Home › Biology Class 11 › Chemical Coordination and Integration
Chemical Coordination and Integration
Biology · Class 11NCERT pp. 239–2492 sets × 25 questions
Key facts and formulas for Chemical Coordination and Integration, three worked sample questions, and two full practice sets. Every question has a hint, a reason for every option and a step-by-step solution, with a calculator or animation where one helps. English and Hinglish.
Key facts for this chapter
| Idea | Rule or fact |
|---|
| Hormone definition | Non-nutrient chemical, trace amounts, intercellular messenger; also made by scattered tissues (heart, kidney, gut) |
| Posterior pituitary | Stores and releases oxytocin and ADH made in the hypothalamus |
| Pars distalis (6) | GH, PRL, TSH, ACTH, LH, FSH; MSH is from pars intermedia |
| Thyroid axis | Hypothalamus TRH → anterior pituitary TSH → thyroid T3, T4 (negative feedback) |
| Calcium control | PTH raises blood Ca2+ (bone, kidney, gut); calcitonin from C cells lowers it |
| Disorders | Cretinism (child), myxoedema (adult), Graves (hyper), goitre (iodine), acromegaly, Cushing, Addison, DI vs DM |
| Adrenal | Cortex from inside: reticularis, fasciculata, glomerulosa; medulla makes adrenaline and noradrenaline |
| Pancreas | Alpha cells glucagon (raises glucose); beta cells insulin (lowers glucose); insulin has 21 + 30 = 51 amino acids |
| Gut and other hormones | Gastrin, secretin, CCK, GIP; ANF from heart; erythropoietin from kidney; hCG, relaxin from placenta |
| Hormone action | Peptides use membrane receptors and second messengers (cAMP); steroids and thyroid hormones use intracellular receptors |
Three sample questions
Q1. Consider these statements about hormones.
I. They are non-nutrient chemicals.
II. They are made in trace amounts.
III. They are made only by organised endocrine glands.
IV. They act as intercellular messengers.
Which are correct?
- I, II and III only
- I, II and IV only
- II, III and IV only
- I, III and IV only
Hint and solution
Hint: Check whether hormones come only from classic glands, or also from scattered tissues like the gut and heart.
- Hormone = non-nutrient, trace, messenger — A hormone is a non-nutrient chemical made in trace amounts that acts as an intercellular messenger. So I, II and IV are true.
- III says: only organised glands — Modern endocrinology says hormones are also made by scattered tissues like the heart, kidney and gastrointestinal tract.
- III is false — Because of the word only, statement III fails.
- Correct set: I, II, IV — The set without III is I, II and IV only. Option B.
Answer: B. Hormones are non-nutrient, trace-amount intercellular messengers. The modern view also includes scattered tissues, so III is wrong.
Q2. Endocrine glands are called ductless because they
- have ducts only on one side
- release hormones into the gut
- do not make any secretion
- pour their hormones directly into the blood
Hint and solution
Hint: Ductless means no tube. Think about where the secretion has to go if there is no duct.
- Endocrine = ductless — Endocrine glands have no ducts to carry their product.
- No duct, so blood is the route — Their hormones are poured directly into the blood or tissue fluid and carried to targets.
- Exocrine glands use ducts — Salivary and sweat glands are exocrine and need ducts, so they are not described this way.
- Answer — The reason is that they pour hormones directly into the blood. Option D.
Answer: D. They have no ducts; hormones enter the blood directly.
Q3. Assertion (A): The posterior pituitary is a store-house of hormones, not a factory.
Reason (R): Oxytocin and vasopressin are made in the hypothalamus and carried down axons to the posterior pituitary.
- Both A and R are true and R is the correct explanation of A
- Both A and R are true but R is not the correct explanation of A
- A is true but R is false
- A is false but R is true
Hint and solution
Hint: Ask where oxytocin and vasopressin are actually made, and then whether R explains why the lobe is only a store.
- Oxytocin, ADH made in hypothalamus — The neurosecretory cells of the hypothalamus synthesise both hormones, so R is true.
- Axons carry them down — The hormones travel along axons to the posterior pituitary, where they are stored.
- A is true — So the posterior pituitary only stores and releases them. It is a store-house, not a factory.
- R explains A — Since synthesis happens elsewhere, the lobe has nothing to make, so R explains A. Option A.
Answer: A. The pars nervosa only stores and releases the two hormones made in the hypothalamus, so R explains A.
How to use this chapter
Read the NCERT pages first, then attempt Set 1 without the hints. Note every wrong answer in a mistake list, read the reason for each option, and retry Set 2 two days later. A topic is solid when you can say why each wrong option is wrong.