Tight junctions: Create a seal between adjacent cells, preventing the leakage of substances across the tissue. They prevent the passage of molecules between cells.
Adhering junctions: Provide strong mechanical attachments between adjacent cells, acting like “spot welds.” They don’t facilitate communication.
Gap junctions: Form channels between adjacent cells, allowing for the passage of ions, small molecules, and signals. They facilitate communication, not create gaps.
Given below are two statements: One is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A): A typical unfertilized, angiosperm embryo sac at maturity is 8-nucleate and 7-celled.
Reason (R): The egg apparatus has 2 polar nuclei.
In the light of the above statements, choose the correct answer from the options given below:
A sphere of radius R is cut from a larger solid sphere of radius 2R as shown in the figure. The ratio of the moment of inertia of the smaller sphere to that of the rest part of the sphere about the Y-axis is :