Cell : The Unit of Life Short Answer Biology Class-9 ICSE Selina Publishers Solutions Chapter-2. Step By Step ICSE Selina Concise Solutions of Chapter-2 Cell : The Unit of Life with Exercise-2 including MCQs, Very Short Answer Type, Short Answer Type, Long Answer Type and Structured/Application Questions Solved . Visit official Website CISCE for detail information about ICSE Board Class-9.
Cell : The Unit of Life Exe-2 Short Answer Biology Class-9 ICSE Concise Selina Publishers
| Board | ICSE |
| Publications | Selina Publication |
| Subject | Biology |
| Class | 9th |
| Chapter-2 | Cell : The Unit of Life |
| Book Name | Concise |
| Topics | Solution of C. Short Answer Type |
| Academic Session | 2023-2024 |
C. Short Answer Type
Cell : The Unit of Life Class-9 Biology Concise Solutions
Page 22
Question 1.
Define the terms:
(a) Cell organelles
(b) Cell inclusions
(c) Cytosol
(d) Cell sap
(e) Cytoplasm
Answer:
(a) Cell organelles: An organelle is a subcellular structure that has one or more specific jobs to perform in the cell, much like an organ does in the body. Among the more important cell organelles are the nuclei, which store genetic information; mitochondria, which produce chemical energy; and ribosomes, which assemble proteins.
(b) Cell inclusions: Cytoplasmic inclusions are the non-living intercellular substances not bound by any of the membranes and did not carry out any other metabolic activity.
(c) Cytosol: The cytosol, by definition, is the fluid in which organelles of the cell reside.
(d) Cell sap: Cell sap is the liquid inside the large central vacuole of a plant cell. Cell sap serves as the storage of materials and provides mechanical support, especially in non-woody plants.
(e) Cytoplasm: Cytoplasm is the gelatinous liquid that fills the inside of a cell. It is composed of water, salts, and various organic molecules. Some intracellular organelles, such the nucleus and mitochondria, are enclosed by membranes that separate them from the cytoplasm.
Question 2.
Write the exact locations of each of the following:
(a) Centrosome
(b) Chromosome
(c) Genes
(d) Mesosome
(e) Plasmid
Answer:
(a) Centrosome: Location: Centrosome is found within cytoplasm near the nucleus.
(b) Chromosome: Chromosomes are thread-like structures located inside the nucleus of animal and plant cells.
(c) Genes: Genes are contained in chromosomes, which are in the cell nucleus.
(d) Mesosome: Mesosomes are organelles formed by plasma membrane infoldings. They are found in the membranes of bacterial cells.
(e) Plasmid: They are most commonly found as small circular, double-stranded DNA molecules in bacteria; however, plasmids are sometimes present in archaea and eukaryotic organisms.
Question 3.
Mention three features found only in plant cells and one found only in animal cells.
Answer:
Features found only in plant cells:
(i) Presence of cell wall
(ii) Presence of large vacuoles. The liquid contained in vacuoles is called cell sap
(iii) Presence of plastids
Features found only in animal cells:
(i) Presence of centrosome
Question 4.
Why are the cells generally of a small size?
Answer:
Cells generally remain small in size because:
(i) To enable different regions of the cell to communicate with each other rapidly for the cell to function effectively
(ii) To have a large surface area is to volume ratio for greater diffusion of substances, in and out of the cell.
Question 5.
It is said that the protoplasm cannot be analysed chemically. Why?
Answer:
Protoplasm is the living matter of the cell. Protoplasm cannot be analysed chemically because the chemical composition of protoplasm is very complex. It varies slightly from one cell to another, although the common elements included in the composition of protoplasm such as carbon, hydrogen, oxygen, nitrogen, sulphur, iron and phosphorus are still the same in all the cells.
Question 6.
What is the difference between an organ and an organelle?
Answer:
Organs of an organism are the parts of the body which have a definite shape and structure and perform specific functions. Cell organelles are also parts of the cell which have a definite shape and structure and perform specific functions. Organelles have the same status in a cell as the organs have in the entire body of an animal or a plant performing specific functions.
Question 7.
Do you think the cells of an elephant would be larger than the cells of a rat? Explain briefly.
Answer:
The cells of an elephant would be of the same size as the cells of a rat. The size of cells does not vary within the organisms, however, the number of cells varies from one organism to another. A larger animal like an elephant will have more number of cells as compared to a smaller animal like a rat. However, the size of the cell will be the same.
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