THE  CELL

JKBOSE Solutions for Class 8 Science

JKBOSE  Solutions for Class 8 Science :

 JKBOSE solutions have been provided below to aid the students with answering the questions correctly, using a logical approach and methodology. The solutions provide best and smartest material to enable students to form a good base and improve the fundamentals of the subject. 

This page provides you all the links to JKBOSE Solutions for Class 8 Science. You can anytime copy or download, Copy paste each and every chapter Solutions to your desktop. Science JKBOSE class 8 solutions are helpful resource developed by our science experts to help students in their class 8 exam.

JKBOSE Solutions for Class 8 Science

The links below provide the detailed solutions for JKBOSE science class 8 textbook.

JKBOSE Solutions for Class 8 Science

JKBOSE textbooks are prescribed by JK BOARD OF SCHOOL EDUCATION as the best books for preparation of the school as well as board examinations. The textbooks are considered as more than enough, without any aid from other refreshers. The solutions are made and designed keeping in mind the lucid language and the simplicity of the explanations that are given in the NCERT textbooks. These are not just the board and school examinations, NCERT textbooks are known to play a very important role in JEE and NEET.

JKBOSE science book class 8 acts as a stepping stone for further higher classes where u might feel that the topic is out of your league and hard to comprehend. The concepts of science social science math syllabus form the backbone of higher classes. JKBOSE class 8 science solutions help to clear our basic concepts and make them very easy and interesting for the students.

We prepared JKBOSE Solutions as per CBSE remodeled assessment structure.  We have discussed and elaborated extensively how are different food crops produced. Which living organisms do we see under a microscope in a drop of water etc ? Are some of our clothes synthetic? How do we conserve biodiversity? What is the internal structure of a plant? and many more.

JKBOSE solutions will help in the following manner:

• Authentic Homework Guide
• The base for the preparation of competitive exams like JEE and NEET
• Strengthening basic concepts of subjects
• Error-free solutions
• Extra problems to build upon the basic concepts

CHAPTER       16    THE  CELL

 

Cell

Robert Hooke's discovery of cells in 1665 was a major milestone in our understanding of life. Cells are the fundamental building blocks of all living organisms, and come in many different shapes and sizes. They can be single-celled or multi-celled, and each type has its own unique functions. Single-celled organisms such as bacteria are capable of performing a variety of functions on their own, while multicellular organisms like humans require the cooperation of multiple cells to perform even the simplest tasks. Different kinds of cells have evolved over time to fulfill various roles within an organism, from providing structural support to carrying out vital metabolic processes. Understanding how these cells work together is essential for us to understand how life works at its most basic level.

Robert Hooke discovered the tiny structural and functional units of life - cells. He observed that living organisms are composed of single cell or multiple unicellular and multicellular structures. This discovery has been a major breakthrough in understanding the different kinds of cells and their structures in different species.

The discovery of cell has helped us to understand how different kinds of cells work together to form complex life forms like human beings. It has also enabled us to study the functions of each kind of cell and how they interact with each other. The knowledge gained from studying cells can be used to develop treatments for various diseases, as well as understand how our bodies function on a cellular level.

Types of cells

Our bodies are made up of various types of cells, each with its own unique function. Muscle cells, bone cells, nerve cells and blood cells are some of the most important types of cells in our body.

Muscle cells are responsible for movement and provide strength and flexibility to our body. Bone cells provide structural support and protection to our internal organs. Nerve cells transmit information from one part of the body to another. Blood cells transport oxygen throughout the body and help fight off infection.

 

Each cell type has its own unique characteristics that enable it to perform its specific functions in the body. Understanding these functions is essential for maintaining a healthy lifestyle as well as diagnosing and treating medical conditions.

 

Microscope

 

A microscope is an instrument used to observe small objects that are too small to be seen by the naked eye. It consists of two main parts, the objective lens and the eyepiece. The objective lens is a high-powered magnifying glass that collects light and focuses it on the specimen being examined. The eyepiece then magnifies this image so that it can be seen by the observer. Other parts of a microscope include a stage, illuminator, diaphragm, and condenser. The stage holds the specimen in place while the illuminator provides light for viewing. The diaphragm controls how much light passes through to the specimen, and finally, the condenser focuses this light onto the specimen for clearer viewing.

Plant cell and it’s structure

Plant cells are the basic units of life in all plants. They are highly specialized, complex structures that allow plants to grow and survive in their environment. Plant cells have many unique features that differentiate them from animal cells, including a rigid cell wall, large central vacuole and chloroplasts. In this article, we will discuss the structure of plant cells and how these structures help them to function. We will also look at some common uses of plant cells in modern science.

Animal cell and it’s structure

Animal cells are the basic unit of life in all animals and are composed of various organelles that work together to perform essential functions. Animal cells have a variety of structures, including a nucleus, mitochondria, endoplasmic reticulum, Golgi apparatus, lysosomes, and vacuoles. Each of these organelles has its own unique role in the cell’s functioning. The nucleus is the control center of the cell and contains genetic material that determines how the cell will function. Mitochondria produce energy for the cell while endoplasmic reticulum helps transport proteins throughout the cell. The Golgi apparatus packages proteins for export from the cell while lysosomes break down waste materials within it. Finally, vacuoles store water and other materials needed by the cell.

Difference between Animal cell and plant cell

Animal cells and plant cells are both eukaryotic cells, meaning they have a nucleus and other organelles enclosed within membranes. However, there are some key differences between the two types of cells. Animal cells lack a cell wall and chloroplasts, while plant cells have both of these structures. Plant cells also contain additional organelles such as the vacuole and plastids that are not found in animal cells. Additionally, plant cell walls provide structural support to the cell while animal cell walls do not.

Cell organelles

Cell organelles are the functional units of a cell. They are responsible for carrying out specific tasks that help keep the cell alive and functioning properly. The most important organelles in a cell are the cell wall, cell membrane, cytoplasm, nucleus, chromosomes, endoplasmic reticulum (ER), ribosomes, mitochondria, Golgi complex, chloroplasts, vacuole and lysosome. Each of these organelles has its own unique function that helps to maintain the health and functioning of the cell.

cell wall

 The cell wall provides structural support to the cell while the membrane regulates what enters and leaves it. It is hard and rigid gives strength to the plant cell it is made of cellulose.

Plasma membrane

The plasma membrane is a semipermeable barrier that surrounds the cell and is made up of lipids and proteins. It acts as a protective layer for the cell, maintaining its shape and allowing for the exchange of materials between the inside and outside of the cell. The plasma membrane also has tiny pores that allow certain molecules to pass through while blocking others. This selective permeability helps regulate what enters and leaves the cell, ensuring that only necessary substances are allowed in or out.

Cytoplasm

The cytoplasm is where all metabolic activities take place is a jell like substances inside cell membrane in which all the cell organelles float. It is in constant movement inside and transports materials from one place to another

Nucleus

the nucleus contains genetic material in form of chromosomes. Nucleus is an organelle found in eukaryotic cells that contains the genetic material of the cell. It is surrounded by a double membrane. Some unicellular organisms have not membrane outside the nucleus it is called then nucleoid. The nucleus also has nuclear pores which allow for the exchange of materials between the nucleus and the cytoplasm. Nucleus plays an important role in heredity as it controls the  genetic material called chromosomes of a cell. These chromosomes contains DNA or RNA . It also helps to regulate gene expression and protein synthesis in a cell.

