cell: fundamental unit of life ( 9th )

1. A -------------is the basic structural and functional unit of all life forms.

Ans: cell

2. Study of structure and composition of cell is called as ------------

Ans: “Cytology”.

3. Cell was first observed by “Robert Hooke” in a dead cork slice in the year 1665. He described about this in his book -----------------

Ans: “Micrographic”.

3. The word cell was derived from a Greek word  ----------  which means small room.

Ans: “Cellulae”

4. First living cell was discovered by -------------

Ans: A.V. Leeuwenhoek

5.  The term protoplasm was coined  ---------- in 1839.

Ans: by purkinje

6.  Protoplasm was discovered by     ------------ and named as sarcode.

Ans: “Felix Dujardin”

7.   --------- is an aggregate of various chemicals such as water, ions, salts and other organic

molecules like proteins, carbohydrates, fats, nucleic acids, vitamins etc.

Ans: Protoplasm

8. Two biologists, “Schleiden and Schwann” gave the “Cell theory” which was later on expanded by -------------

Ans: “Rudolf Virchow ”.

9.  ---------- are the exceptions of cell theory.

Ans: Viruses

10. --------------- cell are primitive and incomplete and have less developed nucleus without nuclear membrane and nucleolus. e.g. Bacteria

Ans. Prokaryotic cells:

2. What is the advantage of multicellularity over unicellularity?

Ans- Division of labor.

3. What are the chromosomes made up of?

Ans- DNA & proteins

4. A cell placed in a solution swells up. What kind of solution is it? Why does it happen?

Ans- It is a hypotonic sol ution & water enters the cell by endosmosis causing the cell to swell up.

5. Why are lysosomes known as “suicidal bags”?

Ans- They secrete powerful digestive enzymes to digest the worn out and damaged cell organelles as well as the cell itself when it loses its functional ability.

6.Why is the nucleus so significant in a cell?

Ans- Nucleus has the following important functions- (i) It controls all cell activities (ii) It contains hereditary material that transmits hereditary information from one generation to the next (iii) It helps in cell division

7. Differentiate between plant and animal cells.

1. PLANT CELL

1- Surrounded by two membranes- cell wall & cell membrane. 2- Possess three types of plastids chloroplasts, chromoplasts, leucoplasts. 3- Do not possess lysosomes. 4- Nucleus is towards the periphery. 5- Centrioles are absent

ANIMAL CELL

1- Surrounded only by cell / plasma membrane. 2-Do not possess plastids. 3-Possess lysosomes 4 -Nucleus is in the center ..  5-Centrioles present & help in cell division.

8. Give the major functions of the following cell organelles-

(a) Endoplasmic reticulum RER-- Synthesis of proteins as it has ribosomes attached to it

SER- Synthesis of lipids required for making cell membrane

(b) Golgi apparatus-----------Storage & packaging of various products.

(c) Mitochondria------Production of ATP(Adenosine Triphosphate) which is a source of energy.

(d) Ribosomes ---Protein synthesis

(e) Golgi ApparatusStorage & packaging of various products.

(f) LysosomesDigestion of worn out & damaged organelles

Q1. Which tissue protects the entire body?

Answer: Epithelial tissue

Q2.Give one example each of: 

Answer
1. Squamous epithelium (simple) - cheek cells 
2. Columnar epithelium - intestine 

Q3.Give one example of connective tissue in which matrix is solid? 

Answer : Bone 

Q4. Name the following: 

Ans:
1. Multinucleate muscle fibre: - skeletal muscle fibre 
2. Spindle shaped muscle fibre: - smooth muscle fibre 
3. Tissue which stores fats: - adipose 
4. Process of neuron, which carries impulse: -axon 

Q5.Name one structure in your body, which bears ciliated epithelium. 

Answer: Respiratory tract 

Q6.What is aerenchyma? 

Ans: It is a specialized parenchyma found in aquatic plants which consists of network of small cells that enclose air cavities. 

Q7.What is the difference between simple plant tissue and simple animal tissue? 

Ans: SIMPLE PLANT TISSUE         SIMPLE ANIMAL TISSUE 
1. Consists of same type of Cells.       Consists of one or more types of Cells. 

2. Arrangement varies.                         Arranged in a single layer. 


Q8.What is the utility of tissues in multicellular organisms? 

Answer: 1.Division of labour 2. Higher organization 3. Higher survival 

Q9.What is a synapse 

Answer: Junction between two neurons. 

Q10.Where is apical meristem found? 

Answer: Root and stem tips 

Q11. Identify the type of tissue in the following? 

Answer: 

 1. Skin - epithelial 

 2. Bark - cork 

 3. Bone - connective 
4. Lining of kidney tubules - epithelial 

 5. Vascular bundle - xylem and phloem 

Q12. What is the role of epidermis? 

Answer: a. Protection 

 b. Regulates transpiration 

 c. Exchange of gases 

Q13.What will happen if apical meristem is damaged? 

Ans:Growth in length will stop. 

Q14.What are the components of phloem? 

Ans:

1. Phloem parenchyma 2. Phloem fibres 3. Sieve tubes 4. Companion cells 

Q15.Name all simple plant tissues? 

