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SBA1B_ans_e

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SBA1B_ans_e

New Senior Secondary Mastering Biology Book 1B Practical workbook answer p.1/26

    Suggested answers to Practical Workbook

    for SBA

Ch 7 Gas exchange in humans

    Practical 7.1 Examination of the mammalian breathing system

    Questions (p. 7-2)

    1

    A Nose B Pharynx C Epiglottis D Trachea E Cartilage F Right bronchus G Right lung H Rib I Intercostal muscle J Diaphragm

    2 Nostrils?nasal cavity?pharynx?larynx?

     trachea?bronchi?bronchioles

     ?air sacs(in lungs)

3 The air is moistened, warmed and cleaner.

4 It closes the entrance to the larynx during swallowing, thereby preventing choking.

5 It protects the lungs and the heart.

Practical 7.2 Examination of the pig lungs

    Results (p. 7-5)

    1 There are three lobes in the left lung and two lobes in the right lung.

2 The trachea is hard. The lung tissue is soft and spongy.

3 The lungs increase in volume. / The lungs expand.

4 The piece of lung tissue floats in water.

? Oxford University Press 2009

New Senior Secondary Mastering Biology Book 1B Practical workbook answer p.2/26

    5

    Questions (p. 7-5) 1 It is because they have a very rich supply of blood vessels.

2 The trachea, but not the lung tissue, is supported by cartilages.

3 Air.

    4 The lungs tissue floats in water because the air in the air sacs gives the lung tissue a low

    density.

? Oxford University Press 2009

New Senior Secondary Mastering Biology Book 1B Practical workbook answer p.3/26

    Practical 7.3 Examination of the mammalian air sacs

    Results (p. 7-8)

    Questions (p. 7-8) 1 In the air sacs, the oxygen concentration is higher than that in the capillaries. Oxygen in

    incoming air dissolves in the water film lining the air sacs, and then diffuses across the

    walls of the air sacs and the capillaries into the blood. In the capillaries, the carbon dioxide

    concentration is higher than that in the air sacs. Carbon dioxide in blood diffuses across the

    walls of the capillaries and the air sacs into the air in the air sacs.

2 The large number of air sacs provides a large surface area for gas exchange. The

    epithelium of the air sac is only one-cell thick. This provides a short distance for rapid

    diffusion of gases. The moist inner surface allows gases to dissolve in the water film for

    diffusion across the epithelium. The air sacs are richly supplied with blood. This allows

    rapid transport of gases to and from the air sacs so that a steep concentration gradient can

    be maintained for rapid diffusion.

Practical 7.4 Comparison of the composition of inhaled air and

    exhaled air Results (p. 7-11)

     Inhaled air Exhaled air

    Burning time of candle(s) 14 10

    Final colour of hydrogencarbonate indicator Red / orange Yellow

? Oxford University Press 2009

New Senior Secondary Mastering Biology Book 1B Practical workbook answer p.4/26

    Questions (p. 7-11)

    1 The exhaled air contains less oxygen than inhaled air. The candle in exhaled air burns

    shorter.

    2 Some oxygen in the inhaled air diffuses from the air sacs into the capillaries. Therefore,

    less oxygen is found in the exhaled air.

    3 The exhaled air contains more carbon dioxide than inhaled air. The colour of

    hydrogencarbonate indicator turns yellow.

    4 Some carbon dioxide diffuses from the capillaries to the air sacs. Therefore, more carbon

    dioxide is found in the exhaled air.

    5 Lime water. The colour of lime water changes from colourless to milky.

Conclusion (p. 7-12)

    The exhaled air contains less oxygen but more carbon dioxide than inhaled air.

? Oxford University Press 2009

New Senior Secondary Mastering Biology Book 1B Practical workbook answer p.5/26

    Ch 8 Transport in humans

    Practical 8.1 Examination of a blood smear

    Results (p. 8-2)

    1

2

     Red blood cell White blood cell Blood platelet

    Biconcave Shape Irregular shape Irregular shape disc shape

    Nucleus No nucleus Round or lobed No nucleus Relative size Medium Large Small Relative number Abundant Rare Occasional

Questions (p. 8-2)

    1 a White blood cell is the largest. Blood platelet is the smallest.

    b Red blood cell is the most abundant. White blood cell is the least abundant.

2 a It is biconcave disc shape. This provides a large surface area to volume ratio to

    facilitate the diffusion of gases.

    ? Oxford University Press 2009

New Senior Secondary Mastering Biology Book 1B Practical workbook answer p.6/26

    b No. The absence of nucleus allows the accommodation of more haemoglobin.This

    increases the oxygen-carrying capacity of the red blood cells.

3 The body is infected with pathogens.

     The body has abnormal cell growth.

