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bk2_ch13_sug ans_e

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bk2_ch13_sug ans_e

New Senior Secondary Mastering Biology Chapter 13 Suggested answers to Exercise and Reading to learn p.1/3

Suggested answers to Exercise and Reading to

    learn

    (Note: The overseas examination boards bear no responsibility for the suggested answers

    contained in this publication. Answers for HKCEE and HKALE questions are not available due

    to copyright restrictions.)

Ch 13 Reproduction in humans

    Exercise

    Multiple-choice questions (p. 13-38) 1 D 2 A 3 B 4 C 5 B 6 D 7 A 8 C 9 A 10 A 11 B 12 D 13 A 14 D 15 D

Short questions (p. 13-40)

    16 a

    Part Number

    Contains smooth muscle to move 4 sperm

    Adds a liquid secretion to sperm 3 before they are released

     1m x 2

     b A scrotum

    It keeps testes cooler / at 35?C so sperm can be made / sperm live longer. 1m

     C erectile tissue

    It can be filled with blood. 1m

     B penis

    It becomes erect / stiff / rigid so it can reach high in vagina / the top of vagina / the

    entrance of uterus.

     Effective communication 1m

17 a i Acrosome releases enzymes / proteases which digest the protective layer of the

     ovum. 2m

     ii The protective layer thickens / hardens / changes in structure. 2m

     b Sperms are produced by meiotic cell division which involves independent assortment

    of chromosomes.

     Homologous / pairs of chromosomes separate independent of each other. 2m

    ? Oxford University Press 2009

New Senior Secondary Mastering Biology Chapter 13 Suggested answers to Exercise and Reading to learn p.2/3

    18 a i umbilical cord 1m

     ii carbon dioxide 1m

     b i uterine 1m

     ii abdominal 1m

     c i mammary glands 1m

     ii antibodies 1m

Structured questions (p. 13-41)

    19 a 25.7 / 25.5026.00 μm 1m

     b These enzymes can break down protective layer and 1m

     allow the entry of sperm nucleus / DNA into the ovum. 1m

     c Mitochondria provide ATP / release energy / carry out respiration 1m

     for the movement of sperm. 1m

     d This increases the chance of reaching the ovum / egg / fertilization 1m

    because sperms have to travel long distance / not all sperm viable / many sperm do not

    survive. 1m

20 HKCEE Biology 1995 I Q1c

21 HKCEE Biology 2006 I Q7

22 HKCEE Human Biology 2005 I Q2b

23 HKCEE Biology 2002 I Q2a

    ? Oxford University Press 2009

New Senior Secondary Mastering Biology Chapter 13 Suggested answers to Exercise and Reading to learn p.3/3

Essay (p. 13-43)

    24 a Any four from: 1m x 4

    Midpiece of sperm contains mitochondria

     which supply ATP

    to the tail for motility.

     Acrosome contains digestive enzymes

     released when membrane rupture

     which digest the protective layer of the ovum.

     Haploid nucleus of sperm can enter the ovum and fuse with nucleus.

     b Breakdown of membranes 1m

    decreases the diffusion distance. 1m

     Presence of villi 1m

    provides large surface area for exchange. 1m

     Slow movement of blood at exchange surfaces 1m

    allows more time for exchange of materials. 1m

    Transport proteins present 1m

    for active transport of ions 1m

     Blood circulating in placenta 1m

    maintains the concentration gradient. 1m

     (3m for features, 3m for reasons)

Reading to learn (p. 13-44)

    1 Condoms and vasectomy 1m x 2

2 Both vasectomy and IVD prevent the transfer of sperm to the female body. 1m

     However, contraception achieved by IVD is reversible while vasectomy is permanent.

     1m

3 Testes 1m

     Testes are the organs which produce male sex hormone. 1m

    ? Oxford University Press 2009

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