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Body Fluids and Circulation

Biology · Class 11NCERT pp. 193–2032 sets × 25 questions

Key facts and formulas for Body Fluids and Circulation, 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.

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Key facts for this chapter

IdeaRule or fact
WBC orderNeutrophils 60-65%, lymphocytes 20-25%, monocytes 6-8%, eosinophils 2-3%, basophils 0.5-1%
ABO blood groupsA: A antigen, anti-B. B: B antigen, anti-A. AB: both antigens, no antibodies. O: no antigens, both antibodies
Donors and recipientsO is universal donor, AB universal recipient. Group B receives only B and O
Rh incompatibilityRh-ve mother with Rh+ve foetus: sensitised at first delivery, later babies at risk. Anti-Rh immunoglobulin prevents it
ClottingInjury → platelet factors → thrombokinase → prothrombin to thrombin → fibrinogen to fibrin. Ca++ needed
Conduction pathwaySA node → AV node → AV bundle → bundle branches → Purkinje fibres
ECGP: atrial depolarisation. QRS: ventricular depolarisation. T: ventricular repolarisation
Cardiac numbersStroke volume = EDV − ESV. Cardiac output = SV × heart rate. Heart rate = 60 / cycle time
Blood pressureNormal 120/80 mm Hg. Hypertension: 140/90 or more. Pulse pressure = systolic − diastolic
Heart factsFish 2 chambers, frog 3, crocodile 4. Lub = AV valves close, dub = semilunar valves close

Three sample questions

Q1. Match the plasma protein with its function.
a. Albumins   i. Clotting
b. Fibrinogen   ii. Defence
c. Globulins   iii. Osmotic balance
  1. a-i, b-iii, c-ii
  2. a-iii, b-i, c-ii
  3. a-ii, b-i, c-iii
  4. a-iii, b-ii, c-i
Hint and solution

Hint: Think of what each name suggests: fibrinogen becomes fibrin threads, and globulins include antibodies.

  1. Albumins → osmotic balance — Albumins are the most abundant plasma protein and they hold water in the blood by osmotic pull. So a pairs with iii.
  2. Fibrinogen → clotting — Fibrinogen is converted into fibrin threads during clotting. So b pairs with i.
  3. Globulins → defence — Globulins include antibodies, which defend the body. So c pairs with ii.
  4. a-iii, b-i, c-ii — Reading all three pairs together gives a-iii, b-i, c-ii. Option B.
Answer: B. Albumins keep osmotic balance, fibrinogen is needed for clotting and globulins defend the body.
Q2. Serum is best described as
  1. plasma from which the clotting factors have been removed
  2. blood without the formed elements and proteins
  3. plasma without any proteins
  4. blood from which water is removed
Hint and solution

Hint: Serum is what is left when blood clots and the clot is removed. Ask which proteins went into the clot.

  1. Plasma − clotting factors = serum — Plasma is the fluid part of blood. When it clots, the clotting factors are used up in the clot.
  2. Albumins, globulins remain — The remaining fluid still has albumins and globulins, so it is not protein-free.
  3. Eliminate — Blood without formed elements is plasma, and removing water is not part of the definition.
  4. Serum = plasma minus clotting factors — So serum is plasma from which the clotting factors have been removed. Option A.
Answer: A. Serum still contains albumins and globulins. Only the clotting factors are missing.
Q3. Consider: (i) Adult RBCs are formed in the spleen. (ii) An RBC lives for about 120 days. (iii) RBCs of most mammals have no nucleus. (iv) A healthy person has 12-16 g of haemoglobin per 100 mL of blood. Which are correct?
  1. (i), (ii) and (iii) only
  2. (i), (iii) and (iv) only
  3. (i), (ii), (iii) and (iv)
  4. (ii), (iii) and (iv) only
Hint and solution

Hint: Check statement (i) first. Where are adult RBCs made, and what does the spleen do to old RBCs?

  1. Adult RBCs: red bone marrow — Statement (i) is false. The spleen destroys old RBCs and stores some, it does not make adult RBCs.
  2. RBC life span: about 120 days — Statement (ii) is true and statement (iii) is true: most mammalian RBCs lack a nucleus.
  3. Hb: 12-16 g per 100 mL — Statement (iv) is the normal haemoglobin range, so it is true.
  4. Correct: (ii), (iii), (iv) — Dropping the false statement (i) leaves (ii), (iii) and (iv). Option D.
Answer: D. Adult RBCs are formed in the red bone marrow. The spleen destroys old RBCs.

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.

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