In most animals,the metabolic reactions proceed in a $A$ temperature range (in humans,it is $37^{\circ} C$). But there are microbes (archaebacteria) that flourish in hot springs and deep sea hydrothermal vents where temperatures far exceed $B$. Choose the correct option for $A$ and $B$.

The organism which tolerates a wide range of salinity is called ...$A$...
$II.$ The organism which tolerates a narrow range of salinity is called ...$B$...
Choose the correct option for $A$ and $B$.

How is a biological community formed?

Differentiate between Ectotherms and Endotherms.

Consider the following four statements $(1-4)$ about certain desert animals such as kangaroo rat.
$(1)$ They have dark colour and high rate of reproduction and excrete solid urine.
$(2)$ They do not drink water,breathe at a slow rate to conserve water and have their body covered with thick hairs.
$(3)$ They feed on dry seeds and do not require drinking water.
$(4)$ They excrete very concentrated urine and do not use water to regulate body temperature.
Which two of the above statements for such animals are true?

Assertion $A$: Aquatic organisms do not experience mechanical shocks while swimming in water.
Reason $R$: Water is a liquid medium for swimming.
Which option is correct for Assertion $A$ and Reason $R$?