The ER

The endoplasmic reticulum (ER) is an organelle found in eukaryotic cells. It is a network of membranes that are involved in the synthesis, folding, and transport of proteins and lipids. The ER has two distinct regions: the smooth endoplasmic reticulum (SER) and the rough endoplasmic reticulum (RER). The SER is responsible for synthesizing lipids while the RER is responsible for synthesizing proteins. Both regions have ribosomes attached to their surfaces which are responsible for translating mRNA into proteins. The ER also plays a role in calcium storage and detoxification of drugs and toxins.It is responsible for protein synthesis

 Ribosomes

Ribosomes are small organelles found in the cytoplasm of cells. They are responsible for the production of proteins, which are essential for cell growth and development. Ribosomes have a unique structure that allows them to carry out their function efficiently. They consist of two subunits, each made up of ribonucleic acid (RNA) and proteins. The two subunits come together to form a complex that is capable of reading genetic instructions from messenger RNA (mRNA) molecules and translating them into proteins. This process is known as translation and it is essential for the functioning of all living organisms by produce proteins from amino acids.

Mitochondria

Mitochondria are organelles found in the cells of all eukaryotic organisms. They are responsible for energy production and other metabolic processes. They produce ATP, which is used as a source of energy for the cell, and they also play a role in cell signaling, calcium homeostasis, and apoptosis. Mitochondria come in different shapes and sizes depending on their function. They are thought to have evolved from ancient bacteria that were engulfed by larger cells billions of years ago. It generates energy for cellular activities

 Golgi complex

The Golgi complex is a cellular organelle that plays an important role in the synthesis, packaging, and delivery of proteins. It is composed of several flattened membrane-bound structures known as cisternae which are connected by tubules. The Golgi complex is responsible for sorting and processing proteins before they are sent to their destination in the cell or outside the cell. It also helps in the formation of lysosomes, which are essential for cellular metabolism. In addition to this, it also helps in the formation of secretory vesicles which are involved in exocytosis. It packages proteins into vesicles for transport within or outside of cells.

Lysosomes

Lysosomes are organelles found in eukaryotic cells. They are responsible for breaking down macromolecules such as proteins, carbohydrates, and lipids. In addition to this, lysosomes also  known as ‘suicide bags’ contain special enzymes which can break down cellular material that is no longer needed or has become damaged. This process of self-digestion is called autolysis and it helps cells to maintain their homeostasis.

Vacoules

Vacuoles are essential components of cells, playing a vital role in maintaining cellular homeostasis. They are membrane-bound organelles that are filled with water and other molecules and can vary in size and shape depending on the cell type. Vacuoles act as storage compartments for nutrients, ions, waste products, and toxins. They also help with cell growth and division by regulating the osmotic pressure within a cell. Understanding the role of vacuoles is important for understanding how cells function properly.

Cell organelles	Discovery	Function
Cell wall	Robert Hooke 1665
Cell Membrane	Robert Hooke 1665
Nucleus	Robert Brown 1831
Cytoplasm	Robert Hooke 1665
Mitochondria	Albert von Kolliker 1857
Endoplasmic Reticulum	Porter and Thompson 1945
Golgi complex	Camillo Golgi in 1898
Lysosomes	Christian de Duve 1965
Vacuoles	Spallanzani (1776) Dujardin (1841)
Plastids	1866, Ernst Haeckel

 

Nerve cell

Nerve cells, also known as neurons, are the basic building blocks of the nervous system. They are responsible for transmitting electrical signals throughout the body and play a vital role in our ability to think, feel, and move. The structure of a nerve cell is complex and consists of several components that work together to allow it to function properly. These components include the cell body, dendrites, axons, synapses, and neurotransmitters. Each component plays an important role in how nerve cells communicate with each other and how they process information from our environment. Understanding the structure of a nerve cell can help us better understand how our nervous system works and why certain diseases or disorders can affect it.

Blood cell

Blood cells are the most important components of the human body. They are responsible for transporting oxygen and nutrients to all parts of the body, as well as removing waste products from our system. There are three main types of blood cells: red blood cells, white blood cells, and platelets. Red blood cells carry oxygen throughout the body, while white blood cells help fight off infections and platelets help with clotting. Each type of cell has its own unique function in keeping us healthy and functioning properly. Understanding these different types of blood cells is essential for maintaining good health.

