The City SchoolNorth Nazimabad Girls Campus

Science Class-8Topic: Microorganisms and Diseases

Name: ______________________ Date_______________ Sec: _________ 1. What are Microbes? Give another term for Microbes.

2. Name the 3 types of Microbes which are eukaryotic.

3. What are Yeasts?

4. What is the use of the flagellum in bacteria?

5. Give 2 differences between a bacterium cell and a fungal cell.Why do scientists say that Virus is NOT a living thing?

6. Give a difference in structure between a virus and a bacterium.

7. Give 2 examples of useful microbes. Explain how are they useful

8. Whivh term is used to describe harmful microbe. How does a microbe harmful to us?

9. Complete the table: Examples of Infectious diseases caused by different group of pathogensViral diseases Bacterial diseases Fungal diseases

10. There are 5 different ways in which infectious diseases can be transmitted from persons to persons. Complete the table with an example of the disease and the type of microbe involved.

Transmission Diseases Group of microbes

FluParasitic protozoan – carried by an infected Mosquito

Water (contamination)Food poisoning

Touch

11. What is the general purpose of having natural barriers in our body?

12. Write down the action of each of these barriers:

Barrier How does it help to defense the body?

Acid in the stomach

Mucus and Cilia in the Windpipe (Trachea)

Tears

Skin

13. There are 2 main types of White blood cells based on their functions:

(1) Phagocytes (that can change body shape) Function:

(2) Lymphocytes (that produce chemicals)Function:

14. What is the difference between antigens and antibodies?

15. What are Antibiotics? Why is it necessary to complete the course of antibiotics?

16. Why do doctors not prescribing antibiotics to people with flu and cold?

17. The following shows a graph related to immunity of a disease

a. How many days did it take for the Primary response to reach the peak?

FIVE GROUPS OF MICROORGANISMS

b. How many days did it take for the Secondary response to reach the peak?

c. Which response is quicker?

d. Give another reason why this response (your answer for c) is more effective?

18. Why is Vaccination important?

19. What are vaccines?

20. Can vaccines work against viruses other than bacteria? Give 2 examples.

21. 1. Based on their characteristics, microorganisms can be classified into five groups. Complete the diagram below.

22. Diagram below shows microorganisms.

Identify the group of microorganisms A, B, C , D and E

A: ………………….. B: ………………….. C: …………………………

D: …………………… E: ………………….. 23. Complete the table below;

Characteristic Group of microorganisms(a) Exist in different shapes and are generally named according to their shapes.

(b) Cannot reproduce outside living cell.

(c) Can be crystallized.

(d) They are able to make their own food by photosynthesis.

(e) Most reproduce asexually by formation of spores or sexually by conjugation.

A B D EC

(f) They are unicellular animals and have the structure of general animal cells.

24. The statements below show the uses and roles of beneficial microorganisms in daily life

A Yeast acts on carbohydrate to produce carbon dioxide that cause breads and cakes to rise.B Dead organisms such as plants and animals undergo a process called decomposition

caused by bacteria and fungiC Penicillin, which is produced from a certain type of fungus helps us to produce

antibiotics.D Microorganisms such as bacteria and virus play an important role in the preparation of

vaccines.E Certain algae produce beta carotene to prevent cancerF Bacteria living in herbivores digestive system secrete an enzyme called cellulose which

helps to digest cellulose.G Nitrogen fixing bacteria helps to bind nitrogen from the atmosphere and convert it to

nitrate in the soil.H Yeast acts on glucose solution to produce alcohol.I Bacteria is used to oxidize alcohol in making of vinegar J Microorganisms are also used in biological control

Group the above statements into five categories

Category Statement (a) Food digestion

(i)………………………………………………………………….(b) Decaying process

(i)………………………………………………………………….

(c) Medicine

(i) ………………………………………………………………..

(ii) ………………………………………………………………..

(iii) ……………………………………………………………….

(d) Agriculture (i) ………………………………………………………………..

(ii) ………………………………………………………………..

(e) Industry

(i) ………………………………………………………………..

(ii) ………………………………………………………………..

(iii) ……………………………………………………………….

25.Some of the cells in the lining TRACHEA are shown below. They are part of your body’snatural defenses against microbes. Label the given diagram.

Some cells produce mucus. How do mucus and ciliated epithelial cells defend the body againstdisease?i mucus __________________________________________________________ii ciliated epithelial cells __________________________________________________________

26. Bacteria in the mouth can cause tooth decay. Toothpaste contains a chemical that helps to killbacteria in the mouth. What might this chemical be? Tick one.

Disinfectant antiseptic antibiotic antibodies

27 The graph shows the change in the numbers of antibodies when a person is infected by thechickenpox virus.

a After the infection, the number of antibodies never goes back to zero. Explain why this is useful to a person.__________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________b Draw a line on the graph to predict the increase in antibodies if the chickenpox virus infectedthis person again one year later. Start your line at day ‘0’ (when the infection occurs) and label

it ‘antibodies due to chickenpox virus’.

