Biology

Cell : The Unit of Life

Question:

Comment on the cartwheel structure of centriole.

Answer:

Centrosome is an organelle that generally have two cylindrical structures known as centrioles. Both the centrioles in a centrosome lie perpendicular to each other in which each has an organisation like the. cartwheel. They are usually made up of nine evenly spaced peripheral fibrils (triplet in nature) of tubulin protein, with which adjacent triplets are also being linked. The centre part of the proximal region of the centriole possess rod-shaped proteinaceous mass known as hub, which is connected with tubule of the peripheral triplet fibrils known as radial spokes made of protein.

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Cell : The Unit of Life

Q 1.

What is the feature of a metacentric chromosome?

Q 2.

What are histones? What are their functions?

Q 3.

What is the function of a polysome?

Q 4.

Give the biochemical composition of plasma membrane. How are lipid molecules arranged in the membrane?

Q 5.

The genomic content of the nucleus is constant for a given species where as the extra chromosomal DNA is found to be variable among the members of a population. Explain.

Q 6.

Are the different types of plastids interchangable? If yes, give examples where they are getting converted from one type to another.

Q 7.

What is refered to as satellite chromosome?

Q 8.

Mention a single membrane bound organelle which is rich in hydrolytic enzymes.

Q 9.

Structure and function are correctable in living organisms. Can you justify this by taking plasma membrane as an example?

Q 10.

What is the function of a polysome?

Q 11.

Are the different types of plastids interchangable? If yes, give examples where they are getting converted from one type to another.

Q 12.

Is there a species specific or region specific type of plastids? Flow does one distinguish one from the other?

Q 13.

Discuss briefly the role of nucleolus in the cells actively involved in protein synthesis.

Q 14.

What structural and functional attributes must a cell have to be called a living cell?

Q 15.

What is the significance of vacuole in a plant cell?

Q 16.

What are plasmids? Describe their role in bacteria.

Q 17.

Briefly describe the cell theory.

Q 18.

Explain the association of carbohydrate to the plasma membrane and its significance.

Q 19.

Write the functions of the following
(a) Centromere (b) Cell wall
(c) Smooth ER (d) Golgi apparatus
(e) Centrioles

Q 20.

Justify the statement, “Mitochondria are power houses of the cell”.

Q 21.

Is extra genomic DNA present in prokaryotes and eukaryotes? If yes, indicate their location in both the types of organisms.

Q 22.

Eukaryotic cells have organelles which may
(a) not be bound by a membrane
(b) bound by a single membrane
(c) bound by a double membrane
Group the various sub-cellular organelles into these three categories.

Q 23.

What does ‘S’ refer to in a 70S and an 80S ribosome?

Q 24.

Comment on the cartwheel structure of centriole.

Q 25.

What are gas vacuoles? State their functions.

Q 26.

Briefly give the contributions of the following scientists in formulating the cell theory.
(a) Rudolf Virchow
(b) Schleiden and Schwann

Q 27.

Differentiate between Rough Endoplasmic Reticulum (RER) and Smooth Endoplasmic Reticulum (SER).