tion Anal tsMisconThink about the following statements carefully. Are theybook to get rid of any misconceptions.

1 Respiration only occurs in the mitochondria of cells.

2 ln anaerobic respiration, glucose is completely broken down.

3 Respiration will always involve any one of the following: oxygen intake, carbon dioxiderelease and lung ventilation.

4 Human lungs are made operative by the muscles of the lungs.

5 Oxygen is transported in the blood plasma.

true or false? Check the answers at the back of the

Review Exercise 8

PAPER 1 Multiple Choice Auestions

lnstruction: Answer all questions. For each questionthere are four possible answers, A, B, C and D.

Choose the one you consider correct and record yourchoice in the bracket.

1 The table below shows the composition of foursamples of air. Which of the samples is inhaledair?

SaturatedA little

Satu ratedA little

4 Which are the characteristics that enable thealveolus to carry out gaseous exchangeefficiently?

I A large surface areall A layer of moisture on its surfacelll A network of blood capillaries around itlV A layer of fat on its surface

A I and lll onlyB ll and lll onlyC l, ll and lll onlyD l, ll, lll and lV (

5 How can oxygen debt that occurs in muscletissues be paid back?

I By breathing rapidly in the recovery periodll By reducing the vigorous activityIll By drinking a lot of waterlV By cooling down the body

A I onlyB I and lll onlyC l, ll and lll onlyD ll, lll and lV only (

6 After a person has exercised, which events takeplace to reduce the amount of carbon dioxidein the blood?

Al Decreases r Decreases

B Decreases lncreases

AB

C

D

0.30.03

7

3

2421

14

29

()

2 What is the similarity between anaerobicrespiration and aerobic respiration in plants?

A Water is produced.B Alcohol is produced.C Oxygen is used.D Carbon dioxide is produced. (

3 Which of the following about anaerobicrespiration in animals are true?

I Carbon dioxide is producedIl Accumulation of lactic acidlll lncomplete breakdown of glucoseIV Occurs in muscle cells

A ll and lll onlyB ll and lV onlyC ll, lll and lV onlyD l, ll, lll and lV

c Decreases

I ncreases

()

Air sampleCarbon

dioxide (o/ol

146

D

I ncreases

I ncreases

,.'Q

GUI

g

-(Jn

Itl

)

)

Oxygen {o/o)Watervapour

()

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7 The diagram below shows a model of theri bcage.

M

8 The diagram below shows an experiment toprove that living organisms release carbondioxide.

stopper

(alive)re gauze

indicator

The experiment needs a control. Which of thefollowing is true of the control experiment?

I Does not contain a snailll ls left aside for the same period of timelll ls exposed to the same conditions as the

experimentlV Does not contain bicarbonate indicator

10 The shaded area of the graph shows anathlete's rate of oxygen uptake before, duringand after a five-minute period of exercise.

L

J

Oxygenconsumption(litre per minute)

oxygenconsumption

oxygen demand5.0

4.0

3.0

2.0

1.0

0

9 Which of the following cause the flow of airinto the lungs during inhalation?

I A decrease in air pressure of thoracic cavityll An increase in temperature of lungsIll An increase in volume of thoracic cavitylV An increase in humidity of the air in

the lungs

A I and lll onlyB ll and lV onlyC l, ll and lll onlyD l, ll, lll and lV (

'l-ime

(minutes)

period of exercise

What represents the unshaded part?

A The amount of oxygen taken inB The amount of oxygen used during exerciseC The amount of oxygen used to pay off the

oxygen debtD The excess oxygen in the lungs ( )

11 The diagram below shows a section of analveolus and its blood supply in the humanlung.

alveolus

bloodcapillary

Which of the following occur at the alveolusduring inhalation?

I The concentraton of oxygen in P is higherthan the concentration of oxygen in theblood capillaries.

ll The concentration of oxygen in P is lowerthan the concentration of oxygen in theblood capillaries.

Il! The gaseous exchange occurs by simplediffusion.

lV A lot of bicarbonate ions are formed.

A I and lll onlyB ll and lV onlyC l, ll and lll onlyD l, lll and lV only

10 15 20 255

P

A I and lll onlyB ll and lV onlyC l, ll and lll onlyD l, ll, lll and lV ()

147

o @o

Which two parts are involved during breathing?

A JandKB JandLC KandMD LandM ( )

EUJ

L

-o

)

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12 An athlete is running a 100 metre race.Thefollowing changes take place in the athlete'sbody during the race.

K - lncreased availability of oxygen to musclesL - lncreased breathing rateM- lncreased carbon dioxide concentration in

the bloodN - Muscle activity produces carbon dioxide

ln which order do these changes occur?

A K,L,MandN B L,N,MandKC N,K,LandM D N,M,LandK

13 The table below shows the ventilation rates ofan adult while resting and while exercising.

What happens at stageY?

A The ribs move upwards and the diaphragmupwards.

B The ribs move upwards and the diaphragmflattens.

C The ribs move downwards and thediaphragm curves upwards.

D The ribs move downwards and thediaphragm flattens. (

15 Look at the set-up below

d tube

What is the volume of air exchanged perminute while exercising?

A 24000 cm3 B 32000 cm3C 40000 cm3 D 48000 cm3 (

14 The graph shows the changes in air pressure inthe lungs during a breathing process.Theatmospheric pressure is 760 mm Hg.