Practical 8.2 Examination of the transverse sections of an artery

    and a vein

    Results (p. 8-4)

    1

2

     Artery Vein

    Thickness of wall Thicker Thinner

    Size of lumen Smaller Larger

Questions (p. 8-5)

    1 Arteries have a thicker wall which contains a thick layer of muscles. The muscles contract

    and relax to regulate the blood flow to body cells. Veins have a larger lumen to reduce

    resistance to blood flow.

2 There are valves in veins but not in arteries (except in pulmonary artery and aorta).

? Oxford University Press 2009

New Senior Secondary Mastering Biology Book 1B Practical workbook answer p.7/26

    Practical 8.3 Examination of the capillary flow in a fish tail fin

    Results (p. 8-7)

    1

     Observations

    Direction of blood flow One way Speed of blood flow Slow Diameter of blood vessels Similar to the diameter of red blood cells

    The red blood cells are squeezing their way through the Behaviour of blood cells capillaries.

2

Questions (p. 8-8)

    1 To provide a large surface area for rapid exchange of materials between the blood and the

    body cells.

     To provide a large total cross-sectional area so that blood flows slowly in the capillaries.

    This allows a longer period of time for exchange of materials.

2 White blood cells can change their shape, so they can move along the narrower capillaries.

    ? Oxford University Press 2009

New Senior Secondary Mastering Biology Book 1B Practical workbook answer p.8/26

    Practical 8.4 Dissection and examination of a pig heart

    Results (p. 8-12)

    1

2

    Water run into What happens venae cavae Water comes out from the pulmonary arteries. pulmonary artery Water cannot enter and no water comes out from any vessels. pulmonary vein Water comes out from the aorta.

    aorta Water cannot enter and no water comes out from any vessels.

? Oxford University Press 2009

New Senior Secondary Mastering Biology Book 1B Practical workbook answer p.9/26

    3

    A Anterior vena cava B Right atrium C Posterior vena cava D Tricuspid valve E Right ventricle F Septum

    G Pulmonary artery H Aorta

    I Pulmonary vein J Semilunar valve K Left atrium

    L Bicuspid

    M Heart tendon N Left ventricle

    Questions (p. 8-13) 1 When water is forced through the venae cavae and the pulmonary vein into the heart, it

    enters the heart and comes out as in the normal circulation. However, when water is forced

    through the pulmonary artery and the aorta, it cannot enter the heart because it is stopped

    by the semilunar valves.

    2 The wall of the left ventricle is thicker than that of the right ventricle. It is because the left

    ventricle has to provide a greater force to pump blood to all parts of the body (except the

    lungs), whereas the right ventricle pumps blood only for a short distance to the lungs.

3 The ventricles have a thicker muscular wall. It is because the ventricles have to provide a

    greater force to pump blood to the lungs or other parts of the body, whereas the atria only

    pump blood to the nearby ventricles.

4 1 The ventricles have a thicker muscular wall to pump blood to all parts of the body.

    2 Valves are present to prevent backflow of blood.

    3 Heart tendons are present to prevent the valves from being turned inside-out when the

    ventricles contract.

5 The septum prevents the oxygenated and deoxygenated blood from mixing. This ensures a

    high oxygen content in the blood in the aorta for the body cells.

? Oxford University Press 2009

New Senior Secondary Mastering Biology Book 1B Practical workbook answer p.10/26

    Ch 9 Nutrition and gas exchange in plants

    Practical 9.1 Investigation of the effects of different minerals on

    plant growth

    Results (p. 9-3)

    1 (Answer varies with seedlings.)

2

    Flask Appearance of seedlings

    A Healthy growth of seedlings.

    B Poor growth. Yellowing of older leaves.

    Poor growth. Depending on the species, leaves may become dull green, C yellow or purple.

    Poor growth. Older leaves start to yellow at the edges, and then turn brown. D Leaves may curl and dead spots appear.

    E Poor growth. Yellowing of older leaves.

Questions (p. 9-4)

    1 This prevents algal growth in the solutions. Algae take up the minerals in the solutions and

    affect the results.

2 It ensures the roots get enough oxygen for respiration. Respiration can provide energy for

    the root to absorb minerals by active transport.

3 All the major elements (e.g. nitrogen, phosphorus, potassium, magnesium, etc.) and trace

    elements (e.g. manganese, copper, zinc, etc.) needed by the plants.

4 It acts as a control to show that symptoms appear in the seedlings are due to the deficiency

    of a particular mineral.

5 Seedlings cannot use atmospheric nitrogen directly. Seedlings obtain nitrogen only in

    dissolved forms of nitrate or ammonium.

    ? Oxford University Press 2009

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