This decreases the volume of the thorax
5. This increases the pressure in the thorax
6. Air forces out by a higher pressure inside the lungs

Question 11

Explain how the process of how air gets to where it’s neede for gaseous exchange

Answer 11

• air enters the trachea
• which splits into 2 bronchi -one bronchus leading to each lung
• each branching off into smaller tubes called bronchioles
• each bronchiole ending with alveoli
• which is where gas exchange takes place

Question 12

What are goblet cells?

Answer 12

• line airways
• secrete mucus
• the mucus traps microorganism and dust particles in the inhaled air, stopping them from reaching the alveoli

Question 13

What are cilia?

Answer 13

• they’re hair like structures on the surface of epithelial cells lining the airways
• they move the mucus (plus the trapped microorganisms) upwards away from the alveoli towards the throat where it’s swallowed
• preventing lung infections

Question 14

What’s the naval cavity?

Answer 14

A rich blood supply to the nasal cavity warms the incoming air

Question 15

Explain the internal structure of the trachea?

Answer 15

• it’s lined with C-shaped rings of cartilage, preventing the trachea from collapsing when bent
• lined with ciliated epithelium
• within the epithelium are goblet cells

Question 16

Explain the internal structure of the bronchioles?

Answer 16

• these have no cartilage
• they’re surrounded by smooth muscle
• when the smooth muscle relaxes, the bronchiole dilates so more air can enter the lungs
• when the smooth muscle contracts, the bronchiole constricts, less air enters the lungs (also preventing the enters of harmful pathogens or particles)

Question 17

What are elastic fibres?

Answer 17

• found in the walls of: trachea, bronchi, bronchioles and alveoli
• when breathing in the lungs inflate and the elastic fibres are stretched
• then the fibres recoil to help push the air out when exhaling

Question 18

What’s smooth muscle?

Answer 18

• found in the walls of: the trachea, bronchi and bronchioles (except the smallest bronchioles) allows there diameter to be controlled
• during exercise the smooth muscle relaxes, making the tubes wider
• so there’s less resistance to airflow and air can move in & out of the lungs more easily

Question 19

What’s cartilage?

Answer 19

• rings of cartilage in the walls of the trachea and bronchi provide support
• strong but flexible-stops the trachea & bronchi collapsing when you breath in and the pressure drops

Question 20

What’s found in the trachea?

Answer 20

1. large C-shaped pieces of Cartilage
2. smooth muscle
3. elastic fibres
4. goblet cells and ciliated epithelium

Question 21

What’s found in the Bronchi?

Answer 21

1. Small pieces of cartilage
2. smooth muscle
3. elastic fibres
4. goblet cells and ciliated epithelium

Question 22

What’s found in the bronchiole?

Answer 22

2. smooth muscle
3. Elastic fibres
4. Goblet cells and ciliated epithelium

Question 23

What’s found in the alveoli?

Answer 23

3. Elastic fibres

Question 24

Explain the adaptations of the alveoli?

Answer 24

-they have a wall that’s 1 cell thick made of squamous epithelium
-a dense capillary network provides a rich oxygen supply taking away blood with oxygen & replacing with deoxygenated blood, maintains the concentration gradient of oxygen
-capillaries and alveoli are situated next to each other, shooter distance for diffusion
-

Question 25

Define breathing rate

Answer 25

Number of breaths per minute

Question 26

Define tidal volume

Answer 26

Volume of air breathed in/out in each breath. This is variable, depends upon exercise

Question 27

Define ventilation rate | And what’s the formula?

Answer 27

Volume of air breathed in/put per minute | Ventilation rate = tidal volume x breathing rate

Question 28

What’s residual volume?

Answer 28

Volume of air that cannot be expelled from the lungs

Question 29

What are the adaptations of fish gills?

Answer 29

- gills have many Gill filaments - on these filaments there are many lamellae - there’s a countercurrent flow mechanism between the flow of water during ventilation and the direction of blood flow through the lamellae

Question 30

How is the concentration gradient maintained in the fish gills?

Answer 30

- blood & water flow in opposite directions, this is countercurrent flow - this ensures the concentration of O2 in the blood and in the water never reaches equilibrium - this maintains a concentration gradient over the entire length of the lamellae - ventilation causes water to flow continuously, whilst the circulation of blood removes oxygenated blood replacing it with deoxygenated blood

Question 31

Explain how ventilation occurs in a fish

Answer 31

- the mouth opens, which lowers the floor of the buccal cavity increasing the volume of the buccal cavity - this lowers the pressure in the buccal cavity and water enters - swimming forwards into water also helps water enter the buccal cavity - the constant ventilation of water over the gills ensures the gills are constantly in contract with oxygenated water

Question 32

How is oxygen transported round insects?

Answer 32

- blood is not involved - oxygen is absorbed by the muscles through diffusion directly from the air - air enters spiracles, travels through the trachea, into the tracheoles and finally oxygen is absorbed by the muscles through diffusion