The Fundamental Unit Of Life Chapter 5 Class 9 Science Worksheets

Students should practice questions given in The Fundamental Unit Of Life Chapter 5 Class 9 Science Worksheets. These worksheets for Class 9 Science have a good collection of important questions and answers which are expected to come in your class tests and examinations. You should learn these solved worksheet questions for Science Class 9 as it will help you to understand all topics and give you more marks.

Class 9 Science Worksheets Chapter 5 The Fundamental Unit Of Life

Please refer to below questions and answers for The Fundamental Unit Of Life Chapter 5 Class 9 Science Worksheets. Prepared by expert teachers for Standard 9 Science

Question. What are ribosomes? Where are ribosomes located in the cell? What is their function?

Question. What is the energy currency of the cell?

Question. What is the cell wall composed of ?

Question. What is osmosis?

Question. What is the full form of DNA?

Question. Name the cell organelle that helps in packaging?

Question. Why does mitochondria have largely folded inner membrane?

Question. Which organelle makes the digestive enzyme of lysosome?

Question. What are cisterns?

Question. Name the cell organelles that have their own DNA and ribosomes. Name the autonomous organelles in the cell.

Question. How do substances like CO₂ and water move in and out of the cell?

Question. What is the role of cell organelles in the cell?

Question. What is the function of ribosome?

Question. Where are genes located in the cell?

Question. Name the cell organelle which helps in the transportation of material.

Question. Name the cell organelle due to which leaves, flowers and fruits get their colour.

Question. Name the cell organelle which helps in the formation of lysosome.

Question. Name the cleaning organelle in the cell.

Question. List two similarities between mitochondria and plastids.

Question. (i) Name the largest animal cell.
(ii) Name the smallest cell.

Question. What is cell wall?

Question. Name the autonomous organelles in the cell.

Question. Name the type of organism in which a single cell constitutes the whole organism.

Question. Where are proteins synthesized inside the cell?

Question. What could happen if nucleus is removed from the cell?

Question. Give example of working of chromoplasts.

Question. What is the function of cell wall and plasma membrane?

Question. Name the smallest cell and the longest cell in human body.

Question. Give brief introduction of Prokaryotic and Eukaryotic cell.
Answer. Prokaryotic cell :
1. Cell size is generally small.
2. Only a single chromosome is present.
3. Nucleolus is absent.
4. Cell division takes place by fission or budding.
Eukaryotic cell :
1. Cell is generally large.
2. More than one chromosome is present.
3. Nucleolus is present.
4. Cell division takes place by mitotic or meiotic.

Question. State the difference between smooth endoplasmic reticulum and rough endoplasmic reticulum.
Answer.

Question. All cells come from pre-existing cells. Justify?
Answer. All organisms around are made up of one or more cells. There are single cells organism called unicellular like amoeba whereas some single body are made up of many cells called multicellular organism. Cells divide to produce cells of their own kind. Hence, all cells come from pre-existing cells.

Question. What is the function of nucleus in a cell?
Answer.The nucleus plays a very important role in the reproduction of cells. It also helps the single cell to divide and form two new daughter cells. It also helps in an important role in determining how cell will develop.

Question. What is endoplasmic reticulum? Write its main functions.
Answer. Endoplasmic reticulum is a network, enclosing a fluidfilled lumen. Its main functions are :
(i) Synthesis of proteins (rough ER).
(ii) Synthesis of lipids and other metabolic products and their secretion (SER).
(iii) Helps in formation of cell plate and nuclear membrane during cell division.
(iv) ER also produces substance for new cellular parts (especially cell membrane).
(v) ER provides internal support to the colloidal cytoplasmic matrix of the cell.

Question. What is the function of plastids?
Answer. Plastids are present only in plant cells. There are two types of plastids chromoplasts (coloured plastids) and leucoplasts (white or colourless).
Chromoplast : Consists of coloured pigments and given different colours to flowers, fruits and leaves.
The green colour pigment present in leaf is called chlorophyll which helps in the photosynthesis and a plastid with chlorophyll is called chloroplast.
Leucoplast : It stores starch, oil and protein granules in it.

Question. List any six functions of nucleus of a cell.
Answer.(i) Nucleus plays a central role in cellular reproduction.
(ii) It plays an important role in determining the way the cell will develop.
(iii) It also determines what form the cell will exhibit at maturity.
(iv) It contains chromosome thus inherits characters.
(v) It is the control centre of the cell.
(vi) It directs chemical activities of the cell.

