ANSWER : OPTION 2.
The temperature receptors located in the skin detects the
changes in the temperature and they send signals to the temperature
regulator center which is located in the hypothalamus which further
gives a to regulate the temperature.
ANSWER : OPTION B
When G protein is activated,aplha subunit detaches by binding
with GTP.Now, both aplha GTP unit and beta-gamma dimer,activate
second messenger pathways.ie. they activte adenyl cyclase which is
an enzyme present in the cell membrane.
Activated G protien does not open calcium channels.so option A,C
Activated adenyl cyclase further convert cytoplasmic ATP into
cyclicAMP OR cAMP.Hence,activation of G protein increases the level
of cAMP.So, option D is wrong.
ANSWER : OPTION A
G protien act as a link between the first messenger (the
hormone) and the second messenger(cAMP).Hormone comes and binds to
the G protein complex which is located in the cell membrane,and it
produces cAMP by activating adenyl cyclase.