Questions and Answers
What is the primary source of energy in food?
Carbohydrate
Fats are needed in small amounts to maintain ______.
health
Which of the following are sources of protein? (Select all that apply)
Vitamins and minerals are not important for health.
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What is the test for the presence of starch?
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What color change indicates the presence of reducing sugar in the Benedict's test?
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What is the purpose of protein in the body?
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What is the significance of digestion?
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Large molecules are synthesized from smaller ______.
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Explain the 'lock and key' hypothesis in terms of enzymes.
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What does peristalsis refer to?
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Study Notes
Importance of Food
- Food provides energy essential for daily activities, cellular processes like respiration, and muscular contraction.
- Nutrients in food are critical for body growth and repair of worn-out parts.
Functions of Nutrients
- Carbohydrates: Primary energy source; found in rice, noodles, and potatoes.
- Proteins: Necessary for growth and repair; serve as chemical messengers; sourced from fish, meat, eggs, beans, and dairy products.
- Fats: Provide energy and insulation; includes butter, oil, and nuts.
- Vitamins and Minerals: Required in small amounts for maintaining health; sourced from fruits, vegetables, and dairy products.
Tests for Nutrients
- Starch (Iodine Test): Add 2-3 drops of iodine solution to sample. Color change to dark blue indicates presence; yellow indicates absence.
- Reducing Sugars (Benedict’s Test): Mix 2.0 cm³ of sample with 2.0 cm³ Benedict’s solution, heat in water bath. Color changes (green to brick-red) indicate presence; blue indicates absence.
- Proteins (Biuret Test): Add 5% sodium hydroxide to the sample, followed by copper(II) sulfate. Color change to purple indicates presence.
Digestion and Its Importance
- Digestion involves breaking down large food molecules into smaller components for absorption and use by the body.
Synthesis of Large Molecules
- Large molecules such as starch, proteins, and fats are synthesized from smaller basic units: glucose, amino acids, and glycerol/fatty acids, respectively.
Enzyme Action
- Enzymes function based on the 'lock and key' hypothesis, where specific substrates fit into specific active sites of enzymes.
- Enzyme-substrate complex formation leads to substrate conversion into products with high specificity.
Alimentary Canal Functions
- Mouth: Ingestion and initial digestion; salivary glands secrete amylase.
- Oesophagus: Transports food to the stomach via peristalsis.
- Stomach: Food digestion continues; acidic environment activates pepsin for protein digestion.
- Small Intestine: Major digestion and absorption occur; enzymes like lipase, maltase, and protease act here.
- Pancreas: Produces digestive enzymes; secretes bicarbonate to neutralize stomach acid.
- Gall Bladder: Stores bile, aiding fat digestion.
- Liver: Processes nutrients and detoxifies substances.
- Large Intestine: Absorption of water; compacts waste.
- Rectum and Anus: Egestion of feces.
Peristalsis
- Rhythmic, wave-like contractions of smooth muscles mix and propel contents throughout the alimentary canal.
Enzyme Functions in Digestion
- Amylase: Breaks down starch into maltose.
- Maltase: Converts maltose into glucose.
- Protease: Breaks down proteins into amino acids.
- Lipase: Digests fats into glycerol and fatty acids.
Structure of a Villus
- Villi are finger-like projections in the small intestine that increase surface area for absorption.
- Capillaries transport nutrients, while lacteals absorb fatty acids and glycerol.
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Description
Explore the key concepts of nutrition in humans, focusing on the enzymes involved in digestion. This quiz covers tests for starch, reducing sugars, proteins, and fats, as well as the synthesis of larger molecules from smaller units. Enhance your understanding of digestion's significance in human health.
