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What is Respiration?What is Respiration?
a process of oxidizing food to
release energy inside cells
Burning of FoodBurning of Food A demonstration of energy released from food
Burning
energywater
carbon dioxide
oxygen food (sugar)
does not occur in living cells because the reaction is too fast and cells would
die as they become so hot
food(sugar) +
oxygencarbon dioxide + water + energy (heat
+ light)
RespirationRespiration reactions are catalyzed by enzymes
main food substance which oxidized in cells is glucose
C6H12O
6
+ 6O2
enzymes
6CO2 + 6H2O
+ energy as it takes place in all living cells, it is
called cellular respiration which is used to
produce energy for cells to use
Comparison of Burning Comparison of Burning and Respiration and Respiration
Similarities
- both involve oxidative processes
- both require the use of oxygen and food and they produce the same products of carbon dioxide and water
- both reactions release energy
Differences
Burning Respiration
takes place in air or oxygen
takes place in cells
a single-step process
a series of chemical reactionsno enzymes
involvedcontrolled by
enzymes
Burning Respiration
Differences
energy release is
vigorous and not
under control
energy release is
slower and under
control energy is released
in form of heat and
light (a flame can
result)
energy is released
in form of heat and
an energy-rich
compound
To Demonstrate Heat To Demonstrate Heat Production by Production by
Respiring Animals Respiring Animals using a Differential Air using a Differential Air
ThermometerThermometer
What is the function of the clips ?Ans: To equalize the pressure on the two sides o
f the capillary tube.
clip clip
graph paper
BA
stoppered air-filled test tube
stoppered air-filled test tub
eU-shaped capillary tube filled with
coloured liquidcotton wool
cotton wool
mouse
Why should the containers be wrapped in cotton wool ?Ans: It acts as an insulator to prevent heat lo
ss.
clip clip
graph paper
BA
stoppered air-filled test tube
stoppered air-filled test tub
eU-shaped capillary tube filled with
coloured liquidcotton wool
cotton wool
mouse
Which is preferable, a capillary tube with a wide bore or one with a narrow bore ?Ans: A capillary tube with a narrow bore is preferred t
han the wide one as it is more sensitive and will give better results.
clip clip
graph paper
BA
stoppered air-filled test tube
stoppered air-filled test tub
eU-shaped capillary tube filled with
coloured liquidcotton wool
cotton wool
mouse
What happens to the levels of the coloured liquid ? Ans: The coloured liquid rises up the left arm of t
he U-shaped capillary tube.
clip clip
graph paper
BA
stoppered air-filled test tube
stoppered air-filled test tub
eU-shaped capillary tube filled with
coloured liquidcotton wool
cotton wool
mouse
Why ?Ans: Because the mouse in container B carries out re
spiration to release heat energy which warms up the air in the test tube.
clip clip
graph paper
BA
stoppered air-filled test tube
stoppered air-filled test tub
eU-shaped capillary tube filled with
coloured liquidcotton wool
cotton wool
mouse
To Demonstrate Heat To Demonstrate Heat Production by Production by
Germinating Seeds Germinating Seeds using Thermos Flasksusing Thermos Flasks
Which thermos flask shows a higher temperature at the end of the experiment ? Ans: Flask A showed a higher temperature at the
end of the experiment.
A
thermos flask
germinating seeds
cotton wool
thermometer
B
Seeds killedby boiling
Why ?
Ans: It is because living seeds produce heat energy.
A
thermos flask
germinating seeds
cotton wool
thermometer
B
Seeds killedby boiling
What is the purpose of washing the seeds with a disinfectant ?Ans: To kill any bacteria and fungi present o
n the seeds.
A
thermos flask
germinating seeds
cotton wool
thermometer
B
Seeds killedby boiling
It is advisable not to fill the flasks completely with seeds. Why ?
Ans: To provide air for the seeds to respire.
A
thermos flask
germinating seeds
cotton wool
thermometer
B
Seeds killedby boiling
Why are the flasks supported in the upside-down position ?
A
thermos flask
germinating seeds
cotton wool
thermometer
B
Seeds killedby boiling
Ans: The flasks are supported in the upside-down position because carbon dioxide, produced during
respiration of the living seeds, is a
heavier gas and may escape
through the cotton wool.
hot air rises up, and inverting it will
ensure that heat will not escape
through the cotton wool.
it is easier to read the thermometer as
the thermos flasks are not transparent.
