HOTS Questions: The Invisible Living World: Beyond Our Naked Eye | Science Class 8 PDF Download

1. The yeast multiply by a process called

(a)    Binary fission

(b)   Budding

(c)    Spore formation

(d)   None of the above

Ans: b

2. The example of protozoan is

(a)    Penicillium

(b)   Blue green algae

(c)    Amoeba

(d)   Bacillus

Ans: c

2. Yeast produces alcohol and carbon dioxide by a process called

(a)   Evaporation

(b)   Respiration

(c)   Fermentation

(d)   Digestion

Ans: c
Yeast produces alcohol and carbon dioxide through a process called fermentation. This process involves:

• Conversion of sugar into alcohol.
• Release of carbon dioxide, which helps dough rise in baking.
• Utilisation of natural sugars found in grains and fruits.

Fermentation is crucial in the production of various foods and beverages, including bread and wine.

3. The algae commonly used as fertilizers are called

(a)   Staphylococcus

(b)   Diatoms

(c)   Blue green algae

(d)   None of the above

Ans: c
Blue-green algae, also known as cyanobacteria, are commonly used as fertilizers due to their ability to:

• Fix nitrogen from the atmosphere.
• Enhance soil fertility.
• Support plant growth by providing essential nutrients.

These algae play a vital role in agriculture and are beneficial for sustainable farming practices.

4. Plant disease citrus canker is caused by

(a)   Virus

(b)   Fungi

(c)   Bacteria

(d)   None of these

Ans: c

5. The bread dough rises because of

(a)   Kneading

(b)   Heat

(c)   Grinding

(d)   Growth of yeast cells

Ans: d

• The bread dough rises due to the growth of yeast cells.
• Yeast ferments the sugars in the dough.
• This process produces carbon dioxide, which creates bubbles.
• These bubbles expand, causing the dough to rise.

6.  Yeast is used in the production of

(a)   Sugar

(b)   Alcohol

(c)   Hydrochloric acid

(d)   Oxygen

Ans: b
Alcohol Yeast is primarily used in the production of:

• Alcohol - Yeast ferments sugars to produce alcohol.
• Other options like sugar, hydrochloric acid, and oxygen are not produced by yeast.

7. The bacterium which promote the formation of curd

(a)   Rhizobium

(b)   Spirogyra

(c)   Breadmould

(d)   Lactobacillus

Ans: d
The bacterium that helps in making curd is Lactobacillus. Here are some key points:

• Lactobacillus is a type of bacteria.
• It multiplies in warm milk, turning it into curd.
• This process is essential for making various dairy products.

8. The bacterium Bacillus Anthracis was discovered by

(a)   Edward Jenner

(b)   Alexander Fleming

(c)   Louis Pasteur

(d)   Robert Koch

Ans: d
Robert Koch Robert Koch discovered the bacterium Bacillus anthracis, which causes anthrax disease. His work was crucial in understanding how this bacterium affects both humans and animals.

9. The process of conversion of sugar into alcohol is called

(a)   Infection

(b)   Moulding

(c)   Nitrogen fixation

(d)   Fermentation

Ans: d

10. Which of the following is not a fungi

(a)    Paramecium

(b)   Bread mould

(c)    Penicillium

(d)   Aspergillus  

Ans: a

• The organism that is not a fungus is A) Paramecium.
• Paramecium is a type of protozoan, which is different from fungi.
• Fungi include organisms like bread mould, Penicillium, and Aspergillus.