PBA BIOLOGY 2025
SOLVED PAPER
Section-A (09 Marks)
Q1: What is meant by the term Antisera?
A1: Antisera are blood serums that contain antibodies against specific antigens. They are used to identify the antigen.
Q2: Briefly explain the principle of agglutination?
A2: Agglutination is the clumping of red blood cells when an antibody reacts with a specific antigen on the RBC surface.
Q3: Identify the blood group in slides I – IV?
A3:
Slide I: A+ve Antigen A and Rh IᴬIᴬ or Iᴬi / DD or Dd
Slide II: AB+ve Antigen A, B and Rh IᴬIᴮ / DD or Dd
Slide III: O-ve No antigen ii / dd
Slide: IV: B+ve Antigen B and Rh IᴮIᴮ or Iᴮi / DD or Dd
Q4: Which slide’s blood group is universal recipient? Give reason.
A4:
Slide II
Because it is blood group AB+ive producing no antibody.
Q5: Write down one difference between Antigen and Antibody?
A5:
Antigen: Any foreign substance that trigger an immune response.
Antibody: Specific proteins produced by the body against antigens.
Section-B (06 Marks)
i. Bones of Hand (Diagram 1):
A: Carpals
B: Metacarpals
No. of Bones in A: 8
No. of Bones in C: 14
ii. Male reproductive system of Frog (Diagram 2):
A: Testes
B: Vas deferens
C: Urinary bladder
D: Cloaca
iii. Function of labelled Part B (Vas deferens) in Diagram 2:
Answer:
Vas deferens helps sperms to travel from the testes to the cloaca during reproduction.
iv. Diagram 3 Identification and Parts:
Identification: Ovary with developing follicles
Part X: Graafian follicle
Part Y: Corpus luteum
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