 

Making a temporary slide of a plant cell from an onion peel is a great way to observe the structure and components of a plant cell. It is an easy and inexpensive way to learn about the different parts of a plant cell. This guide will provide step-by-step instructions on how to make your own temporary slide of an onion peel. With this method, you can observe the nucleus, cytoplasm, vacuoles, and other organelles that make up the structure of a plant cell.

 

JKBOSE Textbook Questions

Question 1. Indicate whether the following statements are True (T) or False (F).
(a) Unicellular organisms have a one-celled body.
(b) Muscle cells are branched.
(c) The basic living unit of an organism is an organ.
(d) Amoeba has an irregular shape.
Answer: (a) True (b) True (c) False (d) True

Question 2. Make a sketch of the human nerve cell. What function do nerve cells perform?
Answer: Function of nerve cells: The function of the nerve cell is to receive and transfer messages, it helps to control and coordinate the working of different parts of the body.

Question 3. Write short notes on the following.
(a) Cytoplasm
(b) Nucleus of a cell
Answer:
(a) Cytoplasm: The jelly-like substance found between the nucleus and the cell membrane is called cytoplasm. It is made up of basic elements like C, H, O, N. Various other components or organelles, like mitochondria, Golgi bodies, ribosomes, etc., of cells are present in the cytoplasm.

(b) Nucleus of a cell: Nucleus of a cell is an important component of the living cell. It is located at the centre of the cell. It is separated from the cytoplasm by a membrane called nuclear membrane. It contains genetic material.

Question 4. Which part of the cell contains organelles?
Answer: Cytoplasm

Question 5. Make sketches of animal and plant cells. State three differences between them.
Answer:

Plant cells	Animal cells
(i) The outermost covering is a cell wall and it is made of cellulose.	(i) The outermost covering of animal cell is the plasma membrane.
(ii) Plastids are present in plant cells.	(ii) Plastids are absent in animal cells.
(iii) Large vacuoles are present in plant cells.	(iii) No or very small vacuoles are present in animal cells.
(iv) It lacks centrosomes and lysosomes.	(iv) They have centrosomes or lysosomes.

Question 6. State the difference between eukaryotes and prokaryotes.
Solution:

Eukaryotes	Prokaryotes
(i) Eukaryotes possess membrane-bound organ­elles.	(i) Prokaryotes lack membrane-bound organelles.
(ii) Nucleus of the cell has nuclear membrane. Example: higher plants and animals.	(ii) Nucleus is not bounded by membrane. Example: bacteria and blue-green algae.

Question 7. Where are chromosomes found in a cell? State their function.
Answer: Chromosomes are present in the nucleus. The functions of chromosomes is to carry genes on them and to transfer the character from parents to the next generation.

Question 8. ‘Cells are the basic structural units of living organisms.’ Explain.
Answer: Different cells combine to form tissues and tissues combine to form organs. Similarly, organs combine to form body. Thus they are termed as the basic structural unit of every living organism.

Question 9. Explain why chloroplast are found only in plant cells?
Answer: Chloroplasts are plastids required for the food making process, called photosynthesis, and thus they are only present in plant cells.

Question 10. Complete the crossword with the help of clues given below.
Across
1. This is necessary for photosynthesis.
3. Term for component present in the cytoplasm.
6. The living substance in the cell.
8. Units of inheritance present on the chromosomes.
Down
1. Green plastids.
2. Formed by collection of tissues.
4. It separates the contents of the cell from the surrounding medium.
5. Empty structure in the cytoplasm.
7. A group of cells.
Solution:

 

Activity 1
The teacher may show a permanent slide of Amoeba and Paramecium under a microscope. Alternatively, the teacher can collect pond water and show these organisms by preparing the slides.
Solution:
Do it yourself.

