Question

. A mouse has a conditional knockout of TrpM5 in taste cells (no expression of TrpM5 protein in all the taste cells). This mouse is likely to lose taste response to the following tastants EXCEPT:

	A.	Sweet
	B.	Bitter
	C.	Umami
	D.	Sour

Which of the following statements about bipolar receptive fields is FALSE?

	A.	In the dark, horizontal cells release GABA
	B.	A light shining on the photoreceptors directly connected to an ON bipolar cell causes bipolar cell depolarization
	C.	A light shining on the photoreceptors connected to the horizontal cell cause an OFF bipolar cell to depolarize
	D.	A light shining on the photoreceptors connected to a horizontal cell cause an ON bipolar cell to depolarize

Answer 1

1) Answer

D) sour.

explannation

• TRMP5 is a cation channel , which help in transduction of bitter , sweet and umami
• all other options are wrong because, these taste sensation are transducted by TRMP5.
• signalling of these taste involves , activation of G-protein coupled receptor which stimulate phospholipase C.

2) Answer

D) a light shining on the photoreceptor s connected to a horizontal cell cause an ON bipolar cell to depolarize.

Explannation

this is the diagram when light falls on center, if light falls on surround, all these depolarization in the diagram become hyperpolarization , all increase become decrease.everything become opposite as we can understand from above diagrams.

according to these diagram,

option a) is true statement because , horizontal cell release GABA.

option b) is true because, bipolar cell get depolarized when light falls on photo receptor cell which directly connected to ON bipolar cells.

option c) is true from , OFF bipolar cells depolarizes, when light falls on photoreceptor connected to horizontal cells.

option d) is wrong , because ON bipolar cells hyperpolarize,as we can understand from the diagram.