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NCERT Class 10 Science Life Processes: In-text questions (page 87) Solutions

Step-by-step working for every question of In-text questions (page 87) 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 87) Q1

   How does autotrophic nutrition differ from heterotrophic nutrition?

   1. Autotrophic nutrition is the process where organisms prepare their own food using simple inorganic substances like carbon dioxide and water.
   2. In autotrophic nutrition, energy is usually obtained from sunlight through photosynthesis, as seen in green plants.
   3. Heterotrophic nutrition is the process where organisms cannot make their own food and must consume other organisms or organic matter.
   4. In heterotrophic nutrition, energy is obtained by breaking down complex organic molecules from food, as seen in animals and fungi.
   5. The main difference is that autotrophs synthesize food from inorganic sources, while heterotrophs depend on ready-made organic food.

   Answer: Autotrophic nutrition involves making food from inorganic substances using light energy, whereas heterotrophic nutrition involves consuming organic food from other sources.

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2. In-text (page 87) Q2

   Where do plants get each raw material for photosynthesis?

   1. Plants absorb carbon dioxide from the air through tiny pores called stomata on their leaves.
   2. They take in water and dissolved minerals from the soil through the roots.
   3. Sunlight provides the energy required to drive the chemical reaction of photosynthesis.
   4. Chlorophyll, a green pigment found in the chloroplasts of leaf cells, captures the light energy.

   Answer: Carbon dioxide from air, water and minerals from soil, sunlight from the sun, and chlorophyll from leaf cells.

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3. In-text (page 87) Q3

   What is the role of the acid in our stomach?

   1. The stomach secretes hydrochloric acid (HCl) along with digestive enzymes.
   2. This acid lowers the pH of the stomach contents to create an acidic environment.
      why?

      pH below 7 is acidic, 7 is neutral and above 7 is basic; the lower the pH, the more hydrogen ions in the solution.

   3. The low pH is essential for the enzyme pepsin to become active and break down proteins.
      why?

      pH below 7 is acidic, 7 is neutral and above 7 is basic; the lower the pH, the more hydrogen ions in the solution.

   4. The acid also kills most of the bacteria and other microorganisms present in the food we eat.
   5. Thus, the acid prepares the food for further digestion and protects the body from infection.

   Answer: The acid in the stomach creates an acidic medium for pepsin to digest proteins and kills bacteria in the food.

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4. In-text (page 87) Q4

   What is the function of digestive enzymes?

   1. Digestive enzymes are biological catalysts secreted by glands in the digestive tract.
   2. They break down large, complex food molecules into smaller, simpler units.
   3. This process is called chemical digestion and makes food molecules small enough to be absorbed.
   4. For example, amylase breaks starch into sugars, and proteases break proteins into amino acids.
   5. Without these enzymes, the body could not absorb nutrients from the food we eat.

   Answer: Digestive enzymes break down complex food molecules into simpler, absorbable units.

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5. In-text (page 87) Q5

   How is the small intestine designed to absorb digested food?

   1. The inner wall of the small intestine has millions of tiny finger-like projections called villi.
   2. These villi increase the surface area for absorption of digested food.
   3. Each villus contains a network of blood capillaries and a lymph capillary called a lacteal.
   4. The capillaries absorb water-soluble nutrients like glucose and amino acids.
   5. The lacteal absorbs fat-soluble nutrients like fatty acids and glycerol.

   Answer: The small intestine is designed with millions of villi to increase surface area, and each villus has blood capillaries and a lacteal to absorb different types of digested nutrients.

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