Activity 2
Boil a hen’s egg. Remove the shell. What do you observe? A white material surrounds the yellow part. The white material is albumin which solidifies on boiling. The yellow part is yolk. It is part of the single cell. You can observe this single cell without any magnifying device.
Solution:
Do it yourself.

Activity 3
In order to observe the basic components of the cell, take an onion bulb. Remove the dry pink coverings (peels). You can easily separate these from the fleshy white layers of the bulb with the help of forceps or even with your hand. You can also break the onion bulb and separate out thin layers. Place a small piece of the thin onion peel in a drop of water on a glass slide. The thin layer can be cut into smaller pieces with the help of a blade or forceps. Add a drop of methylene blue solution to the layer and place a coverslip on it. While placing the coverslip ensure that there are no air bubbles under the coverslip. Observe the slide under the microscope. Draw and label.
Solution:
The boundary of the onion cell is covered by a thick covering called the cell wall. The central dense round body in the centre is called the nucleus. The jelly-like substance between the nucleus and the cell membrane is called cytoptasm.

Activity 4
Take a clean tooth pick, or a matchstick with the tip broken. Scrape inside of your cheek without hurting it. Place it in a drop of water on a glass slide. Add a drop of iodine and place a coverslip over it. Alternatively, add 1 -2 drops of methylene blue solution. Observe it under the microscope. You may notice several cells in the scraped material (Fig. 8.2). You can identify the cell membrane, the cytoplasm and nucleus. A cell wall is absent in animal cells.
Solution:
Do it yourself.

Questions and Answers

Question 1. ………… is the outermost layer of an animal cell.
Answer: Plasma membrane/Cell membrane

Question 2. What is the name given to the green plastids ? [MSE (Chandigarh) 2007]
Answer: The green plastids are called chloroplasts.

Question 3. Name two organelles present in the plant cell but not in the animal cell. [KVS 2005]
Answer: Cell wall and chloroplast are found in plant cell but not in animal cell.

Question 4. Which part of the cell contains organelles ?
Answer: Cytoplasm contains the organelles.

Question 5. Why cells could not be observed before 17th century ?
Answer: Cells could not be observed before 17th century because microscope was not available for viewing the cells.

Question 6. Why Hooke had to take thin slices of cork ?
Answer: He made thin slices of cork because the cork was solid and its details could not be seen.

Question 7. Where did Hooke demonstrate cork slice ?
Answer: Hooke demonstrated cork slice in Royal society of London.

Question 8. Single celled organisms are also called unicellular organisms (True/False)
Answer: True.

Question 9. Name the cells having branched structure.
Answer: Nerve cell.

Question 10. Which cell is observable with unaided eye ?
Answer: Ostrich egg.

Question 11. Name the outermost layer of animal cell.
Answer: Cell membrane or plasma membrane.

Question 12. Mention the layer outside the plasma membrane of a plant cell.
Answer: Cell wall.

Question 13. Which four basic elements constitute 90% of protoplasm ?
Answer: 90% of protoplasm is made up of carbon, hydrogen, nitrogen and oxygen.

Question 14. The term cell was coined by ………….
Answer: Robert Hooke.

Question 15. Cell wall is present in …………. only.
Answer: Plant cell.

Question 16. Which organism has smallest cell ?
Answer: Bacterium mycoplasmas has the smallest cell.

Question 17. How do you differentiate protoplasm from cytoplasm ?
Answer: Cytoplasm is the jelly-like substance occupying most of the space inside the cell. Protoplasm includes the cell membrane, the cytoplasm and the nucleus.

Question 18. Draw a typical cell. Label important organelles.
Answer:

Question 19. What name is given to living things having more than one cell ?
Answer: Multicellular organisms.

Question 20. Can unicellular organisms be seen with the naked eye ?
Answer: Unicellular organisms can only be viewed with the help of a microscope.

