8 Gas Exchange and Respiration

Question 1

Define cellular respiration

Answer 1

release of energy from the chemical bonds in food molecules

Question 2

Features of gas exchange surfaces (4)

Answer 2

Large surface area

short distance over which substances have to diffuse

a good blood supply

good ventilation to supply more oxygen and remove carbon dioxide rapidly

Question 3

Pathway air takes in human respiratory system

Answer 3

Air enters through mouth and nose —-> Passes through larynx (voicebox) —–> reaches trachea to the lungs ——–> bronchi ——> bronchioles

Question 4

Define mucus

Answer 4

Slimy liquid that traps microorganisms and dust particles that are breathed in

Question 5

Define cilia

Answer 5

tiny hairs which are found on the surface of ciliated cells

Question 6

Where are ciliated cells located in the Human respiratory system (2)

Answer 6

Bronchi

Trachea

Question 7

How does the mucus and ciliated cells help to prevent dirt and microorganisms from entering the lungs and causing damage/infection (3)

Answer 7

Mucus traps dirt and microorganisms that are breathed in

Cilia sweep in a co-ordinated motion to move the mucus up from the lungs up the trachea to the mouth

Mucus is swallowed, where the

Question 8

What are goblet cells

Answer 8

cells that secrete mucus

Question 9

Where are goblet cells located in the human respiratory system (3)

Answer 9

trachea

bronchi

bronchioles

Question 10

Where is the site of gas exchange

Answer 10

alveoli

Question 11

Features of alveoli (4)

Answer 11

thin permeable walls - keep diffusion disntace between air and blood minimum

moist lining - gases dissolve before they diffuse across the cell membranes

large surface area - process huge amounts of gas exchange

high conc gradient - because blood is continually flowing, deliving excesss carbon dioxide and taking up oxygen

Question 12

Differences in composition (oxygen, CO2, water) of inspired air and expired air

Answer 12

▮Inspired air:
oxygen - 21%
carbon dioxide 0.04%
water - variable

▮Expired air
oxygen - 16%
carbon dioxide - 4.5%
water - high

Question 13

Why does oxygen level in expired air lower than oxygen level in inspired air (2)

Answer 13

oxygen is removed from blood by respiring cells and used for cellular respiration

blood returning to the lungs has a lower concetration of oxygen than blood leaving lung

Question 14

Why is carbon dioxide level in expired air higher than carbon dioxide level in inspired air (2)

Answer 14

carbon dioxide is produced by respiration and diffuses into blood from respiring cells

blood transports the carbon dioxide to the lungs where it diffuses into the alveoli

Question 15

Why is water vapour concetration high in expired air

Answer 15

Water evaporate from the moist linings of the alveoli

Question 16

What is the relationship between the level of activity and the rate and depth of breathing + explain

Answer 16

As level of activity increases, rate and depth of breathing increases

Increased level of activity —-> muslce contract faster —–> cellular respiration increase —–> more carbon dioxide produced ——> Increase CO2 concetration detected as blood flows past receptors —–> receptors send impulses to lungs causing an increase in the rate of depth of breahting —–> CO2 is removed quicker

Question 17

Why is an increase in the CO2 concetration dangerous (3)

Answer 17

Carbon dioxide is acidic gas that disolves easily in water based solutions

The more carbon dioxide there is in solution, the more acidic the solution is

a change in pH can affect the activity of many cell enzymes

Question 18

Tabacco smoke related diseases (3)

Answer 18

Chronic obstructive pulmonary disease (bronchitis. emphysema)

lung cancer

coronary heart disease

Question 19

Toxic components of tabacco (3)

Answer 19

Carbon monoxide - takes the place of oxygen in hemoglobins and prevents the body from absorbing as much oxygen

Nicotine - addictive and narrows nlood vessels, increasing blood pressure and the risk of coronary heart disease

Tar - Sticky substance that coats the cells of trachea, bronchi, and bronchioles leading to coughing and cell damage.

Question 20

Uses of energy in human cells (6)

Answer 20

produce contraction of muscle cells

protein synthesis

Cell division and cell growth

active transport of molecules across cell membranes

To produce movement of nerve impulses

Maintenance of a constant core body temperature

Question 21

Define aerobic respiration

Answer 21

chemicalreactions in cells that use oxygen to break down nutrient molecules to release energy

Question 22

Word equation for aerobic respiraton

Answer 22

Glucose + oxygen —–> water + carbon dioxide (+energy)

Question 23

Chemical equation for aerobic respiration

Answer 23

C6H12O6 + O2 —–> H2O + CO2 + (energy)

Question 24

Define anaerobic respiration

Answer 24

chemical reactions in cells that break down nutrient molecules to release energy without using
oxygen

Question 25

Word equation for anaerobic respiration

Answer 25

glucose —-> lactic acid (+ energy)

Question 26

Define oxygen debt

Answer 26

amount of oxygen needed after vigorous exercise in order to break down the lactic acid in the muscle and liver cells produced by anaerobic respiration.

Question 27

Word equation for anaerobic respiration in yeast

Answer 27

glucose —> ethanol + carbon dioxide (+ energy)

Question 28

Describe the role of anaerobic respiration in yeast during bread-making

Answer 28

the carbon dioxide released forms bubbles in the dough, making bread light and spongy

Question 29

Aerobic respiration produces more energy per glucose than anaerobic respiration

True or False

Answer 29

True