Question. Explain the structure and function of Golgi bodies.
Answer. Structures : Golgi bodies consist of a system of membrane-bound vesicles arranged in stacks parallel to each other called cisterns. These membranes have connections with the membrane of endoplasmic reticulum (ER).
Functions :
(i) The material synthesized near the ER is packaged and dispatched to various targets inside and outside the cell through Golgi apparatus.
(ii) It also stores, modifies and helps in the packaging of products in vesicles.
(iii) In some cases, complex sugars may be made from simple sugars in it.
(iv) It also helps in the formation of lysosomes.

Question. Name some organelles which are found only in animal cells and those which occur only in plant cells.
Answer.
(i) Structures found only in animal cells : centrosomes, lysosome.
(ii) Structures found only in plant cells : cell wall,plastids and big vacuoles.

Question. What is lacking in a virus which makes it dependant on a living cell to multiply?
Answer. Viruses look selectively permeable process membrane and cell organelles. Thus, they lack a basic structural organization to perform various life processes effectively and in their own way. After entering in a living cell, a virus utilizes its own genetic material and machinery of host cell to multiply.

Question. Give difference between organs and organelles.
Answer. Organs :
They are found in multicellular organisms.
They are large sized.
They may be external or internal to the body of organisms.
Organelles :
1. They are found in all eukaryotic cells.
2. They are very small sized.
3. They are mostly internal.

Question. What is the difference in chromatin, chromosomes and gene?
Answer.

Question. Give difference between diffusion and osmosis.
Answer. Diffusion :
1. Diffusion can occur in any medium.
2. The diffusing molecules may be solids, liquids or gases.
3. Semipermeable membrane is not required.
4. An equilibrium in the free energy of diffusion molecules is achieved in the system.
Osmosis :
1. It occurs only in liquid medium.
2. It involves movement of solvent molecules only.
3. Semipermeable membrane is required.
4. Equilibrium in the free energy of solvent molecules is never achieved.

Question. Explain endocytosis.
Answer. Endocytosis is the ingestion of material by the cells through the plasma membrane. It is a collective term that describes three similar processes : phagocytosis (cell eating), potocytosis (cell drinking) and receptormediated endocytosis. These processes are pathways to specifically internalize solid particles, small molecules and macromolecules, respectively.

Question. Why do plant cells have more in number and big-sized vacuoles as compared to the animal cells?
Answer. Plants cells attain turgidity and rigidity due to the more number of vacuoles as well as large-sized vacuoles help the plant cells to withstand the wear and tear, external environmental conditions. They also help in the storage of essential material required by plants for their growth like amino acids, sugar and various organic substances.

Question. (a) Name the organelle which provides turgidity and rigidity to the plant cell. Name any two substances which are present in it.
(b) How are they useful in unicellular organisms?
Answer.
(a) Plant cells have big vacuoles that provide them turgidity and rigidity. Plant vacuoles store amino acids, sugars, various organic acids and some proteins.
(b) In unicellular organism they can serve the following works :
(i) Forming food vacuoles : In single celled organisms like amoeba, the food vacuole contains the food items that the amoeba has engulfed. After that the food items are digested by the enzymes.
(ii) Removal of excess water and wastes : In some unicellular organisms, vacuoles play important roles in egesting excess water and some wastes from the cell.

Question. Explain the functions of various cell organelles.
Answer. Functions of cell organelles :
(i) Endoplasmic Reticulum : It forms the supporting skeletal framework of the cell.
(ii) Ribosomes : It synthesises proteins.
(iii) Golgi Apparatus : It produces vacuoles which contain cellular secretion.
(iv) Lysosomes : It serves as intracellular digestive system as it digest the foreign materials which enter the cell.
(v) Mitochondria : These are the sites of cellular respirations.
(vi) Plastids : These are present only in plants and trap solar energy to manufacture food for plants.
(vii) Vacuoles : They help to maintain the osmotic pressure in a cell.
(viii) Peroxisomes : They carry-out some oxidative reactions.
(ix) Centrosome : It helps in cell division in the animal cell.

