What are nuclear pores? State their function.
Nuclear pores are tiny holes present in the nuclear membrane of the nucleus. They are formed by the fusion of two nuclear membranes.
These holes allow specific substances to be transferred into a cell and out from it. They allow molecules such as RNA and proteins to move in both directions, between the nucleus and the cytoplasm.
Name two cell-organelles that are double membrane bound. What are the characteristics of these two organelles? State their functions and draw labelled diagrams of both.
Multicellular organisms have division of labour. Explain.
What is a centromere? How does the position of centromere form the basis of classification of chromosomes. Support your answer with a diagram showing the position of centromere on different types of chromosomes.
Cell is the basic unit of life. Discuss in brief.
What is a mesosome in a prokaryotic cell? Mention the functions that it performs.
Which of the following is correct:
(a) Cells of all living organisms have a nucleus.
(b) Both animal and plant cells have a well defined cell wall.
(c) In prokaryotes, there are no membrane bound organelles.
(d) Cells are formed de novo from abiotic materials.
Both lysosomes and vacuoles are endomembrane structures, yet they differ in terms of their functions. Comment.
Describe the structure of the following with the help of labelled diagrams.
(i) Nucleus
(ii) Centrosome
How do neutral solutes move across the plasma membrane? Can the polar molecules also move across it in the same way? If not, then how are these transported across the membrane?
What are the characteristics of prokaryotic cells?
Draw the diagram of a sarcomere of skeletal muscle showing different regions.
Define sliding filament theory of muscle contraction.
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