|History & Civics|
1. Describe the cell theory?
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?
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?
|Plant cell||Animal Cells|
|1. Has a cellwall and it is made up cellulose||1. No cell wall|
|2. Centrosome is not present||2. Centrosome is present|
|3. Usually contain plastids||3. Do not contain plastids|
4. Define Cell?
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?
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?
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?
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 .
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
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.
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.