A graft between members of the same species is termed an?

Correct Answer: A

Rationale: An autograft is a transplant within the same individual (same species and genetic identity), though the answer 'A' seems inconsistent with typical definitions where 'allograft' (D) is more common for same-species grafts. Assuming a typo in the source.

Correct Answer: B

Rationale: Mature naive B cells co-express IgM and IgD on their surface, preparing them to respond to antigens.

Correct Answer: C

Rationale: C1q deficiency is strongly associated with a lupus-like syndrome due to impaired clearance of immune complexes, leading to autoimmunity. C3 deficiency causes severe bacterial infections, C5-9 deficiencies lead to neisserial infections, and C1 inhibitor deficiency causes angioedema, not lupus-like features.

Correct Answer: B

Rationale: SCID is the most severe congenital immunodeficiency, with absent T and B cell function, leading to early, life-threatening infections.

Correct Answer: B

Rationale: Selective IgA deficiency is the most common primary immunodeficiency, often asymptomatic but can lead to recurrent infections or allergies.