Which of the following is a primary lymphoid organ? MCQ with Answer and Explanation

Which of the following is a primary lymphoid organ?
A. Tonsils
B. Lymph node
C. Spleen
D. Bone marrow
Answer: Option D
Solution (By JKSSB Mock Tests)
Primary lymphoid organs are where lymphocytes are produced and mature. Bone marrow (where B cells mature) and thymus (where T cells mature) are primary. Secondary lymphoid organs, like spleen, lymph nodes, and tonsils, are where mature lymphocytes encounter antigens and initiate immune responses. The bone marrow also is the site of hematopoiesis.

Discuss this Question (0)

No comments yet. Be the first to start the discussion!

Practice More Biology Questions

Question #1
The structure that connects bone to bone in a joint is:
A. Tendon
B. Ligament
C. Cartilage
D. Muscle

Correct Answer: Option B


Explanation:
Ligaments are tough, fibrous connective tissue bands that connect bones to other bones, stabilizing joints. Tendons connect muscle to bone. Cartilage cushions joints. Muscles generate movement. Ligaments can stretch to a limited extent; excessive force causes sprains.

This question belongs to: Science Biology
Question #2
The process that introduces new genetic variation into a population is:
A. Gene flow
B. Genetic drift
C. Natural selection
D. Mutation

Correct Answer: Option D


Explanation:
Mutations are random changes in DNA sequence that create new alleles, serving as the ultimate source of genetic variation. Natural selection, genetic drift, and gene flow act on existing variation but do not create new alleles. Mutations can be beneficial, neutral, or deleterious, and are essential for evolution.

This question belongs to: Science Biology
Question #3
Which of the following microorganisms is used in the production of curd from milk?
A. Lactobacillus
B. Streptococcus pneumoniae
C. Clostridium botulinum
D. Salmonella typhi

Correct Answer: Option A


Explanation:
Lactobacillus species convert lactose (milk sugar) into lactic acid, which lowers the pH and causes milk protein casein to coagulate, forming curd. This fermentation process also gives curd its characteristic sour taste. S. pneumoniae causes pneumonia, Salmonella typhi typhoid, Clostridium botulinum botulism. Lactobacillus is also a probiotic.

This question belongs to: Science Biology