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Q1. Hormones travel through:
BloodHormones are chemical messengers secreted by endocrine glands directly into the bloodstream. Blood carries them to target organs throughout the body. Nerves carry electrical impulses, lymph transports some substances but not primarily hormones, and muscles are effectors, not transport pathways.
Q2. Iodised salt is important because it provides:
IodineIodised salt contains added iodine, an essential mineral required for the synthesis of thyroxine hormone by the thyroid gland. Sodium is already in salt, calcium and iron are not provided by iodised salt specifically. Iodine deficiency leads to goitre and other disorders.
Q3. Deficiency of iodine may cause:
GoitreIodine is necessary for thyroxine production. Its deficiency causes the thyroid gland to enlarge (goitre) as it tries to trap more iodine from blood. Diabetes relates to insulin, dwarfism to growth hormone deficiency, anaemia to iron deficiency.
Q4. Nervous system uses:
Electrical impulsesThe nervous system transmits information rapidly via electrical impulses (action potentials) along neurons. Blood is for transport, enzymes catalyse reactions, hormones are chemical messengers of the endocrine system. Electrical impulses are the hallmark of nervous communication.
Q5. Control and coordination in the body is achieved by:
Nervous system and hormonesBoth systems work together: the nervous system provides rapid, short‑lived control, while the endocrine system (hormones) provides slower, long‑lasting coordination. Muscles are effectors, not controllers. Neither system alone achieves full integration.
Q6. Growth hormone is secreted by the:
Pituitary glandThe pituitary gland (anterior lobe) secretes growth hormone (somatotropin), which regulates body growth and development. Adrenal secretes adrenaline, thyroid secretes thyroxine, pancreas secretes insulin and glucagon.
Q7. Diabetes is related to improper secretion of:
InsulinDiabetes mellitus occurs when the pancreas does not produce enough insulin (Type 1) or the body cannot use insulin effectively (Type 2). Insulin regulates blood glucose levels. Growth hormone, adrenaline, and thyroxine are not directly responsible for diabetes.
Q8. Hormones must be secreted in:
Precise quantitiesHormones are very potent; even small changes in concentration can cause significant effects. Too little or too much leads to disorders (e.g., diabetes, goitre, dwarfism). Therefore, secretion must be precisely regulated via feedback mechanisms. Unlimited, large, or random amounts would be harmful.
Q9. Thyroxine is secreted by the:
Thyroid glandThe thyroid gland (located in the neck) produces thyroxine (T4) and triiodothyronine (T3), which regulate metabolism, growth, and development. Adrenal secretes adrenaline, pituitary secretes many hormones, pancreas secretes insulin.
Q10. Hormonal coordination is usually:
Slower but long-lastingHormones travel via blood, taking seconds to minutes to act, but their effects can last from minutes to days or longer (e.g., growth, metabolism). This contrasts with nervous impulses, which are very fast but short‑lived. Hormonal coordination is not absent, very fast, or instant.
Q11. Insulin helps in regulating:
Blood sugar levelInsulin lowers blood glucose by promoting cellular uptake of glucose and glycogenesis in liver and muscles. It does not directly regulate heart rate (adrenaline), blood pressure (multiple factors), or body temperature (thyroxine, hypothalamus).
Q12. Growth hormone mainly affects:
Height and developmentGrowth hormone stimulates cell division, bone elongation, and overall body growth, especially in childhood and adolescence. It influences blood sugar indirectly (anti‑insulin effect) but its primary role is height and development. Heart rate and breathing are not its main targets.
Q13. Insulin secretion is an example of:
Feedback regulationInsulin secretion is controlled by negative feedback: high blood glucose stimulates insulin release; low blood glucose inhibits it. This maintains homeostasis. It is not random, voluntary (conscious), or a reflex (spinal/brainstem automatic but not hormonal feedback).
Q14. Iodine is required for the synthesis of:
ThyroxineThe thyroid gland incorporates iodine into the amino acid tyrosine to produce thyroxine (T4) and triiodothyronine (T3). Iodine is not needed for growth hormone (pituitary), adrenaline (adrenal), or insulin (pancreas).
Q15. Chemical coordination is present in:
Both plants and animalsBoth kingdoms use chemical messengers: animals use hormones, plants use plant hormones (phytohormones) such as auxins, gibberellins, cytokinins, etc. Chemical coordination is not limited to animals or humans alone.
Q16. Plants also show chemical coordination using:
HormonesPlants lack nerves, muscles, and bones. They coordinate growth and responses using plant hormones (phytohormones) like auxin, gibberellin, cytokinin, abscisic acid, and ethylene. These are chemical messengers, hence “hormones.”
