10th Biology Notes Chapter 11 Homeostasis

Chapter 11 of 10th Biology Notes – Homeostasis. In this captivating chapter, we will delve into the remarkable ability of living organisms to maintain a stable internal environment despite fluctuations in the external surroundings. Homeostasis, often referred to as the body’s equilibrium, is a vital mechanism that ensures the proper functioning and survival of organisms.

Throughout this chapter, we will explore the intricate systems and processes that govern this delicate balance, uncovering the fascinating ways in which living beings regulate their body temperature, pH levels, and other essential variables to adapt and thrive in their ever-changing environments. So, let’s embark on this journey of discovery, as we unravel the wonders of homeostasis and gain a deeper understanding of how life maintains its harmonious balance.

Unit 11 Homeostasis of Biology Long Questions

Unit 11 Homeostasis of Biology MCQ’s

Unit 11 Homeostasis of Biology Short Questions

What is homeostasis?
Answer: Homeostasis is the maintenance of the internal conditions of the body at equilibrium, despite changes in the external environment.

Give an example of homeostasis in the human body.
Answer: An example of homeostasis in the human body is the maintenance of core body temperature at about 37°C, regardless of fluctuations in the surrounding air temperature.

Why are stable internal conditions important for body cells?
Answer: Stable internal conditions are important for body cells because they provide an environment in which conditions do not change much, allowing enzymes to function efficiently.

What is thermoregulation?
Answer: Thermoregulation is the maintenance of internal body temperature within a particular range. Enzymes in the body work best at specific temperatures, and any change in body temperature can affect their functioning.

Define excretion in the context of homeostasis.
Answer: Excretion is the process of eliminating metabolic wastes from the body to maintain internal conditions at equilibrium. Metabolic wastes are materials produced during body metabolism that may harm the body if not removed.

How do plants maintain homeostasis of water and other chemicals?
Answer: Plants maintain homeostasis of water and other chemicals through processes like transpiration, diffusion, and osmosis. These mechanisms help regulate the amounts of water, oxygen, carbon dioxide, and nitrogenous materials in plant tissues.

What happens to the extra carbon dioxide and oxygen produced in plants during photosynthesis and respiration?
Answer: During daytime, the carbon dioxide produced during cellular respiration is utilized in photosynthesis and is not a waste product. At night, the surplus carbon dioxide is removed from the tissue cells by diffusion. Oxygen produced during photosynthesis is also removed when not needed.

How do plants remove extra water from their body?
Answer: Plants remove extra water from their body through a process called transpiration. Transpiration is the loss of water vapor from the aerial parts of the plant, mainly through small pores called stomata on leaves.

What are some examples of metabolic wastes deposited by plants?
Answer: Some examples of metabolic wastes deposited by plants are calcium oxalate crystals in the leaves and stems of many plants, resins by coniferous trees, gums by keekar, latex by rubber plants, and mucilage by carnivorous plants and ladyfinger.

How do hydrophytes cope with excess water in their cells?
Answer: Hydrophytes, plants that live partially or completely submerged in freshwater, have broad leaves with a large number of stomata on their upper surfaces. This helps them remove the excess water from their cells.

What adaptations do xerophytes have to survive in dry environments?
Answer: Xerophytes, plants that live in dry environments, possess a thick, waxy cuticle over their epidermis to reduce water loss from internal tissues. They also have fewer stomata to minimize transpiration and deep roots to absorb maximum water from the soil. Some xerophytes have special parenchyma cells in stems or roots to store large quantities of water, known as succulent organs.

How do halophytes adapt to living in salty environments?
Answer: Halophytes, plants that live in sea waters, adapt to salty environments by allowing salts to enter their cells due to their higher concentration in sea water. They carry out active transport to move and store large amounts of salts in vacuoles. This keeps the sap of vacuoles even more hypertonic than sea water, preventing water from moving out of the cells.

What are the main organs involved in homeostasis in humans?
Answer: The main organs involved in homeostasis in humans are the lungs, skin, and kidneys.

What role does the skin play in maintaining body temperature and eliminating metabolic wastes?
Answer: The skin helps regulate body temperature by insulating the body with a thin layer of fat cells and producing sweat to cool down through evaporation. It also eliminates metabolic wastes such as excess water, salts, urea, and uric acid through sweat.

How do the lungs maintain the concentration of carbon dioxide in the blood?
Answer: The lungs remove excess carbon dioxide from the blood through the process of respiration. Carbon dioxide diffuses from the cells into the blood and is then eliminated through the lungs into the air.

Describe the structure of the kidneys and their role in the urinary system.
Answer: The kidneys are bean-shaped organs located in the abdominal cavity, each weighing about 120 grams. They consist of the renal cortex (outer part) and the renal medulla (inner part). The kidneys filter blood to produce urine, which is carried by the ureters to the urinary bladder for temporary storage before being released from the body through the urethra.

