Biology

Cell : The Unit of Life

Question:

What are gas vacuoles? State their functions.

Answer:

Gas vacuole is an air vacuole. They are found only in prokaryotes. It consists of a number of smaller submicroscopic vesicles. Each vesicle is surrounded by a protein membrane and encloses metabolic gases. Air vacuoles not only store gases but provide buoyancy, mechanical strength and protection from harmful radiations.

previuos
next

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.

What is refered to as satellite chromosome?

Q 7.

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

Q 8.

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

Q 9.

What is the function of a polysome?

Q 10.

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

Q 11.

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

Q 12.

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

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).