28.Emma made some yoghurt.She washed a pot with boiling water, then let the pot cool. She put some milk into the pot and added something called ‘yoghurt starter culture’. She covered the pot with cling film and left it in the refrigerator.a Suggest what was in the ‘yoghurt starter culture’.______________________________________________________________________

b Why was it a good idea to wash the pot out with boiling water?..............................................................................................................................c Why was it important to let the pot cool down before adding the milk and starter culture?..............................................................................................................................

d Emma was disappointed to find that the milk was taking a very long time to turn into yoghurt. What could she have done to speed it up?..............................................................................................................................

e Emma measured the pH of the milk before she put it into the pot, and found that it was 6.4. The pH of the yoghurt that she made was 5.2. What had been happening in the pot to cause this change in pH?..............................................................................................................................

29. This diagram shows the apparatus you could use to investigate respiration inyeast.

a On the diagram, draw label lines and label:i solution containing yeastii lime water

b What else needs to be added to the yeast solution, so that the yeast can respire?..............................................................................................................................

c Describe what you will see happening in the lime water, and explain why this happens...............................................................................................................................

..............................................................................................................................

..............................................................................................................................d How does yeast respiration help us to make bread?..........................................................................................................................................................................................................................................................................................................................................................................................

30. Dr Simms wanted to find out which antibiotic was most effective against a particular kind of bacteria.She poured a liquid containing the bacteria over some agar jelly in a Petri dish. She soaked little circles of filter paper in four different antibiotics. She placed the filter paper circles onto the agar jelly. She taped the lid on, and put the dish into a warm place.

a Dr Simms made sure the Petri dish and the agar jelly were sterile before she began her experiment. Suggest why this was important.............................................................................................................................................................................................................................................................

b The clear areas around some of the discs showed that the antibiotics in these discs had stopped the bacteria reproducing and forming colonies. Measure the diameter of the clear area around each disc. Record yourresults in a table in this space.c Which antibiotic was most effective at stopping the bacteria from reproducing?..............................................................................................................................

d Suggest how the molecules of antibiotic had spread out into the agar jelly around the discs.............................................................................................................................................................................................................................................................e Explain why antibiotics are no use for curing ’flu.............................................................................................................................................................................................................................................................31. The graph below shows the deaths from infectious disease in the UK for most of the twentieth century.

1. Describe the trend the graph shows.

2. Write down as many reasons why this trend has occurred, there are at least 4.

3. In which period of 10 years does the death rate decline most rapidly?

4. Give a reason why the death rate drops so much in this time.

5. There are two periods when the death rates increased again, give a reason for these

32.How can a body that previously came into contact with an antigen be immunized against future infections by the same agent?33.The picture is showing how lymphocytes help to kill bacteria, explain this process.

OBJECTIVESQ1.Complete these sentences, using some of these words. Antibiotics antibodies bacterium disinfectant immune pathogen red vaccine virus whiteA micro-organism that can cause disease is called a ......................................... .If some of these micro-organisms get into your body, they may breed and make you ill. Your ...................... blood cells help to defend you against them, by making chemicals called ......................................... .When you have had the disease once, your body will be ready to destroy that nkind of micro-organism again, so you have become .........................................to that disease. Another way of becoming immune is to be injected with a........................... containing dead or weakened micro-organisms.

Q2.Multiple Choice 1. Which of the following CORRECTLY describes the size of fungi compared to the size of bacteria? A. Fungi are larger. B. Bacteria are larger. C. They are about the same size. D. They are the same size but different shapes. Use the diagram of the paramecium to answer questions #2 & #3 2. What is the paramecium’s body composed of?A. thousands of cells B. four cells C. one cell and its parts D. several body organ systems 3. What is the function of the cilia marked by “X”? A. to move the paramecium B. to take in water and remove wastes C. to control cell division D. to make food from sunshine and air 4. Which of the following BEST describes where microorganisms live?

A. Underwater. B. In warm, humid places. C. Nearly everywhere D. Sunny, dry areas.

The foods listed on this data table were left in plastic bags in a warm container for five days. Observations were made and recorded at the end of the experiment. Use this information to answer questions #5 thru #8..

X

5. Which of these hypotheses might have been tested in this experiment? A. Foods left in the dark will rot differently than foods in light. B. Will foods react differently to plastic bags? C. If different foods are decayed, they will not decay the same. D. What kind of bacteria is best for making cheese? 6. What variable was tested in this experiment? A. The length of time it takes for food to rot. B. What kind of bags allows rotting to occur? C. The temperature microorganisms like best. D. How different kinds of food rot. 7. Which of the following is a conclusion you could make concerning these data? A. All foods rot when left in a warm place for 5 days. B. Bread is better for you to eat than cheese. C. Different microorganisms prefer different kinds of food. D. Meat is less safe to eat than other foods because it smells bad. 8. How might a student improve this experiment? A. Count the number of microorganisms on each food with a toothpick.

