NCERT Class 10 Science — Chapter 1: Life Processes

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Assertion (A): Starchy foods like bread or rice begin to taste sweet after they are chewed thoroughly. Reason (R): Saliva contains an enzyme called salivary amylase that breaks down starch into simple sugars.

Official previous-year question

Verified 1 Aug 2026.

Options

ABoth A and R are true and R is the correct explanation of A
BBoth A and R are true but R is NOT the correct explanation of A
CA is true but R is false
DA is false but R is true

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Solution

Correct Option

The correct option is

Both A and R are true and R is the correct explanation of A

Explanation

Digestion involves the mechanical and chemical breakdown of complex food substances into simpler, absorbable forms. In humans, the chemical digestion of carbohydrates initiates in the oral cavity (buccal cavity) through the action of specific enzymes present in saliva.

Statement-wise Analysis

Assertion (A): Correct. Starch is a complex polysaccharide that is generally tasteless. When starchy foods such as bread or rice are chewed thoroughly, they are mechanically broken down and mixed with saliva. As the starch is hydrolyzed into simpler sugars (disaccharides), the food begins to taste sweet.
Reason (R): Correct. Saliva contains a digestive enzyme called salivary amylase (also known as ptyalin). This enzyme catalyzes the hydrolysis of starch into maltose (a disaccharide) and dextrins at a pH of approximately 6.8. Since maltose is a sugar with a sweet taste, the enzymatic breakdown of starch by salivary amylase is the direct cause of the sweetness experienced during chewing. Therefore, the reason correctly explains the assertion.

Key Takeaway: The digestion of carbohydrates begins in the mouth, where salivary amylase converts complex starch into simpler sugars like maltose, resulting in a sweet taste.

Your note

More from Chapter 1: Life Processes

Which enzyme, present in saliva and pancreatic juice, is primarily responsible for the breakdown of starch into simpler sugars?

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The accumulation of which compound in muscle cells leads to cramps during sudden physical activity or anaerobic respiration?

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Which hair-like structures lining the upper respiratory tract help in filtering air by trapping dust and particles?

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In the circulatory system of fishes, the heart is characteristically composed of how many chambers?

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With reference to maintenance functions in organisms, consider the following statements: 1. The transfer of energy source from outside to inside is referred to as respiration. 2. These processes require energy sourced from outside the body. 3. All organisms obtain energy directly from sunlight. Which of the statements given above is/are correct?

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Correct Option

The correct option is

Both A and R are true and R is the correct explanation of A

Explanation

Statement-wise Analysis

Assertion (A): Correct. Starch is a complex polysaccharide that is generally tasteless. When starchy foods such as bread or rice are chewed thoroughly, they are mechanically broken down and mixed with saliva. As the starch is hydrolyzed into simpler sugars (disaccharides), the food begins to taste sweet.
Reason (R): Correct. Saliva contains a digestive enzyme called salivary amylase (also known as ptyalin). This enzyme catalyzes the hydrolysis of starch into maltose (a disaccharide) and dextrins at a pH of approximately 6.8. Since maltose is a sugar with a sweet taste, the enzymatic breakdown of starch by salivary amylase is the direct cause of the sweetness experienced during chewing. Therefore, the reason correctly explains the assertion.

Key Takeaway: The digestion of carbohydrates begins in the mouth, where salivary amylase converts complex starch into simpler sugars like maltose, resulting in a sweet taste.