Assertion : External parasitism is generally marked by much more exterme specialisation than internal parasitism.
Reason : The structure of an internal parasite is usually very complex possessing suckers, reproductive organs, etc.

Assertion: Series combination of cells is used when their internal resistance is much smaller than the external resistance. Reason: I=(n epsilon)/(R+nr) where is symbols have their standard meaning in series connection

Assertion: In flatworms, fertilisation is internal and development is through many larval stages. Reason: Some parasitic flatworms absorb nutrients from the host directly through their body surface.

Assertion: Modern taxonomic studies provide more accurate grouping of various organisms. Reason: Modern taxonomic studies are based on external and internal structures along with the structure of cell, development process and ecological informations.

In the following questions, a statement of assertion is followed by a statement of reason. Mark the correct choice as (a) If both assertion and reason are true and reason is the correct explanation of assertion. (b) If both assertion and reason are true but reason is not the correct explanation of assertion. (c ) If assertion is true but reason is false. (d) If assertion and reason are false. Q. Assertion: Lead is more elastic than rubber. Reason: if the same load is attached to lead and rubber wires of the same cross-sectional area, the strain of lead is very much less than that of rubber.

In the following questions, a statement of assertion is followed by a statement of reason. Mark the correct choice as (a) If both assertion and reason are true and reason is the correct explanation of assertion. (b) If both assertion and reason are true but reason is not the correct explanation of assertion. (c ) If assertion is true but reason is false. (d) If assertion and reason are false. Q. Assertion: Stress is the internal force per unit area of a body. Reason: Rubber is more elastic than steel: