The Invisible Living World Beyond Our Naked Eye Class 8 MCQ
hardThe Invisible Living World Beyond Our Naked Eye Class 8 MCQ
The Invisible Living World Beyond Our Naked Eye Class 8 MCQ
Question 1.
What is the basic unit of life?
(a) Tissue
(b) Organ
(c) Cell
(d) Organism
Answer:
(c) Cell
Question 2.
What distinguishes bacterial cells from plant and animal cells?
(a) Presence of a cell wall
(b) Presence of chloroplasts
(c) Lack of a well-defined nucleus
(d) Presence of a cell membrane
Answer:
(c) Lack of a well-defined nucleus
Question 3.
Which microorganism is known for its role in making bread and cakes fluffy?
(a) Lactobacillus
(b) Yeast
(c) Rhizobium
(d) Amoeba
Answer:
(b) Yeast
Question 4.
What is the role of Rhizobium bacteria in agriculture?
(a) They cause diseases in plants.
(b) They produce alcohol.
(c) They help in nitrogen fixation.
(d) They decompose organic matter.
Answer:
(c) They help in nitrogen fixation.
Question 5.
What happens to milk when Lactobacillus bacteria are added?
(a) It becomes sour and forms curd.
(b) It turns into yogurt.
(c) It remains unchanged.
(d) It produces alcohol.
Answer:
(a) It becomes sour and forms curd.
Question 6.
Which of the following is NOT a characteristic of microorganisms?
(a) They can be found in extreme environments.
(b) They are visible to the naked eye.
(c) They can be unicellular or multicellular.
(d) They are essential for various ecological processes.
Answer:
(b) They are visible to the naked eye.
Question 7.
What is the function of the cell wall in fungal cells?
(a) To store nutrients
(b) To provide shape and protection
(c) To facilitate movement
(d) To conduct photosynthesis
Answer:
(b) To provide shape and protection
Question 8. Which of the following environments can microorganisms thrive in?
(a) Only in soil
(b) Only in water
(c) Only in the human body
(d) All kinds of environments
Answer:
(d) All kinds of environments
Question 9.
What is the purpose of using a microscope to observe microorganisms?
(a) To increase the temperature of the sample
(b) To enhance visibility and detail of small structures
(c) To change the chemical composition of the sample
(d) To sterilize the sample
Answer:
(b) To enhance visibility and detail of small structures
Case Study
I. Biogas Production
Microorganisms play a crucial role in the production of biogas, a renewable energy source. In anaerobic environments, certain bacteria decompose organic waste, such as plant and animal matter, releasing gases like methane and carbon dioxide. This biogas can be harnessed for cooking, heating, and even generating electricity. By utilising these microorganisms, we not only manage waste effectively but also reduce our reliance on fossil fuels, contributing to a more sustainable energy future.
Question 1.
What type of environment do the bacteria that produce biogas thrive in?
(a) Aerobic
(b) Anaerobic
(c) Hypertoxic
(d) Hypoxic
Answer:
(b) Anaerobic
Question 2.
Which gas is primarily produced during the decomposition of organic waste by microorganisms in biogas production?
(a) Oxygen
(b) Nitrogen
(c) Methane
(d) Hydrogen
Answer:
(c) Methane
Question 3.
Microorganisms that decompose organic waste in anaerobic environments release gases such as ............ and .............
Answer:
methane, carbon dioxide
Question 4.
The utilisation of biogas helps in managing waste effectively and reduces our reliance on ............ fuels.
Answer:
fossil
Question 5.
Biogas can only be used for cooking and heating, but not for generating electricity. (True/False)
Answer:
False
II. Curd Formation
The process of making curd from milk showcases the beneficial role of microorganisms in food production. When milk is left at warm temperatures with added bacteria, particularly Lactobacillus, these microorganisms ferment the lactose in the milk, producing lactic acid.
This acid not only thickens the milk but also gives curd its characteristic sour taste. This natural fermentation process highlights how microorganisms can enhance food flavours and textures, making them essential in culinary practices worldwide.
Question 1.
What is the primary microorganism responsible for the fermentation of milk into curd?
(a) Yeast
(b) Lactobacillus
(c) E. coli
(d) Rhizobium
Answer:
(b) Lactobacillus
Question 2.
What is the effect of warm temperatures on the fermentation process of milk into curd?
(a) It prevents the growth of bacteria.
(b) It enhances the growth of Lactobacillus.
(c) It causes the milk to spoil.
(d) It reduces the acidity of the milk.
Answer:
(b) It enhances the growth of Lactobacillus.
Question 3.
The process of making curd involves the fermentation of lactose in milk by the bacterium ............
Answer:
Lactobacillus
Question 4.
The lactic acid produced during fermentation not only thickens the milk but also gives curd its characteristic ............ taste.
Answer:
sour
Question 5.
Curd formation occurs best at low temperatures. (True/False)
Answer:
False