3.1.1 exchange surfaces NOT ON MOCK

Question 1

why do multicellular organisms require specialised gas exchange surfaces

Answer 1

They’re smaller surface area to volume ratio means the distance that needs to be crossed is larger and substances cannot easily into the cells as in a single celled organism

Question 2

How is surface area to volume ratio Calculated

Answer 2

ratio equal surface area divided by volume

Question 3

Name three features of an efficient gas exchange surface

Answer 3

large surface area e.g. root hair cells

short diffusion distance e.g. alveoli

Steep concentration gradient maintained by blood supply/ventilation e.g. gills

Question 4

Describe the trachea and its function in the mammalian exchange system

Answer 4

wide tube supported by C shaped Cartlidge to keep the air passage open during pressure changes. Lined by ciliated epithelium cells which move mucus produced by goblet cells towards the throat to be swallowed preventing lung infections. Carries air the bronchi

Question 5

Describe the bronchi and their function in the gas exchange

Answer 5

Supported by rings of cartilage and aligned by ciliated epithelium cells and goblet cells. More narrower, two of them and allow passage of it into bronchioles

Question 6

Describe the bronchioles and their function in the gas exchange system

Answer 6

narrower than bronchi mostly have smooth muscle and elastic fibres so they can contract and relax easily during ventilation and allow passage of air into alveoli

Question 7

Describe the alveoli and their function

Answer 7

Mini air sacks, lined with epithelium cells, sight of gas exchange. Walls are only one cell thick and covered with capillaries which facilitate gas diffusion

Question 8

Explain the process of inspiration and the changes that occur throughout the thorax

Answer 8

External intercostal muscles contract, pulling the ribs up and out. Diaphragm contracts and flattens, volume of thorax increases and air moves in

Question 9

Explain the process of expiration

Answer 9

External intercostal muscles relax, bringing the ribs down and in, diaphragm relaxes and downs upwards and volume of the thorax decreases and air moves out

Question 10

Explain how this spirometer works

Answer 10

used to measure lung volume. Person breves into airtight chamber which leaves a trace on graph which shows volume

Question 11

Define vital capacity

Answer 11

The maximum volume of air that could be taken in or expelled for the lungs in one breath. Can be calculated from graph by finding the max amplitude

Question 12

Define tidal volume

Answer 12

The volume of air we breathe in and out during each breath at rest. Can be calculated from the graph by finding the amplitude at rest

Question 13

Define breathing rate

Answer 13

Number of breaths per minute. Can be calculated from the graph by counting the number of peaks in one minute

Question 14

Name and describe the two main features of a fish gas transport system

Answer 14

Gills: located within the body, supported by arches, along which are multiple projections of Gill filaments, which are stacked up in piles.

Lamellae At right angles to the Gill filaments, give an increased surface area. Blood and water flow across them in opposite directions counter current flow

Question 15

How does the counter current exchange system maximise oxygen absorbed by the fish

Answer 15

Maintains a steep concentration gradient as water is always next to blood of low oxygen concentration. Keeps rate of diffusion constant and enables 80% of available oxygen to be absorbed

Question 16

Name and describe the three main features of an insect gas transport system

Answer 16

spiracles: holes on the body surface which may be opened or closed by a valve for gas or water exchange
trachea: large tubes extending through all body tissues supported by rings to prevent collapse

tracheoles Smaller branches dividing of the trachea

Question 17

Explain the process of gas exchange in insects

Answer 17

Gases move in and out of the trachea through the spiracles. A diffusion gradient allows oxygen to diffuse into the body tissue while waste carbon dioxide defuses out, contraction of muscles in the trachea allows mass movement of air in and out

Question 18

ppq: Name the two types of epithelial tissue found in the lungs

Answer 18

Ciliated and squamous

Question 19

ppq: Explain how the alveoli creates a surface for efficient gas exchange

Answer 19

Wall is one cell thick for shorter diffusion distance, squamous cells provide short diffusion distance, they are elastic so recoil helps ventilation and large numbers of alveoli provide a large surface area

Question 20

ppq: List three reasons why a large multi cellular animal needs a transport system

Answer 20

Small surface area to volume ratio, diffusion pathway too long and has a high demand for oxygen