Q4. Assertion: maternal sensitisation at an RhD-positive delivery can endanger a later RhD-positive foetus. Reason: maternal IgG anti-D can cross the placenta and destroy foetal RBCs. Are both true, and does the reason explain the assertion?
Both are true, and the reason explains the assertion. This describes NCERT’s classic mechanism of erythroblastosis foetalis; an Rh mismatch without maternal antibodies does not itself establish disease (page 196; NHS, “Rhesus disease”).
Q5. Which WBCs are the most and the least abundant?
Neutrophils are the most abundant (60–65 per cent) and basophils the least (0.5–1 per cent) (NCERT page 194).
Q6. From which cells are platelets produced?
From megakaryocytes, special cells in the bone marrow (NCERT page 195).
Q7. How can erythroblastosis foetalis be avoided?
NCERT names anti-Rh antibodies after delivery. Modern anti-D prophylaxis is for eligible, unsensitised RhD-negative mothers: antenatally, after relevant sensitising events and after an RhD-positive birth. It prevents anti-D formation; it does not remove established immune anti-D (Newcastle Hospitals, “Antenatal / Postnatal Suitability”).
Q8. How many RBCs are there in 1 mL of blood with 5 million RBCs per mm? (1 mL = 1000 mm.)
5 million × 1000 = 5000 million, that is 5 × 10 RBCs (count from NCERT page 194).