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.
(c) Membrane-bound organelles are organelles surrounded by a double or a single membrane like Nucleus, mitochondria, chloroplasts, Lysosomes, ER, Golgi bodies etc. are examples of such organelles. These cell organelles are absent in prokaryotes.
(a) Only eukaryotic cells have nuclei. They are absent in prokaryotes.
(b) Cell walls are only present in plant cells. They are absent in all animal cells.
(d) All cells arise from pre-existing cells.
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.
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
What are nuclear pores? State their function.
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?
Define sliding filament theory of muscle contraction.
What is meant by the term osmoregulation?
But in option a ....it is all cell but we know that RBC and sieve tube cells are enucleate
But prokaryotes have a nucleus so (a) statement is also correct.