Podcast
Questions and Answers
What breaks down large food molecules into smaller and soluble ones?
What breaks down large food molecules into smaller and soluble ones?
Digestion
Physical digestion involves chemical change of food.
Physical digestion involves chemical change of food.
False
What is the function of enzymes in digestion?
What is the function of enzymes in digestion?
To speed up chemical reactions and break down food molecules.
What is the optimum temperature range for enzyme activity?
What is the optimum temperature range for enzyme activity?
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Increasing temperature enhances enzyme-substrate complex formation until an optimum temperature is reached.
Increasing temperature enhances enzyme-substrate complex formation until an optimum temperature is reached.
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What is the effect of extreme pH on enzymes?
What is the effect of extreme pH on enzymes?
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Match the following enzymes with their functions in digestion:
Match the following enzymes with their functions in digestion:
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Where does digestion begin?
Where does digestion begin?
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The tube that connects the mouth to the stomach is called the ______.
The tube that connects the mouth to the stomach is called the ______.
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Study Notes
Human Digestive System
- Complex molecules such as starch, proteins, and fats are too large to diffuse into the bloodstream; they require digestion.
- Digestion involves breaking down large food molecules into smaller, absorbable units for body cell usage.
Physical Digestion
- Involves mechanically breaking food into smaller pieces, e.g., chewing, stomach churning, and bile salt action.
- Increases surface area of food particles, enhancing efficiency of subsequent chemical digestion by enzymes.
Chemical Digestion
- Breaks down large food molecules into smaller ones via enzymatic actions.
- Allows smaller molecules to be absorbed through the walls of the villi into the bloodstream, reaching various body cells.
Enzymes
- Specialized proteins that accelerate chemical reactions without being altered themselves.
- They are substrate-specific, meaning each enzyme acts on a specific molecule.
- Produced in the cytoplasm under genetic instructions from chromosomes.
- Optimal performance occurs at specific temperatures and pH levels; extreme deviations lead to denaturation.
Effects of Temperature on Enzyme Action
- Enzymes function best within a specific temperature range, typically around 40-45°C.
- Below optimal temperature, enzymes become inactivated; above it, they denature.
- Rate of reaction doubles with every 10°C increase until reaching the optimum, due to increased molecular motion.
- Excessive heat alters enzyme conformation, disrupting enzyme-substrate complex formation.
- Enzymes can regain function if temperature is restored after being chilled.
Effect of pH on Enzyme Action
- Each enzyme has an optimum pH for peak activity; deviations diminish effectiveness.
- Extreme pH levels can denature enzymes.
- Enzymes must work in environments tailored to their specific functions in the body.
Digestive Enzymes
- Amylase: Breaks down starch into maltose.
- Maltase: Converts maltose into glucose.
- Pepsin: Decomposes proteins into polypeptides.
- Proteases (e.g., peptidases): Further break down polypeptides into amino acids.
- Lipase: Catalyzes the breakdown of fats into fatty acids and glycerol.
The Digestive System
- Alimentary canal: Continuous tube from mouth to anus, facilitating digestion.
- Digestive system: Encompasses the alimentary canal and accessory organs like salivary glands, liver, gallbladder, and pancreas.
Mouth
- Initiates digestion through physical breakdown of food and mixing with saliva.
- Saliva contains salivary amylase, initiating the chemical digestion of starch into maltose.
- The tongue forms a bolus from the mixed food to facilitate swallowing.
Oesophagus
- Connects the mouth to the stomach through a long, narrow tube.
- No digestive enzyme secretion; only starch digestion occurs as bolus transitions to the stomach.
- Wave-like muscle contractions (peristalsis) push food down the oesophagus.
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Description
This quiz covers the Human Digestive System as part of Lower Secondary Science curriculum. Focused on complex molecules like starch, proteins, and fats, the quiz helps reinforce understanding of how digestion breaks down food for absorption. Dive into essential concepts related to physical digestion and cellular processes.
