Biology - Digestion

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  • Created by: Qian Ru
  • Created on: 16-09-13 09:55
What are the 2 types of digestion?
Physical and chemical digestion
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Why must food be digested?
So that the food is able to pass through the cell surface mambrane and enter the cells.
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What is digestion?
It is the breaking down of large, insoluble food molecules into smaller, soluble molecules in the body.
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What are enzymes?
Enzymes are biological or organic catalyts made up of proteins that increase the rate of chemical reactions without being chemically changed at the end of the reaction.
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What are 2 characteristics of enzymes?
Enzymes remain chemically unchanged at the end of a reaction. Enzymes are specific in the action to the type of substrate.
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Name 3 enzymes.
Carbohydrases, proteases and lipases.
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What is starch broken down by?
It is broken down by salivary amylase.
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What is the process of the breakdown of starch?
Starch is broken down by amylase into maltose, which is broken down by maltase into glucose.
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What is hydrolysis?
It is the breakdown of nutrients using water.
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What is the oppostite of hydrolysis and what is it?
Condensation. It condenses small molecules into bigger molecules and water is produced.
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What is the rate of enzyme reaction affected by?
It is affected by temperature and pH.
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What is the enzyme activity at low temperatures?
It is very insctive as the enzymes and reactants have very low kinetic energy which leads to less collisions and therefore, less reactions.
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What is the enzyme activity as the temperature gradually increases?
The enzyme rate increases as the enzymes and reactants have more kinetic energy which leads to more frequent effective collision therefore, more reactions occur.
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What is the enzyme activity after the temperature passes the optimum temperature?
Enzyme activity decreases until enzyme is denatured.
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What is denatureation?
It is the shape of the enzyme being altered by high heat or chemicals. Enzymes become less soluble and congulated. Active sites are lost so substrates cannot fit into active sites therefore, it cannot act as a catalyst.
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How does extreme pH level affects enzymes?
Extremely high or low pH level causes denaturation of enzymes.
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What points should be included when describing a chemical digestion?
-The name of the enzyme. -The name of the substrate. -The name of the product.
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What does the mouth do?
Teeth cut and grind food. Saliva mixed with food contains enzymes called salivary amylase which only digests starch molecules into maltose. mucin in saliva helps soften the food. The tongue rolls the food into small balls into the gullet.
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What is the pH level of the saliva?
pH 7
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What does the gullet do?
The muscles contract and relax, producing peristalsis to mix and propel the contents in the alimentary canal.
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What are the does the gastric juice contains?
Hydrochloric acid, enzymes and water.
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What enzymes are present in the stomach?
Proteases.
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What is the purpose of the hydrochloric acid?
To kill bacteria and other harmful microorganisms. Denatures salivary amylase and provides an acidic medium for the functioning of protease.
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What does protease digests?
Proteins into polypeptides.
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Card 2

Front

Why must food be digested?

Back

So that the food is able to pass through the cell surface mambrane and enter the cells.

Card 3

Front

What is digestion?

Back

Preview of the front of card 3

Card 4

Front

What are enzymes?

Back

Preview of the front of card 4

Card 5

Front

What are 2 characteristics of enzymes?

Back

Preview of the front of card 5
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