Samacheer Kalvi Class 8 Science Unit 16 Microorganisms Solutions
Welcome to NCTB Solutions. Here with this post we are going to help 8th class students by providing Solutions for Samacheer Kalvi Class 8 Science Unit 16 Microorganisms. Here students can easily find all the solved solution for Microorganisms Exercise questions. Also here our Expert Science Teacher’s solved all the questions with easily understandable language with proper guidance so that all the students can understand easily. Here on this post students will get Unit 16 Microorganisms exercise solutions. Here all the solutions are based on Tamil Nadu State Board latest syllabus.
Unit 16 Microorganisms Exercise Questions Solutions :
(I) Choose the best answer
(1) Microorganisms are measure in
(a) Cm
(b) Mm
(c) Micron
(d) Meter
Answer :
Correct Option → (b)
Microorganisms are measure in Mm.
(2) __ shows both living and nonliving characteristics.
(a) Protozoa
(b) Virus
(c) Bacteria
(d) Fungi
Answer :
Correct Option → (b)
Virus shows both living and nonliving characteristics.
(3) __ is a prokaryotic microorganism
(a) Virus
(b) Algae
(c) Fungi
(d) Bacteria
Answer :
Correct Option → (d)
Bacteria is a prokaryotic microorganism.
(4) Based on shape the bacteria are classified into ___ types
(a) Two
(b) Three
(c) Four
(d) Five
Answer :
Correct Option → (c)
Based on shape the bacteria are classified into Four types.
(5) Common cold in human is caused by
(a) Plasmodium
(b) Influenza
(c) Vibrio cholera
(d) Apthovirus
Answer :
Correct Option → (b)
Common cold in human is caused by Influenza.
(II) Fill in the blanks
(1) __ is prepared from a mould called penicillium.
(2) __ are the infectious protein particles.
(3) The infecting virus particle found outside the host cell is __
(4) Microorganism can be seen with the help of a __
(5) Bacteria, which has a flagellum at one end is classified as __
Answer :
(1) → Penicillin
(2) → Prions
(3) → Influenza
(4) → Microscope
(5) → Five types
(III) State true or false. If false, correct the statement
(1) Disease causing microorganisms are called pathogens.
(2) Female anopheles mosquito is a carrier of dengue virus.
(3) Chicken pox is a communicable disease.
(4) Citrus canker is transmitted by insects.
(5) Yeast is used in the large scale production of alcohol.
Answer :
(1) → True
(2) → False, because Female anopheles mosquito is carrier of malaria disease.
(3) → False, because this disease caused by virus.
(4) → False, because citrus canker is transmitted by bacteria.
(5) → True
(VI) Answer very briefly
(1) Write the name of any nitrogen fixing bacteria.
Answer :
A nitrogen fixing bacteria is Rhizobium bacteria.
(2) Name the bacteria used in the production of vinegar.
Answer :
Lactobacillus bacteria is used in the production of vinegar.
(3) Write the names of any three protozoans.
Answer :
Paramecia, Amoeba and Euglena are three protozoans.
(4) Who discovered penicillin?
Answer :
Sir Alexander Fleming discovered penicillin.
(5) Which diseases can be prevented by vaccination?
Answer :
Polio, Smallpox, Cholera, Typhoid, four diseases which can be prevented by vaccination.
(VII) Answer briefly
(1) Write the four types of bacteria, based on their shape.
Answer :
There are four types of bacteria based on their shape are as followings: –
(a) Bacilli : rod shaped bacteria.
Example : Bacillus anthracis.
(b) Spirilla : spiral shaped bacteria.
Example : Helicobacter pylori.
(c) Cocci : spherical or ball shaped bacteria.
(d) Vibrio : common shaped bacteria.
Example : Vibrio cholera.
(2) What are antibiotics?
