{"id":25417,"date":"2021-06-22T18:50:32","date_gmt":"2021-06-22T13:20:32","guid":{"rendered":"https:\/\/ncertsolutions.guru\/?p=25417"},"modified":"2021-06-22T18:50:32","modified_gmt":"2021-06-22T13:20:32","slug":"ncert-solutions-for-class-8-science-chapter-8","status":"publish","type":"post","link":"https:\/\/ncertsolutions.guru\/ncert-solutions-for-class-8-science-chapter-8\/","title":{"rendered":"NCERT Solutions for Class 8 Science Chapter 8 Cell \u2013 Structure and Functions"},"content":{"rendered":"

These NCERT Solutions for Class 8 Science<\/a> Chapter 8 Cell \u2013 Structure and Functions Questions and Answers are prepared by our highly skilled subject experts to help students while preparing for their exams.<\/p>\n

Cell \u2013 Structure and Functions NCERT Solutions for Class 8 Science Chapter 8<\/h2>\n

Class 8 Science Chapter 8 Cell \u2013 Structure and Functions Textbook Exercise Questions and Answers<\/h3>\n

Page-98<\/span><\/p>\n

Question 1.
\nIndicate whether the following statements are True (T) or False (F).
\na. Unicellular organisms have one-celled body. (T\/F)
\nb. Muscle cells are branched. (T\/F)
\nc. The basic living unit of an organism is an organ. (T\/F)
\nd. Amoeba has irregular shape. (T\/F)
\nAnswer:
\n(a) True,
\n(b) False,
\n(c) False,
\n(d) True<\/p>\n

Question 2.
\nMake a sketch of the human nerve cell. What function do nerve cells perform?
\nAnswer:
\n\"NCERT
\nThe function of a nerve cell is to transmit messages to the brain and also from the brain to the receptor organs. Thus, it controls the working of different parts of the body.<\/p>\n

Question 3.
\nWrite short notes on the following:
\na. Cytoplasm
\nb. Nucleus of a cell
\nAnswer:
\na. Cytoplasm: A jelly-like substance present between the cell membrane and the nucleus is called cytoplasm. Different cell organelles are present in the cytoplasm. Examples of cell organelles are mitochondria, Golgi body, ribosomes, lysosomes, chloroplasts, etc. The cytoplasm acts as a medium for the exchange of materials across the cell organelles.<\/p>\n

b. Nucleus of a cell: This is a spherical structure which is present inside the celt usually at the centre of the cell. Nucleus is surrounded by a double membrane called nuclear membrane. A spherical structure called nucleolus is present inside the nucleus. Nucleus contains chromosomes which are thread-like structures carrying genes. These genes are responsible for transferring the characters from parents to their offspring.<\/p>\n

Question 4.
\nWhich part of the cell contains organelles?
\nAnswer:
\nCytoplasm is the part of the cell that contains various organelles such as mitochondria, ribosomes, Golgi bodies, etc.<\/p>\n

\"NCERT<\/p>\n

Question 5.
\nMake sketches of animal and plant cells. State three differences between them.
\nAnswer:
\n\"NCERT
\n\"NCERT<\/p>\n\n\n\n\n\n\n\n
\n

S. No.<\/p>\n<\/td>\n

Animal cell<\/td>\n\n

Plant cell<\/p>\n<\/td>\n<\/tr>\n

I.<\/td>\nThey are generally small in size.<\/td>\nThey are usually larger than animal cells.<\/td>\n<\/tr>\n
2.<\/td>\nCell wall is absent.<\/td>\nCell wall is present.<\/td>\n<\/tr>\n
3.<\/td>\nVacuoles are smaller in size.<\/td>\nVacuoles are larger in size.<\/td>\n<\/tr>\n
4.<\/td>\nPlastids are absent in general.<\/td>\nPlastids are present.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Question 6.
\nState the difference between eukaryotes and prokaryotes.
\nAnswer:<\/p>\n\n\n\n\n\n\n\n\n
Prokaryotes<\/td>\nEukaryotes<\/td>\n<\/tr>\n
1. Most prokaryotes are unicellular.<\/td>\n1. Most eukaryotes are multicellular.<\/td>\n<\/tr>\n
2. The nucleus is poorly defined due to the absence of a nuclear membrane.<\/td>\n2. The nucleus is well defined and is surrounded by a nuclear membrane.<\/td>\n<\/tr>\n
3. Nucleolus is absent.<\/td>\n3. Nucleolus is present.<\/td>\n<\/tr>\n
4. Cell organelles such as plastids, mitochondria, Golgi bodies, etc., are absent.<\/td>\n4. Cell organelles such as plastids, mitochondria, Golgi bodies, etc., are present.<\/td>\n<\/tr>\n
5. Bacteria and blue\u00ad green algae are prokaryotic cells.<\/td>\n5. Fungi, plant and animal cells are eukaryotic cells.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Question 7.
\nWhere are chromosomes found in a cell? State their function.
\nAnswer:
\nChromosomes are found inside the nucleus. Chromosomes are responsible for the inheritance of characters from one generation to the next.<\/p>\n

