Cell structure and functions Class 8 CBSE Extra Questions
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Short answer type questions/HOTS:
Question 1. Short answer type questions:
(i)What is cell division?
(ii)Which part of the cell is called the powerhouse of the cell?
(iii)Name the scientist who discovered the three-dimensional helical model of the DNA.
(iv)What is the full form of DNA?
(v) What are genes? Answer
Cell division is a process of multiplying or replicating cells.
Mitochondria
Francis Crick and James Watson.
Deoxyribose Nucleic Acid.
Genes are the basic unit of inheritance.
Question 2.
In a biology laboratory, Amelia noticed a unfertilized egg of an ostrich which is a largest cell but she didn't see the smallest cell with naked eye. How can she see one cell but not the other? Explain your response specifically. Answer
Amelia noticed a unfertilized egg of an ostrich while she didn't notice the smallest one because the size of the smallest cell is about 0.01 mm-0.10 mm which can’t be observed with naked eye. We can observe the small cells under a microscope. On the other hand, the size of a unfertilized egg of an ostrich is big and weighs 2.25 Kg.
Question 3.
Which part of the cell is called its boundary which is responsible for the entry and exit of the components inside and outside the cell? Answer
Cell membrane is known as the boundary of the cell, which is semi-permeable in nature, decides the movement of the components inside or outside the cell.
Question 4.
What do you understand by the term “Cytoplasm”? Explain its function. Answer
Cytoplasm is a jelly-like substance present inside the cell that contains the cell organelles like nucleus, mitochondria and endoplasmic reticulum etc. The function of the cytoplasm is to store and release energy and it is also a site of all metabolic activities.
Question 5.
Explain the postulates of the cell theory. Answer
The following postulates of the cell theory are as follows: -
(a)The cell is considered as the basic structural and functional unit of life.
(b)All living organisms are made up of cells or cell.
(c)New cells develop from existing cells.
Question 6.
Distinguish between unicellular and multicellular organisms. Answer
The differences between unicellular and multicellular organisms are given below in a table: -
Long answer type questions:
Question 7.
Draw a well-labelled diagram of Amoeba. Answer
Question 8.
Draw a well-labelled diagram of a plant cell. Answer
Question 9.
Draw a well-labelled diagram of animal cell. Answer
Question 10.
Distinguish between animal and plant cell. Answer
The differences between animal and plant cell are given below: -
Question 11.
Describe the function of the following cell organelles: Answer
Nucleus
Nucleus is the most important organelle of a cell. It is a spherical-shaped surrounded by a nuclear membrane in eukaryotic cells. It is a site of chromosomes which contains the genetic information which describes all the features of the human body. Protein Synthesis process is also started here.
Endoplasmic Reticulum
Endoplasmic reticulum is a network of membranous tubes near the nucleus. It is responsible for the transportation of substances in or out and protein synthesis.
Cytoplasm
Cytoplasm is a jelly-like substance present inside the cell that contains the cell organelles. It is a site of all metabolic activities and store or release energy.
Cell membrane
The outer covering of the cell that is responsible for the transportation of the components inside or outside the cell. It is semi-permeable in nature.
Lysosomes
Lysosomes are small and rounded sacs present inside the cell. They are responsible for the digestion of foreign bodies. Therefore, they are also called suicidal bags.
Summary
This Cell structure and functions Class 8 Extra Questions and asnwers is prepared keeping in mind the latest syllabus of CBSE . This has been designed in a way to improve the academic performance of the students. If you find mistakes , please do provide the feedback on the mail.
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