In-text Questions — Animal Hormones — Control and Coordination

1. 12 marksNCERT Cl-10 Science, In-text Qs after §6.3/Table 6.1, Q1

   How does chemical coordination take place in animals?

   Hint. Name the glands, the substance they release, and how that substance actually reaches its target.

   Step 1 — Name the source. Endocrine glands secrete chemical substances called hormones directly into the blood.

   Step 2 — Describe how they travel. The blood carries these hormones to different parts of the body, so that target organs or tissues with the means to detect them can respond accordingly.

   Step 3 — Note the trade-off. This is slower than nervous signalling, but it can reach all cells of the body regardless of nervous connections, acting steadily and persistently.

   ✦ Answer: Endocrine glands secrete hormones into the blood, which carries them to target organs throughout the body — slower than nerve impulses, but able to reach every cell rather than only those on a nervous pathway.

   Where students slip. Describing hormones as travelling through nerves — hormones are specifically carried by the blood, which is what distinguishes chemical coordination from nervous coordination.

2. 22 marksNCERT Cl-10 Science, In-text Qs after §6.3/Table 6.1, Q2

   Why is the use of iodised salt advisable?

   Hint. Trace the chain: iodine → a gland → a hormone → what happens if that hormone can't be made properly.

   Step 1 — Recall what iodine is needed for. Iodine is essential for the thyroid gland to synthesise the hormone thyroxine.

   Step 2 — Recall what thyroxine does. Thyroxine regulates carbohydrate, protein and fat metabolism in the body, since keeping this metabolic rate steady is what allows normal physical and mental growth to proceed.

   Step 3 — State the consequence of deficiency. Without enough iodine, thyroxine can't be made properly, and this can lead to goitre (a swollen neck, among other symptoms).

   ✦ Answer: Iodine is needed to make thyroxine, which regulates metabolism for growth; iodised salt ensures enough iodine intake to prevent thyroxine deficiency and goitre.

   Where students slip. Saying iodised salt 'boosts' thyroxine production beyond normal — its role is to supply the raw material (iodine) needed for normal thyroxine synthesis, preventing a deficiency, not to enhance it beyond what's needed.

3. 32 marksNCERT Cl-10 Science, In-text Qs after §6.3/Table 6.1, Q3

   How does our body respond when adrenaline is secreted into the blood?

   Hint. Think 'fight or flight' — what needs to speed up, and what can afford to slow down, when danger is detected?

   Step 1 — Heart and muscles. The heart beats faster, supplying more oxygen to the muscles.

   Step 2 — Blood redirection. Blood flow to the digestive system and skin is reduced, since small arteries there contract, diverting blood to the skeletal muscles instead.

   Step 3 — Breathing. The breathing rate increases, due to contractions of the diaphragm and rib muscles.

   ✦ Answer: Adrenaline makes the heart beat faster (more oxygen to muscles), reduces blood flow to the digestive system and skin (diverting it to skeletal muscles), and increases breathing rate — preparing the body for 'fight or flight.'

   Where students slip. Saying adrenaline increases blood flow everywhere equally — it specifically redirects blood away from digestion and skin toward the muscles that need it most in an emergency.

4. 42 marksNCERT Cl-10 Science, In-text Qs after §6.3/Table 6.1, Q4

   Why are some patients of diabetes treated by giving injections of insulin?

   Hint. Insulin's job is regulating blood sugar — think about what goes wrong in diabetes specifically.

   Step 1 — Recall insulin's role. Insulin, produced by the pancreas, helps regulate blood sugar levels.

   Step 2 — Recall what goes wrong in diabetes. In diabetes, the body doesn't secrete or use insulin properly, so blood sugar levels rise, causing harmful effects.

   Step 3 — Explain the treatment. Insulin injections supply the hormone the body isn't producing or using adequately on its own, helping bring blood sugar back into a regulated range.

   ✦ Answer: Insulin regulates blood sugar, and diabetes involves insufficient or ineffective insulin — injections supply what the body lacks, helping control blood sugar levels.

   Where students slip. Saying insulin injections 'cure' diabetes — they manage the blood sugar problem caused by insufficient insulin, rather than curing the underlying condition.

Solutions written by the tuition.in editorial team and checked against the NCERT Class 10 Science textbook, Reprint 2026-27 (jesc106.pdf) — three in-text question sets (14 questions total) plus one end-of-chapter Exercise (12 questions). Unchanged by rationalisation, though the chapter examines the brain as fore-brain/mid-brain/hind-brain (never 'cerebrum') and covers only four plant hormones (auxin, gibberellins, cytokinins, abscisic acid — no ethylene) and six animal hormones (no glucagon or progesterone).. Questions are referenced from the NCERT textbook for identification.