Questions

Karst topography is created by the chemical weathering of the rocks such as limestone, dolomite etc...

Metamorphism is the method of changing the structure of a rock by using heat and temperature.

Hence, for this to happen the parent rock must be in solid form only. Therefore, option C) is true.

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.