NEET Practice Quiz on Tissues

Assertion (A): Cardiac muscle cells are connected by intercalated discs. Reason (R): Intercalated discs help in synchronizing heart contraction.

• Both A and R are true, and R is the correct explanation of A.

• Both A and R are true, but R is not the correct explanation of A.

• A is true, but R is false.

• A is false, but R is true.

Answer explanation

Both the assertion and reason are true. Cardiac muscle cells are indeed connected by intercalated discs, which facilitate synchronized contractions of the heart, making R the correct explanation for A.

Assertion (A): Smooth muscles are involuntary in nature. Reason (R): Smooth muscles do not show striations under a microscope.

• A is true, R is true.

• A is true, R is false.

• A is false, R is true.

• A is false, R is false.

Answer explanation

Assertion (A) is true as smooth muscles are indeed involuntary. Reason (R) is also true because smooth muscles lack striations, distinguishing them from skeletal muscles. Therefore, both A and R are true.

Assertion (A): RBCs are non-nucleated in mammals. Reason (R): This allows maximum space for hemoglobin storage.

• A is true, R is true.

• A is true, R is false.

• A is false, R is true.

• A is false, R is false.

Answer explanation

Assertion A is true; mammalian RBCs lack nuclei. Reason R is also true; this adaptation maximizes space for hemoglobin, enhancing oxygen transport. Therefore, both A and R are true.

Assertion (A): Myelin sheath speeds up nerve impulse conduction. Reason (R): It insulates axons and allows saltatory conduction.

• A is true, R is true.

• A is true, R is false.

• A is false, R is true.

• A is false, R is false.

Answer explanation

Assertion (A) is true because the myelin sheath does speed up nerve impulse conduction. Reason (R) is also true as it insulates axons and facilitates saltatory conduction, where impulses jump between nodes of Ranvier.

Assertion (A): Platelets play a major role in blood clotting. Reason (R): Platelets secrete histamine and heparin.

• A is true, R is true.

• A is true, R is false.

• A is false, R is true.

• A is false, R is false.

Answer explanation

Assertion A is true because platelets are essential for blood clotting. However, Reason R is false; platelets do not secrete histamine and heparin. Histamine is released by mast cells, and heparin is produced by basophils.

Assertion (A): Skeletal muscles are multinucleated. Reason (R): They arise from the fusion of many uninucleate cells.

• A is true, R is true.

• A is true, R is false.

• A is false, R is true.

• A is false, R is false.

Answer explanation

Assertion A is true because skeletal muscles are indeed multinucleated. Reason R is also true as these muscles arise from the fusion of many uninucleate cells, confirming both statements are correct.

Assertion (A): Neurons have poor regenerative capacity. Reason (R): They lack centrioles and hence do not divide.

• A is true, R is true.

• A is true, R is false.

• A is false, R is true.

• A is false, R is false.

Answer explanation

Assertion A is true as neurons indeed have poor regenerative capacity. Reason R is also true because neurons lack centrioles, which are essential for cell division. Thus, both A and R are true.

Assertion (A): Eosinophils increase during parasitic infection. Reason (R): Eosinophils release histamine which kills parasites.

• A is true, R is true.

• A is true, R is false.

• A is false, R is true.

• A is false, R is false.

Answer explanation

Assertion (A) is true; eosinophils do increase during parasitic infections. However, Reason (R) is false because eosinophils release substances like major basic protein, not histamine, to combat parasites.

Assertion (A): Cardiac muscle is involuntary and rhythmic. Reason (R): It has centrally placed nuclei and striations.

• A is true, R is true.

• A is true, R is false.

• A is false, R is true.

• A is false, R is false.

Answer explanation

Assertion A is true as cardiac muscle is indeed involuntary and rhythmic. Reason R is also true because cardiac muscle cells have centrally placed nuclei and striations, which are characteristic features.

Assertion (A): Lymph lacks RBCs and platelets. Reason (R): Lymphatic capillaries do not allow large cells to pass.

• A is true, R is true.

• A is true, R is false.

• A is false, R is true.

• A is false, R is false.

Answer explanation

Assertion A is true because lymph does lack RBCs and platelets. Reason R is also true as lymphatic capillaries are designed to prevent large cells from passing through, supporting A.