In this unit, students will learn about osmoregulation in animals and in different environments, excretion in representative animals and vertebrates, and thermoregulation in mammals (humans). These topics are essential for understanding how the human body and other organisms maintain water balance, remove metabolic waste, and regulate body temperature.
This post provides complete Class 12 Biology Unit 15 Homeostasis notes, including solved MCQs, short questions, long questions, and full exercise solutions, designed specifically for Punjab Board exams 2026. With these notes, students can easily revise, practice, and score high marks.
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Skip to PDF contentGet complete and exam-focused notes of Class 12 Biology Unit 15 – Homeostasis in one PDF file. These notes are specially prepared for Punjab Board students to help in better exam preparation.
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❓FAQs – Homeostasis
Q1. What is osmoregulation and why is it important?
Osmoregulation is the control of water and salt balance in animals. It is important because it keeps cells and body fluids stable for proper functioning.
Q2. What is the main function of kidneys in homeostasis?
Kidneys filter blood, remove waste, and maintain water & salt balance in the body. They are the most important organs for excretion.
Q3. How do humans regulate body temperature?
Humans regulate temperature through sweating to cool down and shivering to warm up, which is part of thermoregulation.
Q4. What is included in these notes?
These notes include MCQs, short questions, long questions, and solved exercise for exam preparation.
📝 MCQs – Class 12 Biology Unit 15 Homeostasis
1. Homeostasis in animals helps to:
a) Increase reproduction rate
b) Maintain internal balance
c) Produce more energy
d) Control growth
✅ Answer: b) Maintain internal balance
2. Which of the following is a functional unit of kidney?
a) Neuron
b) Nephron
c) Bowman’s capsule
d) Tubule
✅ Answer: b) Nephron
3. Osmoregulation in freshwater fish is different from marine fish because:
a) Freshwater fish lose water by osmosis
b) Marine fish gain water by osmosis
c) Freshwater fish gain water by osmosis and marine fish lose water
d) Both gain water equally
✅ Answer: c) Freshwater fish gain water by osmosis and marine fish lose water
4. Which organ is mainly responsible for excretion in humans?
a) Liver
b) Kidney
c) Lungs
d) Heart
✅ Answer: b) Kidney
5. Which of these is a common kidney problem?
a) Kidney stone
b) Liver cirrhosis
c) Asthma
d) Arthritis
✅ Answer: a) Kidney stone
6. Which part of nephron is involved in filtration?
a) Loop of Henle
b) Bowman’s capsule
c) Collecting duct
d) Distal tubule
✅ Answer: b) Bowman’s capsule