1. RESPIRATION 1
ENERGY
It is important to understand that the biological meaning of ‘Respiration’ refers to a chemical process taking place in all living cells. The function of this chemical process is to make energy available for all the cell’s activities which keep it alive.
‘Breathing’, in some cases, plays a part but ‘respiration’ to a biologist does not mean the same as ‘breathing’.

2. 3
Respiration is the burning or combustion of organic molecules to release energy.

3. 6 CO2 oxygen energy release source of carbon source of carbon
Coal and wood are the carbon sources. The carbon dioxide goes up the chimney.
oxygen
source of carbon
source of carbon

4. The chemical reactions of respiration take place in all living cells7
The chemical reactions of respiration take place
in all living cells
The reaction takes place between oxygen and a
substance which contains carbon. The reaction
produces carbon dioxide and water, and releases
energy.
The word ‘respiration’ is used in everyday language to mean breathing; as in,for example, ‘respiration rate’ (breathing rate) or ‘artificial respiration’. In biology, it is best to avoid confusion by using the term ‘respiration’ for the chemical reaction in cells. ‘Artificial respiration’, is better described as ‘resuscitation’.

5. The carbon-containing substances come from FOOD 8
The carbon-containing substances come from FOOD
The oxygen comes from the AIR (or water)
The energy is used to drive other chemical reactions taking place in cells
One example of this is the release of energy in muscle cells to make them contract and produce movement
Organisms living in water absorb oxygen from it. But it is not the O of H2O that they use. The oxygen which they can use is dissolved in the water and comes, originally, from the air.

6. 9
One example of an energy-producing reaction in cells is the breakdown of sugar when it combines with oxygen
This can be represented by the equation
C6H12O O2
6CO H2O +
energy
sugar (glucose)
oxygen
carbon dioxide
water
This means that one molecule of sugar reacts with six molecules of oxygen to produce six molecules of carbon dioxide and six molecules of water Energy is released during this process
The carbon-containing substance in this case, is glucose (C6H12O6) but all food contains some carbon.
Although the reaction is shown as if it takes place in one step, there are many more intermediate changes and the energy is released in stages,
The progress of each step in controlled by chemicals called enzymes which are the subject of a separate presentation

7. Some examples of the use of energy in organisms10
Some examples of the use
of energy in organisms
muscle
contraction
Respiration
supplies
the energy for
germination
chemical changes in cells
cell division
These are only a few examples. Every living process in living organisms needs energy from respiration

8. Energy use in muscle contraction11
shoulder blade
The blood stream brings food and oxygen to the muscle cells. Respiration occurs in the cells and releases energy which……
upper arm
bone
The drawing represents the human arm bones with two of the muscles which produce movement (biceps and triceps)
lower arm bones

9. …….makes the muscle contract12
…….makes the muscle contract
and pull the lower
arm up

10. food store 13
(a)
(c)
(b)
shoot
embryo
shoot
embryo
root
(a) is a section cut through the
length of a maize seedling. Areas
of rapid respiration are stained pink.
(b) and (c) are drawings of the seed
and the seedling that grows from it.
Can you suggest reasons why respiration should be so rapid in the stained regions?
root
root

11. Answer The most intensely stained areas are in the root tip and the14
Answer
The most intensely stained areas are in the root tip and the
shoot tip. These are regions where very rapid cell division is taking place to produce growth. Making new cells and new cytoplasm takes a great deal of energy.
You might also have noticed that, in the root, there are two
faint streaks of pink. These occur in the conducting tissue of
the seedling. Energy is needed to transport food from the
food store to the growing region.

12. One example of respiration in ourselves15
One example of respiration in ourselves
2. The lungs absorb oxygen
from the air
1. Air taken in
1.Food taken in
2.The stomach and
intestine digest food.
One of the products
is glucose
3.The blood stream
carries glucose and oxygen to the muscles
Glucose and oxygen react to produce energy for muscle contraction
4 RESPIRATION
The water produced as a waste product of respiration is picked up by the blood stream and may be lost in sweat, water vapour from the lungs or in urine
5 Carbon dioxide
is carried to the lungs
by the blood

13. 17
Question 2
In which part of the human body is respiration most likely to be occurring?
(a) The lungs
(b) The heart
(c) The muscles
(d) All of these
Respiration will be occurring in all parts of the human body that consists of living cells.
Fingernails, toenails and hair do not contain living cells and so will not be respiring

14. Question 3 Which of these are waste products of respiration?18
Question 3
Which of these are waste products of respiration?
(a) Carbon dioxide
(b) Water
(c) Oxygen
(d) Nitrogen

15. 19
Question 4
Which of the following would be reliable indicators of respiration in a living organism?
(a) Output of water vapour (H2O)
(b) Output of carbon dioxide (CO2)
(c) Uptake of oxygen (O2)
(d) Production of energy
Any wet or damp non-living material (e.g. a line full of washing) will be releasing water vapour.

16. Question 5 Which of the following statements are correct?20
Question 5
Which of the following statements are correct?
(a) We breathe in air
(b) We breathe in oxygen
(c) We breathe out air
(d) We breathe out carbon dioxide
Air is a mixture of nitrogen, oxygen, carbon dioxide and a small proportion of other gases. We cannot selectively breathe in only oxygen and breathe out only carbon dioxide. The lungs absorb oxygen from the air we breathe in and give out carbon dioxide. So the air we breathe out contains less oxygen and more carbon dioxide than the air we breathe in.

