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AQA Biology > 3.3 Digestion & Absorption > Flashcards

3.3 Digestion & Absorption Flashcards

1
Q

Where does stage 1 of protein digestion occur in the body?

A

Stomach

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2
Q

What is the first stage of protein breakdown?

A

Break long polypeptide chains in shorter chains

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3
Q

How do endopeptidases speed up the digestion of proteins?

A

Hydrolyse bonds in the middle of the chain
Create more ends/greater surface area for exopeptidases

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4
Q

What bonds do peptidases hydrolyse?

A

Peptide

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5
Q

Where does the second stage of protein breakdown occur?

A

Duodenum (small intestine)

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6
Q

What enzyme carries out stage 2 of protein breakdown?

A

Exopeptidases

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7
Q

What is the product in stage 2 of protein breakdown?

A

Dipeptides

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8
Q

What is a dipeptide?

A

2 amino acids joined by peptide bond

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9
Q

What enzyme carries out stage 3 of protein breakdown?

A

Dipeptidases

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10
Q

What is the product in stage 3 of protein breakdown?

A

Single amino acids

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11
Q

What is the first stage of starch breakdown?

A

Some starch is hydrolysed to maltose

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12
Q

Where does stage 1 of starch breakdown occur?

A

Mouth/salivary glands

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13
Q

What kind of biological molecule is starch?

A

Carbohydrate

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14
Q

What bonds does amylase hydrolyse?

A

Glycosidic

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15
Q

What reaction does amylase catalyse?

A

starch -> maltose

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16
Q

What kind of digestion is done by the teeth?

A

Mechanical

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17
Q

Why is it important to rip and grind food into smaller pieces?

A

Increase surface area:volume to increase enzyme action

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18
Q

What reaction does lactase catalyse?

A

lactose -> galactose + glucose

19
Q

What reaction does sucrase catalyse?

A

sucrose -> glucose + fructose

20
Q

What reaction does maltase catalyse?

A

disaccharides -> glucose

21
Q

What is found in epithelial cells making up the wall of the ileum (small intestine)?

A

Dipeptidases
Lactase
Maltase
Sucrase

22
Q

What problem is there with digestion of hydrophobic fats?

A

Form large globules in the body that have a small surface area:volume making enzyme action slow

23
Q

What is bile?

A

A chemical produced in the liver that increases the surface area:volume of fats

24
Q

Where is bile secreted?

A

Small intestine

25
Q

How does bile increase the surface area:volume of fats?

A

Emulsifies fats into smaller droplets

26
Q

What reaction does lipase catalyse?

A

fats -> fatty acids + glycerol

27
Q

Where does lipase act?

A

Small intestine

28
Q

What forms micelles?

A

Bile salts and fatty acids

29
Q

Why are micelles important?

A

More soluble in water
Transport fatty acids to epithelial cell membrane
Ensures higher concentration of fatty acids outside of epithelial cell than inside

30
Q

How do fatty acids move into epithelial cell?

A

Diffusion
Lipid soluble so can move straight through phospholipid bilayer

31
Q

Name two membrane bound dipeptidases.

A

Endopeptidase
Exopeptidase

32
Q

Where are endopeptidases produced?

A

Stomach

33
Q

What is the role of endopeptidases?

A

Hydrolyse bonds in the middle of protein chains

34
Q

What is the role of exopeptidases?

A

Hydrolyse bonds at the end of protein chains

35
Q

How do endopeptidases make exopeptidase action quicker?

A

Make more ends to increase surface area for exopeptidases

36
Q

How are amino acids absorbed into the blood?

A

Facilitated diffusion

37
Q

How are amino acids absorbed into epithelial cells?

A

Co transport

38
Q

How is glucose absorbed into epithelial cells?

A

Co transport

39
Q

How is glucose absorbed into the blood?

A

Facilitated diffusion

40
Q

Name 4 adaptations of epithelial cells for absorption.

A

Microvilli = large surface area
Mitochondria = active transport
Many protein channels = facilitated diffusion
Many protein carriers = active transport

41
Q

Where are dipeptidases found?

A

Membrane of epithelial cells

42
Q

How are fats absorbed into epithelial cells and into the blood?

A

Diffusion

43
Q

Why does cotransport stop when respiration is prevented?

A

Sodium concentration gradient is no longer maintained

AQA Biology (35 decks)

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