Questions

Parvovirus B19 causes severe anemia because it preferentially infects erythrocyte precursors.

a. Parvovirus B19 binds preferentially to the erythrocyte blood group P antigen on erythroid precursor cells.

Answers B, C, D are incorrect:

b. after entry the single-stranded viral DNA genome is transported to the cell nucleus where the host DNA polymerase synthesizes the complimentary DNA strand.

c. Parvovirus B19 infection can be diagnosed by direct detection of viral DNA not RNA.

d. the fetus of a seropositive mother is protected from infection by maternal circulating antibodies.

A RNA copy of a DNA gene is called as messenger RNA or mRNA. mRna is used in translation because information is translated from one language (nucleotides) into another (amino acids).

Hence, mRNA is used to transfer genetic information by a cell.

Footsteps. 

Yes, as you walk forward, you will leave the footstep behind you.

The first oil well was dug in 1859. The oil production has since declined but it retains its name for high grade oil

The plants which flower only once in their lifetime are called Monocarpic Plants.