CBSE 8th Science The Invisible Living World : Beyond Our Naked Eyes - New Model Questions Papers Study Material - QB365 Set B | QB365

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CBSE 8th Science The Invisible Living World : Beyond Our Naked Eyes - New Model Questions Papers Study Material - QB365 Set B

Published on: 14/08/2026

CBSE 8th Science The Invisible Living World : Beyond Our Naked Eyes - New Model Questions Papers Study Material - QB365 Set B

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Std: 8th Standard CBSE - Science

chapter: The Invisible Living World : Beyond Our Naked Eyes - New - Model Questions Papers

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Questions:

Short Answer Type Questions

23 x 2 = 46

1.

What are microalgae, and how do they support both aquatic life and human needs?

2.

How does Rhizobiun bacteria benefit both itself and the leguminous plant it lives in?

3.

Why is yeast added to bread dough, and under what conditions does it grow best?

4.

What are the tiny living organisms that act as natural decomposers. Where are they commonly found?

5.

Give two ways in which microorganisms contribute to environmental balance.

6.

List any two microorganisms found in pond water and soll suspension and mention one characteristic feature of each.

7.

How do the structures of plant cells differ from those of animal cells? Mention any two differences.

8.

Why is the nucleus considered an important part of a cell? What roles does it play?

9.

How do fruit and vegetable peels turn into manure over time?

10.

How does the diversity of microorganisms playa role in our daily life? How do they help clean the environment?

11.

Why do microorganisms not infect pickels and murabbas ?

12.

When food items like lemon, tomato, or orange are left outside and start to rot, a powdery or cotton-like growth appears on them. What causes this, and how do these microbes come in contact with the food?

13.

Are the cells of microorganisms similar to plant and animal cells, or do they have a different structure?What do these tinycells look like?

14.

Do different animal cells also vary In their shape and structure? Why do cells have different shapes and structures? How Is the shape of a cell related to the function it performs?

15.

What is the role of the main parts of a cell i.e. the cell membrane, cytoplasm and nucleus? Why are these parts important for the functioning and survival of the cell?

16.

What are the similarities and differences you observe in onion peel cells and cheek cells?

17.

How was the invisible world of tiny living organisms discovered? What scientific invention made it possible to observe them for the first time?

18.

What do you observe when you look at letters through awater-filled flask? How does this compare to using a real magnifying glass to observe small organisms like an ant?

19.

You might have seen some people using reading glasses. How does it help them see better? Or what happens when we use a magnifying glass to observe something?

20.

What is the smallest living organism that can be seen without using a microscope? How small can the human eye actually see?

21.

Have you thought how tiny living beings found in nature interact with each other?

22.

How do you think your observation of this hidden world might change the way you think about size, complexity, or even what counts as living"?

23.

Have you ever wondered what you might see if the invisible world around you became visible?

Generic 2

2 x 2 = 4

24.

A student observed that when curd is left out for a day, it becomes more sour. What can be two possible explanations for this?

25.

Take 2 slices of bread. Place one slice in a plate near the sink. Place the other slice it the refrigerator. Compare after three days. Note your observations. Give reasons for your observations.

Generic 3

1 x 3 = 3

26.

Various parts of a cell are given below. Write them in the appropriate places in the following diagram. Nucleus, Cytoplasm, Chloroplast, Cell wall, Cell membrane, Nucleoid

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Answers Key:

Short Answer Type Questions

23 x 2 = 46

1.

Microalgae are microscopic plant-like organisms found in water that perform photosynthesis. They support aquatic life by producing oxygen and serve human needs by being used in food, medicine, and biofuel production.

2.

Rhizobium bacteria benefit by getting shelter and nutrients from the leguminous plant, while the plant benefits by receiving usable nitrogen fixed by the bacteria from the air.

3.

Yeast is added to bread dough to make it rise by producing carbon dioxide gas. It grows best in warm, moist, and sugary conditions.

4.

Tiny living organisms such as bacteria and fungi act as natural decomposers. They break down dead plants and animals into simpler substances, recycling nutrients back into the environment. They are commonly found in soil, decaying matter, compost piles, and forest floors.

5.

Microorganisms contribute to environmental balance by decomposing dead organic matter and by fixing atmospheric nitrogen in the soil.

6.

The two microorganisms found in pond water and soil suspension are as follows
1. Amoeba (Protozoa) A single-celled organism with an irregular shape.
2. Paramecium (Protozoa) A single-celled organism that moves with the help of specialised structures.

7.

Plant cells have a cell wall and chloroplasts, while animal cells do not. Also, plant cells usually have a large central vacuole, which is smaller or absent in animal cells.