17. 21
Answer
Correct

18. 22
Answer
Incorrect

19. Anaerobic Respiration23
Anaerobic respiration is involved at some stage in the preparation of these foodstuffs

20. 24
The process of respiration described so far has been defined as the release of energy when foodstuffs such as glucose react with oxygen to produce carbon dioxide and water.
This form of respiration, which needs oxygen, is called aerobic respiration.
There is another form of respiration which does not need oxygen and is called anaerobic respiration.
In anaerobic respiration, glucose is still broken down to carbon dioxide with the release of energy, but without the involvement of oxygen
The glucose is not completely broken down to CO2 and H2O but to CO2 and alcohol (ethanol).

21. 25
Anaerobic respiration can be represented by the equation
C6H12O C2H5OH CO2
glucose alcohol
energy
The energy released by anaerobic respiration is considerably
less than the energy from aerobic respiration.
Anaerobic respiration takes place at some stage in the cells
of most living organisms.
For example, our own muscles resort to anaerobic respiration when oxygen is not delivered to them fast enough.

22. Micro-organisms 26
Anaerobic respiration is widely used by many micro-organisms
such as bacteria and yeasts.
Bacteria and yeasts are microscopic single-celled organisms.
Bacteria are to be found everywhere, in or on organisms,
in water, air and soil
Yeasts are usually found in close association with vegetable matter such as fruit

23. Bacteria a single bacterium 27 cell wall there are many
species of bacteria
and they have different
shapes and sizes
nucleus
cytoplasm
0.002mm
The vast majority of bacteria are harmless. Some are beneficial, such as those which bring about decay of dead remains. A very small proportion are harmful and cause disease in animals and plants.
a single bacterium

24. Aerobic and anaerobic bacteria28
Aerobic and anaerobic bacteria
Bacteria which need oxygen in order to respire are called
aerobic bacteria.
Aerobic bacteria are likely to be found in the air, water
and soil where oxygen is available
Bacteria which can respire without needing oxygen are
called anaerobic bacteria
Some bacteria can use both aerobic or anaerobic respiration according to the availability of oxygen, There are some anaerobic bacteria which cannot survive in the presence of oxygen.
Anaerobic bacteria are to be found in situations where
oxygen is lacking, such as in stagnant water, waterlogged
soils or the intestines of animals

25. 30
Fermentation
One form of anaerobic respiration in bacteria and yeasts
is called fermentation.
During fermentation, sugar is broken down to alcohol and
carbon dioxide
The reaction described in slide 25 is an example
of fermentation
Fermentation is involved in brewing and wine-making

26. Yeasts 29 cell wall nucleus cytoplasm 0.005mm vacuole
Yeast cells dividing
0.005mm
vacuole
Yeasts can be seen as a thin, greyish ‘bloom’ on the surface of grapes, but they are present on the surface of most fruits. When these fruits are crushed and mixed with water, the anaerobic respiration of the yeasts causes fermentation with the production of carbon dioxide and alcohol.
single yeast cell

27. 31
Wine making
Grapes are crushed and the sugar they contain is fermented
by yeasts to produce alcohol and carbon dioxide.
The carbon dioxide usually escapes but if the wine is
bottled before fermentation is complete, the carbon dioxide
dissolves and escapes as bubble when the bottle is opened
This is the case with ‘sparkling’ wines such as Champagne
Different varieties of grape produce different types of wine

28. Black grapes growing in a vineyard32
Black grapes growing in a vineyard
© Ilan’s Wine Making

29. 33
Brewing
In brewing beer, a sugary product (malt) is dissolved out of germinating barley
Yeast is added to this solution and fermentation begins, producing alcohol and carbon dioxide
Some of the carbon dioxide escapes but the rest dissolves in the beer when it is bottled or put into casks
When the bottles or casks are opened, the dissolved CO2 escapes as bubbles

30. Beer fermenting 34 ©Stuart Boreham/CEPHAS
The carbon dioxide bubbles plus some of the beer constituents produce a dense froth on top of the beer. The fermentation vessel is an old-fashioned open type.
©Stuart Boreham/CEPHAS

31. Baking 35 In baking, yeast is added to a mixture of flour and water,
made into the form of a dough
The yeast first changes the flour starch into sugar and then
ferments the sugar into alcohol and CO2
The CO2 forms bubbles in the dough which cause it to
expand (‘rise’)
When the dough is baked, the heat evaporates the
alcohol but makes the trapped bubbles expand giving the
bread a ‘light’ texture

32. Dough rising 36 The yeast is mixed with the dough
After 1 hour in a warm
place the dough has risen as a result of the carbon dioxide
produced by the yeast

33. 37
The ‘holes’ in the
bread are made by
the carbon dioxide
bubbles.
This gives the bread a ‘light’ texture

34. Question 1 Which statements are correct ?38
Which statements are correct ?
Anaerobic respiration is different from aerobic
respiration because
a it produces CO2
b it does not need glucose
c it does not need oxygen
d it produces less energy

35. Question 2 In what circumstances do our muscle use anaerobic39
In what circumstances do our muscle use anaerobic
respiration ?
a When insufficient glucose reaches the
muscles
b When the carbon dioxide level increases
c When insufficient oxygen reaches the
d When we are asleep

36. Question 3 Anaerobic bacteria are most likely to be found40
Question 3
Anaerobic bacteria are most likely to be found
a in the middle of a compost heap
b in the air
c in fast-flowing streams
d on the surface of the skin

37. Question 4 In which of the following is the production of CO241
Question 4
In which of the following is the production of CO2
more important than the production of alcohol ?
a Brewing beer
b Fermenting grape juice
c Making bread
d Bottling wine

38. 42
Answer
Incorrect

39. 43
Answer
Correct