Answer :
Antibiotics is a substance produced by living organism which is toxic for other organism. Antibiotics are used as preventing measures against disease .antibiotics are first time discovered by the person Sir Alexander Fleming in the year 1928. The antibiotic penicillin was obtained from the fungi Penicillium chrysogenum. Antibiotics used to treat disease like tetanus and diphtheria.
(3) What are pathogens?
Answer :
Some microorganism are harmful to plants, animals and humans they causes diseases therefore they are called as pathogens. Pathogens enter into the body through cuts and wounds in the skin, mouth or nose and causes disease.
(5) Why microorganisms are essential for agriculture?
Answer :
Microorganisms are called as decomposers because they act upon degradable wastes. During the process of nitrates and other inorganic nutrients are released into the soil, making the soil fertile are do by microorganism .there are some bacteria also which fixes nitrogen in the soil. Some microorganism act as bio control agents they protect crops from some pest therefore microorganism re essential for agriculture.
(VIII) Answer in detail
(1) Write a short note on bacteria and its structure.
Answer :
Bacteria are the singled celled prokaryotes. They consisted to be the first living organism on the earth. Bacteria are grouped under the kingdom Monera. The study of bacteria called bacteriology. The size of bacteria ranges from 1um to 5um. Cell structure of bacteria: –
A bacterium has an outer covering known as the cell wall. Nuclear material is represented by a nucleotide without nuclear membrane. An extra chromosomal DNA called plasmid is present in the cytoplasm. Protein synthesis is carried out by 70s ribosomes. Other cell organells are absent. Flagella aids in locomotion.
Bacteria are classified according to their shape into four types: –
- Bacilli –rod shaped bacteria for eg. Bacillus anthracis.
- Spirilla- spiral shaped bacteria. For eg.- Helocobacter pylori.
- Cocci- spherical or ball shaped bacteria.
- Vibrio- common shaped bacteri. For eg- Vibrio cholera.
Bacteria also classified form their flagella into five types: –
- Monotrichous
- Lophotrichous
- Amphitrichous
- Peritrichous and
- Atrichous
(2) How microorganisms are useful in the field of medicine?
Answer :
Microorganism are useful in the medicinal field is like we obtained antibiotics and vaccine form microorganism.
- Antibiotics :
Antibiotics is a substance produced by living organism which is toxic for other organism. Antibiotics are used as preventing measures against disease antibiotics are first time discovered by the person Sir Alexander Fleming in the year 1928. The antibiotic penicillin was obtained from the fungi Penicillium chrysogenum. Antibiotics used to treat disease like tetanus and diphtheria.
- Vaccines :
Vaccines are prepared from dead or weakened microbes. Edward Jennar was the first person to discover small pox vaccine. He coined term vaccination. When the vaccine is injected to the body of a paitent, the body produces antibodies to fight against the grems. This antibodies remain inside the body and protect from future invansion of the grems. Therefore vaccination is otherwise called immunization. Eg. BCG vaccine is given preventing tuberculosis.
This are the uses of microorganism in medicines as antibiotics and vaccines.
(3) Write a short note on common human diseases caused by microorganisms.
Answer :
Some common human diseases caused by microorganisms are
- Tuberculosis – Mycobacterium tuberculosis bacteria
- cholera – Vibrio cholera bacteria
- Common cold – Influenza virus
- Rabies – Rahabdo viridae virus
- Malaria – Plasmodium protozoa
This are the some common disease and causative microorganism which are spread through air, infected person to healthy person ,food, water and flies, through mosquito etc from this microorganism transfer and spread disease.
(5) Write a short note on probiotics.
Answer :
Probiotics are live food supplements used in yogurt and other fermented milk products. For eg. Lactobacillus acidophilus and Bifidobacterium bifidum. These bacteria improve the microbial spectrum in the gut and contribute to followings are effects
(a) Decreases the risk of colon cancer.
(b) Decreases cholesterol absorption
(c) Prevent diarrheal disease by increasing immunity.
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