Q17. Hormones act on:
Target organsHormones circulate in blood but only affect cells that have specific receptors for that hormone – called target cells or target organs. They do not act on all cells equally, nor only on bones or muscles. Specificity is key.
Q18. Controlled growth in animals prevents:
Abnormal growthHormonal regulation ensures that growth occurs in a coordinated, controlled manner. Without it, abnormal growth (e.g., dwarfism, gigantism, tumours) can occur. Controlled growth does not prevent proper shape or body design – it enables them. Puberty is a normal process, not prevented.
Q19. Testosterone is secreted mainly in:
MalesTestosterone is the primary male sex hormone, produced mainly in the testes of males. Females produce smaller amounts in ovaries and adrenal glands. It is secreted from puberty onward, not mainly in old people or children (though low levels exist).
Q20. Chemical coordination differs from nervous coordination because it is:
ChemicalThe most fundamental difference is that chemical coordination uses chemical messengers (hormones), while nervous coordination uses electrical impulses (plus neurotransmitters at synapses). Nervous coordination is faster and instant; chemical coordination is slower. “Chemical” directly names the nature of the difference.
Q21. Insulin helps prevent:
High blood sugarInsulin lowers blood glucose, thus preventing hyperglycemia (high blood sugar). It does not affect puberty, dwarfism (growth hormone), or goitre (iodine/thyroxine). Lack of insulin causes diabetes with high blood sugar.
Q22. Diabetes occurs due to improper regulation of:
Blood glucoseDiabetes is a metabolic disorder characterized by high blood glucose levels due to insufficient insulin or insulin resistance. Proteins, fats (though affected secondarily), and oxygen are not the direct cause. Blood glucose regulation is the core issue.
Q23. Hormonal control is essential for:
Balance and coordinationHormones regulate a wide range of functions including growth, metabolism, reproduction, fluid balance, and stress responses – all contributing to overall balance and coordination of body systems. It is not limited to growth, movement, or digestion alone.
Q24. Endocrine glands are also called:
Ductless glandsEndocrine glands secrete hormones directly into the bloodstream without any ducts, hence “ductless glands.” Salivary and digestive glands are exocrine (have ducts). “Duct glands” refers to exocrine glands.
Q25. Chemical coordination in animals occurs through:
BloodHormones are transported via the bloodstream to target organs. Blood is the medium for chemical coordination. Bones, muscles, and skin are not the transport medium, though they may be targets.
Q26. Insulin is produced by the:
PancreasInsulin is secreted by the beta cells of the islets of Langerhans in the pancreas. Adrenal produces adrenaline, thyroid produces thyroxine, liver does not produce insulin (it stores glycogen).
Q27. Unlike plants, animals do not show:
Directional growth due to light or gravityPlants exhibit tropisms – directional growth toward or away from stimuli (light, gravity). Animals do not grow directionally in response to light or gravity; they move their whole body or parts. Both plants and animals show growth, hormonal control (though different hormones), and metabolism.
Q28. Iodine deficiency affects the:
Thyroid glandIodine is essential for thyroxine synthesis. Deficiency primarily affects the thyroid gland, causing goitre (enlargement) and hypothyroidism. Adrenal, pancreas, and pituitary are not directly affected by iodine deficiency.
Q29. Diabetic patients are sometimes treated with:
Insulin injectionsType 1 diabetics lack insulin and require insulin injections to control blood glucose. Type 2 may use oral drugs or insulin. Growth hormone, adrenaline, and thyroxine are not used to treat diabetes; they would worsen glucose control.
Q30. Regulation of hormone secretion is done by:
Feedback mechanismsHormone levels are primarily regulated by negative feedback loops (e.g., high thyroxine inhibits TSH release). Nerves can influence some glands (e.g., adrenal medulla), but the general regulatory mechanism is feedback, not bones, nerves only, or muscles.
Q31. One visible symptom of goitre is:
Swollen neckGoitre is an enlargement of the thyroid gland, which is located in the front of the neck. The swelling is clearly visible as a lump or enlarged neck. Hair loss, weak legs, and thin arms are not characteristic of goitre.
Q32. Hormones are secreted by:
Endocrine glandsBy definition, endocrine glands secrete hormones. Sweat, exocrine (general category), and salivary glands secrete other substances (sweat, digestive enzymes) through ducts, not hormones.
Q33. Puberty‑related changes occur usually around the age of:
10–12 yearsPuberty typically begins between ages 10–12 in girls (slightly earlier) and 12–14 in boys. 20–25 is adulthood, 5–7 is early childhood, 2–4 is toddler stage. Thus, 10–12 years is the closest general answer.
