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NCERT Class 10 Science Life Processes: In-text questions (page 98) Solutions

Step-by-step working for every question of In-text questions (page 98) in NCERT's Class 10 Science book, chapter “Life Processes”, written by Shishya. Each question is in our own short words; open the NCERT chapter for the exact wording and figures.

1. In-text (page 98) Q1

   Describe the structure and functioning of nephrons.

   1. A nephron is the structural and functional unit of the kidney that filters blood and forms urine.
   2. Each nephron consists of a Bowman's capsule, a glomerulus, and a long tubular part.
   3. The glomerulus is a ball of capillaries located inside the Bowman's capsule.
   4. The Bowman's capsule surrounds the glomerulus and collects the filtrate.
   5. The tubular part is divided into the proximal convoluted tubule, loop of Henle, and distal convoluted tubule.
   6. Blood enters the glomerulus through the afferent arteriole and leaves via the efferent arteriole.
   7. During ultrafiltration, blood pressure forces water, glucose, amino acids, urea, and salts out of the glomerulus into the Bowman's capsule.
   8. The filtrate then passes through the tubular part where selective reabsorption occurs.
   9. Useful substances like glucose, amino acids, and most water are reabsorbed back into the blood capillaries surrounding the tubules.
   10. The remaining fluid, containing excess water, urea, and salts, becomes urine and flows into the collecting duct.

   Answer: The nephron consists of a Bowman's capsule, glomerulus, and tubular parts; it filters blood via ultrafiltration and reabsorbs useful substances to form urine.

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2. In-text (page 98) Q2

   How do plants get rid of excretory products?

   1. Plants do not have a specialized excretory system like animals.
   2. Waste products such as oxygen from photosynthesis are released through stomata.
   3. Excess water is removed from the plant body via transpiration through stomata.
   4. Some wastes are stored in vacuoles or in leaves, which eventually fall off.
   5. Other wastes may be stored in permanent structures like bark or wood.

   Answer: Plants eliminate excretory products through stomata (oxygen and water vapor), transpiration, storage in vacuoles, and shedding of leaves or bark.

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3. In-text (page 98) Q3

   How is the amount of urine produced regulated?

   1. The kidneys regulate urine volume by adjusting how much water is reabsorbed from the filtrate.
   2. When the body has excess water, the hypothalamus signals the pituitary gland to release less antidiuretic hormone (ADH).
   3. Low ADH levels make the collecting ducts less permeable to water, so less water is reabsorbed into the blood.
   4. This results in a larger volume of dilute urine being produced to remove the excess water.
   5. When the body is dehydrated, the hypothalamus signals the pituitary gland to release more ADH.
   6. High ADH levels make the collecting ducts highly permeable to water, allowing more water to be reabsorbed.
   7. This conserves water in the blood and results in a smaller volume of concentrated urine being produced.

   Answer: Urine production is regulated by the level of antidiuretic hormone (ADH) released by the pituitary gland, which controls the reabsorption of water in the kidney's collecting ducts.

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