241: The deficiency of Vitamin D causes:
(a) Rickets
(b) Night blindness
(c) Pellagra
(d) Scurvy
242: Consider the following statements :
AIDS is transmitted
I. by sexual intercourse.
II. by blood transfusion.
III. by mosquitoes and other blood sucking insects.
IV. across the placenta.
Of these statements
(a) I, II and III are correct
(b) I, II and IV are correct
(c) I, II and IV are correct
(d) I and III are correct
Explanation:
Mosquitoes and other blood sucking insects cannot transmit AIDS because the HIV causing AIDS does not replicate inside mosquito, bed bug, flea or other blood sucking insects and the lack of replication of HIV in arthropod cells is due to lack of T4 antigen on cell surface.
243: The characteristic feature of virus is that
(a) It is made of fats.
(b) It multiplies only on dead animals.
(c) It multiplies only on hosts.
(d) It lacks chlorophyll.
244: Isotopes of the same element differ in the number of:
(a) Protons
(b) Neutrons
(c) Electrons
(d) Positrons
245: Assertion (A):
In the periodic table of chemical elements, electron affinity is always found to increase from top to bottom in a group.
Reason (R):
In a group, the atomic radial generally increase from top to bottom.
(a) Both A and R are individually true and R is the correct explanation of A
(b) Both A and R are individually true but R is NOT the correct explanation of A
(c) A is true but R is false
(d) A is false but R is true
Explanation:
Electron affinity of chemical elements is found to decrease from top to bottom in a group in the periodic table. The atomic radii in a group generally increase from top to bottom.