Thursday, 21 May 2026

Test Class 8 The Microorganisms

 20 MCQs (Without Answers)

Based on the given chapter – Microorganisms & Microalgae

Which bacterium is mainly responsible for converting milk into curd?

a) Rhizobium

b) Lactobacillus

c) Yeast

d) Chlorella

Lactobacillus feeds on which sugar present in milk?

a) Glucose

b) Fructose

c) Lactose

d) Sucrose

During curd formation, bacteria produce:

a) Alcohol

b) Oxygen

c) Lactic acid

d) Water

Curd formation occurs faster in:

a) Cold conditions

b) Warm conditions

c) Dry conditions

d) Windy conditions

Which of the following is NOT a category of microorganisms?

a) Protozoa

b) Fungi

c) Bacteria

d) Mammals

Rhizobium bacteria are commonly found in:

a) Leaves

b) Flowers

c) Root nodules

d) Fruits

Root nodules are mainly found in the roots of:

a) Mango plants

b) Legume plants

c) Coconut plants

d) Rose plants

Which of the following is a legume?

a) Wheat

b) Rice

c) Lentil

d) Maize

Rhizobium bacteria help plants by trapping:

a) Oxygen from air

b) Carbon dioxide from air

c) Nitrogen from air

d) Water from soil

Growing legumes with other crops helps to:

a) Decrease soil fertility

b) Increase nitrogen in soil

c) Dry the soil

d) Reduce oxygen

Microalgae are __________ organisms.

a) Large aquatic animals

b) Microscopic plant-like organisms

c) Flowering plants

d) Reptiles

Microalgae can live in:

a) Water only

b) Soil only

c) Air only

d) Water, soil, air, and on trees

Microalgae prepare their own food using:

a) Moonlight

b) Minerals only

c) Sunlight

d) Heat

More than half of Earth’s oxygen supply is produced by:

a) Animals

b) Microalgae

c) Rocks

d) Insects

Which of the following is an example of microalgae?

a) Rhizobium

b) Lactobacillus

c) Spirulina

d) Yeast

Spirulina, Chlorella, and Diatoms are used by humans as:

a) Fuels only

b) Building materials

c) Health supplements and medicines

d) Pesticides

Microalgae help in:

a) Polluting water

b) Cleaning water

c) Reducing oxygen

d) Drying soil

Microalgae are also used to make:

a) Cement

b) Plastic

c) Biofuel

d) Glass

Which factor is threatening microalgal diversity?

a) Pollution

b) Climate change

c) Habitat destruction

d) All of these

Conserving microalgae is important to maintain:

a) Noise balance

b) Oxygen balance on Earth

c) Temperature of stars

d) Soil colour

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