The Fundamental Unit of Life Extra Questions and Answers Science Chapter 5
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- One-line questions (1 mark)
Q.1) State the Cell theory?
Ans. The cell theory was given by, Schleiden (1838)and Schwann (1839) states that all living organisms are made up of cells and arise from already existing cells.
Q.2) What are the three essential features of a cell?
Ans. The three essential features of the cells include plasma membrane, nucleus and cytoplasm. These three components allow the cells to interact with the environment and also carry out all the cell activities.
Q.3) Define diffusion?
Ans. Diffusion is the movement of atoms, molecules or gases from area of high concentration to area of low concentration. In a cell molecule like CO2, O2 and H2O are transported by diffusion.
Q.4) What is plasmolysis?
Ans. Water loses in a plant cell by the process of osmosis, which leads the cells to shrink is called plasmolysis.
Q.5) What is cellulose? State its function in plant cells.
Ans. Cellulose is a long polymer made of glucose. It is the main component plant cell wall which gives structural support to the plant.
Q.6) Give the significance of cell membranes with respect to viruses?
Ans. Viruses do not contain the cell membranes, so they lack living character. They have to enter inside a living host and use the host enzymes and machinery to multiply.
Q.7) What are cisterns?
Ans. Cisterns are flattened membrane-bound vesicles placed parallel to each otherin stacks which are called cisterns.
Q.8) What is the cytoplasm? Explain briefly its function in a cell
Ans. 1.) Cytoplasm is the fluid matrix of the cell which is enclosed by the plasma membrane.
2.) It is matrix which houses the cell organelles which in turn perform specialized function for the cell.
- Short answer questions (2 mark)
Q.1) What are the two types of endoplasmic reticulum? State its functions.
Ans. a.) The two types of ER are the rough endoplasmic reticulum (RER) and smooth endoplasmic reticulum (SER).
b.) The rough endoplasmic reticulum is the site of protein synthesis.
c.) The smooth endoplasmic reticulum is responsible for fat or lipid synthesis. It also helps in detoxification of poisons and drugs.
Q.2) Explain in brief the types and functions of plastids.
Ans. a.) There are two types of plastids in plant cells.
b.) The chromoplasts is the chlorophyll containing colored plastid. It is also known as chloroplast which is important to perform photosynthesis.
c.) Leucoplasts is a white colored or colorless plastids. Leucoplasts are store houses of starch, oils and protein granules in the cell.
Q.3) Describe the structure and function of vacuoles?
Ans.1.)Vacuoles are present in both animals and plants.
2.) The plant vacuole contains cell sap and provide the cell with rigidity and turgidity.
3.) The vacuoles are store house for amino acids, sugars, organic acids etc.
4.) In animal cells a number of small vacuoles are found. A special type of food vacuole is present in animal cells.
Q.4) Write a short note on: Lysosomes
Ans. 1.) Lysosomes popularly known as the suicide bags are membrane-bound organelles.
2.) These are sacs containg digestive enzymes which help in removal of any foreign entity such as bacteria, food out of the cell.
3.) Lysosomes thus function as a waste disposal system to clear out worn-out cell organelles.
4.) Lysosomes break down all organic material so that they can be recycled.
- Long answer questions (5 mark)
Q.1) Explain the difference in hypotonic, hypertonic and isotonic solution.
Ans. There are three types of tonicities that a solution can have relative to another-
1.Hypertonic solution -A solution with a higher solute content than a cell is called as Hypertonic solution. If a cell is placed in a hypertonic solution it will shrink as water the medium surrounding the cell has lower water concentration than the cell
2.Hypotonic solution -A solution with a lower solute content than a cell is called as Hypotonic solution. If the cell is placed in a hypotonic solution the cell swells up as the medium surrounding the cell has a higher water concentration than the cell
3.Isotonic solution –A solution has the same solute content as cell is called as isotonic solution. When the cells are placed in an isotonic solution, their size remains constant. This happens because the amount of water going inside the cells and outside the cell is the same.
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Q.2) Write a short note: Nucleus.
Ans. 1.) The nucleus is a double layered membrane containg the chromosomes.
2.) Chromosomes contain hereditary material such DNA or RNA
3.) Genes are small segments of DNA which provide functional information about constructing and organizing cells.
4.) The nucleus functions in organizing cellular reproduction and determining the way the cell will develop after reaching maturity.
5.) thus it is the organizing center in a cell.
MCQs
1) _____________ are known as ‘Suicidal Bag’ of the cells.
a) Mitochondria
b) Lysosomes
c) Golgi apparatus
d) Ribosomes
2) Mitochondrion is known to perform the functions except
a) electron transport
b) ATP production
c) Fatty acid breakdown
d) Glycolysis
3) Which of the following is not a membrane bound cell organelle?
a) Ribosomes
b) Mitochondria
c) Rough endoplasmic reticulum
d) Nucleus
4.) __________ is the movement of water through a semipermeable membrane, from area of higher concentration to lower concentration.
a.) osmosis
b.) diffusion
c.) facilated diffusion
d.) all the above
5.) amoeba engulf food by the process of___________
a.) endocytosis
b.) exocytosis
c.) diffusion
d.) none of the above
6.) _____________ are present only in plant cells
a.) Mitochondria
b.) Plastids
c.) Nucleus
d.) ribosomes
7.) The new cells formed after _________________ only have half the number of chromosomes than that of the mother cells.
a.) mitosis
b.) meiosis
8.) Protein synthesis occurs on ________
a) ribosomes
b) mitochondria
c.) nucleus
d.) perioxisomes.
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