Air pressure in thelungs (mm Hg)

cottonwool

paraffin

boiled glucosesolution and yeast

After a while, an increase in temperature wasnoted.The limewater also turned chalky. Whatconclusion can be drawn?

I Yeast carried out aerobic respiration andproduced carbon dioxide.

ll Yeast carried out anaerobic respiration andproduced carbon dioxide.

lll Yeast carried out respiration and producedenergy.

lV Yeast carried out respiration and producedalcohol.

A I and lll onlyB ll and lV onlyC l, lll and lV onlyD ll, lll and lV only

5101520(b) After vigorous activity

Resting 400

Exercising 1200

20

40

8000

765

760

755 Time

PAPER 2 Structured and Free-response Auestions

Section A Structured Ouestions

1 The graphs below show the changes in the volume of air in the lungs when relaxing and after vigorousactivity.

oO)cl

.=

6ooEfo

C

oo,c:l.c'(!

ooEf6

5

5

4

3

'I

0 't0 15 20

(a) Relaxing

Volume ofair inhaledper breath

(cm3l

148

Time Time

EIJJ

o-

o

Adultman

Number ofbreaths per

minute

Volume of airexchangedper minute

{cmt}

?

)

)

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(a) Calculate the rate of breathing in breaths per minute(i) while relaxing.(ii) after vigorous activitY.

(b) What is the maximum volume of air in the lungs(i) while relaxing?(ii) after vigorous activity?

(c) (i) Name the process which occurs during vigorous activity'(ii) what condition would exist in the muscles during vigorous activity?

(d)Why does the volume of air exchanged increase so drastically after vigorous activity?(e) Air flows into the lungs when the atmospheric pressure inside the lungs decreases' Explain how this

happens.(f) The table below shows the results of an experiment to study the effect of vigorous exercise on the

heart rate and the content of air in the alveolus'

75

(i) What happens to the heart rate after exercise?(ii) What conclusion can be drawn from the results based on the content of air in the

alveolus after exercise?(iii) Give an explanation for the change in the percentage of carbon dioxide in the alveolus

after the exercise.(iv) Give three characteristics of the respiratory surface in the alveolus for efficient gaseous

exchange.

A candle was burned under an inverted beaker filled with air.The time taken for the candle flame to

extinguish was noted.The experiment was repeated using a beaker filled with exhaled air from a

person's lungs.The results are given below.

28 '13

(a) What is the reason for the difference in the results of the two experiments?(b)Name the chemical process in the person's body which made the exhaled air different from the

ordinary air.(c) How is the process in (b) useful to humans?(d)Write a word equation for this process.

3 The table below shows the composition of inhaled air and exhaled air of a person (excluding water

vapour).

Carbon dioxide 0.03

Nitrogen

Oxygen

Others

(a) How do the alveoli of the lungs bring about the changes shown in the table?(b) What are the two characteristics of alveoli that help to bring about these changes?

(c) Where does the reaction that causes these changes take place?

89 co,3.9% or12.1% cor4.6% or1o.3%

2

exerclse After

. Time takgn for,,the.r,candle llame to extinguish (s1,,

Exhaled air,Ordindry air

't49

Heart rate (beats per minute) Conteni of air in the alveolus

Before exercise After exercise

!r

Compgnent% compositon

lnhaled air Exhaled air

4

Elr|

o-

I(J

6

78

21

0.97

16

2

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4 The amount of lactic acid in the blood rises sharply within the first few minutes of strenuous exercise,causing muscle fatigue.

(a)What are the conditions leading to this state?(b) Write a word equation describing the chemical changes leading to this state.(c) How can the lactic acid level in the blood fall back to the normal level?

Section B Free-response Ouestions

5 ln humans, lungs play an important role in respiration. Hence, maintaining a healthy respiratory system is veryimportant.

(a) Describe the gas exchange processes involved in respiration beginning from when the air enters thenose until the time the air enters the bloodstream.

(b) Explain how the lungs are adapted to carry out gaseous exchange efficiently.(c) Explain why smoking reduces the efficiency of the function of the lungs.

6 (a) Explain(i) the importance of an increased pulse rate during vigorous exercise, and(ii) why it takes several minutes for the pulse rate to return to normal after exercise.

(b) lf an athlete is a regular smoker, explain how this might affect both his pulse and his breathing rateduring vigorous exercise.

. Haemoglobin is involved in cell respiration.. Rate of breathing increases after vigorous exercise.o The muscles ache and the body is tired after vigorous exercise.

(c) The above information was obtained from a student's study on respiration. Based on your biologicalknowledge, write a repoft to explain the statements above.

ln an experiment to study the relationship between various activities and the rate of breathing, thevolume of air taken in at each breath and the number of breaths per minute were measured whilst aperson performed different activities.The results are given in the table below.

Running

28Walking

Standing 22

20Sleeping

(a) what is the volume of air breathed in per minute when the person is(i) walking?(ii) running?

(b) (i) The volume of air breathed in per minute increases when the person switches fromwalking to running.This can be achieved in two ways as seen in the table.What arethese two ways?

(ii) What is the reason for the increase in the volume of air breathed in per minute when theperson switches from walking to running?

(c) Calculate the increase in volume of air breathed in per minute when the person changes from(i) sleeping to standing.(ii) standing to walking.

7

1 000

700

550

500

a

Volurne of air per breath'(cml)

150

I

I

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