chapter 7

Activity 1

1.1

1. /
2. x
3. x
4. x
5. /
6. x
7. /
8. /
9. x
10. /
11. x
12. /

1.2

Air moves into the lungs.                                7

                       

The ribs move upwards and outwards.         2

 

The volume of the thoracic cavity increases.    5

 

The external intercostals muscles contract.      1

 

Diaphragm flattens.   4          

 

Pressure in the thoracic cavity decreases     .    6

           

Diaphragm muscles contract.    3      

1.3

1. large
2. thin
3. Gills
4. Mouth
5. Operculum
6. Tracheal system
7. Abdominal
8. Mouth
9. Lungs
10. Thin
11. Muscles
12. Alveoli
13. Blood capillary
14. Intercostals

Activity 2

1. A         6.  C                11.  D              16.  B
2. A         7.  D                12.  C              17.  C
3. A         8.  D                13.  A              18.  D
4. C         9.  A                14.  C              19.  A
5. D         10. B               15.  C              20.  D

Activity 3

1. (a)  88-16 = 72 mg/100 cm³ of blood

(b)             (i)  When performing vigorous exercise, oxygen is used up at a faster rate than the rate of oxygen supplied to the muscle. Hence, the cells will carry out anaerobic respiration that produces lactic acid

(ii)  Lactic acid concentration will increase.

(c)             To obtain more oxygen for the removal of lactic acid that was produced in the body

(d)             About 5/6 of the excess lactic acid will be oxidized to produce energy. This energy will be used to convert the remaining 5/6 lactic acid into glucose.

(e)             (i)  anaerobic respiration

(ii)  Glucose  → lactic acid + energy

(f)               (i)  Oxygen debt repaid

(g)             (i)  Lactic acid removal rate

= 24/26 mg/100 cm³ blood/ min

= 0.92 mg/100 cm³ blood/min

                             (ii)  76 minutes after the exercise begins.

2. (a)  P : Trachea                                              S :  external intercostal

      Q :  bronchus                                           T :  rib

                  R :  lungs                                                  U : alveolus

           

            (b) Lungs

            (c)   (i)  Cartilage rings

                   (ii)  Prevents the collapse of the trachea when exhaling air.

            (d)  Alveolus

            (e)  (i)  S relaxes

                   (ii)  the ribcage moves upward and outward

3. (a)  - to kill microbes present in the glucose solution

      - to drive off the dissolved gases in the glucose solution

(b)  To prevent killing the yeast cells as high temperature denatures the enzymes

(c)  To prevent atmospheric oxygen diffusing into the glucose solution

(d)       (i)  The lime water turns cloudy

(ii)  Carbon dioxide released from anaerobic respiration dissolves in the lime water to form calcium carbonate

            (e)  (i)  An increase in temperature   

                  (ii)  Heat energy released causes an increase in thermometer reading

(f)      Ethanol

(g)    Glucose + oxygen→ethanol + carbon dioxide+ energy

(h)    (i)  Some heat is lost from tube I to the surrounding resulting in a lower thermometer reading

(ii)  Cover tube I with a layer of cotton wool which acts as a heat insulation

(i)      (i)  The ethanol produced can make all sorts of alcoholic drinks such as beer and wine

(ii)  carbon dioxide produced causes the dough to rise in bread making.

Activity 4

1.  (a)  Inspiration

·        The external intercostals muscles contract and the internal intercostals muscles relax. [1m]

·        This pulls the ribcage up and out[1m]

·        At the same time, the muscles of the diaphragm contracts and become flatten[1m]

·        The volume of the thoracic cavity increases[1m]

·        Pressure in the thoracic cavity decreases[1m]

·        Atmospheric air has a higher pressure. Air enters into the lungs, the lungs become inflated. [1m]

·         

Expiration

·        The internal intercostal muscles contract and the external intercostals muscle relax[1m]

·        The ribcage is moved down and inwards [1m]

·        At the same time, the diaphragm relaxes and becomes domed shape [1m]

·        The volume of the thoracic cavity decreases[1m]

·        The pressure in the thoracic cavity increases[1m

·        The pressure is above that of atmospheric air pressure. Air is forced out of the lungs.[1m]

                                                                                  Max : 10 m

(b)     (i)

·        At times of strenuous exercise, the reserves of ATP become exhausted.      [1m]

·        The supply of oxygen to muscles is sufficient to maintain the amount of oxygen needed for aerobic respiration  [1m]

·        Anaerobic respiration occurs.     [1m]

·        The glucose is converted into lactic is converted into lactic acid, with only a limited amount of energy being released. [1m]

·        An oxygen debts builds up in the body. [1m]

·        High levels of lactic acid in the muscles may lead to cramp [1m]

·        After strenuous exercise, the athlete breathes ,ore rapidly and deeply than normal for several minutes  [1m]

·        There is a recovery period when oxygen is paid back during aerobic respiration.  [1m]

·        About 1/6 lactic acid is oxidized to carbon dioxide, water and energy.[1m]

·        The energy released is used to convert the remaining lactic acid to glucose and glycogen for storage in liver or in muscles cells. [1m]

Max : 7m

(b) (ii)

• Warming up exercises improve the coordination between pairs of antagonistic muscles [1m]
• It improves the blood circulation, bringing more blood and oxygen to the muscle cells. [1m]
• More rapid muscle contractions can take place.[1m]
• If warming up exercises are not taken, it may result in straining or tearing of muscle tissue.[1m]
• After strenuous exercise, for example, running a 400 meters race, the muscles are usually shorter and tighter.[1m]
• Cooling down exercises by gently stretching the body will increase muscle flexibility and avoid muscle injury after a race[1m]

Max : 3 m