Biological Molecules and Enzymes Quiz
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Questions and Answers

What is the main purpose of physical digestion?

  • To break down food into smaller pieces without changing its chemical structure (correct)
  • To eliminate undigested food from the body
  • To chemically change the food molecules into sugars
  • To absorb nutrients directly into the bloodstream

Which of the following correctly describes the function of amylase?

  • Neutralizes gastric acid in the stomach
  • Breaks down starch to simple reducing sugars (correct)
  • Breaks down protein to amino acids
  • Emulsifies fats for easier digestion

What role does bile play in digestion?

  • Neutralizes acidic food before it enters the small intestine (correct)
  • Digests proteins in the stomach
  • Absorbs nutrients from digested food
  • Produces enzymes needed for digestion

What is the function of hydrochloric acid in gastric juice?

<p>To kill harmful microorganisms and optimize protease activity (B)</p> Signup and view all the answers

Which statement best describes chemical digestion?

<p>The breakdown of insoluble molecules into soluble molecules (A)</p> Signup and view all the answers

Which elements are primarily found in proteins?

<p>Carbon, Hydrogen, Oxygen, Nitrogen (B)</p> Signup and view all the answers

What is the primary substrate from which starch is synthesized?

<p>Glucose (C)</p> Signup and view all the answers

Which test would be used to detect the presence of reducing sugars?

<p>Benedict's solution test (C)</p> Signup and view all the answers

What role do enzymes primarily play in metabolic reactions?

<p>They act as biological catalysts. (C)</p> Signup and view all the answers

What could happen to an enzyme if the temperature increases too much?

<p>It will denature. (A)</p> Signup and view all the answers

What constitutes a balanced diet?

<p>A variety of foods providing all necessary nutrients (C)</p> Signup and view all the answers

What is the primary cause of scurvy?

<p>Vitamin C deficiency (B)</p> Signup and view all the answers

Which organ is NOT part of the alimentary canal?

<p>Liver (A)</p> Signup and view all the answers

Flashcards

What is chemical digestion?

The breakdown of large food molecules into smaller, soluble molecules that can be absorbed.

Why is physical digestion important?

Physical digestion increases the surface area of food, allowing enzymes to work more efficiently during chemical digestion.

What are the main digestive enzymes and their functions?

Amylase breaks down starch into simple sugars, proteases break down protein into amino acids, and lipase breaks down fats and oils into fatty acids and glycerol.

Why is bile important in digestion?

Bile is an alkaline substance that neutralizes the acidic food mixture from the stomach, creating the ideal pH for enzymes in the small intestine.

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How does bile help with fat digestion?

Bile emulsifies fats, breaking them into smaller droplets, increasing their surface area for lipase to act on.

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What are the elements that make up carbohydrates, fats, and proteins?

The four main chemical elements that make up carbohydrates are carbon, hydrogen, and oxygen. Fats and oils are composed of carbon, hydrogen, and oxygen. Proteins consist of carbon, hydrogen, oxygen, and nitrogen.

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How are large molecules like starch, proteins, and fats made?

Large biological molecules are created from smaller building blocks. Starch, glycogen, and cellulose are all formed from chains of glucose molecules. Proteins are made from long chains of amino acids. Fats and oils are made from combinations of fatty acids and glycerol.

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How do you test for starch, reducing sugars, proteins, and fats?

The iodine solution test is used to detect starch. If starch is present, the solution will turn a blue-black color. Benedict's solution is used to test for reducing sugars like glucose. A change in the color of the solution from blue to green, yellow, orange, or red indicates the presence of reducing sugars. The biuret test identifies proteins. A purple color indicates the presence of proteins. An emulsion test is used to identify fats and oils. If fats or oils are present, the solution will turn cloudy.

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What are enzymes?

Enzymes are proteins that act as catalysts in metabolic reactions. They speed up chemical reactions without being used up in the process.

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What is an active site and an enzyme-substrate complex?

The active site of an enzyme is a specific 3D region where a substrate molecule binds. The enzyme-substrate complex is the temporary union formed when a substrate molecule binds to the active site of an enzyme.

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Explain the specificity of enzymes.

Enzymes are highly specific. They work on only one or a few specific substrates due to the shape of their active site matching the shape of the substrate. It's like a lock only fitting one specific key.

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How does temperature affect enzyme activity?

Increased temperature increases enzyme activity up to an optimal point. This is because more collisions occur. However, at very high temperatures, enzymes denature, losing their shape and functionality. Low temperature reduces enzyme activity as there are fewer collisions.

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How does pH affect enzyme activity?

Extreme pH values beyond the optimal range can change the shape of the active site, affecting its ability to bind to the substrate. Enzymes function best at a specific pH. If the pH deviates from the optimum, enzyme activity can decrease or the enzyme may denature.

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Study Notes

Biological Molecules

  • List chemical elements in carbohydrates, fats, and proteins
  • Large molecules are made from smaller ones (starch, glycogen, cellulose from glucose; proteins from amino acids; fats and oils from fatty acids and glycerol)
  • Iodine solution tests for starch
  • Benedict's solution tests for reducing sugars
  • Biuret test for proteins
  • Ethanol emulsion test for fats and oils

Enzymes

  • Enzymes are proteins involved in all metabolic reactions as biological catalysts
  • Enzymes are specific, meaning only certain substrates will bind to their active sites, which are the areas of the enzyme with a complementary shape.
  • Enzyme action is described through enzyme-substrate complexes, substrate and product, and active site specificity
  • Enzyme activity is affected by temperature changing enzyme shape and fit, frequency of effective collisions, and denaturation.
  • Enzyme activity is affected by pH changing enzyme shape and fit and denaturation.

Human Nutrition - Diet

  • A balanced diet contains carbohydrates, fats and oils, proteins, vitamins (like C and D), minerals (like calcium and iron), fiber (roughage), and water
  • Scurvy and rickets are caused by deficiencies in vitamin C and vitamin D, respectively.
  • Dietary sources of each nutrient should be considered.

Human Nutrition - Digestive System

  • Main organs of the digestive system (alimentary canal: mouth, oesophagus, stomach, small intestines, large intestine; associated organs: salivary glands, pancreas, liver, gall bladder)
  • Digestive system functions: ingestion, digestion, absorption, assimilation, and egestion
  • Digestive organs' functions are to be described in relation to these processes.

Human Nutrition - Digestion

  • Physical digestion breaks down food into smaller pieces without chemical change.
  • Surface area of food increases for enzyme action in chemical digestion.
  • Chemical digestion breaks down large, insoluble molecules (like starch, proteins, fats) into small, soluble molecules able to be absorbed.
  • Enzymes (amylase, protease, lipase) break down these different large molecules in different locations, and different enzymes act on them in different areas of the digestive system.
  • Hydrochloric acid (HCl) from gastric juice functions to kill microorganisms in food, and to provide an acidic pH necessary for certain enzymes to act efficiently.
  • Bile neutralises the acidic food and gastric juices and emulsifies fats to increase the surface area for chemical digestion.

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Description

Test your knowledge on biological molecules including carbohydrates, proteins, and fats. This quiz also covers the role of enzymes in metabolic reactions, their specificity, and factors affecting their activity. Participate to see how well you understand these essential concepts in human nutrition.

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