Question 21. Give two examples of unicellular animals.
Answer: Amoeba, paramoecium.

Question 22. Name the parts of the cell.
Answer: The three parts of cell — The Cell membrane, Cytoplasm and Nucleus.

Question 23. What is the jelly-like fluid inside the nucleus called ?
Answer: The jelly-like fluid inside the nucleus is called nucleoplasm.

Question 24. What are chromosomes ?
Answer: Chromosomes are thread-like structures which play an important role in the inheritance of characters from one generation to another

Question 25. What is the function of Golgi bodies ?
Answer: Golgi bodies collect and distribute the substances made in the cell.

Question 26. Which part of the animal cell is concerned with cell division ?
Answer: Centrioles and centrosome.

Question 27. Give other name for cell membrane.
Answer: Plasma membrane.

Question 28. What are vacuoles ?
Answer: The clear spaces surrounded by a membrane present in the cytoplasm are called vacuoles.

Question 29. What is meant by division of labour ?
Answer: In multicellular organisms, the cells are specialised to the perform certain functions. This is known as division of labour.

Question 30. What is meant by cell division ?
Answer: New cells for growth and reproduction are formed by cell division.

Question 31. Why are the nerve cells long and thread like ?
Answer: Nerve cells are long and thread-like projections, as they have to convey messages to different parts of the body.

Question 32. Which cells in our body grow and divide all through the life ?
Answer: The cells of the skin grow and divide all through the life.

Question 33. Name a unicellular organism which is about 10 cm in length.
Answer: An alga known as Acetabularia.

Question 34. Human body has

one million cells

 one billion cells

one trillion cells

more than a trillion cells

Answer: more than a trillion cells.

Question 35. Name the basic structural and functional unit of life.
Answer: Cell.

Question 36. Distinguish between prokaryotes and eukaryotes.
Answer:
Differences:

Prokaryotes	Eukaryotes
(i) The organisms having prokaryotic cells are called prokaryotes.	(i) The organisms have eukaryotic cells are called eukaryotes.
(ii) In prokaryotes, there is no nuclear membrane in cells.	(ii) There is a nuclear membrane around the nucleus.
(iii) e.g., Bacteria and blue green algae	(iii) e.g., Onion cells and cheek cells.

Question 37. Make a sketch of the human nerve cell. What function do nerve cells perform ?
Answer: Nerve cell — Nerve cells receive messages through dendron and transfer it through axon.

Question 38. If you boil a hen’s egg, what changes do you observe ?
Answer: When a hen’s egg is boiled, a white material surrounds the yellow part. White material is albumin which solidifies on boiling. The yellow component is yolk.

Question 39. What are the functions of the cell membrane ?
Answer: It protects the cell.

It provides shape to the cell.

It allows materials to enter and leave the cell through the tiny holes.

Question 40. Give the functions of the following :

Endoplasmic reticulum

Golgi complex

Ribosomes

Answer:

Endoplasmic reticulum being a network of membranes, provides a large surface area for life functions to take place.

Golgi complex collects and distributes the substance made in the cell and it synthesises and secretes many materials.

Ribosomes is the site of protein synthesis.

Question 41. Differentiate between plant and animal cell.
Answer: Differences:

Animal Cell	Plant Cell
(i) Cell wall is absent.	(i) A rigid cell wall is present
(ii) Chloroplasts are absent.	(ii) Chloroplasts are present.
(iii) Centrosome (a cell organelle that helps in cell division) is present near the nucleus.	(iii) Centrosome is absent
(iv) Vacuoles are absent; small in size.	(iv) Vacuoles are present and larger in size.

Question 42. Describe the variations in shape and size of cells.
Answer: Cell size. Some cells are very small and visible only with a microscope. Smallest cell is of bacterium, PPLO. An ostrich egg is the largest animal cell. In plants an alga, Acetabularia has a single cell of about 10 cm in length.
Cell shapes are very diverse. Some cells like those of Amoeba and white blood cells continuously change their shape. Most cells, however, maintain their constant shape. The shape of the cell is related to its function.

