Bacteria

IGCSE Programme Biology 0610 –Revision Test Name: ________________________ Class: Date: __ / __ / First Semester 2010 ____ _____ Topic: Bacteria. Mark: out of [40] Duration: (45 min) Dear Students, this revision test will cover everything related to bacteria related to in Biology 0610 Syllabus. Answer ALL Questions. 1. When bacteria are spread onto agar in a Petri dish they form colonies. Each colony forms from one bacterium. Fig. 4.1 shows an investigation into antibiotic resistance in a species of bacterium that causes disease. To be uploaded to CIE

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(a) Explain what is meant by the term antibiotic. ……………………………………………………………………………………………………………………………… ……………………………………………………….. ……………………………………………………………………………………………………………………………… ……………………………………………………….. ……………………………………………………………………………………………………………………………… ………………………………………………… [2] (b) Explain why (i) only a few bacteria grew in dish B compared with dish A, ……………………………………………………………………………………………………………………………… ……………………………………………………….. ……………………………………………………………………………………………………………………………… ………………………………………………… [1] (ii) more bacteria grew in C than in B. ……………………………………………………………………………………………………………………………… ……………………………………………………….. ……………………………………………………………………………………………………………………………… ………………………………………………… [1] (c) Fig. 4.1 shows the effect of an antibiotic on a species of disease-causing bacterium. Suggest why antibiotics should not be used too often. ……………………………………………………………………………………………………………………………… ……………………………………………………….. ……………………………………………………………………………………………………………………………… ……………………………………………………….. ……………………………………………………………………………………………………………………………… ……………………………………………………….. ……………………………………………………………………………………………………………………………… …………………………………………..…… [2] (d) Explain the possible effect of the X-rays on the bacteria. ……………………………………………………………………………………………………………………………… ……………………………………………………….. ……………………………………………………………………………………………………………………………… ……………………………………………………….. ……………………………………………………………………………………………………………………………… ……………………………………………………….. ……………………………………………………………………………………………………………………………… …………………………………………..…… [3] 2

(e) State two ways in which the structure of a bacterium differs from the structure of a virus. 1……………………………………………………………………………………………………………………………… ………………………………………………….. ……………………………………………………………………………………………………………………………… ……………………………………………………. 2……………………………………………………………………………………………………………………………… …………………………………………………… ……………………………………………………………………………………………………………………………… …………………………………………..…… [2] [Total: 11]

0610/32/M/J/10

2. Fig. 4.1 shows the change in percentage of disease-causing bacteria that were resistant to the antibiotic penicillin from 1991 to 1995.

(a) (i) Describe the change in the percentage of bacteria resistant to penicillin between 1991 and 1995. ……………………………………………………………………………………………………………………………… ……………………………………………………….. ……………………………………………………………………………………………………………………………… ……………………………………………………….. ……………………………………………………………………………………………………………………………… ……………………………………………………….. ……………………………………………………………………………………………………………………………… …………………………………………..…… [2] (ii) Explain how a population of antibiotic-resistant bacteria can develop. ……………………………………………………………………………………………………………………………… ……………………………………………………….. ……………………………………………………………………………………………………………………………… ………………………………………………………..

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……………………………………………………………………………………………………………………………… ……………………………………………………….. ……………………………………………………………………………………………………………………………… ……………………………………………………….. ……………………………………………………………………………………………………………………………… …………………………………………..…… [4] (b) Although bacteria can cause disease, many species are useful in processes such as food production and maintaining soil fertility. (i) Name one type of food produced using bacteria. ……………………………………………………………………………………………………………………………… ………………………………………………… [1] (ii) Outline the role of bacteria in maintaining soil fertility. ……………………………………………………………………………………………………………………………… ……………………………………………………….. ……………………………………………………………………………………………………………………………… ……………………………………………………….. ……………………………………………………………………………………………………………………………… ……………………………………………………….. ……………………………………………………………………………………………………………………………… …………………………………………..…… [3] (c) Bacteria are also used in genetic engineering. Fig. 4.2 outlines the process of inserting human insulin genes into bacteria using genetic engineering.

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Complete the table below by identifying one of the stages shown in Fig. 4.2 that matches each description.

[5] [Total: 15] 0610/03/O/N/06

3. The antibiotic penicillin is produced by fungi that are grown in a fermenter, as shown in Fig. 3.1. The process is similar to the manufacture of enzymes.