What is the functional unit of the kidneys, and how many nephrons are present in each kidney?
Answer: The functional unit of the kidneys is called a nephron. Each kidney contains over one million nephrons. Nephrons consist of the renal corpuscle (glomerulus and Bowman’s capsule) and the renal tubule (proximal convoluted tubule, Loop of Henle, and distal convoluted tubule).

What is the main function of the kidney?
Answer: The main function of the kidney is urine formation.

How many steps are involved in urine formation in the kidney?
Answer: Urine formation in the kidney takes place in three steps: pressure filtration, reabsorption, and secretion.

What happens during pressure filtration in the kidney?
Answer: During pressure filtration, high-pressure blood forces water, salts, glucose, and urea out of glomerular capillaries into Bowman’s capsule, forming the glomerular filtrate.

What is the typical volume of urine produced by an average adult per day?
Answer: The typical volume of urine produced by an average adult is around 1.4 liters per day.

What is osmoregulation, and what role does the kidney play in it?
Answer: Osmoregulation is the regulation of the concentration of water and salts in blood and other body fluids. The kidney plays an important role in osmoregulation by regulating the water content of blood.

How does the kidney produce dilute (hypotonic) urine when there is excess water in the body fluids?
Answer: When there is excess water in body fluids, the kidney filters more water from glomerular capillaries into Bowman’s capsule and reabsorbs less water, producing abundant dilute urine.

How does the kidney produce concentrated (hypertonic) urine when there is a shortage of water in the body fluids?
Answer: When there is a shortage of water in body fluids, the kidney filters less water from glomerular capillaries and increases the rate of water reabsorption, producing a small amount of concentrated urine.

What are kidney stones, and how are they formed?
Answer: Kidney stones are hard deposits formed when urine becomes concentrated with crystals of salts such as calcium oxalate, calcium and ammonium phosphate, and uric acid. These crystals cannot pass in urine, leading to the formation of kidney stones.

What are the major causes of kidney stones?
Answer: The major causes of kidney stones include age, diet (high intake of green vegetables, salts, and vitamins C and D), recurring urinary tract infections, inadequate water intake, and alcohol consumption.

How can kidney stones be treated?
Answer: About 90% of kidney stones can pass through the urinary system with plenty of water intake. In surgical treatment, the affected area is opened, and the stones are removed. Lithotripsy is another method where shock waves are used to break down the stones, making them pass through urine.

What are the leading causes of kidney failure?
Answer: Diabetes mellitus and hypertension are the leading causes of kidney failure.

What are the symptoms of kidney failure?
Answer: The main symptoms of kidney failure include high levels of urea and other waste products in the blood, leading to vomiting, nausea, weight loss, frequent urination, blood in urine, swelling of legs and face, and shortness of breath.

How is kidney failure treated?
Answer: Kidney failure can be treated with dialysis or kidney transplant. Dialysis involves the cleaning of blood by artificial means, while kidney transplant replaces the patient’s damaged kidney with a healthy donor kidney.

What are the two methods of dialysis?
Answer: The two methods of dialysis are peritoneal dialysis, where the dialysis fluid is pumped into the peritoneal cavity, and haemodialysis, where the patient’s blood is pumped through a dialyzer with semi-permeable membranes.

What are the potential problems after a kidney transplant?
Answer: Potential problems after a kidney transplant may include transplant rejection, infections, imbalances in body salts, leading to bone problems and ulcers. The average lifetime for a donated kidney is ten to fifteen years.

Question: Describe the process of selective re-absorption in the kidneys.
Selective reabsorption in the kidneys is a vital process that occurs in the renal tubules to regulate the composition of body fluids and maintain homeostasis. After the initial filtration of blood in the glomerulus, the filtrate (glomerular filtrate) contains water, essential ions, glucose, amino acids, and other small molecules. During selective reabsorption, some of these filtered substances are selectively reabsorbed back into the bloodstream while waste products and excess ions remain in the tubules to form urine.
The process of selective reabsorption mainly occurs in the proximal convoluted tubule (PCT) and the distal convoluted tubule (DCT). Here’s a step-by-step description of the process:

Proximal Convoluted Tubule (PCT):

  • Sodium (Na+) ions are actively transported out of the tubule cells into the interstitial fluid surrounding the tubules. This creates a concentration gradient, causing Na+ ions to move passively from the tubule lumen into the tubule cells.
  • As Na+ ions move into the tubule cells, other substances like glucose, amino acids, and ions like chloride (Cl-) and bicarbonate (HCO3-) follow by facilitated diffusion due to cotransport mechanisms.
  • Water follows the solutes by osmosis, reabsorbing the filtered water from the tubule back into the bloodstream. This process is called obligatory water reabsorption, and it occurs because of the osmotic gradient created by the reabsorption of solutes.


