The Invisible Living World Beyond Our Naked Eye Class 8 Extra Questions and Answers Science Chapter 2

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Class 8 Science Chapter 2 The Invisible Living World Beyond Our Naked Eye Extra Questions

Class 8 Science Chapter 2 Extra Questions on The Invisible Living World Beyond Our Naked Eye

The Invisible Living World Beyond Our Naked Eye Class 8 Very Short Question Answer

Question 1.
Some cells appear to have an extra layer around their boundary, which gives them a defined shape. What is this layer called?
Answer:
This layer is called the cell wall.

Question 2.
You look through a microscope and see neatly packed rectangular structures in an onion peel. What are these structures?
Answer:
These structures are plant cells.

Question 3.
A glass slide shows irregular-shaped, colourless structures with a central dark spot from the inside of the cheek. What are these?
Answer:
These are human cheek cells.

Question 4.
A student looks through a foldscope at a water sample from a pond and sees tiny, constantly moving structures. What group of organisms is likely present?
Answer:
The group of organisms likely present is protozoa.

Question 5.
We noticed that garbage and dry leaves in a pit slowly disappear after some days. What is this natural process called?
Answer:
This natural process is called decomposition.

Question 6.
A fluffy, sour substance is seen forming when curd is left in warm milk. What kind of organism is behind this change?
Answer:
A type of bacteria known as Lactobacillus is behind this change.

Question 7.
While kneading dough with yeast, it becomes airy and rises after a few hours. What gas causes this change?
Answer:
Carbon dioxide gas causes this change.

Question 8.
A pea plant root nodule has tiny swellings filled with bacteria. What do these bacteria help fix from the air? (Competency Based Que.)

Answer:
These bacteria help fix nitrogen from the air.

The Invisible Living World Beyond Our Naked Eye Class 8 Short Question Answer

Question 1.
Why is the nucleus considered an important part of a cell? What roles does it play?
Answer:
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.

Question 2.
How do the structures of plant cells differ from those of animal cells? Mention any two differences.
Answer:
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.

Question 3.
List any two microorganisms found in pond water and soil suspension and mention one characteristic feature of each.
Answer:
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.

Question 4.
Give two ways in which microorganisms contribute to environmental balance.
Answer:
Microorganisms contribute to environmental balance by decomposing dead organic matter and by fixing atmospheric nitrogen in the soil.

Question 5.
What are the tiny living organisms that act as natural decomposers. Where are they commonly found? (Competency Based Que.)
Answer:
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.

Question 6.
Why is yeast added to bread dough, and under what conditions does it grow best?
Answer:
Yeast is added to bread dough to make it rise by producing carbon dioxide gas. It grows best in warm, moist, and sugary conditions.

Question 7.
How does Rhizobium bacteria benefit both itself and the leguminous plant it lives in?
Answer:
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.

Question 8.
What are microalgae, and how do they support both aquatic life and human needs?
Answer:
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.

The Invisible Living World Beyond Our Naked Eye Class 8 Long Question Answer

Question 1.
Describe the structure and functions of the basic parts of a cell. Explain their roles in maintaining life processes. (Competency Based Que.)
Answer:
A cell has three basic parts, i.e. the cell membrane, cytoplasm, and nucleus. The cell membrane is the outer boundary that controls the movement of substances in and out of the cell. The cytoplasm is a jelly-like substance where cell organelles are suspended and many chemical reactions occur. The nucleus is the control center of the cell, containing genetic material that regulates all cell activities. Together, the membrane protects and manages material exchange, the cytoplasm supports internal functions, and the nucleus directs the cell’s life processes.

Question 2.
Describe the method of preparing a slide of onion peel for observing plant cells. What precautions should be taken while placing the coverslip and viewing under a microscope?
Answer:
The steps involved in preparation of slide of onion peel are as follows

• To prepare a slide of onion peel, a thin layer is gently peeled from an onion and placed in a drop of water on a glass slide
• A coverslip is then placed over it carefully to avoid air bubbles.
• The slide is viewed under a microscope.
• Precautions that should be taken include using a clean slide and coverslip, handling the coverslip gently, and avoiding folding or tearing the peel to ensure a clear view of the cells.

Question 3.
(i) Identify the part labeled ‘X’
(ii) Mention differences between plant and animal cells based on structure observed under microscope. (Competency Based Que.)

Answer:
(i) The part labeled ‘X’ is the cytoplasm.
(ii) The differences between plant and animal cells based on their microscopic observation are as follows

Feature	Plant Cell (Onion Peel)	Animal Cell (Cheek Cell)
Cell wall	Present as a rigid outer covering	Absent
Shape	Regular and rectangular	Irregular or polygonal
Arrangement	Cells are closely packed without spaces	Cells appear loosely arranged with some gaps
Outer covnering	Cell wall and cell membrane both are present	Only cell membrane is present.