B. Use a microscope to identify the kinds of microorganisms. C. Add some strong chemicals and see what they do to the foods. D. Kill the microorganisms and make the food safe.

9. What have experiments shown scientists about the cause of disease?A. Diseases are caused by sudden changes in the weather. B. Diseases are caused by too much exercise. C. Microorganisms cause many diseases. D. Little can be done to prevent disease. 10. Which of the following practices is based on an understanding of microorganisms? A. Walking downhill instead of running. B. Looking both ways before crossing a street. C. Wearing lightweight clothes in the summer. D. Washing your hands before eating. 11. What important function do microorganisms have in an ecosystem? A. They produce food from sunlight. B. They reduce the number of large animals. C. They decompose dead organisms. D. They help to clean the air.12. How does adding yeast change bread dough? A. Bubbles of gas form in the dough B. Yeast changes the breads’ color. C. More dough is produced as yeast multiply. D. Yeast makes it more less lumpy. 13. How do bacteria help our bodies’ function? A. They make our muscles and lungs stronger B. They help to digest food in the intestines. C. They circulate in our blood and help carry oxygen. D. They make our skin flexible and clean. 14. Which of the following correctly pairs a microorganism with the disease it creates? A. protozoa-the flu C. bacteria-strep throat B. virus-athlete’s foot D. fungi-a cold 15. Which statement is true of ALL bacteria? A. All bacteria are single-celled organisms. C. All bacteria have a cell with a nucleus. B. All bacteria are producers. D. All bacteria live in water. Every morning Sara eats an orange. Her mother keeps a bowl of fruit on the kitchen table for the family. Sara has noticed that this summer, the oranges have a few spots with white powdery appearance and taste bitter. She wonders what is happening.

16. Using your knowledge of fungi, which of the following might prevent the mold from growing? A. Buy a different type of orange. C. Put the oranges in a warm place. B. Keep the oranges in the refrigerator. D. Put the oranges in a damp place. 17. What can many protozoa do that other microorganisms cannot do? A. Speed the decay of dead organisms. C. Produce waste products harmful to people. B. Depend on other organisms for food. D. Move by themselves.

Q.3Matching Study the following drawings and then match the organism to its characteristic. PLEASE NOTE: There may be more than one answer per question. Answers may be used once, more than once, or not at all.

Organism Characteristic ____________ 1. Bacteria a. structures for movement b. simplest form ____________ 2. Fungi c. anchored in one spot d. observable nucleus ____________ 3. Algae e. some forms can be seen with our eyes only

f. green in color ____________ 4. Protozoan g. observable nucleus

h. producer Q.4True/False Correct Read the following statements. If it is true, circle “T” and go to the next questions. If the answer is false, circle “F” and CHANGE THE STATEMENT SO IT IS TRUE. T F 1. Algae are producers. T F 2. An example of a decomposer is fungi. T F 3. A consumer MAKES its own food. T F 4. Anton Van Leeuwenhoek is considered the father of the microscope. T F 5. An amoeba moves using pseudopods. T F 6. Three shapes of bacteria are round, rod, and spiral. T F 7. Bacteria help make foods like chocolate and cheese. T F 8. Fungi cause most crop disease.

Q.5Matching, _____ 1. Algae A. Neither plant nor animals, but have characteristics of both and absorb food from whatever they are growing on. _____ 2. Bacteria B. Single-celled animal-like organism that lives in water. _____ 3. Conclusion C. Organism made up of only one cell. _____ 4. Control D. Living thing (like a plant) that makes its own food. _____ 5. Culture E. Living thing that can only be seen with the aid of magnification. _____ 6. Decomposer F. Idea that can be tested through an experiment. _____ 7. Fungi G. Summary of an experiment. _____ 8. Hypothesis H. Breaks down dead plant and animal matter. _____ 9. Microorganism I. Part of an experiment that can be changed. _____ 10. Organism J. Grow microorganisms in a specially prepared nutrient. _____ 11. Protozoan K. Plant-like; lives in water; produces oxygen through photosynthesis. _____ 12. Producer L. A part of the experiment that is unchanged. _____ 13. Single-Celled M. Microscopic, single-celled organism that exists everywhere. _____ 14. Variable N. Any living thing.

Q.6

Q.7

a. How many yeast cells were in the sample after 7 days? 2 days?b. How do you think the rate of growth would have been affected if the following factors were altered? the wine was kept at a lower temperature

more sugar was added before it fermented

c. After seven days the rate of growth of the population started to slow down, give a reason for this.

d. What is a factor called that causes a population to stopdecreasing?

Q.8The pictures below show some examples of micro organisms with a scale given for each. 1µm (micrometre) = 0.001 mm, 1 nm (nanometre) = 0.000001 mm.

Look carefully at each microbe and its scale. Draw a table in the space below to show the lengths (or diameters if circular). Put the organisms in order of size starting with the largest.

Q.9