Most hormones travel from the gland where they were produced to the tissues and cells which they act upon:

Correct Answer: C

Rationale: Hormones travel in the bloodstream from endocrine glands (e.g., thyroid) to target tissues (e.g., muscles), enabling systemic effects like metabolism regulation (T3/T4). Nerve fibres and synapses are neural neurotransmitters act locally, not hormonally. Ducts are exocrine (e.g., pancreas digestion), not endocrine hormones are ductless. Diffusion suits paracrine signaling, not distant endocrine targets. Bloodstream transport distinguishes endocrine reach, critical for widespread chemical signaling, unlike neural, exocrine, or local mechanisms.

Correct Answer: D

Rationale: Endocrine glands secrete hormones into the bloodstream without ducts (e.g., thyroid), while exocrine glands (e.g., sweat) use ducts not waste-specific, not connectivity-based, nor tissue-type defined (both are epithelial). This ductless trait distinguishes endocrine function, critical for systemic signaling, a foundational NEET concept.

Correct Answer: A

Rationale: Luteinizing hormone (LH) from the anterior pituitary stimulates Leydig cells in testes to secrete testosterone, driving male reproduction. Progesterone, a female hormone, doesn't trigger this. FSH targets seminiferous tubules for spermatogenesis, not testosterone directly. ACTH stimulates adrenal cortisol, not gonadal testosterone. LH's specific gonadotropin role distinguishes it, essential for androgen production, unlike other hormones' functions.

Correct Answer: C

Rationale: Oxytocin is released via the pars nervosa (posterior pituitary), synthesized in the hypothalamus, aiding childbirth and lactation. TSH, prolactin, and LH come from the anterior pituitary (adenohypophysis), regulating thyroid, lactation, and gonads. Pars nervosa, neural tissue, stores and secretes hypothalamic hormones, distinguishing oxytocin's path, key to neurohypophyseal function, unlike anterior glandular secretions.

Correct Answer: B

Rationale: Steroid hormones (e.g., cortisol), lipid-soluble, cross cell membranes to bind receptor proteins in the nucleus, altering gene expression. Cell membrane receptors suit peptide hormones (e.g., insulin). Nuclear membrane or nucleoplasm lack specific steroid receptors nucleus houses them broadly. Nuclear binding drives steroids' slow, genomic effects, distinguishing them, critical for their regulatory role, unlike membrane-based signaling.