Which substance is secreted by eosinophils during an allergic reaction?

The $pH$ of the blood is maintained by balancing the ratio of

Which of the following is used during the process of blood clotting?

$A$: Yellow bone marrow is reserve erythropoietic tissue.
$R$: After severe bleeding,yellow marrow may convert to red marrow.

What does the hematocrit value indicate?

Which of the following statements are correct regarding thrombocytes?
$I$ - Also known as blood platelets.
$II$ - They are cell fragments.
$III$ - Produced from megakaryocytes.
$IV$ - Their count in a normal individual ranges from $3,50,000$ to $6,00,000$ per $mm^3$.
$V$ - Involved in the process of blood coagulation.