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SBA2_ans_e[1]

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SBA2_ans_e[1]

New Senior Secondary Mastering Biology Book 2 Practical workbook answer p.1/15

    Suggested answers to Practical Workbook

    for SBA

    Ch 11 Cell cycle and division

    Practical 11.1 Examination of different stages of the cell cycle

    Questions (p. 11-2)

    1

    Mitosis (Nuclear division) Cell growth Cytoplasmic Cell Stage 2 Stage 3 Stage 4 (Prophase) division Stage 1 (Metaphase) (Anaphase) (Telophase)

    ? A

    ? B

    ? C

    ? D

    ? E

    ? F

    ? G

    ? H

    ? I

    ? J

2 Interphase: Individual chromosomes cannot be distinguished.

     Prophase: Chromosomes become visible, each is seen to consist of two chromatids held

    together at the centromere. The nuclear membrane disintegrates.

     Metaphase: The chromosomes line up in the middle of the cell.

     Anaphase: The two chromatids of each chromosome separate and move to the opposite

    poles of the cell. The cytoplasm starts to divide.

     Telophase: New nuclear membranes form around each set of chromosomes. The

    chromosomes uncoil to become chromatin again.

3 The cells near the tips divide actively by mitotic cell division.

? Oxford University Press 2009

New Senior Secondary Mastering Biology Book 2 Practical workbook answer p.2/15

    Practical 11.2 Investigation of the relative time required for each

    stage of the cell cycle

    Results (p. 11-6)

    1

2

    Number of cells in the stage Relative time spent in the stage Stage (min) Area 1 (A) Area 2 (A) Area 3 (A) 123

    Interphase 23 25 24 551

    Prophase 3 2 3 61

    Metaphase 2 2 1 38

    Anaphase 1 1 1 23

    Telophase 1 2 1 30

    Cytoplasmic 1 0 1 15 division

    Total number of cells in each area T1 = 31 T2 = 32 T3 = 31 ? Oxford University Press 2009

New Senior Secondary Mastering Biology Book 2 Practical workbook answer p.3/15

3

    Questions (p. 11-8) 1 To expose more cells for observation.

2 a To intensify the stain.

    b To avoid the slide being overheated and broken.

3 The number of cells in each phase is directly proportional to the time required by the cells

    in that phase.

4 a (Answer varies with results.)

    b (Answer varies with results.)

    5 a The results are different. This is because different students and groups used slightly

    different criteria to categorize the phases (i.e. personal judgment and subjectivity) or

    different groups collected their data from different samples.

    b No. The findings are based on an assumption without testing. If the assumption is

    wrong, the findings will also be incorrect.

    c Subjectivity; Tentativeness; Observation vs. Inference; Creativity; Empirically

    based.

    Conclusion (p. 11-9) Interphase takes the longest time in the cell cycle. Phases in mitosis are relatively short.

    ? Oxford University Press 2009

New Senior Secondary Mastering Biology Book 2 Practical workbook answer p.4/15

    Practical 11.3 Examination of meiotic cell division

    Questions (p. 11-13)

    1 4.

2 8.

3 a?b?d?c?e

     a) Homologous chromosomes line up at the middle of the cell. ? b) Separation of

    homologous chromosomes. ? d) Formation of two daughter cells each with chromosome

    number halved. ? c) Arrangement of chromosomes at the middle of the cell. ? e)

    Formation of four haploid daughter cells.

? Oxford University Press 2009

New Senior Secondary Mastering Biology Book 2 Practical workbook answer p.5/15

    Ch 12 Reproduction in flowering plants

    Practical 12.1 Examination of binary fission in bacteria

    Results (p. 12-2)

    Questions (p. 12-2) 1 2

2 Mitotic cell division.

    3 a Binary fission is a type of asexual reproduction.

     b Binary fission does not involve gametes.

    The offspring are genetically identical to each other and to the parent.

4 b?a?c

? Oxford University Press 2009

New Senior Secondary Mastering Biology Book 2 Practical workbook answer p.6/15

    Practical 12.2 Examination and cultivation of a vegetative

    propagating organ

    Results (p. 12-5) 1

2 The iodine solution turns dark blue in colour.

3 a (Results vary with Ss.)

     b (Results vary with Ss.)

Questions (p. 12-6)

    1 Vegetative propagation is the process by which the vegetative parts of the flowering plants

    develop into new plants.

2 Starch is stored in the tuber.

3 The buds of the tuber.

4 The swollen end of an underground stem.

    5 The potato tuber becomes smaller because food stored in the tuber is used up for the

    development of a new plant.

    6 1 In spring, the buds use the food stored in the tuber to produce adventitious roots and

    shoots.

     2 In summer, some food made in the leaves is sent to the underground shoots and

    stored. The ends of underground shoots swell and form new tubers.

     3 In winter, the aerial shoots die and the new tubers remain dormant.

     4 In the next growing season, each bud in the tubers may grow into a new plant.

    ? Oxford University Press 2009

New Senior Secondary Mastering Biology Book 2 Practical workbook answer p.7/15

    Practical 12.3 Dissection and examination of a flower

    Results (p. 12-11)

    1

    Floral part Colour Number

    Sepal Greenish yellow 5

    Petal Yellow 5

    Stamen Brown 10

    Carpel Greenish yellow 1

2

? Oxford University Press 2009

New Senior Secondary Mastering Biology Book 2 Practical workbook answer p.8/15

    3

4

    L.S. of ovary

    T.S. of ovary

? Oxford University Press 2009

New Senior Secondary Mastering Biology Book 2 Practical workbook answer p.9/15

    Questions (p. 12-13)

    1

    Name Function Stigma Receives pollen grains

    Ovary Contains ovules which carry female gametes Flower stalk Attaches the flower to the main stem of the plant Style Supports the stigma

    Anther Produces pollen grains which carry male gametes Filament Supports the anther

    Petal Protects the inner parts of the flower and attracts insects Sepal Protects the inner parts of the flower when it is a bud

2 a carpel

     stamen

     b corolla

     calyx

3 The ovary develops into the fruit.

4 The flowers are bisexual because they have both stamens and carpels in the same flower.

? Oxford University Press 2009

New Senior Secondary Mastering Biology Book 2 Practical workbook answer p.10/15

    Practical 12.4 Examination of an insect-pollinated flower and a

    wind-pollinated flower

    Results (p. 12-17)

    1

    Part of the Feature Gladiolus flower Grass flower flower

    Size Large Small Petal (Result depends on the Colour Brown specimen.)

    Way of attachment to Firmly attached Loosely attached the filament Anther Enclosed inside the Position Hang outside the flower flower

    Quantity Small in number Large in number Pollen grain

    Texture Rough and sticky Smooth and dry

    Size Relatively smaller Relatively larger

    Enclosed inside the Stigma Position Hang outside the flower flower

    Texture Sticky Feathery Nectary Present / Absent Present Absent

2

    Gladiolus flower Grass flower

? Oxford University Press 2009

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