Q34. Animal hormones mainly help in:
Coordinated growth and regulationAnimal hormones coordinate growth, metabolism, reproduction, homeostasis, and responses to stress. They do not cause directional growth like plants (animals move), nor photosynthesis (plants only), nor random growth. Coordinated regulation is their primary role.
Q35. As blood sugar level falls, insulin secretion is:
ReducedNegative feedback: low blood glucose inhibits insulin secretion from pancreatic beta cells. This prevents further lowering of glucose. It is reduced, not increased, unchanged, or permanently stopped (it resumes when glucose rises again).
Q36. Oestrogen is secreted mainly in:
FemalesOestrogen is the primary female sex hormone, produced mainly in the ovaries. Males produce small amounts, but mainly in females. Infants and children produce very low levels before puberty.
Q37. Feedback mechanism helps in:
Maintaining balanceFeedback mechanisms (especially negative feedback) maintain homeostasis – a stable internal environment. They regulate hormone levels, body temperature, blood glucose, etc. They do not cause random secretion, stop growth, or break hormones (breakdown is separate).
Q38. Hormonal control is important because hormones act:
SystemicallyHormones travel through the bloodstream and can affect multiple target organs throughout the body – i.e., systemically (widespread effect). They are not limited locally (paracrine signals are not the main hormones), not only in plants, and not on a single cell.
Q39. When blood sugar level rises, pancreas secretes:
More insulinHigh blood glucose triggers pancreatic beta cells to release more insulin, which lowers glucose by promoting uptake and storage. Thyroxine is unrelated; less or no insulin would worsen hyperglycemia.
Q40. In animals, growth occurs:
In carefully controlled placesAnimal growth is highly regulated by hormones (growth hormone, thyroid hormones, sex steroids) and occurs in specific tissues (growth plates, organs) in a coordinated, non‑random manner. Not only in roots (plants), not only during sleep, and not random.
Q41. Proper hormone secretion depends on:
Feedback mechanismHormone secretion is precisely regulated by feedback loops (negative and positive) involving the hypothalamus, pituitary, and target glands. Skin, bones, and muscles are not the primary regulators, though they may be targets or provide some input.
Q42. Changes during puberty are caused by:
Sex hormonesPubertal changes (breast development, facial hair, voice change, etc.) are driven by sex hormones – testosterone in males, oestrogen and progesterone in females. Adrenaline (stress), thyroxine (metabolism), insulin (glucose) are not primarily responsible.
Q43. Extremely short or tall stature is related to:
Growth hormoneHypersecretion of growth hormone in childhood causes gigantism (tall stature); hyposecretion causes dwarfism (short stature). Adrenaline, insulin, and thyroxine affect growth indirectly but are not the primary cause of extreme height abnormalities.
Q44. Thyroxine regulates the metabolism of:
Carbohydrates, proteins and fatsThyroxine increases the basal metabolic rate and affects the metabolism of all major nutrients – carbohydrates, proteins, and fats. It is not limited to one type. Vitamins are cofactors, not directly regulated by thyroxine.
Q45. Sex hormones are responsible for:
Secondary sexual charactersSex hormones (testosterone, oestrogen) cause the development of secondary sexual characteristics (e.g., facial hair, breast development, voice change) at puberty. Involuntary actions (heartbeat) are controlled by the autonomic nervous system, reflex actions by spinal cord, digestion by multiple systems.
Q46. Lack of insulin causes blood sugar level to:
RiseWithout insulin, cells cannot take up glucose effectively, and the liver produces more glucose. Blood glucose levels rise significantly – hyperglycemia, which is the hallmark of untreated diabetes. It does not stop, decrease, or remain constant.
Q47. Swollen neck in goitre is related to the position of:
Thyroid glandThe thyroid gland is located in the front of the neck. When it enlarges (goitre), it causes a visible swelling in the neck. Adrenal glands are above kidneys, pituitary at base of brain, pancreas in abdomen – none cause neck swelling.
Q48. Hormonal imbalance can lead to:
Harmful effectsHormones are potent; even small imbalances can cause disorders: diabetes, goitre, dwarfism, gigantism, infertility, etc. Thus, harmful effects result. No effect, faster digestion (specific to some but not general), or proper growth are not correct.
Q49. Deficiency of growth hormone in childhood leads to:
DwarfismLack of growth hormone during childhood results in abnormally short stature (pituitary dwarfism) with normal body proportions. Diabetes (insulin), obesity (multiple causes), goitre (iodine/thyroxine) are not direct results of growth hormone deficiency.
Q50. The controlled design of the body is maintained during:
Childhood growthThe overall body design (proportions, organ placement) is maintained as the body grows during childhood, thanks to hormonal regulation (growth hormone, thyroxine, etc.). Old age involves some loss of design, digestion is temporary, sleep is rest – not the period of maintaining design.