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Science Year 9 > Digestive system > Flashcards

Digestive system Flashcards

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1
Q

What is the alimentary canal?

A

The alimentary canal is the digestive tract that runs from the mouth to the anus.

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2
Q

What enzyme do the salivary glands produce?

A

The salivary glands produce a carbohydraese enzyme called amylase.

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3
Q

What is the role of the pancreas?

A

Produces protease, lipase, and amylase enzymes.

It releases these into the small intestine.

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4
Q

What is the role of bile?

A

Emulsifies fats.

Neutralizes stomach acid.

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5
Q

Why are proteins needed in our body?

A

Proteins are needed for growth and repair.

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6
Q

What two forms do carbohydrates come in?

A

Carbohydrates come in starches ( polymers of glucose) and sugars (sucrose.)

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7
Q

Why are fats needed in our body?

A

Fats are needed for energy, makeup parts of cell membranes, essential for normal growth. To insulate the body.

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8
Q

Why are food molecules broken down?

A

Food molecules are broken down because they are too big to pass through the gut wall.
They are reassembled into the forms required by the body not that animal/ plant forms.

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9
Q

Why are carbohydrates needed in our body?

A
  • They are a source of energy.

- Glucose is the main respiratory substrate.

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10
Q

What is the chemical used to test for starch/ what colour would it turn in the presence of starch?

A
  • Iodine.

- It will turn from orange to blue-black.

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11
Q

How can iodine be used with a microscope?

A

Iodine can be added to starch grains in plant cells.

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12
Q

What are three safety precautions when testing for starch with iodine?

A
  • Be wearing goggles.
  • Iodine is an irritant.
  • Avoid contact with skin and eyes.
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13
Q

How can you test the presence of sugars? Give a step-to-step process.

A

1.) Grind up the food sample with a pestle and mortar.
2.) Add to test-tube with Benedict’s solution.
3.) Heat up the solution in water bath.
If it turns red from blue then it has sugar in it.
If no sugar, there will be no change.

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14
Q

What are the safety precautions for testing for sugars with Benedict’s solution?

A
  • Be wearing goggles.
  • Benedict’s solution is an irritant.
  • Avoid contact with skin and eyes.
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15
Q

What colour does Benedict’s solution go if there is only a small amount of sugar?

A

It will turn a green orange colour.

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16
Q

How can you test for the presence of protein? Give a step-to-step process.

A
  • Grind up the food with a pestle and mortar.
  • Add food to a test tube with biuret solution.
  • If protein is present, the biuret solution will change from blue to purple.
    If no protein, there will be no change.
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17
Q

What are the safety precautions for testing for protein with Biuret solution?

A
  • Wear goggles.
  • Biuret solution is corrsoive and irritant.
  • Avoid contact with eyes and skin.
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18
Q

How can you test for the presence of fat?

A
  • EMULSION TEST
  • Grind up food with pestle and mortar.
  • Add to a test tube with ethanol +water.
  • If fat is present, it will change from clear/ colourless to cloudy.
    If no fat, there will be no change.
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19
Q

What are the safety precautions for testing for fats using ethanol +water?

A
  • Wear goggles.
  • Ethanol is flammable.
  • Avoid contact with skin and eyes.
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20
Q

What are proteins made up of?

A

Proteins are made up of amino acids.

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21
Q

What happens when glucose molecules are transported to cells?

A
  • They are used for respiration.

- Reassembled into the storage form of carbohydrates, glycogen.

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22
Q

What is protein synthesis?

A

Protein synthesis is the production of proteins from amino acids which takes place in the ribosomes of cells. Excess amino acids are broken down by the liver.

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23
Q

What are lipids/ fats made of?

A

Lipids/ fats are made of esters of fatty acid and glycerol.

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24
Q

What are qualitative tests?

A

Qualitative tests are tests described as present or absent with colours.

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25
Q

What are the two functions of the digestive system?

A
  • Breaks down complex food substances. (large insoluble molecules into small soluble molecules.)
  • Provides a large surface area for maximum absorption.
26
Q

What are large insoluble molecules converted into in digestion?

A

Large insoluble molecules change into small soluble molecules in digestion.

27
Q

What’s the function of the mouth in the digestive system?

A
  • Breaks down food physically by chewing.

- Breaks down food chemically by producing amylase from salivary glands.

28
Q

Give two examples of mechanical digestion.

A
  • Food is pulverized by teeth and stomach.
29
Q

What are enzymes?

A

Enzymes are biological catalysts- speed up chemical reactions without being used up.

30
Q

What is the substrate?

A

The substrate is the food molecule that the enzyme binds to.

31
Q

What model is used to explain enzymes and complementary shape?

A

The lock and key model explains how enzymes work.