Question 8.
\n\u2018Cells are the basic structural units of living organisms\u2019. Explain.
\nAnswer:
\nAll organisms are made up of cells. The way a building is made up of bricks, an organism is made up of cells. Many cells group together to make a tissue. Many tissues come together to make an organ which in turn come together to make an organ system. Many organ systems together make an organism. Thus, it is clear that cells are the basic structural units of living organisms.<\/p>\n

Question 9.
\nExplain why chloroplasts are found only in plant cells?
\nAnswer:
\nChloroplasts contain a green pigment called chlorophyll. This green pigment is important for photosynthesis in green plants. This chlorophyll pigment traps solar energy and utilises it to manufacture food for the plant. Since animals do not photosynthesise, they do not require chlorophyll. Hence, chloroplasts are found only in plant cells.<\/p>\n

\"NCERT<\/p>\n

Question 10.
\nComplete the crossword with the help of clues given below.
\nAcross
\n1. This is necessary for photosynthesis.
\n3. Term for component present in the cytoplasm.
\n6. The living substance in the cell.
\n8. Units of inheritance present on the chromosomes.
\nDown
\n1. Green plastids.
\n2. Formed by collection of tissues.
\n4. It separates the contents of the cell from the surrounding medium.
\n5. Empty structure in the cytoplasm.
\n7. A group of cells.
\n\"NCERT
\nAnswer:
\nAcross
\n1. Chlorophyll
\n3. Organelle
\n6. Protoplasm
\n8. Genes<\/p>\n

Down
\n1. Chloroplasts
\n2. Organ
\n4. Membrane
\n5. Vacuole
\n7. Tissue<\/p>\n

NCERT Extended Learning Activities and Projects<\/span><\/p>\n

Question 1.
\nVisit a laboratory for senior secondary students in your school or in a neighbouring school. Learn about the functioning of a microscope in the laboratory. Also observe how a slide is observed under the microscope.
\nHint:
\nDo it yourself.<\/p>\n

Question 2.
\nTalk to the senior biology teacher in your school or a neighbouring school. Find out if there are diseases which are passed on from parents to the offspring. Find out how these are carried and also if these diseases can be treated. For this you can also visit a doctor.
\nHint:
\nYes, there are several diseases which are passed on from the parents to their offsprings. These are genetic diseases which are controlled by the chromosomes. Some examples include haemophilia, sickle cell anaemia, Huntington\u2019s disease, etc.<\/p>\n

Question 3.
\nVisit an agriculture extension centre in your area. Find out about genetically modified (GM) crops. Prepare a short speech for your class on this topic.
\nHint:
\nGenetically modified or GM crops refer to the plants whose DNA (or specific genes) has been modified with the help of genetic engineering techniques and are then grown and cultivated. Mutation breeding was the earlier alternative to provide better yields where an organism is exposed to radiations or chemicals to bring permanent changes in the quality of the plant and its yield. The objectives were primarily to prevent the attack of insects and pests, resistance to diseases and changing environmental conditions, enabling a plant to grow in a different soil and climate than the one in which it normally grows. Golden rice is a variety of rice produced through genetic engineering to incorporate vitamin A in it. This improves the nutritional value of rice. Hence, required traits can be incorporated into the GM crops by genetic modifications.<\/p>\n

\"NCERT<\/p>\n

Question 4.
\nFind out about Bt cotton from an agriculture expert. Prepare a short note on its advantages\/disadvantages.
\nHint:
\nBut cotton is a genetically modified crop and a pest resistant variety. It contains a gene taken from the bacterium, Bacillus thuringiensis. This gene produces an enzyme which is poisonous to the pests. In this way, But cotton is able to produce this enzyme and kill the invading pests.<\/p>\n

Activity 1<\/span><\/p>\n

Objective: To study the permanent slide of Amoeba.
\nMaterials Required: Slide of Amoeba and a microscope.
\nProcedure:<\/p>\n