Question

janet has anti - b antibodies in her blood but no rh antibody despite having received a transfusion of rh+ blood before. what blood type does she have?
○ a -
○ o+
○ ab+
○ b+
○ a+
○ o -
○ b -
○ ab -

Explanation:

1. Understand Blood Type Antigens/Antibodies: Blood types have A/B antigens (on red blood cells) and corresponding anti - A/anti - B antibodies (in plasma). For Rh factor, Rh+ has Rh antigen, Rh- does not; Rh- people develop anti - Rh antibodies if exposed to Rh+ blood, Rh+ people do not.
2. Analyze Anti - B Antibodies: Having anti - B antibodies means the blood does not have B antigen (since if there was B antigen, the anti - B antibodies would react with it). So possible blood types are A (A or A+ or A -) or O (O or O+ or O -).
3. Analyze Rh Antibody Situation: Janet received Rh+ blood but has no Rh antibody. This means she is Rh+ (because Rh- people would develop anti - Rh antibodies after exposure to Rh+ blood, while Rh+ people do not develop anti - Rh antibodies even after exposure to Rh+ blood).
4. Evaluate Options:

• Option A-: Rh- (would have developed anti - Rh after Rh+ transfusion, so wrong).
• Option O+: Has anti - A and anti - B antibodies (but Janet only has anti - B, so wrong).
• Option AB+: Has A and B antigens, so no anti - A or anti - B antibodies (but Janet has anti - B, so wrong).
• Option B+: Has B antigen, so no anti - B antibodies (but Janet has anti - B, so wrong).
• Option A+: Has A antigen (so no anti - A), has anti - B antibodies (matches Janet's anti - B), and is Rh+ (so no anti - Rh after Rh+ transfusion, matches).
• Option O-: Rh- (would have developed anti - Rh after Rh+ transfusion, so wrong).
• Option B-: Has B antigen (no anti - B), Rh- (would have developed anti - Rh), so wrong.
• Option AB-: Has A and B antigens (no anti - A/anti - B), Rh- (would have developed anti - Rh), so wrong.

Answer:

A. A+