8/12/2019 [Edu.joshuatly.com] Johor Trial STPM 2010 Biology Paper 2 Section B [D0583877]

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CONFIDENTIAL* 20

Section B [60 marksl

Answer any four questions in this section

All the main energy-releasing pathways in acell start with glycolysis, which takes

cytoplasm and can proceed in the presence or absence ofoxygen.

(a) Outline the main stages of glycolysis.

(b) Explain what happens to the NADH that is formed in glycolysis

(i) in the presence ofoxygen(ii) in the absence of oxygen

6 (a) With the aid of a labelled diagram describe the structure of a skeletal musclethrough an electron microscoPe.

(a) Explain

(i) What causes the abnormalitY(ii) Theconsequencesfollowingfertilisation.

(b) Down syndrome is caused by mutation. Explain how it occurs.

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question paper is CONFIDENTIAL until the examination is over.

(b) Describe the sequence of events involved in the stimulation and contraction of a skeletal

muscle fibre.

(Start your answer at the point where the impulse reaches the end of the motor fibre.)

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The diagram below shows the process of abnormal spermatogenesis followed byfertilisation in humans.

iIIIII

IIII

l=_-I

I

I

l=_ --

lAf/\.(ryYvFertilisation

place in the

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8/12/2019 [Edu.joshuatly.com] Johor Trial STPM 2010 Biology Paper 2 Section B [D0583877]

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CONFIDENTIAL*

8 (a) What is lactose operon?(b) Explain how lactose operon is switched on and off.

(a) Define the following terms

(i) genomic library

(ii) oDNA library(b) Explain how transgenic bacteria containing the human gene for insulin can

using recombinant DNA technology.

l0 (a) (i) Define the term ecosystem.(ii) State three reasons why ecosystems are said to be dynamic.With named examples, state the roles of bacteria in the sulphur cycle.

Explain the trophic relationships in a tropical rain forest.

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question paper is CONFIDENTIAL untiltheexamination is over.

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(b)

(c)

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[6 marks]

19 marks)

[2 marks]

be produced

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