To Show Production of To Show Production of Carbon Dioxide by a Carbon Dioxide by a
Respiring AnimalRespiring Animal
lime water
lime water
to suction pump
CBA
potassium hydroxide
solution
glass platemouse
bell jar
Why is it necessary to bubble the incoming air through potassium hydroxide solution before it is supplied to the mouse ?Ans: It is used to remove carbon dioxide in the i
ncoming air.
Which solution changes colour at the end of the experiment ? What does this show ?Ans: The lime water in flask C turns milky. It is beca
use carbon dioxide is given off by the mouse.
lime water
lime water
to suction pump
CBA
potassium hydroxide
solution
glass platemouse
bell jar
To Show the Release of To Show the Release of Carbon Dioxide by Carbon Dioxide by Germinating SeedsGerminating Seeds
Why is it necessary to wash the seeds with a disinfectant ?
Ans: It is used to kill microorganisms.
hydrogencarbonate indicator solution
seeds (heat-killed)germinating
seeds
muslin bag
threadthread
moist cotton wool
A B
What is the function of the moist cotton wool inside the muslin bag ?Ans: It prevents the seeds from drying out.
hydrogencarbonate indicator solution
seeds (heat-killed)germinating
seeds
muslin bag
threadthread
moist cotton wool
A B
What has happened to the hydrogencarbonate indicator solution in the two tubes ?Ans: Indicator solution in tube A turns yellow while
the indicator solution in tube B remains unchanged.
hydrogencarbonate indicator solution
seeds (heat-killed)germinating
seeds
muslin bag
threadthread
moist cotton wool
A B
What can be concluded from this experiment ?
Ans: Carbon dioxide is released by the germinating seeds.
hydrogencarbonate indicator solution
seeds (heat-killed)germinating
seeds
muslin bag
threadthread
moist cotton wool
A B
Uses of the Energy Released Uses of the Energy Released during Respirationduring Respiration
Human Other Animals
Plants
produce light in fireflies
muscle contraction
absorb mineral salts by active transport keep warm produce
sound in some birds
transport food substances absorb food
by active transport
produce smell in some mammals
ATPATP energy is mainly released as heat and
ATP during respiration in cells
however, during respiration, some ATP
should be consumed first before other
ATP can be formed
the ATP consumed is used to form other
ATP from ADP and phosphate groups
ADP + energy (from
breakdown of glucose)+ phosphate ATP
ATP is a high-energy compound while ADP is
a low-energy one
ATP can only store energy for a short period
ATP is made inside organelles, mitochondria,
which is scattered in the cytoplasm of a cell
Anaerobic RespirationAnaerobic Respirationrespiration in human is mainly
aerobic respiration as oxygen is
essential
when oxygen is not needed during
respiration, it is called anaerobic
respiration
yeast and muscle cells are examples
which they can respire anaerobically
for a short time
Alcoholic FermentationAlcoholic Fermentation without oxygen, yeast cells respire as
follows:C6H12O6 + energy+ 2C2H5OH (ethanol)2CO2
enzymes
amount of energy released
anaerobically is smaller when
compared with the aerobic method
anaerobic respiration
aerobic respiration
amount of energy
released
large small
oxidation of glucose completely partly
place of occurrence
mitochondria cytoplasm
Industrial Use of Industrial Use of
Yeast FermentationYeast Fermentationalcohol produced is used for:
brewing beer
making wine
carbon dioxide released is used
for:
baking bread
Lactic Acid FermentationLactic Acid Fermentation extra oxygen is required for undertaking
sternuous exercise
people cannot supply enough oxygen
to muscles even they breathe faster
and deeper
lactic acid will cause muscle fatigue and
muscle cramps if they are allowed to
accumulate
C6H12O6 2C3H6O3 + energy
enzymes
muscle need to produce energy
anaerobically by breaking down
glucose into lactic acid
a large amount of oxygen is needed to
break down the accumulated lactic acid
into carbon dioxide and water or turn to
glycogen in liver for storage so we pant
after doing exercise the amount of oxygen required to get
rid of lactic acid is called oxygen debt
To Show Anaerobic To Show Anaerobic Respiration of Respiration of
Germinating Seeds in Germinating Seeds in OilOil
Does the boiling tube contain a gas after 2 days?Ans: Yes.
