Biology · Chemical Coordination and Integration · NEET
A hormone is NON-nutrient. This means the body does not use it for energy or for building tissue, the way it uses glucose, fats, proteins or vitamins. A hormone only carries a message. NCERT stresses "non-nutrient" to separate hormones from food molecules. NEET has framed options where a hormone is wrongly called a nutrient, so hold this point firmly.
"Inter" means between. A hormone is made in one cell and carries a signal to a different (target) cell. So it is a messenger that works between cells, not inside one cell. This is the reason NCERT uses the phrase "intercellular messengers" in the modern definition. Do not write "intracellular" (which means inside one cell) — that is a common spelling trap.
The classical definition said a hormone is a chemical made by an endocrine gland, released into blood, and carried to a distant target organ. The modern (current scientific) NCERT definition is broader: "Hormones are non-nutrient chemicals which act as intercellular messengers and are produced in trace amounts." The new definition also includes many messenger molecules that are NOT made by organised endocrine glands (for example, some made by scattered tissues). NEET usually asks for the MODERN definition.
Not in the modern view. The classical definition required transport through blood to a distant target. But the current NCERT definition drops that strict rule, so it covers messenger molecules that may act more locally. That is exactly why the modern definition is broader. For NEET, quote the modern definition unless the question clearly asks for the classical one.
No. Hormones are produced in trace amounts, meaning very tiny quantities. Even a very small amount can cause a large effect on the target cells. If a NEET option says hormones are made in "large amounts" or "bulk", it is wrong.
Try the real previous-year questions from this chapter — each with the answer and a full solution.
"Hormones are non-nutrient chemicals which act as intercellular messengers and are produced in trace amounts." This is the current (modern) scientific definition given in NCERT Class 11, Chapter 19.
Non-nutrient (not used for energy or building), intercellular messenger (carries a signal between cells), and produced in trace amounts (very small quantity). Remember them as N-I-T.
Because the classical definition (made by an endocrine gland, carried by blood to a distant organ) was too narrow. Many new messenger molecules were discovered that are not made by organised endocrine glands, so the broader modern definition was adopted.
Under the modern definition, many such intercellular messenger molecules can be counted as hormones because the new definition does not require an organised endocrine gland or transport to a distant organ. This broadening is exactly the point NCERT makes.
No. Endocrine glands are ductless (they lack ducts), and their secretions — the hormones — are released directly into the blood or body fluid. Duct-carrying glands are exocrine, not endocrine.
