Alight-year measures the that light travels in 1 year.

distance

Explanation:

Light year is a unit of measurement that is used for astronomical purposes only.  

Basically it is equivalent to the distance traveled by light in a time frame of one year.  

One light year is equal to km which is approximately equal to six million miles.  

In case of distant stars and planets where human have not yet reached or are not even aware of the distance at which they are,  light year is used as a distance measuring unit.  

the right side of the picture going down is:

polymerase

protein

transport vesicle

modified protein

the left side of the picture going down is:

dna helix

single-stranded rna

endoplasmic reticulum

ribosome

golgi apparatus

protein released from vesicle

click to let others know, how is it

read more on -

answer: "circumcision is a common procedure in which the skin covering the tip of the penis is surgically removed."