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(a) (i) Name the two raw materials likely to be present in the feedstock. 1……………………………………………………………………………………………………………………………… ………………………………………………….. 2……………………………………………………………………………………………………………………………… ……………………………………………… [2] (ii) State the function of X. …………………….. ……………………………………………………………………………………………………………………………… ………………………… [1] (iii) Suggest the name of the main gas present in the waste gases. …………………….. ……………………………………………………………………………………………………………………………… ………………………… [1] (b) During the fermenting process, the temperature in the container would rise unless steps are taken to maintain a constant temperature. (i) Suggest a suitable temperature for the feedstock. …………………….. ……………………………………………………………………………………………………………………………… ………………………… [1] (ii) Explain why the temperature rises. 6

……………………………………………………………………………………………………………………………… ……………………………………………………….. ……………………………………………………………………………………………………………………………… ………………………………………………… [2] (iii) Explain why a constant temperature has to be maintained. ……………………………………………………………………………………………………………………………… ……………………………………………………….. ……………………………………………………………………………………………………………………………… ……………………………………………………….. ……………………………………………………………………………………………………………………………… …………………………………………………. [2] (iv) Using the information from Fig. 3.1, suggest how a constant temperature is maintained. …………………….. ……………………………………………………………………………………………………………………………… ………………………..… [1] [Total: 10] 0610/31/O/N/08 4. (a) Penicillin can be used to treat bacterial infections. Suggest why penicillin can be used to treat bacterial infections in humans. ……………………………………………………………………………………………………………………………… ……………………………………………………….. ……………………………………………………………………………………………………………………………… ……………………………………………………….. ……………………………………………………………………………………………………………………………… …………………………………………..…… [2] (b) Seven small paper discs were soaked in solutions of different antibiotics, A to G. The paper discs were placed on an agar plate which was evenly covered with growing bacteria. This was left for a short time. The results are shown in Fig. 3.4.

(i) Select which antibiotic, A to G, is most effective.

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…………………….. ……………………………………………………………………………………………………………………………… ………………………..… [1] (ii) Give a reason for this choice of antibiotic in (i). ……………………………………………………………………………………………………………………………… ……………………………………………………….. ……………………………………………………………………………………………………………………………… …………………………………………………. [1] [Total: 4] 0610/62/M/J/10

Name: ________________________ Topic: Bacteria.

IGCSE Programme Biology 0610 Test Class: Date: __ / __ / ____ _____ Mark: out of [40]

First Semester 2010 Duration: (45 min)

Mark Scheme & Material Related 1. (a)

drug / medicine(AW) / chemical / substance ; produced by microorganisms ; A ref to idea of synthetic analogues kills / stops, growth of, bacteria / other microbes ;

medicine / AW e.g. ‘(antibiotic) used to treat infection’ is worth a mark A examples e.g. penicillin qualified ‘penicillin is an antibiotic that kills bacteria/AW’ would gain 2 marks [2] penicillin alone cannot score R viruses

(b )

(i) (most) were killed by the antibiotic ; ora [1]

(c)

resistant bacteria, survive / not killed / are selected for / selection pressure ; eventually, all / many, become resistant ; AVP ; e.g. any consequence of overuse / antibiotic no longer effective ; [max 2]

(d )

X-rays caused mutations ; change in DNA ; ref to, gene / allele ; mutation causes antibiotic resistance ; [max 3]

(e)

assume answer is about bacteria unless told otherwise, accept ora / AVP for viruses e.g. capsid

(ii) (only) antibiotic-resistant bacteria transferred from B / (only) resistant bacteria in C / fewer resistant bacteria in B / non-resistant bacteria were killed in B ; [1] R references to immunity as alternative to resistance

ALLOW radiation

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R nucleus in bacteria IGNORE composition of cell

bacteria have cells ; cell wall ; cell membrane ; cytoplasm ; ribosome(s) ; flagellum ; capsule ; AVP ;

wall

[max 2] 2.

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3.

4. (a) human cells lack cell wall; human cells not affected; bacteria can’t grow / killed / weakened / unable to reproduce; (b) (i) E; [1] more than one letter = 0 (ii) largest clear area surrounding disk /more bacteria are affected / killed; [1]

Material Required for this Test: Everything about Bacteria including: -

Classification of Bacteria

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Natural Selection in Bacteria

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Genetic Engineering

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Uses of bacteria and about the antibiotic penicillin, its manufacture, mechanism of action.

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Understand how mutation takes place in Bacteria .

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Role of nitrifying and denitrifying bacteria in soil.

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