Questions

Footsteps. 

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

Our atmosphere is made up of

78% Nitrogen,

21% Oxygen and

1% all other gases like argon, carbon dioxide, neon, and helium.

So, Nitrogen makes up the majority of our atmosphere.

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.

Smooth Endoplasmic Reticulumdoes not contain ribosomes on its surface for which it is regarded as smooth. So, proteins cannotbe synthesised by SER provided protein synthesis is the primary task of ribosomes.

Phenol with a molecular formula [C₆H₅OH] is also called as Carbolic Acid. It is a white poisonous clear compound with sweet smell. It is used in making plastics, detergents and drugs.

Protested is used because here the villagers express their feeling by making an objection to what has been done.

Exercise can boost your memory and thinking skills by improvising alertness, attention and motivation.