Gas Exchange, Respiration and Movement of Substances

Question 1

What is diffusion?

Answer 1

The net movement of particles from an area of high concentration to an area of low concentration (down the concentration gradient)

Question 2

What increases the rate of diffusion?

Answer 2

1) steeper concentration gradient
2) higher temperature
3) larger surface area to volume ratio

Question 3

What is osmosis?

Answer 3

The net movement of water from an area of high concentration of water to an area of low concentration of water across a partially permeable membrane

Question 4

What is the pressure within a plant cell that keeps it turgid?

Answer 4

Turgour pressure

Question 5

What is a cell described as when it loses water due to osmosis?

Answer 5

Flaccid

Question 6

What has happened to a cell when it becomes plasmolysed?

Answer 6

When the cell shrinks so much that the membrane and cytoplasm split away from the cell wall

Question 7

What is active transport?

Answer 7

The movement of particles against the concentration gradient using energy from respiration

Question 8

Describe a demonstration to illustrate diffusion

Answer 8

1) prepare petri dish with 2cm of agar jelly dyed purple with potassium permanganate
2) cut three cubes of different sizes out of the jelly with side lengths 2cm, 1cm and 0.5cm
3) drop cubes into a beaker of dilute hydrochloric acid
4) record the time taken for each cube to turn colourless

Question 9

Describe an experiment to show osmosis occurring

Answer 9

1) fill one boiling tube with tap water and fill a second with concentrated sucrose solution leaving the third tube empty
2) cut a potato into 3 pieces measuring 5cm x 1cm x 1cm
3) blot each chip to remove excess moisture and weigh in a balance
4) after 30 minutes remove from the boiling tube and blot
5) weight the chips on the balance and calculate the percentage change in mass

Question 10

what is respiration?

Answer 10

Breaking down small food molecules in order to release their stored chemical energy

Question 11

What is the chemical equation for cellular respiration?

Answer 11

C6H12O6 + 6O2 —> 6CO2 + 6H2O

Question 12

What is the equation for anaerobic respiration in yeast cells?

Answer 12

Glucose —> ethanol + carbon dioxide

Question 13

What is the equation for anaerobic respiration in animal cells?

Answer 13

Glucose —> lactic acid

Question 14

What is the oxygen debt?

Answer 14

The extra oxygen needed to break down lactic acid which has built up during anaerobic respiration

Question 15

What happens when you breathe in?

Answer 15

1) external intercostal muscles contract pulling ribs up
2) internal intercostal muscles relax
3) muscles of diaphragm contract pulling the diaphragm down
4) this increases the volume and hence decreases the pressure so air is sucked in

Question 16

How are alveoli adapted for gas exchange?

Answer 16

1) large surface area
2) wall is only one cell thick
3) rich blood supply
4) thin layer of fluid lining the alveolus for the oxygen to dissolve in before it diffuses into the blood

Question 17

What happens if someone has bronchitis?

Answer 17

1) cilia are destroyed by the chemicals in the smoke
2) due to the reduced number of cilia mucus is not swept away from the lungs but remains, clogging up the passages
3) this irritates the bronchial tree and may cause infections from the bacteria in the mucus, blocking the normal air flow

Question 18

What happens when someone has emphysema?

Answer 18

1) smoke damages the walls of the alveoli causing them to break down and fuse together
2) this greatly reduces the surface area for gas exchange making gas exchange inefficient
3) therefore the blood of a person with emphysema carries less oxygen

Question 19

How does smoking cause cancer?

Answer 19

1) tar contains lots of carcinogenic chemicals which cause lung cancer
2) cells in the lung mutate and start to divide uncontrollably forming a Timor

Question 20

How is carbon monoxide harmful?

Answer 20

1) bonds more strongly with haemoglobin than oxygen forming carboxyhaemolglobin
2) this inhibits the ability of the blood to carry oxygen around the body

Question 21

Describe an investigation into the affect of exercise on breathing rate

Answer 21

1) count the number of breaths of someone who has been resting for 5 minutes
2) repeat every minute until the value for resting rate is stable
3) person runs on treadmill for 3 minutes
4) record subjects breaths per minute every minute until it returns to resting rate
5) repeat with different durations of running on the treadmill

Question 22

How can the reliability of results in an investigation be increased?

Answer 22

1) use more than one organism
2) calculate an average
3) ignore anonymous results

Question 23

What is the trachea?

Answer 23

Wind pipe which is enclosed by rings of cartel lodge to keep the tube open

Question 24

What do the bronchi do?

Answer 24

Carry air to the lungs

Question 25

What do the bronchioles do?

Answer 25

Carry air from the bronchus to the alveoli

Question 26

What do the pleural membranes do?

Answer 26

Form airtight seal around lungs and separate inside of the thorax from lungs

Question 27

describe a demonstration to show the production of carbon dioxide by living organisms

Answer 27

1) Place hydrogen carbonate indicator in boiling tube
2) Place small organisms (e.g woodlice or germinating seeds) on gauze platform above the hydrogencarbonate indicator in order to stop them coming into contact with it
3) Place a bung on the boiling tube
4) Leave for one hour
5) Record colour of hydrogencarbonate indicator

Question 28

describe an experiment to show that heat is produced by respiration

Answer 28

1) Soak 100g of peas in water for 24 hours so they start to germinate
2) Boil a second batch of 100g to kill the peas
3) Wash each set of peas in 1% bleach solution in order to steralise them and kill any bacteria present
4) Rinse peas twice in distilled water to remove any traces of bleach
5) Place each set of peas in an inverted vacuum flask leaving some air in each flask
6) Place thermometer at base of each inverted vacuum flask, securing it with cotton wool
7) Record initial temperature
8) Leave for 5 hours and record temperature

Question 29

what does the net exchange of carbon dioxide and oxygen depend on in a plant?

Answer 29

the intensity of light as this determines the rate of photosynthesis (respiration is occurring all the time)

Question 30

describe an experiment to investigate the effect of light on the net gas exchange of a leaf

Answer 30

1) Put 10cm3 of indicator solution in the base of 4 boiling tubes and place 3 large leaves in 3 of the boiling tubes
2) Seal each tube with a bung (one without the leaf is the control)
3) For the tubes containing a leaf, cover one with silver foil (so its in the dark), cover one with translucent material (so the light intensity is limited), and place one in bright light
4) After 3 hours, check the colour of the indicator (leaf in light = purple and leaf in dark = yellow)

Question 31

what are the causes of emphysema?

Answer 31

1) smoking
2) dust
3) fumes
4) genetic
5) bronchitis

Question 32

suggest how damage to the air sacs can cause breathlessness

Answer 32

1) less surface area
2) diffusion/gas exchange
3) insufficient oxygen

Question 33

describe the biological consequences of cigarette smoking on the human lungs

Answer 33

1) emphysema
2) less surface area/damage to alveoli
3) bronchitis
4) bacteria/infection;
5) cilia damaged
6) more mucus/build up of mucus
7) cancer/carcinogens
8) tar