2 Respiration + Gas Exchange

Question 1

What is respiration?

Answer 1

the process of transferring energy from glucose, which happens constantly in every living cell

Question 2

How is energy transferred by respiration?

Answer 2

Used to make ATP which stores the energy needed for many cell processes

Question 3

What is ATP?

Answer 3

adenosine triphosphate, releases energy quickly

Question 4

How is ATP used?

Answer 4

ATP molecules are broken down and energy is released.

Question 5

What is the word and chemical equation for aerobic respiration?

Answer 5

glucose + oxygen -> carbon dioxide + water ( + energy)
C₆H₁₂O₆ + 6O₂ -> 6CO₂ + 6H₂O

Question 6

How many molecules of ATP are produced during aerobic respiration?

Answer 6

32 molecules per molecule of glucose
(most efficient way to transfer energy from glucose)

Question 7

What is the word equation for anaerobic respiration in animals?

Answer 7

glucose -> lactic acid (+energy)

Question 8

Why do we anaerobically respire?

Answer 8

doing vigorous exercise means your body can’t supply enough oxygen to working muscles for aerobic respiration. Instead muscles respire without oxygen

Question 9

How many molecules of ATP are produced during anaerobic respiration?

Answer 9

2 molecules per glucose molecule

Question 10

What happens when lactic acid is produced?

Answer 10

glucose is only partially broken down and lactic acid is produced which builds up in muscles - painful and leads to cramp

Question 11

How is lactic acid removed?

Answer 11

by blood flowing through muscles

Question 12

What is the word equation for anaerobic respiration in plants?

Answer 12

glucose -> ethanol + carbon dioxide (+ energy)

Question 13

What are the differences between aerobic and anaerobic respiration?

Answer 13

aerobic = with oxygen, releases more energy but slowly
anaerobic = without oxygen, releases less energy but quicker

Question 14

PAPER 2 What is the role of diffusion in gas exchange in a leaf?

Answer 14

carbon dioxide diffuses into leaf through stomata while oxygen diffuses out of leaf through stomata

Question 15

PAPER 2 How are leaves adapted for gas exchange?

Answer 15

Leaves are broad - large SA for diffusion, increasing number of stomata, carbon dioxide diffuses quicker
Stomata allow gases to diffuse in and out of air spaces of leaf, provides short diffusion to mesophyll cells
Guard cells change shape to alter size of stomata
Thin - gases travel a short distance
Air spaces inside leaf - lets gases move easily between cells. Increases SA for gas exchange
Stomata close to reduce water loss and gas exchange

Question 16

PAPER 2 What is the role of the stomata in gas exchange?

Answer 16

Stomata close as it gets dark. Photosynthesis cant happen in dark, so don’t need to be open to let in CO₂
water can’t escape when closed, stops plant drying out
Opening and closing is controlled by guard cells. do this by changing their shape and volume (increase in volume to open up, decrease to close)

Question 17

PAPER 2 Why is photosynthesis faster than respiration during the day?

Answer 17

higher light intensities - net uptake of carbon dioxide and net release of oxygen. Oxygen secreted from leaves

Question 18

PAPER 2 Why is respiration faster than photosynthesis during the night?

Answer 18

low light intensities - net uptake of oxygen and net release of carbon dioxide. Carbon dioxide is secreted from leaves

Question 19

PAPER 2 What does it mean if photosynthesis is faster than respiration?

Answer 19

oxygen is excreted from leaves

Question 20

PAPER 2 What does it mean if respiration is faster than photosynthesis?

Answer 20

carbon dioxide is excreted from leaves

Question 21

PAPER 2 What does it mean if photosynthesis and respiration occur at the same rate?

Answer 21

no net gas exchange

Question 22

PAPER 2 Describe the investigation of how light affects gas exchange from a leaf?

Answer 22

Privet leaves placed in 3 boiling tubes containing 2cm³ of sodium hydrogen carbonate indicator (red/orange)
One tube in bright light, one wrapped in foil, one wrapped in tissue paper (weak light)
Place a dead privet leaf in test tube in bright light
Tubes left for 40 mins

Question 23

PAPER 2 What are the expected results of the investigation on how light effects leaves?

Answer 23

Leaf with aluminium cover: yellow,
respiration > photosynthesis
CO₂ > O₂
Leaf with tissue: red,
respiration = photosynthesis
Leaf with no cover: purple,
respiration < photosynthesis
CO₂ < O₂
Dead leaf: red,
no living cells

Question 24

Describe the structure of the thorax

Answer 24

Trachea
Bronchi
Bronchioles
Rib
Intercostal muscles
alveoli
diaphragm
pleural membrane

Question 25

Describe the trachea

Answer 25

When we breathe, air passes down
Surrounded by c-shaped cartilage
Keeps trachea open and makes swallowing easier

Question 26

Describe the bronchi

Answer 26

Lead to lungs
Also surrounded by cartilage rings

Question 27

Describe the bronchioles

Answer 27

carry air deep into thorax

Question 28

What happens at the alveoli?

