What is Respiration? a process of oxidizing food to release energy inside cells

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





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





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





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





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


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


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


Why are the flasks supported in the upside-down position ?

A

thermos flask

germinating seeds

cotton wool

thermometer

B


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.



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.



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.



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


wire gauze

What happens to the hydrogencarbonate indicator solution when the gas is bubbled through it?Ans: The solution turns yellow.


paraffin oil

germinating seeds

gas

syringe


wire gauze

What is the gas produced?Ans: It is carbon dioxide.


paraffin oil

germinating seeds

gas

syringe


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.


paraffin oil

germinating seeds

gas

syringe


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



cooled down


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



cooled down


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



cooled down


tion

liquid paraffin

thermos flask

What does this show?Ans: This shows that yeast can respire anaerobica

lly to produce energy.

thermometer



cooled down


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



cooled down


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



cooled down


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

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Documents

What is Respiration? a process of oxidizing food to release energy inside cells