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Science questions, unit 3
Nama / NameKelas / ClassTarikh / Date

Microorganisms

40 marks. Use Practice to check each answer as you go, or Exam to answer everything first. Ask a grown-up to help you mark the written answers.

Section A: objective questions

12 marks
Choose the best answer for each question.
1

Question 1

What does the word microorganism mean?
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B
Micro means very small and organism means living thing.
For the teacher: Remembering, low difficulty, standard 3.1.1
Textbook p. 34
2

Question 2

Which microorganism reproduces by producing spores?
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A
Fungi, such as mould, reproduce by spores.
For the teacher: Remembering, low difficulty, standard 3.1.2
Textbook p. 34
3

Question 3

Diagram 1 shows three types of algae. Why are algae said to have the characteristics of plants?
Algae: Chlorella, Volvox and Chlamydomonas
Diagram 1
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B
Algae have chlorophyll and make food by photosynthesis, like plants.
For the teacher: Understanding, low difficulty, standard 3.1.2
Textbook p. 35
4

Question 4

Which is the smallest type of microorganism?
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C
Viruses are the smallest and need an electron microscope to be seen.
For the teacher: Remembering, low difficulty, standard 3.1.2
Textbook p. 35
5

Question 5

Paramecium and Amoeba are found in pond water. They can move to find food. What are they?
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D
Protozoa have animal characteristics: they move to find food.
For the teacher: Understanding, low difficulty, standard 3.1.2
Textbook p. 35
6

Question 6

A balloon is fixed on a bottle with yeast, sugar and warm water. After 30 minutes the balloon is bigger. What does this show?
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B
Yeast gives out gas as it breathes, so the balloon inflates.
For the teacher: Applying, medium difficulty, standard 3.1.3
Textbook p. 36
7

Question 7

Why is milk in a supermarket kept in a cold area?
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B
Low temperature slows growth, so the milk does not spoil quickly.
For the teacher: Applying, medium difficulty, standard 3.1.4
Textbook p. 40
8

Question 8

Vacuum-packed vegetables last longer than unpacked vegetables. Which factor is removed?
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C
A vacuum pack has no air, so microorganisms cannot grow well.
For the teacher: Applying, medium difficulty, standard 3.1.4
Textbook p. 42
9

Question 9

One apple slice is soaked in vinegar and another in tap water. The slice in vinegar stays fresh longer. What conclusion can be made?
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A
Vinegar is acidic, which is unsuitable for microorganisms to grow.
For the teacher: Analysing, high difficulty, standard 3.1.4
Textbook p. 44
10

Question 10

Which food product is made using bacteria?
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C
Bacteria are used to make yogurt. Yeast makes bread and fermented rice; fungi make tempeh.
For the teacher: Understanding, low difficulty, standard 3.1.5
Textbook p. 44
11

Question 11

Penicillin is an antibiotic made from some fungi. What does it do?
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A
Penicillin stops the growth of harmful bacteria.
For the teacher: Remembering, low difficulty, standard 3.1.5
Textbook p. 45
12

Question 12

Which disease is caused by fungi?
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D
Ringworm is a skin infection caused by fungi. The others are caused by viruses.
For the teacher: Understanding, low difficulty, standard 3.1.5
Textbook p. 46

Section B: structured questions

28 marks
Answer all questions.
13

Question 13

State the type of microorganism that fits each characteristic.
[1 mark] (a)Can produce its own food by photosynthesis.
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Algae
[1 mark] (b)Lives and reproduces only inside other living things.
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Viruses
[1 mark] (c)Has spherical, rod or spiral forms.
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Bacteria
[1 mark] (d)Reproduces through spores.
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Fungi
For the teacher: Remembering, low difficulty, standard 3.1.2
Textbook p. 34
14

Question 14

A drop of pond water is observed under a microscope. Organism X in the drop is an Amoeba.
[1 mark] (a)Name the type of microorganism that X is.
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[1 mark] (b)Predict the position of X after 5 minutes.
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[1 mark] (c)Give an inference for your answer in (b).
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[1 mark] (d)Name the life process shown.
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For the teacher: Applying, low difficulty, standard 3.1.3
Textbook p. 38
15

Question 15

Three equal glasses of fresh milk are treated as follows. A: kept in a refrigerator. B: kept at room temperature. C: boiled, then sealed in a thermal flask. The milk is observed daily for three days.
[1 mark] (a)State the manipulated variable.
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[1 mark] (b)State the responding variable.
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[2 marks] (c)Which milk spoils first? Explain.
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[1 mark] (d)State one thing that must be kept the same.
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For the teacher: Analysing, medium difficulty, standard 3.1.4
Textbook p. 40
16

Question 16

Two pieces of dried bread, A and B, are left in the same place. Only B is dipped in water. After five days B has mould and A has none.
[1 mark] (a)What factor affecting growth is being tested?
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[2 marks] (b)Explain the result.
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[2 marks] (c)Salmah says: "Bread A will never grow mould." Do you agree? Give a reason.
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For the teacher: Evaluating, medium difficulty, standard 3.1.4
Textbook p. 42
17

Question 17

Microorganisms can be useful and harmful.
[2 marks] (a)State two uses of microorganisms in making food.
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[1 mark] (b)How are bacteria useful in sewage treatment?
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[2 marks] (c)Explain how bacteria in the mouth cause tooth decay.
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[1 mark] (d)Name one infectious disease caused by a virus.
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For the teacher: Understanding, low difficulty, standard 3.1.5
Textbook p. 45
18

Question 18

A class makes a mould terrarium with a slice of bread and an orange peel, sprays water on each and closes the lid.
[1 mark] (a)Why is water sprayed on the food scraps?
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[1 mark] (b)Why must the lid of the terrarium not be opened?
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[2 marks] (c)Suggest where to place the terrarium for the fastest growth, and why.
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For the teacher: Creating, high difficulty, standard 3.1.6
Textbook p. 47