Which organism has the least visible postanal tail as an adult?
a. crow
b. fish
c. lizard
d. human
e. dog

Option 'D' is correct.

Explanation:

Human has least visible postanal tail as an adult.

Whereas fish, lizard, crow and dog has developed visible postanal tail.

Human too have tails but it does not developed as much as to be visible after infancy.

Hence, option 'D' is correct.

many other transport proteins, often called pumps, move materials against a concentration gradient. active transport drives molecules across a membrane from a region of lower concentration to a region of higher concentration. this process, shown in figure 5.1, uses transport proteins powered by chemi- cal energy.