Class 8 Science


Extra Questions

Multiple Choice Questions

Question 1: Which microbe is used for production of alcohol?

  • Yeast
  • Plasmodium
  • Lactobacillus
  • Rhizobium

    Answer: (a) Yeast

Question 2: How much nitrogen is present in the atmosphere?

  • 78%
  • 88%
  • 68%
  • 58%

    Answer: (a) 78%

Question 3: Malaria is caused by which type of microbe?

  • Bacteria
  • Fungi
  • Algae
  • Protozoa

    Answer: (d) Protozoa

Question 4: Common cold is caused by which type of microbe?

  • Bacteria
  • Virus
  • Algae
  • Fungi

    Answer: (b) Virus

Question 5: Which of the following diseases is caused by a fungus?

  • Cholera
  • Common cold
  • Ringworm
  • Dengue

    Answer: (c) Ringworm

Question 6: Which of the following helps in making curd from milk?

  • Lactobacillus
  • Plasmodium
  • Yeast
  • Salmonella

    Answer: (a) Lactobacillus

Question 7: Antibiotics are effective against which of the following?

  • Bacteria
  • Fungi
  • Virus
  • All of the above

    Answer: (a) Bacteria

Question 8: Penicillin was discovered by which scientist?

  • Edward Jenner
  • Louis Pasteur
  • Alexander Fleming
  • Robert Koch

    Answer: (c) Alexander Fleming

Very Short Answer Type Questions

  • What are microorganisms?

    Answer: Organisms which cannot be seen by naked eyes are called microorganisms or microbes.
  • What is an antibiotic?

    Answer: A substance which kills or stops the growth of bacteria is called antibiotic.
  • What is fermentation?

    Answer: The process of conversion of sugar into alcohol by yeast through anaerobic respiration is called fermentation.
  • What is Polio?

    Answer: Polio is a disease which affects nerves and results in paralysis; especially of legs.
  • What is communicable disease?

    Answer: A disease which can spread from one person to another is called communicable disease.
  • What is a pathogen?

    Answer: A microorganism which causes disease is called a pathogen.
  • What is food preservation?

    Answer: Use of some techniques to prolong the shelf life of a food is called food preservation.
  • What is nitrogen fixation?

    Answer: The process of changing atmospheric nitrogen into compounds of nitrogen so that plants can take up nitrogen is is called nitrogen fixation.
  • What is nitrogen cycle?

    Answer: The sequence of events by which nitrogen is channelized to the living world and back to atmosphere is called nitrogen cycle.