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Biology IGCSE > Energy for Life > Flashcards

Energy for Life Flashcards

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1
Q

Word equation for aerobic respiration

A

glucose + oxygen –> carbon dioxide + water

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2
Q

What type of energy is released in aerobic repsiration?

A

Most: ATP
Some: Heat

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3
Q

Balanced symbol equation for aerobic respiration

A

C6 H12 O6 + 6O2 → 6CO2 + 6H2O

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4
Q

What happens in anaerobic respiration?

A

Glucose is not completely broken down and so less ATP is produced and therefore less energy is released.

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5
Q

Anaerobic respiration in fungi and plants word equation

A

Glucose –> Ethanol + Carbon dioxide

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6
Q

Anaerobic respiration in animals word equation

A

Glucose –> Lactic acid

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7
Q

Why do we keep breathing heavily after exercise?

A

To supply the extra oxygen needed to dispose of the lactic acid in our bodies. (oxygen debt).

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8
Q

When does anaerobic respiration occur?

A

Occurs in muscle cells, when there is a shortage of oxygen (often during intensive exercise). If muscles are worked very hard they need large quantities of energy,
more than can be provided by aerobic respiration. The glycogen stored in muscle cells is
broken down into glucose. This is respired anaerobically, providing an additional energy
supply.

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9
Q

What is oxygen debt?

A

The volume of oxygen needed to oxidise the lactic acid.

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10
Q

Explain the ‘germinating peas’ experiment.

A

As the peas start to grow they respire,
releasing heat. The thermos flask is
insulated, so heat is not transferred to
the surroundings and we can measure
the change in temperature. The flask with boiled peas remains at room temperature because the peas are dead and they don’t respire.

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11
Q

Why do we cover the peas in Milton solution (bleach)?

A

To kill bacteria. Bacteria would respire and affect the results.

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12
Q

How could we show that the flask with alive peas (A) is respiring aerobically?

A

We could also use gas delivery tubes to collect any gas produced. The gas can then be
bubbled through limewater. The gas from flask A only would turn the limewater
cloudy - this shows that carbon dioxide is produced.

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13
Q

What does it mean when the hydrogen carbonate indicator turn yellow?

A

High levels of C02

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14
Q

What does it mean when the hydrogen carbonate indicator turn orange/red?

A

Normal atmospheric level of CO2

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15
Q

What does it mean when the hydrogen carbonate indicator turns purple?

A

Low levels of CO2

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16
Q

What is the control experiment with the hydrogen carbonate solution? Why?

A

A test tube with no insect which allows us to see if the indicator turns yellow without CO2.

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17
Q

What causes the test tube with the insect to turn the hydrogen carbonate indicator yellow?

A

The insect respires aerobically and produces CO2.

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18
Q

What could also be used to test for CO2 rather than hydrogen carbonate indicator?

A

Limewater (turns cloudy white when bubbled through CO2).

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19
Q

Describe questions

A

Describe - say what the results are
(pattern, comparison between experiment
and control, quote data)

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20
Q

Explain questions

A

Explain - say why the results occur
(use your scientific knowledge!)

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21
Q

Evaluation of Germinating Seeds (measuring temp) experiment (CORMS)

A

Change - We will change the content of the flasks (germinating seeds or dead seeds)
Organisms - The seeds used should all be of the same age, size and species
Repeat - We will repeat the investigation several times to ensure our results are reliable
Measurement 1 - We will observe the change in the temperature on the thermometer
Measurement 2 - …after 4 days
Same - We will control the number of seeds, the starting temperature of the flasks, the material and size of the flasks

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22
Q

Evaluation of Hydrogen Carbonate experiment (CORMS)

A

Change - We will change the content of the boiling tube (germinating seeds, dead seeds or glass beads)
Organisms - The seeds used should all be of the same age, size and species
Repeat - We will repeat the investigation several times to ensure our results are reliable
Measurement 1 - We will observe the change in the hydrogen carbonate indicator
Measurement 2 - …after 3 hours
Same - We will control the volume of hydrogen carbonate indicator, the number of seeds/beads, the temperature of the environment

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23
Q

Definition of diffusion

A

Diffusion is the random movement of particles/molecules from an area of high concentration to an area of lower concentration.

24
Q

How does the layer of oil affect the respiration of the yeast suspension?

A

The layer of oil prevents air entering the yeast suspension, this means no oxygen reaches the yeast so only anaerobic respiration can take place.

25
Q

What is the dependant variable(s) of the yeast suspension experiment?

A

The time taken for the limewater to become cloudy.
Alternatively, you could connect the delivery tube to a gas syringe, to measure the
volume of carbon dioxide produced.

26
Q

What are the main factors affecting the rate of diffusion?

A

Temperature, Concentration gradient, Distance, Surface area, Surface area to volume ratio.

27
Q

How does temperature affect the rate of diffusion?

A

At higher temperatures, molecules have more kinetic energy and so move faster.
Therefore diffusion occurs faster.

28
Q

How does concentration gradient affect the rate of diffusion?

A

If there is a very large difference in concentration between two areas,
molecules will diffuse from the higher to the lower concentration quickly. If the concentration gradient is small, diffusion will happen more slowly.

29
Q

How does distance affect the rate of diffusion?

A

Diffusion takes longer if the molecules have to travel further, this is why cells are small.

30
Q

How does surface area affect the rate of diffusion?

