energy

RESPIRATION

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All living cells are made up of chemical substances The processes of living involve reactions between the substances A reaction is an event which produces a change in a substance For example, a reaction between carbon and oxygen (such as burning coal in air) changes the carbon in the coal, and oxygen in the air into carbon dioxide
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This reaction can be represented by the equation
C + O2
CO2
carbon
oxygen
carbon dioxide


C
o
o
an atom of carbon c
a molecule of oxygen O2
combine to form a molecule of carbon dioxide CO2
plus
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The reaction between carbon and oxygen also releases energy in the form of heat and light (flames) Living organisms get their energy from reactions like this (but not reactions which are violent enough to produce flames)
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One of the energy-producing reactions is called respiration
(Respiration is not the same thing as breathing)
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 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
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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
C6H12O6 + 6O2
6CO2 + 6H2O +
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

Respiration supplies the energy for

muscle contraction
germination
cell division
chemical changes in cells
Some examples of the use of energy in organisms
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The blood stream brings food and oxygen to the muscle cells. Respiration occurs in the cells and releases energy which…… shoulder blade
upper arm bone
lower arm bones
Energy use in muscle contraction
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…….makes the muscle contract and pull the lower arm up



Glucose and oxygen react to produce energy for muscle contraction
4 RESPIRATION
5 Carbon dioxide is carried to the lungs by the blood
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One example of respiration in ourselves
1. Air taken in
1.Food taken in
2. The lungs absorb oxygen from the air
2.The stomach and intestine digest food. One of the products is glucose
3.The blood stream carries glucose and oxygen to the muscles

Question 1

What is the most important point about respiration? (a) it uses oxygen (b) It produces energy (c) It produces carbon dioxide (d) It needs food and air
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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
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Question 3

Which of these are waste products of respiration? (a) Carbon dioxide (b) Water (c) Oxygen (d) Nitrogen
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Question 4

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
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Adenosine triphosphate

The energy released during respiration is not used directly by cells. Instead it is used to make a molecule called ATP which stores the energy until it is needed. ATP = Adenosine triphosphate

What does ATP do?

ATP supplies energy for all the processes that need it. For example: movement chemical reactions growth.
slow twitch/fast twitch investigation

Formation of ATP

ATP is made when another molecule called adenosine diphosphate (ADP) is bonded to a third inorganic phosphate (Pi) using the energy released from glucose.


Pi
adenosine
Pi
Pi
+
adenosine
Pi
Pi
Pi
Enzymes
Energy from respiration
Energy Rich bond formed

Summarised as:

ADP + Pi ATP
The whole process is under the control of enzymes

The role of ATP

ATP stores the energy in the third bond of the molecule The energy is released when that bond is broken to release the third inorganic phosphate (Pi) .


Pi
adenosine
Pi
Pi
+
Energy released to do work
ATP
ADP
Enzymes
adenosine
Pi
Pi
Pi

Summary

ATP
ADP + Pi
energy (out)
energy (in)
cellular respiration
cell activities
ATP
energy (out)
cellular respiration
cell activities
The whole process is an enzyme controlled reaction.

Types of respiration

Anaerobic Respiration aerobic Respiration

Anaerobic Respiration

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The 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.
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aerobic respiration.

The products of aerobic respiration are carbon dioxide, water and ATP.One glucose molecule (C6H12O6) can produce 36 ATP molecules. The following formula summarizes the reactions involved in aerobic respiration:C6H12O6 + 6O2 + 36 ADP + 36Pi ͢ 6CO2 + 6H2O + 36 ATP

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).

ANAEROBIC RESPIRATION

Anaerobic respiration takes place in the absence of oxygen. There are two types of anaerobic respiration: lactic acid fermentation and alcoholic fermentation

glycolysis still happens as it does not require oxygen

in absence of oxygen pyruvic acid is turned into lactic acid.


pyruvic acid
lactic acid
glucose
2 ADP + 2 Pi 2 ATP


A build up of lactic acid produces muscle fatigue. Muscle fatigue makes muscles ache and contract less powerfully.A recovery period is needed. During this time more oxygen is taken in to convert the lactic acid back into pyruvic acid again.The volume of oxygen needed is called the oxygen debt.

Summary

oxygen debt e.g. during hard exercise
oxygen debt repaid during recovery time
glucose
pyruvic acid
lactic acid

Lactic Acid Fermentation

Lactic acid fermentation occurs in the cells of animals, in particular in the hardworking muscle cells. Glucose is partially broken down into lactic acid and energy is released in the process.

Alcoholic Fermentation

One form of anaerobic respiration in bacteria and yeasts is called fermentation.
During fermentation, sugar is broken down to alcohol and carbon dioxide Alcoholic fermentation also only produces 2 molecules of ATP.
Fermentation is involved in brewing and wine-making
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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
Anaerobic bacteria are to be found in situations where oxygen is lacking, such as in stagnant water, waterlogged soils or the intestines of animals
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Micro-organisms

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
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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
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Black grapes growing in a vineyard

© Ilan’s Wine Making 32

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
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Beer fermenting

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Baking

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 35

Dough rising

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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


The ‘holes’ in the bread are made bythe carbon dioxidebubbles.This gives the bread a ‘light’ texture 37

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
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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
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Comparison of aerobic and anaerobic respiration

Aerobic respiration
Anaerobic Respiration
in animals
in plants and yeast
Oxygen required?
yes
no
no
Glycolysis occurs
yes
yes
yes
ATP yield
38ATP
2ATP
2ATP
Glucose completely broke down?
yes
no
no
End products
Carbon dioxide and water
Lactic acid
Ethanol and carbon dioxide