8.

The nucleus is considered an important part of a cell because it controls all the activities of the cell and stores the genetic material needed for inheritance and reproduction.

9.

When fruit and vegetable peels are left in a compost pit or open area, microorganisms such as bacteria and fungi start acting on them. These microbes break down the complex substances in the peels into simpler forms. Over time, this process of decomposition changes the waste into dark, nutrient-rich manure that can be used to enrich the soil and help plants grow better.

10.

Microorganisms show great diversity and are found all around us-in air, water, soil, and even inside our bodies. They play a vital role in our daily life
1. In Food Production Some microorganismns are used in making curd, bread, and cheese. They help in fermentation, improving texture and taste.
2. In Cleaning the Environment Certain microbes break down dead plants and animals into simpler substances. This process helps in the natural cleaning of our surroundings and recycling of nutrients.
3. In Decomposing Waste Microorganisms act as natural decomposers. They break down organic waste and convert it into useful compost, making soil fertile.

11.

Microorganisms do not affect pickels and murabbas because various spices along with salt or sugar are added to these food, which act as preservative.

12.

The powdery or cotton-like growth seen on rotting food is caused by microbes such as fungi. These microbes are present in the air around us. When food is left uncovered or in damp conditions, these airborne microbes settle on it, grow, and cause it to rot.

13.

Microorganisms have different kindsof cells. Some have simple cells without a clearly defined nucleus, while others have well-organised cells with a proper nucleus and other cell parts. Their cell structure is not always like that of plant or animal cells, but each is suited to carry out its own functions.

14.

Yes, Cells differ in shape, size, and structure because each type of cell performs a specific function in the body. Some examples include
• Inner cheek cells are thin and flat, which helps them form a protective lining.
• Nerve cells have a long and branched shape that allows them to carry messages quickly to different parts of the body.
•In plants, cells can be rectangular, oval, elongated, or tube-like; some plant cells form long tubes that help in transporting water. .
•In the digestive system, muscle cells in the food pipe are spindle-shaped and flexible, allowing them to push food downward.

15.

Each part of a cell performs a specific function. The cell membrane controls what enters and exits the cell. The cytoplasm holds the cellparts and helps in transporting materials. The nucleus controls the cell's activities and carries instructions for its growth and reproduction. "These structures are essential because they help the cell stay alive and carry out its functions properly.

16.

Both onion peel cells and cheek cells have a cell membrane,cytoplasm, and nucleus. However, onion cells also have a cell wall, while cheek cells do not. This is because onion cells are extracted from a plant, and plant cells have a cell wall that gives them shape and strength.

17.

The invention of the microscope helped us see the invisible world of microorganisms for the first time. It allowed scientists to observe tiny life forms like bacteria and protozoa, which cannot be seen with the unaided eye. This discovery opened up a new world of study in science.

18.

When letters are viewed through a water-filled flask, they appear larger. This happens because the curved glass and water bend light, magnifying the image. Similarly, a real magnifying glass helps to see small organisms like an ant in greater detail by enlarging their appearance.

19.

Reading glasses or magnifying glasses bend light rays in a way that helps us see smallor unclear objects more clearly. A magnifying glass enlarges the image of an object, making it easier to observe fine details. This is useful when looking at tiny organisms or small texts.

20.

The smallest living organism isible to the naked eye is often a tiny insect or an organism like an ant or a mold spore. The human eye can generally see objects as small as about 0.1millimetres. Anything smaller usually requires a microscope to be seen clearly.

21.

Tiny living beings interact in many ways. Some help each other grow, while others conpete for food or space. These interactions play an important role in maintaining balance in natural systems such as soil, water bodies, and even the human body.

22.

Observing the hidden world would help in Complete Explanations of all NCERT's QUestions Page & understanding that even the smallest organisms can be highly complex and perform all the basic functions of life. It would also broaden the idea of what is considered living, showing that living beings can exist in many forms and sizes.

23.

If the invisible world became visible, it would show a wide variety of tiny living organisms present all around, in air, water, soil, and even on everyday objects. It would reveal how active and crowded the microscopic world is, even in places that seem clean or empty.

Generic 2

2 x 2 = 4

24.

Two possible explanations for this are as follows: Lactobacillus bacteria multiply over time, producing more lactic acid, which increases sourness. Warm temperature encourages bacterial growth, making the curd sour faster.

25.

The bread slice kept near the sink showed fungal growth, whereas the slice kept in the refrigerator remained unchanged. As the microorganisms grow well in warm and moist places and the cold temperature in the refrigerator inhibits their growth.

Generic 3

1 x 3 = 3

26.

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