1. Describe  the cell theory?

Ans

  Cell is the smallest unit of structure of all living things. It is the unit of function of all living things. All cells arise from pre existing cells.

2. It is said that protoplasm cannot be analysed chemically. Why?

Ans

  The chemical composition of protoplasm is very  complex.  It varies from one cell to another.   It is the living  matter, the total substance of a living cell.  Protoplasm cannot  be analysed chemically because it  ceases to be protoplasm as soon as it is removed from the organism.

3. Give three difference between animal cell and  plant cell?

4. Define Cell?

Ans

    The cell is the basic  structural  building block of living organisms consisting of protoplasm enclosed by a cell membrane.

5. What is the difference between  an organ and organelles?

Ans

    The parts of  a cell have a definite shape, a definite structure and a definite function such parts are called organelles. Cell organelles are living parts.

6.Why do  different cell have different shapes?

Ans

   Cells vary greatly in shape.  The cells have different shapes to perform different functions. eg: Human blood cells  are circular and biconcave. White Blood Cells are  amoeboid in nature.

7. Do you think the cells of  an elephant would be larger than the cells  of a rate. Explain briefly?

Ans

    The cells of an elephant would be large in number and not in size, as  larger is an organisms the cells will be greater.

8. State the major functions of the following parts in a cell .

Ans

Plasma membrane- Maintains the shape of the cell,  regulates the entry of solutes and ions, separates contents of cell from, its surroundings.

Centrosome- Initiates  and regulates cell division.  Forms spindle fibres.

Mitochondria - Power house of the cell.  Release of energy from pyruvic acid in cytoplasm in the form of ATP.  Synthesis of respiratory enzymes.

Ribosomes- Helps in protein synthesis

Lysosomes- Intracellular digestion, destroys  foreign substances when cells are old or injured destroy organelles.   Formation of bones by digesting  cartilage.

Golgi apparatus- In plant cell it is called dictyosome synthesis and secretion of enzymes, hormones etc.

9. Given below  is a diagram of a cell (plant). Name the structures labelled  as A,B, C, and D

A- Cell wall, B- Vacoule, C- Plastid, D- Nucleus

Ans

  Picture of Plastids -

This is a plant cell because it contains cell wall, plastids

10. Differentiate between Protoplasm and cytoplasm, Nucleolus and nucleus, Centrosome and  chromosome.

Ans

Protoplasm and Cytoplasm

Protoplasm :- Protoplasm is the living part of a cell.

Cytoplasm contains a mixture of water and  soluble inorganic and organic compounds.  It occupies most part of the cell within the cell membrane.

Nucleolus and nucleus

Nucleolus:-  It is one or more round shaped nucleoli. Participates in protein synthesis by forming and storing RNA.

Nucleus:- It is the largest cell organelle. Regulates cell function.

Centrosome and  Chromosome

Centrosome: - It is the region surrounding the centrioles contains one or more centrioles.  Initiates and regulates cell division.

Chromosome:- It carry hereditary information are the genes.