at the start after two days
paraffin oil
germinating seeds
gas
syringe
hydrogencarbonate indicator solution
wire gauze
What happens to the hydrogencarbonate indicator solution when the gas is bubbled through it?Ans: The solution turns yellow.
at the start after two days
paraffin oil
germinating seeds
gas
syringe
hydrogencarbonate indicator solution
wire gauze
What is the gas produced?Ans: It is carbon dioxide.
at the start after two days
paraffin oil
germinating seeds
gas
syringe
hydrogencarbonate indicator solution
wire gauze
What can be learned about the respiration of germinating seeds from this experiment?Ans: Germinating seeds can respire anaerobically and
release carbon dioxide in the absence of oxygen.
at the start after two days
paraffin oil
germinating seeds
gas
syringe
hydrogencarbonate indicator solution
wire gauze
To Show Production of To Show Production of Ethanol and Carbon Ethanol and Carbon
Dioxide during Dioxide during Fermentation of Fermentation of Glucose by YeastGlucose by Yeast
thermometer
yeast in glucose solution which has
been previously boiled and then
cooled down
hydrogencarbonate indicator solu
tion
liquid paraffin
thermos flask
Why is it important to boil the glucose solution?Ans: This drives off any dissolved oxygen.
Why must the glucose solution be cooled down before yeast is added?
Ans: It is because yeast would be killed when hot.
thermometer
yeast in glucose solution which has
been previously boiled and then
cooled down
hydrogencarbonate indicator solu
tion
liquid paraffin
thermos flask
What is the function of liquid paraffin?Ans: It prevents the mixture from coming into con
tact with air.
thermometer
yeast in glucose solution which has
been previously boiled and then
cooled down
hydrogencarbonate indicator solu
tion
liquid paraffin
thermos flask
What has happened to the hydrogencarbonate indicator solution? Ans: The hydrogencarbonate indicator solution ha
s changed from red to yellow.
thermometer
yeast in glucose solution which has
been previously boiled and then
cooled down
hydrogencarbonate indicator solu
tion
liquid paraffin
thermos flask
What does this show?Ans: This shows that yeast can respire anaerobica
lly to produce energy.
thermometer
yeast in glucose solution which has
been previously boiled and then
cooled down
hydrogencarbonate indicator solu
tion
liquid paraffin
thermos flask
What has happened to the reading of each thermometer?Ans: The reading of the thermometer of the exper
imental set-up rises.
thermometer
yeast in glucose solution which has
been previously boiled and then
cooled down
hydrogencarbonate indicator solu
tion
liquid paraffin
thermos flask
At the end of the experiment, what new substance would you expect to find in the glucose solution containing living yeast?Ans: We can find alcohol in it.
thermometer
yeast in glucose solution which has
been previously boiled and then
cooled down
hydrogencarbonate indicator solu
tion
liquid paraffin
thermos flask
Comparison of Aerobic and AComparison of Aerobic and Anaerobic Respirationnaerobic Respiration
Similarity
Sugar is broken down to release
energy
ATP is made
Both are controlled by enzymes
Differencesaerobic
respirationanaerobic respiration
complete oxidation
incomplete
oxidation
oxidation of sugar
essentialoxygen
requirement
nil
energy released
large amount
small amount
aerobic respiration
anaerobic respiration
in most living cells
in lower organisms (e.g.
bacteria and yeast) and vertebrate muscles
occurrence
inorganic: CO2 and
H2O
end products
organic: ethanol or lactic acid
Differences between RespDifferences between Respiration and Photosynthesisiration and Photosynthesis
aerobic respiration
photosynthesis
energy is released
energy (light) is absorbed
produces carbon dioxide
and water
requires carbon dioxide and
water
an oxidative process
a reductive process
aerobic respiration
photosynthesis
occurs in all living cells at all times
occurs in green plants only when light is available
a breaking down process
a synthetic process
occurs in mitochondria
occurs in chloroplast
s
~ ~
ENDEND ~~