Loop of Henle and Distal Convoluted Tubule (DCT):

  • In the loop of Henle, a countercurrent multiplier system maintains a concentration gradient in the medulla of the kidney, allowing for further water reabsorption later in the process.
  • The DCT fine-tunes the reabsorption of sodium and water based on the body’s needs and hormonal signals like aldosterone and antidiuretic hormone (ADH).
  • Aldosterone, released by the adrenal glands, stimulates the reabsorption of sodium and the secretion of potassium (K+) ions in the DCT and collecting ducts.
  • ADH, released by the pituitary gland, increases water permeability in the collecting ducts, allowing for more water reabsorption and concentrating the urine.
  • By selectively reabsorbing essential substances, the kidneys ensure that the body retains vital nutrients while getting rid of waste products and excess ions through urine formation. This process helps maintain the body’s internal environment and plays a crucial role in homeostasis.

Question: How do the plants excrete extra water and salts from their bodies?
Plants excrete extra water and salts primarily through the process of transpiration and guttation.
Transpiration: Transpiration is the loss of water vapor from the aerial parts of the plant, mainly through tiny openings called stomata present on the leaves. During photosynthesis, water is taken up by plant roots and transported through the xylem to the leaves. When the stomata open to allow for gas exchange (CO2 intake for photosynthesis), water vapor also escapes from the leaf surface into the atmosphere. This loss of water helps plants regulate their water content and prevent excess accumulation of water.

Guttation: Guttation is the exudation of water droplets from the tips or edges of leaves in some plants, particularly during the night or early morning. It occurs when the root pressure is higher than the rate of transpiration. Guttation allows excess water to be expelled from the plant’s vascular system, which helps maintain the water balance.

Overall, these processes assist plants in regulating their water and salt balance, preventing waterlogging and maintaining proper cellular functions.

Question: What is the functional unit of the kidney? Describe its structure
The functional unit of the kidney is the nephron. Each kidney contains over one million nephrons, and they are responsible for filtering and processing the blood to produce urine. The nephron consists of two main parts: the renal corpuscle and the renal tubule.
Renal Corpuscle: The renal corpuscle consists of two components – the glomerulus and Bowman’s capsule. The glomerulus is a cluster of capillaries formed by the afferent arteriole. Blood is filtered through the glomerulus, and the filtrate enters the space within Bowman’s capsule called the Bowman’s space.

Renal Tubule: The filtrate from the glomerulus enters the renal tubule. The renal tubule is a long, convoluted tube that is divided into several segments, including the proximal convoluted tubule (PCT), loop of Henle, and distal convoluted tubule (DCT). The PCT is the first segment where most of the selective reabsorption takes place, and the loop of Henle establishes the concentration gradient in the medulla. The DCT fine-tunes the reabsorption of water and electrolytes based on hormonal signals.

Question: What steps are involved in the formation of urine in the kidneys?
The formation of urine in the kidneys involves several steps:
Filtration: Blood is filtered in the glomerulus of the renal corpuscle, where small molecules such as water, glucose, salts, and waste products like urea and creatinine are filtered out of the blood and form a filtrate. This process is driven by blood pressure.

Selective Reabsorption: As the filtrate passes through the renal tubules, essential substances like glucose, amino acids, and most of the water are selectively reabsorbed back into the bloodstream. This process occurs mainly in the proximal convoluted tubule (PCT) and the loop of Henle.

Tubular Secretion: Some substances, such as certain drugs, ions, and hydrogen ions (H+), are actively transported from the blood into the renal tubules. This process helps in eliminating additional waste products and maintaining acid-base balance.

Concentration: The loop of Henle establishes a concentration gradient in the medulla of the kidney, which helps in concentrating the urine and conserving water in the body.

Collection: The concentrated urine is collected in the collecting ducts and then transported to the renal pelvis, where it eventually drains into the ureter and then into the urinary bladder.

Elimination: The urine is stored in the urinary bladder until it is eliminated from the body through the urethra during urination.

Question:“Along with excretion, kidneys also play role in Osmoregulation.” Comment on this statement.
The statement “Along with excretion, kidneys also play a role in osmoregulation” is accurate. Osmoregulation refers to the process by which organisms regulate the balance of water and solutes in their body fluids to maintain proper internal osmotic balance.
The kidneys play a crucial role in osmoregulation through processes such as selective reabsorption and the production of concentrated or diluted urine, as mentioned earlier. By adjusting the amount of water and solutes reabsorbed or excreted, the kidneys help regulate the osmolarity (concentration of solutes) of body fluids. This is essential for maintaining stable cell function, preventing dehydration or overhydration, and overall homeostasis.

In summary, the kidneys not only remove waste products through excretion but also contribute significantly to the regulation of water and solute levels in the body, which is vital for maintaining a balanced internal environment.

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