Question 43. Name the different parts of the nucleus and give the function of each part.
Answer: Nuclear membrane — It separates the nucleus from the cytoplasm. It allows the exchange of substances between the nucleoplasm and the cytoplasm.

Nucleoplasm — Chromosomes and nucleoli are present in the nucleoplasm.

Chromosomes — Play an important role in the inheritance of characters from one generation to another.

Question 44. Give the functions of the following parts of the cell:

Vacuoles.

Centrioles.

Cellulose.

Plasma membrane.

Nucleus.

Answer:

Vacuoles store the chemicalproducts which accumulate within the cell due to the various life functions taking place inside the cell.

Centrioles present in animal cells are concerned with cell division.

Cellulose is present in plant cell and provides rigidity and protection to the cell.

Plasma membrane protects the cell and allows materials to enter and leave through the tiny holes.

Nucleus controls everything that takes place in the cell.

Question 45. Explain the mode of cell division in Amoeba.
Answer: The cell divides and splits into two parts known as daughter cells. The daughter cells are identical to the parent cell. The nucleus of the parent cell divides into two, followed by the division of cytoplasm. Finally, the two daughter cells are formed.

Question 46. In multicellular organisms, how does growth take place ?
Answer: In multicellular organisms, the cells divide for reproduction and also multiply for growth. The increase in the number of cells is brought about by cell division. The cells so produced undergo a change in size and shape and the whole organism shows over all growth.

MCQs

Question 1. The structure which Robert Hooke observed under his self-designed microscope was
(a) cell wall                         (b) cell membrane
(c) both (a) and (b)            (d) living cell
Answer: (a)

Question 2. Which of the following is covered by a single membrane ?
(a) Mitochondria           (b) Vacuole
(c) Lysosome                  (d) Plastid
Answer: (b)

Question 3.   Kitchen of the cells is known as
(a) mitochondria         (b) endoplasmic reticulum
(c) chloroplast             (d) Golgi apparatus.
Answer: (c)

Question 4. Cell theory was given by
(a) Schleiden and Schwann           (b) Virchow
(c) Robert Hooke                            (d) Haeckel
Answer: (a)

Question 5. The only cell organelle seen in prokaryotic cell is
(a) mitochondria              (b) ribosomes
(c) plastids                         (d) lysosomes
Answer: (b)

Question 6. Organelle without a cell membrane is
(a) ribosome                           (b) Golgi apparatus
(c) chloroplast                        (d) nucleus
Answer: (a)

Question 7. Which organelle is known as the store house of the ! cell ?
(a) Mitochondria                         (b) Vacuole
(c) Ribosomes                              (d) Golgi complex
Answer: (d)

Question 8. Green plastids are also called
(a) chromoplasts                       (b) chloroplasts
(c) chromatin                             (d) none of these
Answer: (b)

Question 9.  Which of the following is not unicellular ?
(a) Euglena          (b) Paramecium
(c) Chicken          (d) Amoeba
Answer: (c)

Question 10. Thread-like body that lies in the nucleus of the cell is
(a) cytoplasm                (b) chromosome
(c) nucleoplasm             (d) mitochondrion
Answer:    (b)

Question 11. Which of these cells will have cell wall around them ?
(a) Cheek cells              (b) Nerve cells
(c) Onion peel cells     (d) Blood cells
Answer: (c)

 

 

Class 8 Science Chapter 1 

Microorganisms: Friends and Foe

This chapter manages destructive and valuable kinds of microbes and their significance in different areas. The places where microorganisms live, microorganisms and us, harmful microorganisms, food preservation, nitrogen fixation, and nitrogen cycle are a portion of the primary topics covered in this chapter.

