Digestion

Question 1

Enzyme

Answer 1

A protein that acts as a catalyst and so lowers the activation energy needed for a reaction.

Question 2

Absorption

Answer 2

Movement of digested food molecules through the wall of the intestine into the blood or lymph

Question 3

Oesophagus

Answer 3

Muscular tube which carries food from the mouth to the stomach

Question 4

A muscular sac with an inner layer that produces enzymes. Its role is so store and digest food, especially proteins.

Answer 4

Stomach

Question 5

A long muscular tube where food is further digested. Enzymes are produced by its walls and by glands that pour their secretions into it. Inner walls are folded into villi which gives them a large surface area. Where products of digestion are absorbed into the bloodstream.

Answer 5

Ileum

Question 6

Where water is absorbed.

Answer 6

Large intestine

Question 7

The final section of the intestines where the faeces is stored before being egested by the anus.

Answer 7

Rectum

Question 8

Salivary glands

Answer 8

Situated near the mouth. They pass their secretions via a duct into the mouth which contain salivary amylase which hydrolyses starch into maltose.

Question 9

A large gland situated below the stomach. It produces a secretion called pancreatic juice, which contains proteases to hydrolyse proteins, lipase to hydrolyse lipids and amylase to hydrolyse starch.

Answer 9

Pancreas

Question 10

Type of digestive enzyme which hydrolyse carbohydrates, ultimately to monosaccharides.

Answer 10

Carbohydrases

Question 11

Type of digestive enzyme which hydrolyse lipids (fats and oils) into glycerol and fatty acids.

Answer 11

Lipases

Question 12

Proteases

Answer 12

Type of digestive enzyme which hydrolyse proteins, ultimately into amino acids.

Question 13

Produced by the salivary glands and released into the mouth and starts hydrolysing starch in food to maltose.

Answer 13

Salivary amylase

Question 14

Pancreatic amylase

Answer 14

Produced by the pancreas and released into the small intestine where it continues the hydrolysis of starch to maltose.

Question 15

Maltase

Answer 15

Produced by the epithelial lining and is a membrane-bound disaccharidase which breaks down maltose into glucose.

Question 16

An enzyme which is not released into the lumen of the ileum but is part of the cell-surface membranes of the epithelial cells that line the ileum. E.g. maltase

Answer 16

Membrane-bound disaccharidase

Question 17

Sucrase

Answer 17

Produced by the epithelial lining and is a membrane-bound disaccharidase which breaks down sucrose into the monosaccharides glucose and fructose.

Question 18

Produced by the epithelial lining and is a membrane-bound disaccharidase which breaks down lactose into the monosaccharides glucose and galactose.

Answer 18

Lactase

Question 19

Produced by the liver and split up lipids into tiny droplets called micelles.

Answer 19

Bile salt

Question 20

Emulsification

Answer 20

The process by which lipids are split up into tiny droplets called micelles by bile salts, which are produced by the liver. It increases the surface area of the lipids so that the action of lipases is sped up.

Question 21

Micelles

Answer 21

Tiny structures (4-7nm in diameter) formed when monoglycerides and fatty acids remain in association with the bile salts that initially emulsified the lipid droplets. They break down as they come into contact with the epithelial cells lining the villi of the ileum and release the monoglycerides and fatty acids which diffuse across the cell membrane into the epithelial cells.

Question 22

A structure formed when triglycerides associate with cholesterol and lipoproteins, which are adapted for the transport of lipids. Start forming in the endoplasmic reticulum and continuing in the Golgi apparatus.

Answer 22

Chylomicrons

Question 23

Lymphatic capillaries that are found in the centre of each villus, where chylomicrons pass into and then enter the bloodstream.

Answer 23

Lacteals

Question 24

Exocytosis

Answer 24

The outward bulk transport of materials through the cell-surface membrane. How chylomicrons move out of the epithelial cells by this process.

Question 25

Endopeptidases

Answer 25

A type of protease which hydrolyses the peptide bonds between amino acids in the central region of a protein molecule forming a series of peptide molecules.

Question 26

A type of protease which hydrolyses the peptide bonds on the terminal amino acids of the peptide molecules formed by endopeptidases. They progressively release dipeptides and single amino acids.

Answer 26

Exopeptidases

Question 27

Dipeptidases

Answer 27

A type of protease which hydrolyse the bond between the two amino acids of a dipeptide. Dipeptidases are membrane-bound, being part of the cell-surface membrane of the epithelial cells lining the ileum.

Question 28

The cavity of the intestines

Answer 28

Lumen

Question 29

Villi

Answer 29

Folded finger-like projections of the ileum wall, about 1mm long, which are increase the surface area of the ileum and therefore accelerate the rate of absorption.

Question 30

Tiny finger-like projections from the cell-surface membrane of some animal cells.

Answer 30

Microvilli