Class 8 science chapter 2 extra questions and Answers

Bacteria are classified regarding their shape and they are as follows:- i. Spirilla:- spiral-shaped bacteria ii. Cocci:- sphere-shaped bacteria iii. Bacilli:- rod-shaped bacteria iv. Vibrios:- curved-shaped bacteria

The process in which the microorganisms are converted into alcohol or sugar is called fermentation.

A technique that is used to increase the immunity of the body to fight against disease-causing microorganisms is called vaccination or immunization.

A special type of microscope that can detect organisms of much smaller size like viruses.

1. a
2. d
3. c
4. b
5. a

Living organisms that are too tiny to be seen with the unaided human eyes. They only can be seen through Microscope.

Algae are plant like organisms & have cell wall around them. They are autotrophs as they contain chlorophyll.

Ex: Spirogyra, volvox

Algae
§ Have cell wall
§ Possesses chlorophyll
§ Unicellular or Multicellular
Protozoa
§ No cell wall
§ Heterotrophic
§ Unicellular

Viruses when enters hosts body they start behaving like a living organisms. It reproduces & carries out other life processes inside host body.

Official name of Coronavirus is Covid 19 or SARS-COV-2.

• Microorgansim Lactobacillus converts milk into curd.
• Fungus penicillium used as antibiotics in medicinal field

Process by which the microorganisms converts a sugar into an acid or an alcohol is called fermentation.

Microorganisms that cause diseases are called pathogens.

Ex: Common cold , Tuberculosis

Bacteria are unicellular organisms. They live together in colonies of millions.Most of them are harmless but few of them are disease causing bacterias such as Cholera & Tuberculosis.

Based on their shapes bacteria are classified into four types-

Spirilla- Spiral bacteria

Cocci- Sphere Shaped Bacteria

Bacilli- Rod Shaped Bacteria

Vibrios- Comma Shaped Bacteria

Our food can be contaminated by microorganisms. Food preservation is the process of making sure our food doesn't get contaminated by microorganisms. Food can be preserved in a number of ways. Some of food preservation methods are:

1. Drying: It reduces the moisture in food, which stops the growth of microorganisms.
2. Refrigeration and freezing: This growth of microorganisms is slowed by low temperatures. As a result, it is suitable for human consumption.
3. By oil and vinegar : Using oil and vinegar to preserve pickles minimizes spoiling since bacteria cannot survive in such an environment.
4. Using common salt and sugar: Dry salt is applied to meat and fish to prevent microbial growth. Sugar lowers moisture content, preventing the formation of microorganisms that ruin food.

Antibiotics are medications that are preferred during illness. They are used to treat bacterial infections in humans and animals. They either kill the bacteria or make it hard for the bacteria to grow and multiply. Precautions to take while using antibiotics include:
(i) They should only be used with the advice of a trained doctor.
(ii) The doctor-recommended course must be completed.
(iii) They should only be taken in the recommended doses.
(iv) Do not take these medications when they are unnecessary or in the incorrect dosage. It may make the drug less effective if you need it in the future.
(v) Unnecessary antibiotic use can kill beneficial microorganisms in the body.

Microorganisms can be harmful in a number of ways. Some microorganisms, for example, cause diseases in humans, other animals, and plants. Pathogens are microorganisms that cause disease. Pathogens can be bacteria, viruses, protozoa, or fungi, among other things.

Diseases caused by microorganisms include tuberculosis (TB), tetanus, diphtheria, whooping cough, cholera, typhoid, AIDS, food poisoning, malaria, smallpox, and chickenpox, etc..

Apart from causing disases some microorganisms contaminate food, clothing, and leather items.

(1) Microbiology

(2) Unicellular or Multicellular

(3) Trypnosoma

(4) Rhizopus

(5) Bacteriophages

(6) All of them

(7) Common cold

(8) Asthma

(9) Citrus canker

(10) fungus