A

A larger surface area speeds up the rate of diffusion as there are more opportunities for the molecules to move, which is why surfaces such as alveoli in lungs are so large.

31
Q

How does surface area to volume ratio affect the rate of diffusion?

A

An efficient exchange surface has a surface area which is very large compared to the distance the
molecules must travel. SA:V is increased when structures are small.

32
Q

What is equilibrium?

A

When the molecules are evenly spread out.

33
Q

Inhalation

A

Diaphragm contracts-moves down
Intercostal muscles contract, moving rib cage up and
out.
Volume of thorax increases
and air pressure decreases.
Air pressure in the thorax is now lower than
atmospheric pressure, causing air to move into the
lungs.

34
Q

Exhalation

A

Diaphragm relaxes, moving up.
Intercostal muscles relax, moving rib cage down and
in.
Volume in thorax decreases, air pressure increases.
Air pressure in the thorax is now higher than
atmospheric pressure, causing air to be forced out of the
lungs.

35
Q

Journey of oxygen through the body

A

Mouth, trachea, bronchus, bronchioles, alveoli, capillary, red blood cell (haemoglobin)

36
Q

Gas Exchange

A

Oxygen diffuses from the air into the red blood cells, where it binds with the haemoglobin for transport. Carbon
dioxide, dissolved in the plasma,
diffuses from the blood into the
alveolus. Oxygen in, Carbon Dioxide out.

37
Q

How is the alveoli adapted for gas exchange? (Large Surface area)

A

Many alveoli–> Large Surface Area –> Increases rate of diffusion

38
Q

How is the alveoli adapted for gas exchange? (Distance)

A

Walls of the alveoli and capillary are each are only one cell thick–> Short diffusion distance (gases don’t need to travel far)–> Speeds up diffusion.

39
Q

How is the alveoli adapted for gas exchange? (Concentration gradient)

A

Each alveolus surrounded by a network of capillaries–> Good blood supply–> Steep concentration gradient for CO2 and O2–> Increases rate of diffusion.

40
Q

Why does Breathing rate increase during exercise?

A

Because our breathing rate increases, we excrete carbon dioxide more rapidly. Oxygen can also diffuse into the blood at a faster rate (as there is a higher concentration gradient). This, along with an increase
in heart rate, supplies more oxygen to the muscles for aerobic respiration. The breathing rate and volume of each breath increases to bring more oxygen into the body and remove the carbon dioxide produced

41
Q

How does Carbon Monoxide affect respiration?

A

Binds to haemoglobin in red blood cells, reduces amount of oxygen transported by blood.

42
Q

How do cilia and goblet cells prevent lung infections?

A

Goblet cells produce mucus which traps dust and pathogens. The cilia move and transport the mucus up the airways.

43
Q

Explain how bronchitis develops

A

Chemicals in tobacco smoke destroy cilia, reducing their number. At the same time mucus
production will increase; this is in response to the smoke. The mucus cannot be moved out
of the airways quickly and so builds up. Bronchitis is a disease resulting from the build-up of infected mucus in the
bronchi and bronchioles.

44
Q

Emphysema

A

Alveoli are damaged and become deformed, this reduces their surface area for gas exchange so less oxygen diffuses into the blood.

45
Q

Definition of Breathing.

A

Movement of air to and from the lungs.

46
Q

Definition of respiration.

A

Chemical process of releasing energy from glucose.

47
Q

Reasons for why the body needs energy.

A

Maintaining constant internal temperature.
Chemical reactions to build larger molecules.
Movement (contracting muscles)
Absorbing digested food from small intestine to blood.

48
Q

Function of the alveoli

A

Tiny air sacs, site of gas exchange.

49
Q

Function of ribs.

A

The ribs help to protect the organs in the thorax.

50
Q

Function of trachea.

A

Windpipe that connects nose and mouth to the lungs. C-shaped rings of cartilage.

51
Q

Function of intercostal muscles.

A

Muscles found between the ribs, moves ribs causing exhalation and inhalation.

52
Q

Function of Bronchi.

A

Large tubes branching off from trachea. One bronchus per lung. Also have cartilage rings.

53
Q

Function of Bronchioles.

A

Bronchi split and form these. Connected to alveoli and carry air deeper into the lungs.

54
Q

Function of diaphragm.

A

Sheet of tissue and muscle at bottom of thorax. Changes volume of thorax to allow inhalation and exhalation.

55
Q

Function of pleural cavity.

A

Fluid filled space between pleural membranes which reduces friction and allows lungs to move easliy.

56
Q

Analysis of breathing rate during exercise.

A

Frequency of breathing increases when exercising
This is because muscles are working harder and aerobically respiring more and they need more oxygen to be delivered to them (and carbon dioxide removed) to keep up with the energy demand
If they cannot meet the energy demand they will also respire anaerobically, producing lactic acid

57
Q

Analysis of breathing rate after exercise.

A

After exercise has finished, the breathing rate remained elevated for a period of time
Lactic acid built up in muscles needs to be removed as it lowers the pH of cells and can denature enzymes catalysing cell reactions
It can only be removed by combining it with oxygen - this is known as ‘repaying the oxygen debt’
This can be tested by seeing how long it takes after exercise for the breathing rate to return to normal
The longer it takes, the more lactic acid produced during exercise and the greater the oxygen debt that needs to be repaid

Biology IGCSE (15 decks)

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