Question 4.
What are microorganisms? Describe the types of microorganisms based on their cellular structure.
Answer:
Microorganisms are tiny living organisms that cannot be seen with the naked eye. They are found in water, soil, air, and even inside our bodies. These organisms may be made up of a single cell or many cells. Based on the number of cells in microorganisms are of two types

1. Unicellular Microorganisms : These are made up of only one cell. Examples include bacteria, Amoeba, and Paramecium.
2. Multicellular Microorganisms : These are made up of many cells. Some fungi and algae are multicellular in nature.

Question 5.
Explain the role of microorganisms in the recycling of nutrients. How do microbes help in the decomposition of organic matter and improve soil fertility?
Answer:
Microorganisms play a vital role in recycling nutrients by breaking down organic matter into simpler substances. Decomposers like bacteria and fungi feed on dead plants and animals, releasing nutrients back into the soil. This process improves soil fertility and maintains the nutrient cycle. By decomposing organic waste, microbes help convert complex compounds into forms that plants can absorb, supporting healthy growth and agricultural productivity.

Question 6.
Discuss the usefulness of microorganisms in the production of food items. Give examples of how bacteria and fungi are involved in the preparation of curd, bread, and cheese.
Answer:
Microorganisms are useful in food production through fermentation. Bacteria such as Lactobacillus convert milk into curd by producing lactic acid. Yeast, a type of fungus, is added to dough to make bread rise by producing carbon dioxide. Cheese is made using specific bacteria and fungi that ferment milk and give it unique texture and flavor. These microorganisms enhance taste, texture, and shelf-life of food items.

Question 7.
What are microalgae? List some important uses of microalgae in different fields.
Answer:
Microalgae are microscopic, plant-like organisms that live in water, soil, air, and on trees.
They make their own food using sunlight and release oxygen during this process. Uses of microalgae are as follows

1. They serve as food for many aquatic animals.
2. Microalgae like Spirulina and Chlorella are used as health supplements.
3. They are used in making medicines and vitamin B12.
4. Microalgae help in cleaning polluted water.
5. They are used in the production of biofuel.

The Invisible Living World Beyond Our Naked Eye Class 8 Case Based Questions

Question 1.
A glass of fresh milk was left on the table in a room for a few hours. Kamal did not know that the milk was no longer fresh and he drank it. He, then complained to his mother that the milk tasted sour.
A few hours later, Kamal fell ill.
(i) Why did Kamal fell ill?
(ii) Name the method by which we can prevent fresh milk from turning sour.
Answer:
(i) Kamal fell ill because the milk had turned sour due to the growth of microorganisms, likely Lactobacillus, which produced lactic acid and spoiled the milk.

(ii) Fresh milk can be prevented from turning sour by storing it in a refrigerator. As the microorganism that turn milk sour need warm environment. Low temperature slow down the activity of these microorganisms.

Skill Based Questions

Question 1.
You are provided with an onion bulb and asked to prepare a slide of its peel to observe under a microscope. Describe the steps you would follow to prepare the slide. What observations would help you conclude that the cell is from a plant? (Experiment skill)

Question 2.
You conduct an experiment where you add yeast to sugar solution and keep it in a warm place. After some time, bubbles form. What do these bubbles indicate, and what does this experiment show about microorganisms? (Thinking skill)

Question 3.
Analyze how the presence of a cell wall in plant cells and its absence in animal cells supports their respective lifestyles and needs. (Analytical Skill)

Question 4.
A group of students grow two sets of pea plants, one in normal soil and the other in soil enriched with Rhizobium. After three weeks, they compare plant height and leaf color. Predict the likely result and explain the reason behind it.

The Invisible Living World Beyond Our Naked Eye Extra Questions for Practice

Very Short Answer Type Questions

Question 1.
Name the organelle responsible for giving shape and support in a plant cell.

Question 2.
Which part of the cell controls its activities?

Question 3.
What is observed when pond water is viewed under a microscope?

Question 4.
Which microorganism is used in the making of dough?

Short Answer Type Questions

Question 1.
Mention any two roles of microorganisms in the environment.

Question 2.
Why is Rhizobium important for leguminous plants?

Question 3.
How do microalgae contribute to maintaining oxygen balance on Earth?

Long Answer Type Questions

Question 1.
Draw a well-labelled diagram of a plant cell and explain the function of any two parts.

Question 2.
What are the basic differences between plant cells and animal cells?

Question 3.
Explain how manure is formed with the help of microorganisms.