Ans:1. Parenchyma 2. Collenchyma 3. Sclerenchyma

1. What is plasma membrane? What are their functions?

Ans:

·                     Plasma membrane also called as cell membrane, is the outer covering of a cell that separates the cell contents (protoplasm) from the surrounding medium.

·                     It is made up of proteins and lipids.

·                     It gives form (shape and size) to the cell

·                     It maintains the individuality of the cell (i.e. seperates cells)

·                     It keeps the cell contents in place

2. What are cell organelles ?

Ans: The certain specific living parts of a cell with a definite function are celled Cell organelles. All cell are found to have same organelles and together these constitute to the basic unit of life.

3. What is cellulose and its functions?

Ans: Cellulose is the main component of a plant cell wall. It is responsible for giving structural shape to the cell and also to protect the protoplasm.

4.  What is a Prokaryotic cell? Give an Example.

Ans: The cells that do not have a nuclear membrane and membrane bound cell organelles (i.e. well-defined nucleus) are known as Prokaryotic Cells.  Example:-  Blue green algae, Bacteria, Mycoplasma etc.

5. What are the advantages of multicellularity ?

Ans:

·                     The division of labour in a multicellular organism increases the efficiency of the organism.

·                     It increases the Chance of survival.

6. What are vacuoles? What are their functions?

Ans:

·                     Vacuoles are clear fluid/gas filled spaces in the cytoplasm.

·                     In plant cells, it is larger and less in number as compared to the animal cells.

·                     Vacuoles help in the storage of water, food and other waste substances.

7.  What is ER ? Name two types of ER. Write its main functions.

Ans:

·                     Endoplasmic Reticulum or ER, is a network of tube like structures found in the cytoplasm.

·                     The two types of ER are Rough Endoplasmic Reticulum (RER) and Smooth Endoplasmic Reticulum (SER).

·                     It provides channel for quick transport of materials

·                     It provides materials (i.e. lipids and proteins) for membrane biogenesis.

8. Write the Function of Chromatin material.

Ans: The Chromatin material mainly consists of DNA’s, therefore plays an important role in storing and transmitting hereditary information (DNA) from one generation to another.

9. Name a cell that lacks membrane. Where is it prepared?

Ans: Ribosomes is  a cell organelle which lacks membrane and is prepared in the Nucleolus.

10. What is plasmolysis? What happens to a plasmolysed cell when it is placed in water ?

Ans:

·                     The detachment of  cell membrane of the plant cell from the cell wall when put in Hypertonic Solution is known as Plasmolysis.

·                     The cell that has undergone plasmolysis i.e. plasmolysed cell when placed in water, the water moves into the cell from the solution due to the higher concentration of water in the solution (Endosmosis) and therefore the cell swells.

11. What do yo mean by nucleoid?

Ans: The undefined nuclear region of prokaryotic cells like blue green algae are known as nucleoid. The nucleoid contains nucleic acid but does not have any membrane covering it.

12. What are the factors which restrict the size of the cell?

Ans: The factors which restrict the size of the cell are:

·                     Functions of cell.

·                     Cell’s requirement of oxygen and other materials from the environment.

·                     Regulating ability of the nucleus of the cell.

13. Name the two nucleic acids present in the cell and their functions.

Ans:

1.             Ribose Nucleic Acid (RNA) – It helps in protein synthesis.

2.             Deoxyribo Nucleic Acid (DNA) – It stores heriditary information.

14. Give any two functions of plastids.

Ans:

·                     Chloroplast is the site of photosynthesis  and helps in preparing food (in case of plant cells).

·                     Leucoplast are the site of storage of food.

·                     Chromoplast provide colour to various flowers and fruits.

15. Write down the main functions of cell wall.

Ans:

·                     Cell wall provides shape as well as rigidity to the cell.

·                     It protects the protoplasm.

·                     It is involved in the movement of materials in and out of the cell.

·                     It prevents the cell from bursting even in very dilute solution.

16. Describe in short the chief components of a nucleus.

Ans:

·                     Nucleoplasm – the semi-fluid part of protoplasm lying inside the nucleus, in which nucleoli and Chromatin fibers are found.

·                     Nucleolus – a dense, spherical, darkly stained structure, which the site of formation and store house of RNA’s.

·                     Nuclear Membrane-  The membrane that bounds the nucleus, which semi-permeable, double layered and porous.

17.  What role does a nucleus play in cellular reproduction?

Ans: The nucleus plays the central role in the cell division/reproduction. Nucleus carry the hereditary information and it divides to form two new cell by the process of cellular reproduction. Apart from that, nucleus also plays a vital role in determining when the cell will divide.

18. Write functions of lysosomes?

Ans:

·                     They take part in intracellular digestion of foreign particles.

·                     They provide energy during starvation.

·                     They help in defence against bacterial and viral infections.

·                     They remove cellular debris.

19. Define Osmosis. In what ways it is different from diffusion?

Ans:

Diffusion

Diffusion is defined as the movement of particles from a region of high concentration to a region of low concentration. 

Osmosis

Osmosis is defined as the passage of water from a region of high water concentration to a region of low concentration through a Semi-permeable membrane.

 20. Write one function each of – Ribosomes, Vacuole, Plasma Membrane

Ans:

·                     Ribosomes : It helps in Protein Synthesis

·                     Vacuole : They help in the storage of water, food and other waste substances.

·                     Plasma Membrane : It regulates the flow materials in and out of the cell.