32
Q

Use the lock and key theory to explain why maltase can break down maltose and not other molecules.

A

Maltase is the enzyme (lock) and maltose is the substrate (key.)
Maltase has an active site that will only fit maltose.
So other molecules won’t be broken down.

33
Q

What is starch broken down by and what are the products?

A

Starch is broken down by amylase and the product is glucose.

34
Q

What is protein broken down by and what are the products?

A

Protein is broken down by protease and the products are amino acids.

35
Q

What is fat broken down by and what are the products?

A

Fat is broken down by lipase and the products are fatty acids and glycerol.

36
Q

What is the gut?

A

The gut is the digestive system.

37
Q

Where can villi be found and what are their features?

A
  • Be found in the small intestine.
  • Increase surface area.
  • One cell thick to ensure only a short distance for absorption to happen by diffusion/ active transport. - Network of capillaries transports glucose/ amino acids into the blood (steep concentration gradient between blood and small intestine.)
  • Internal structure called lacteal which transports fatty acids and glycerol to the lymph.
38
Q

What is the active site in an enzyme?

A

The part of the enzyme that a substrate can attach/ fit to.

39
Q

What is the optimum temperature for enzymes and what happens if it is too high?

A
  • 37 degrees Celcius, so the molecular movement increases by a high temperature.
  • If too high, the enzyme will become denatured.
40
Q

What is meant by the term “denature”?

A

Denature means to change the shape of an enzyme’s active site.

41
Q

What do epithelial cells in the small intestine have on their surface and what do they do?

A

Epithelial cells have microvilli which increase the surface area for absorption.

42
Q

What PH range do cellular enzymes work the best at?

A

Most enzymes work the best at a cellular PH of 7.0 - 7.4.

43
Q

Explain in full detail how PH affects enzymes.

A
  • If the PH is too high or too low it can interfere with bonds holding the enzyme together.
  • This causes the active site to change shape, denatures.
44
Q

What is the PH of pancreatic protease, trypsin?

A

The PH of trypsin in the pancreas is 7.5 - 8.0.

45
Q

What is the PH for salivary amylase?

A

The PH of salivary amylase is 6.8.

46
Q

What is the PH for stomach protease, pepsin?

A

The PH for stomach protease is 1.5 - 2.0.

47
Q

What are carbohydrates broken down into?

A

Carbohydrates are broken down into simple sugars.

48
Q

Where is amylase found?

A
  • Salivary glands.
  • Pancreatic fluid.
  • Small intestine.
49
Q

Where are protease enzymes found/ what enzymes are produced?

A
  • Stomach (Pepsin.) Gastric glands in the stomach.

- Small intestine: duodenum (trypsin) Produced by the pancreas.

50
Q

Where do lipase enzymes break down lipids?

A

Lipase enzymes break down lipids in the small intestine.

This lipase is produced by the pancreas.

51
Q

What are buffer solutions used for?

A

Buffer solutions are used to control the PH.

52
Q

Explain how you would investigate the effect PH has on amylase.

A
  • Set up a test tube with amylase solution.
  • Add the buffer solution.
  • The starch solution is added to a series of solutions set up at different PH’s (start timing.)
  • Every 10 seconds take a sample from each test tube and test the presence of starch using iodine.
    If starch is present iodine will turn blue/ black from orange-brown.
    Record how long it takes for each PH to get rid of the starch (break it down.)
53
Q

What are the safety precautions for testing the effect of PH on amylase?

A
  • Wear safety goggles.
  • Amylase solution may cause allergic reactions.
  • Iodine is irritant (avoid contact with skin/ eyes.)
54
Q

What role does the liver have in digestion?

A
  • Contains sodium hydrogen carbonate which neutralizes stomach acid, creates optimum PH for pancreatic enzymes to be released in the small intestine.
  • Bile is produced in the liver but stored and concentrated in the gall bladder.
  • Breaks down large fat droplets into smaller droplets (gives bigger surface area for lipase to work on.)
55
Q

What is the wave-like contraction that moves the globule of food down the oesophagus called?

A

The wave-like contraction is called peristalsis.

56
Q

What is the role of the stomach?

A
  • Plummets food with muscular walls.
  • Produces protease enzyme pepsin.
  • Produces hydrochloric acid to kill bacteria and give the right PH for enzymes to be working in.
57
Q

What is the role of the gall bladder?

A

The gall bladder is where bile is stored before it’s released into the small intestine.

58
Q

What is the role of the large intestine?

A

The large intestine is where excess water is absorbed from the food.

59
Q

What is the role of the rectum?

A

The rectum is where faeces are stored before they leave out of the anus.

60
Q

Why does the small intestine have folded walls?

A
  • Has folded walls.
  • Larger surface area.
  • Increases the rate of diffusion

Science Year 9 (25 decks)

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