NCERT Solutions Class 8 Science Cell Structure and Functions

Scroll down for PDF

NCERT Solutions for Class 8 Science for chapter 8 Cell Structure and Functions

Exercises

Question-1 Indicate whether the following statements are true (T) or false (F).

a) Unicellular organisms have one-celled body. (T/F)
b) Musclecells are branched. (T/F)
c) The basic living unit of an organism is an organ. (T/F)
d) Amoeba has irregular shape. (T/F)

Answer:

a) Unicellular organisms have one-celled body. (T)
b) Muscle cells are branched.(F)
c) The basic living unit of an organism is an orga (F)
d) Amoeba has irregular shape. (T)

Question-2. Make a sketch of human nerve cell. What functions do nerve cells perform?

Answer:

image

The nerve cell receives and transfers messages 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 - In a cell, a jelly-like substance present between the nucleus and the cell membrane is called cytoplasm. It contains various cell organelles such as mitochondria, golgi apparatus, endoplasmic reticulum, lysosomes, etc. It helps in the exchange of material between the cell organelles.

b) Nucleus of a cell - Nucleus is generally spherical in shape and located centrally in a cell. A porous membrane called nuclear membrane separates the nucleus from the cytoplasm. Nuclear membrane allows the exchange of materials between the nucleus and the cytoplasm. Nucleus contains a smaller spherical body called nucleolus and thread-like structures called chromosomes. Chromosomes carry genes and help in the transfer of characters from one generation to the next generation. In addition to the function of inheritance of characters, nucleus regulates all the activities of a cell.


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


Question-5 Make sketches of animal and plant cells. Statethree differences between them.
Answer:

The spetch is as follows-

image

 

Differences between animal cell and pant cell

Parts of cell

Animal Cell

Plant Cell

Cell wall

Absent

Present

Plastids

Absent

Present

Vacuoles

Many but small in size

One big central


Question-6 State the difference between eukaryotes and prokaryotes.

Answer: Following are the differences between eukaryotes and prokaryotes

Features

Eukaryotes

Prokaryotes

Number of cells present

Multicellular

Unicellular

Nucleus

Well defined, and true nucleus

Poorly defined, and a primitive nucleus

Nuclear membrane

Present

Absent


Question-7 Where are chromosomes found in a cell? State their function.

Answer: Chromosomes are found in the nucleus of a cell. Chromosomes are thread-like structures that carry genes which play a vital role in the inheritance of characters from parents to their offspring.


Question-8 Cells are the basic structural units of living organisms. Explain.

Answer: In a living organism, various organs are present which perform various functions such as digestion, respiration, reproduction, movement, etc. Organs are specific for their function that they perform. For example, leaves carry out photosynthesis, ovary produces ova, etc. In an organism specific tissues are present that facilitate it to perform its specific function. Furthermore, a tissue is composed of similar types of cells. Hence, we can say that cells ate the basic structural unit of living organisms.


Question-9 Explain why chloroplasts are found only in plant cells?

Answer: Chloroplast is a type of plastid that contains green coloured pigment chlorophyll. Chlorophyll is one of the essential requirements for photosynthesis to occur. Plastids are the organelles that are present only in plant cells. Hence, chloroplasts are found only 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. Unit of inheritance present on the chromosome.

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.

Answer:

Across
1. Chlorophyll

3. Organelle

6. Protoplasm

8. Genes

Down

1. Chloroplasts

2. Organ

4. Membrane

5. Vacuole

7. Tissue

Tags: 

Click on the text For more study material for Science please click here - Science

Latest NCERT & CBSE News

Read the latest news and announcements from NCERT and CBSE below. Important updates relating to your studies which will help you to keep yourself updated with latest happenings in school level education. Keep yourself updated with all latest news and also read articles from teachers which will help you to improve your studies, increase motivation level and promote faster learning

CBSE Board Exam 2020 Major developments

CBSE Board Exam 2020: Major developments for Class 9th, 10th, 11th and 12th | Check details : CBSE board exam 2020: Here are all the major decisions that the CBSE (Central Board of Secondary Education) has taken for Classes 9th, 10th, 11th and 12th. In the last 2...

CBSE Board Practical Exam 2020

CBSE Board Practical Exam 2020: Important changes in date sheet, internal/external examiners and more Are you doing preparations for class 10 and 12 CBSE board exams? If yes, then you have to see what major changes CBSE has brought in the CBSE date sheet for class 10...

Class 10 and 12 exam 2020 application process for private candidates

CBSE 10th, 12th exam 2020 application process for private candidates begins to apply by 30th Sept at cbse.nic.in CBSE Board Exam 2020 application begins: The Central Board of Secondary Education (CBSE) has officially started the online application process for the...

Top Classroom Challenges According to the Teachers

Teacher plays a major role in our lives in the classrooms. Not only is studying, but the teacher also serves many other roles in the classrooms. A teacher is always a role model for a student who can inspire him to live a better future life. Besides this, life of a...

What Is The Secret Of Choosing A Good Tutor For Your Child?

Is your child lost in the maze of syllabus, chapters, millions of topics and huge books? Does your child feel lost in a class filled with many students? Is your child unable to bring in the best results? Well, then, you definitely need to find some alternative...

CBSE Instructs schools to form Eco Clubs

The Central Board of Secondary Education has directed schools to form Eco Clubs under the Board for Environmental Protection. They have further asked the schools to ensure that every student would save one litre of water at home and school every day. It was started by...

×
Studies Today