Answer 28

microscopic air sacs
site of gas exchange

Question 29

what are the lungs surrounded by?

Answer 29

pleural membrane

Question 30

What is the pleural membrane?

Answer 30

forms a double layer between lungs and thorax walls.
Thin layer between membranes of pleural fluid.
Together form air tight seal and prevent lungs from sticking to thorax wall as they inflate and deflate

Question 31

What do the ribs do?

Answer 31

Help protect organs in thorax

Question 32

What do the intercostal muscles do?

Answer 32

between ribs help to connect bones and important in moving air into and out of lungs

Question 33

Describe the diaphragm

Answer 33

Separates organs of thorax and abdomen
domed sheet of muscle and fibrous tissue
important in moving air into and out of lungs

Question 34

What is ventilation?

Answer 34

the process of moving air into and out of the lungs
moving air relies on differences in air pressure between lungs and atmosphere

Question 35

What happens to the thorax during inhalation?

Answer 35

diaphragm contracts, moving down and flattening.
Intercostal muscles contract, moving rib cage up and out
Causes volume of thorax to increase and air pressure to decrease
causes air to move into lungs as air pressure in thorax is less than atmospheric pressure

Question 36

What happens to the thorax during exhalation?

Answer 36

Diaphragm relaxes, moving up and doming
Intercostal muscles relax, moving rib cage down and in
causes volume to decrease and air pressure increase
air pressure more than atmospheric pressure so air moves out of lungs

Question 37

How do oxygen and carbon dioxide diffuse in and out of the alveoli?

Answer 37

oxygen diffuses into red blood cells and binds to haemoglobin for transport
carbon dioxide, dissolved in plasma, diffuses from blood into alveolus

Question 38

How are alveoli adapated for gas exchange?

Answer 38

large surface area - lots of alveoli increases rate
capillaries - surrounded by network, which constantly carry deoxygenated blood to alveolus and move oxygenated blood away - maintains high concentration gradient
short distance - walls one (flattened) cell thick

Question 39

Describe an investigation that compares the content of inhaled and exhaled air

Answer 39

T-tube arrangement going from mouthpiece to two boiling tubes
student breathes in and out
limewater:
inhaled = stays colourless
exhaled = turns milky white

Question 40

How do you investigate the effect of exercise on breathing?

Answer 40

Counting number of breaths someone takes in 1 minute at rest
then exercise e.g. jog on spot for 5 minutes
count number of breaths taken in first min after exercise
valid conclusion = investigate lots of people
Control variables: age, gender, fitness, type of exercise, length of exercise

Question 41

Why does breathing rate increase during exercise?

Answer 41

breathing and depth increases in response to increase in concentration of carbon dioxide in blood

Question 42

What happens as breathing rate increases?

Answer 42

We excrete carbon dioxide more rapidly.
Oxygen diffuses into blood faster rate
Increase heart rate
All supplies more oxygen to muscles for aerobic respiration

Question 43

What happens if we anaerobically respire during exercise?

Answer 43

breathing rate remains high to supply extra oxygen to oxidise lactic acid

Question 44

What is the highly addictive drug present in tobacco smoke?

Answer 44

Nicotine - many treatments contain nicotine to gradually reduce intake without exposure to other harmful chemicals

Question 45

What are carcinogens?

Answer 45

chemicals in tobacco smoke which can alter DNA and increase risk of cancer

Question 46

What is an example of a carcinogen?

Answer 46

tar

Question 47

What does carbon monoxide do?

Answer 47

found in tobacco smoke
irreversibly binds to haemoglobin, forming carboxyhaemoglobin, reducing amount of oxygen transported by blood

Question 48

What happens if a pregnant women smokes?

Answer 48

baby will receive less oxygen, resulting in weighing less at birth which can lead to other problems

Question 49

How are healthy lungs specialised to prevent dirt and bacteria entering lungs?

Answer 49

Goblet cells produce mucus, which traps dust and pathogens
Cilia on lining of cells move, transporting mucus up airways

Question 50

How do the lining of trachea and bronchi change from tobacco smoke?

Answer 50

chemicals destroy cili, reducing their number
Mucus production increases in response to smoke
mucus cannot be removed out of airways and quickly builds up
causes smokers cough and increases risk of infection

Question 51

What is Bronchitis

Answer 51

the disease resulting from build-up of infected mucus in bronchi and bronchioles?

Question 52

How does smoke affect the alveoli?h

Answer 52

alveoli walls break down in places and fuse together, forming larger irregular air spaces.
Decreases surface area for gas exchange, so less oxygen diffuses into blood
Disease called emphysema