Chemical Coordination and Integration — Class 11 MCQs with Answers

Chemical Coordination and Integration — important questions & MCQs with answers (Class 11 Biology)

14 solved questions from this chapter's difficulty levels, each with its answer and explanation. The other 76 are timed and scored when you sign in.

1. Q1Easy

   Master gland of endocrine system:

   A.Adrenal

   B.Thyroid

   C.Pituitary✓ Correct

   D.Pancreas

   Answer: C. Pituitary

   Explanation: The anterior pituitary releases tropic hormones (TSH, ACTH, LH/FSH) that drive the thyroid, adrenal cortex and gonads — those are its targets, not fellow controllers.

2. Q2Easy

   Insulin lowers:

   A.Body temperature

   B.Blood pressure

   C.Heart rate

   D.Blood glucose✓ Correct

   Answer: D. Blood glucose

   Explanation: Insulin, made by β-cells of the pancreas, lowers blood glucose by driving cellular uptake and glycogen storage — the opposite effect to glucagon from α-cells.

3. Q3Easy

   Hormones are best defined as:

   A.Proteins produced by liver

   B.Enzymes produced by digestive glands

   C.Chemical messengers secreted by endocrine glands into blood✓ Correct

   D.Coenzymes secreted by neurons

   Answer: C. Chemical messengers secreted by endocrine glands into blood

   Explanation: Hormones are chemical messengers that endocrine glands secrete straight into blood to reach distant targets — unlike enzymes, which act locally, not through circulation.

4. Q4Easy

   The pituitary gland is located in a bony cavity called the:

   A.Orbital fossa

   B.Foramen magnum

   C.Sella tursica✓ Correct

   D.Neural canal

   Answer: C. Sella tursica

   Explanation: The pituitary gland is located in a bony cavity called sella tursica and is attached to the hypothalamus by a stalk.

5. Q5Easy

   Element essential for synthesis of thyroid hormones is:

   A.Iron

   B.Iodine✓ Correct

   C.Calcium

   D.Phosphorus

   Answer: B. Iodine

   Explanation: Thyroid hormones T3 and T4 are built by attaching iodine atoms to tyrosine residues in thyroglobulin — no other listed mineral serves this role.

6. Q6Easy

   Steroid hormones are derived from:

   A.Tryptophan

   B.Tyrosine

   C.Cholesterol✓ Correct

   D.Arachidonic acid

   Answer: C. Cholesterol

   Explanation: All steroid hormones (cortisol, aldosterone, testosterone, oestrogen) share cholesterol's four-ring skeleton; tyrosine and tryptophan instead give amine hormones.

7. Q7Medium

   Which hormone is NOT secreted by anterior pituitary?

   A.ACTH

   B.GH

   C.TSH

   D.Oxytocin✓ Correct

   Answer: D. Oxytocin

   Explanation: Oxytocin is synthesised in the hypothalamus and only stored and released by the posterior pituitary, unlike ACTH, GH and TSH, which the anterior lobe itself makes.

8. Q8Medium

   Glucagon is secreted by ___ cells of pancreas.

   A.Acinar

   B.β (beta)

   C.δ (delta)

   D.α (alpha)✓ Correct

   Answer: D. α (alpha)

   Explanation: α-cells of the pancreatic islets secrete glucagon, which raises blood glucose by breaking down liver glycogen — β-cells make insulin, which does the opposite.

9. Q9Medium

   Angiotensinogen is produced by:

   A.Heart

   B.Kidney

   C.Adrenal

   D.Liver✓ Correct

   Answer: D. Liver

   Explanation: The liver continuously secretes angiotensinogen into blood; kidney-released renin then cleaves it to angiotensin I, starting the pressure-raising cascade.

10. Q10Medium

    The pars distalis of the pituitary is commonly called the:

    A.Neurohypophysis

    B.Posterior pituitary

    C.Pars intermedia

    D.Anterior pituitary✓ Correct

    Answer: D. Anterior pituitary

    Explanation: The pars distalis region of the pituitary, commonly called the anterior pituitary, produces GH, prolactin, TSH, ACTH, LH and FSH.

11. Q11Medium

    Posterior pituitary stores and releases:

    A.TSH and FSH

    B.GH and prolactin

    C.Oxytocin and ADH✓ Correct

    D.LH and MSH

    Answer: C. Oxytocin and ADH

    Explanation: The posterior pituitary releases oxytocin and ADH, both made in the hypothalamus and carried down neuron axons — the anterior lobe instead makes TSH, FSH, GH and LH.

12. Q12Hard

    Most endocrine secretion is regulated by:

    A.Positive feedback only

    B.Negative feedback loops✓ Correct

    C.Random pulses

    D.Light

    Answer: B. Negative feedback loops

    Explanation: Most endocrine axes use negative feedback: rising hormone levels suppress further release (e.g. T4 dampening TSH) — oxytocin in labour is the rare positive-feedback exception.

13. Q13Hard

    Iodine is essential for the synthesis of:

    A.Thyroxine (T4)✓ Correct

    B.Insulin

    C.Adrenaline

    D.Testosterone

    Answer: A. Thyroxine (T4)

    Explanation: Iodine is incorporated onto tyrosine residues in the thyroid to make T4 (thyroxine); insulin, adrenaline and testosterone contain no iodine at all.

14. Q14Hard

    Assertion: Hormones act in very low concentrations. Reason: They require enzymatic activation in target cells.

    A.A true, R false✓ Correct

    B.Both true; R explains A

    C.Both false

    D.A false, R true

    Answer: A. A true, R false

    Explanation: Hormones do act at very low (nanomolar) concentrations because high-affinity receptors amplify their signal — they bind receptors directly, without enzymatic activation first.

Chemical Coordination and Integration — FAQs

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