Question. Write a note on the structure of cell.
Answer.
(a) Cell is the basic unit of all living organisms. It is surrounded by an outer selectively permeable Plasma Membrane. Plant cells have an additional covering called “cell wall” outer to the Plasma Membrane.
(b) Inside the plasma membrane there is a translucent viscous substance the cytoplasm in which the organelles are embedded. The control centre of the cell is the nucleus; it contains all the information necessary for the cell to function and to reproduce. Surrounding the nucleus is the endoplasmic reticulum (ER) on which ribosomes may be embedded. Ribosomes are granular structures which are the site of protein synthesis.
(c) The powerhouse of cell is the mitochondria. It helps in releasing energy by the oxidation of food in cell. There are flat membranous secretory structures in the cell called the Golgi bodies. In plant cells, an additional structure located near the nucleus called the chloroplast, is also present.They are the site of photosynthesis.
(d) Cells also contain lysosomes which are also called suicide bags. They digest and remove the unwanted debris of the cell. Centriole located near the nucleus helps in cell division. Cytoplasm also contains vacuoles filled with the cell sap. In plant cells, vacuole is large and centrally placed.

Question. Give brief information about the mitochondria.Describe the structure of mitochondria.
Answer. The mitochondria are tiny bodies of varying shapes and size. Each mitochondria is bounded by a double membrane envelope. Outer membrane is porous. The inner membrane is thrown into folds. These folds are called cristae and are studded with small rounded bodies known as oxysomes. The interior cavity of the mitochondria is filled with a protein matrix which contains a few small-sized ribosomes, a circular DNA molecule and phosphate granules. Mitochondria are sites of cellular respiration.Mitochondria are membrane bound cell organelle found in the cytoplasm. Each mitochondria is a double membrane bounded structure. The outer membrane of mitochondrion is smooth. But, the inner membrane of the mitochondrion is folded inwardly, into the matrix of mitochondrion forming finger like projections. The inward finger like projections of inner membrane is called cristae. Cristae greatly increase the surface area of inner membrane. Mitochondria contain extra nuclear DNA.

Question. Draw a neat labelled diagram of plant cell.
Answer.

Figure: Plant cell

Question. (i) Name the organelle which provides turgidity and rigidity to the plant cell. Name any two substances which are present in it.
(ii) How are they useful in unicellular organisms?
Answer.
(i) Plant cells have big vacuoles full of cell sap that provide them turgidity and rigidity. Plant vacuoles store amino acids, sugars, various organic acids and some proteins.
(ii) In unicellular organism they may serve the following purposes :
1. Forming food vacuoles : In single celled organisms like amoeba, the food vacuole contains the food items that the amoeba has ingested. The food items are digested by the enzymes later on.
2. Removal of excess water and wastes : In some unicellular organisms, specialized vacuoles play important roles in expelling excess water and some wastes from the cell.

Question. Describe the role played by the lysosomes. Why are these termed as suicidal bags? How do they perform their functions?
Answer. Functions of lysosomes :
1. Extracellular digestion. Sometimes lysosome enzymes are released outside the cell to break down extracellular material.
2. Digestion of foreign material. Lysosome also destroys any foreign material which enters inside the cell such as bacteria.
3. Cellular digestion. In damaged cells, ageing cells or dead cells lysosomes get ruptured and enzymes are released. These enzymes digest their own cell. Lysosomes contain about 40 hydrolytic enzymes.When the cell gets damaged, lysosomes burst and their enzymes digest their own cell. So, lysosomes are called ‘suicide bags’.

Question. Describe an activity to demonstrate endosmosis and exosmosis. Draw a diagram also.
Answer.
1. Endosmosis : The movement of water in the cell or a body through a semipermeable membrane is called endosmosis. It can be demonstrated as follows :
(i) Take some raisins with stalks and put them in plain water in a beaker.
(ii) Observation : Raisins absorb water and swell.Raisins have high concentration of sugar than surrounding plain water. Because of this, water from the outside passing through semipermeable membrane enters into the cell.
This is endosmosis.

2. Exosmosis : The movement of water out from a cell or a body through a semipermeable membrane is called exosmosis. This can be demonstrated as follows :
(i) We place the swollen raisins (from above activity) into a beaker containing a concentrated solution of sugar or salt.
(ii) Observation : When swollen raisins are placed in concentrated sugar or salt solution, they shrink because the solution surrounding the raisins is having low water concentration.
Thus, raisins loose water by osmosis, this process is called exosmosis.

Question. Draw a neat labelled diagram of Animal cell.
Answer.

Figure: Animal cell

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