NEET Study Guide 2026

The pituitary gland is called the master gland because it secretes hormones that regulate other endocrine glands throughout the body.

Baroreceptors are pressure-sensitive receptors located in blood vessel walls (especially carotid sinus and aortic arch) that detect blood pressure changes.

The hypothalamus is a critical neuroendocrine organ because it serves as the primary link between the nervous and endocrine systems. It receives neural signals and, in response, produces and secretes various releasing and inhibiting hormones that control the secretion of hormones from the anterior pituitary gland. It also produces ADH and oxytocin, which are stored and released by the posterior pituitary.

Interstitial compounds are formed when small non-metal atoms, such as carbon, nitrogen, or hydrogen, occupy the interstitial voids within the crystal lattice of transition metals. The formation of these compounds typically makes the transition metals significantly harder, more rigid, and increases their melting points. However, they generally become less ductile and less malleable, not more so.

If the center of mass of a system of bodies is at the origin, it means the weighted average position of all particles is zero. For this to be true, if some particles have positive X-coordinates, there must be other particles with negative X-coordinates to balance them out. It's impossible for all particles to have only positive or only negative X-coordinates, as that would shift the center of mass away from the origin.

Equisetum, a pteridophyte (horsetail), possesses tracheids as its primary water-conducting elements but lacks true xylem vessels. While the question asks about the absence of 'vessels or tracheids,' Equisetum clearly has tracheids. However, among the given options, it is known for lacking vessels, a characteristic shared with most pteridophytes and gymnosperms (except Gnetum).