Class 8 Science Chapter 2 

Coal and Petroleum

Coal and petroleum manage the two most imperative fuels ever found by humankind. The chapter additionally explains natural gas and how the characteristics assets are getting depleted because of huge and uncontrolled usage.

Class 8 Science Chapter 3 

Conservation of Plants and Animals

Conservation of plants and animals is a critical subject of science. This part will push the students to not just to understand the human exercise that negatively affects the nature’s abundance yet in addition to manners by which they can ensure the fauna and flora of the ecosystem.

Class 8 Science Chapter 4 

Reproduction in Animals

It explains the modes and procedure of reproduction in creatures. It is fundamental for the continuation of a species. In this chapter, u will figure out how reproduction happens in animals is talked about in detail.

Class 8 Science Chapter 5 

Sound

Sound talks about the distinction between music and noise. Noise pollution, its causes, impacts, and control measures are explained towards the finish off the chapter. This chapter will strengthen your base for future complex topics.

Class 8 Science Chapter 6

Food Production and Management

This chapter explains rural practices related to the creation of yield and their administration.It includes the presentation of various harvest, their climatic and nourishing necessities and the preparation of soil for comprehensive improvement of the crops 

Class 8 Science Chapter 7 

Combustion and Flame

In this chapter, you will learn about different sorts of fuels are utilized for a different purpose at home, in industry and for running autos. Powers like cow dung, wood, coal, charcoal, petroleum, diesel, packed gaseous petrol (CNG) and so on are known to the students. In combustion and flame, the chemical procedure of burning and the sorts of flames created amid this procedure are considered in detail.

Class 8 Science Chapter 8 

Chemical Effects of Electric Current

In this chapter, we will discover that metals, for example, copper and aluminum conducts electricity while materials, for example, rubber, plastic, and wood don’t conduct electricity.

Class 8 Science Chapter 9 

Force and Pressure

This chapter will take the students through the brilliant world of force and pressure. It will push them to build u uphold of the point as well as ace the ideas that will assist them with performing better.

Class 8 Science Chapter 10 

Reaching the Age of Adolescence

In this chapter, the student will find out about changed that happen in the human body after which an individual ends up fitting for reproduction.in this chapter we will learn about the human conceptive organs and the role of hormones in the development of an individual.

Class 8 Science Chapter 11

Materials: Metals and Non-metals

This chapter explains the world of metals, non-metals, their properties, and employment. This section will assist the students with classifying the components into metals and non-metals based on their properties. Physical properties of metals and non-metals, chemical properties of metals and non-metals, use of metals and non-metals are a portion of the vital topics talked about in this chapter. 

Class 8 Science Chapter 12

Light

Light talks about the key properties, impacts, and utilization of light and its subordinates. This chapter also gives information about regular reflection, diffused reflection, laws of reflection, etc.

 

Class 8 Science Chapter 13 

 Pollution of Air and Water

This chapter addresses the solution for the unsafe wonder of pollution and how might one add to its decrease in the individual dimension. Air pollution, how does air get polluted are some of the significant topics discussed in this chapter.

Class 8 Science Chapter 14

Friction

It is an essential section of physics that manages the backing off or opposition of movement. Its causes, impacts, applications and other key properties are talked about in his chapter.

 

Class 8 Science Chapter 15 

Stars and Solar System

This chapter explains about the celestial objects. Position of those objects, their structure and centrality are portrayed in this chapter. This part also discusses the moon, periods of the moon its situation in the planetary system and surface of the moon.

Class 8 Science Chapter 16

Cell: Structure and Functions

It explains the inside and out information about the major unit of life -cell. It enlightens the students regarding the discovery of the cell, its inclination, properties, and composition

 

Class 8 Science Chapter 17 

Some Natural Phenomenon

This chapter throws light on the wonderful phenomenon of nature, for example, lightning and earthquake. Causes, impacts, magnitude and properties of lightning are discussed in this chapter.