Exchange Systems

Question 1

What is absorption?

Answer 1

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

Question 2

What is an active site?

Answer 2

A group of amino acids that makes up the region of an enzyme into which the substrate fits in order to catalyse a reaction.

Question 3

What is the alveoli?

Answer 3

Minute air sacs with a diameter of between 100um and 300um at the end id the bronchioles. They are lined with epithelium. Between the alveoli there are some collagen and elastic fibres

Question 4

What is bile salt?

Answer 4

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

Question 5

What is the bronchi?

Answer 5

Two divisions of the trachea each leading to one lung, Amount of cartilage reduced as they get smaller. Also produce mucus to trap first particles and cilia that move this towards the throat

Question 6

What are three bronchioles?

Answer 6

A series of branching subdivisions of the bronchi whose walls are made up of muscle (which constricts to control the flow of air in and out of the alveoli) lined with epithelial cells

Question 7

What are carbohydrases?

Answer 7

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

Question 8

What are chylomicrons?

Answer 8

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

Question 9

What does complimentary mean?

Answer 9

Describes the relationship between the active site of an enzyme and the substrate molecule - the way in which they fit together

Question 10

What is a countercurrent flow?

Answer 10

Describes how the flow of water over the gill lamellae and the flow of blood within them are in opposite directions. Allows a diffusion gradient to be maintained all the way across the gill lamellae

Question 11

What is a concurrent flow?

Answer 11

Describes how the flow of water over the gill lamellae and the flow of blood within them are in same direction. Less oxygen would be absorbed since the concentration gradient reaches equilibrium – diffusion only occurs in first part of lamellae

Question 12

What is the diaphragm?

Answer 12

A sheet of muscle that separates the thorax from the abdomen

Question 13

What are dipepitidases?

Answer 13

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 14

What is emulsification?

Answer 14

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 lipase is sped up

Question 15

What are endipeptidases?

Answer 15

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 16

What is an enzyme?

Answer 16

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

Question 17

What is exocytosis?

Answer 17

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

Question 18

What is expiration?

Answer 18

A largely passive process when external intercostal muscles relax, internal intercostal muscles contract, ribs move downwards and inwards and the diaphragm muscles relax, decreasing the volume of the thorax, which increase the pressure

Question 19

What are exopepitdases?

Answer 19

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

Question 20

What is the ileum?

Answer 20

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.

Question 21

What are intercostal muscles?

Answer 21

Lie between the rips. Two sets – internal whose contraction leads to expiration and external whose contraction leads to inspiration

Question 22

What is inspiration?

Answer 22

An active process when external intercostal muscles contract, internal intercostal muscles relax, ribs are puller upwards and outwards and the diagram muscles contract causing it to flatten, increasing the volume of the thorax, which reduces the pressure

Question 23

What are lungs?

Answer 23

A pair of lobe structures made up of a series of highly branched tubules called bronchioles, which end in tiny air sacs called alveoli

Question 24

What is the gill?

Answer 24

Located within the body of the fish, behind the head

Question 25

What are gill filaments?

Answer 25

Make up the gills of a fish – they are stacked up in a pile

Question 26

What is the gill lamellae?

Answer 26

At a right angle to the gill filaments, which increases the surface area of the gills

Question 27

What are lactase?

Answer 27

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

Question 28

What are lacteals?

Answer 28

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

Question 29

What are lipases?

Answer 29

Type of digestive enzyme which hydrolyse lipids into glycerol and fatty acids

Question 30

What is the lumen?

Answer 30

The cavity of the intestines

Question 31

What are maltese?

Answer 31

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

Question 32

What are membrane bound disaccharidase?

Answer 32

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

Question 33

What are micelles?

Answer 33

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 epithelial cells

Question 34

What are microvilli?

Answer 34

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

Question 35

What are monoglycerides?

Answer 35

A single glycerol molecule attached to one fatty acid

Question 36

What is the pancreas?

Answer 36

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

Question 37

What are pancreatic amylase?

Answer 37

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

Question 38

What is the pH?

Answer 38

A figure expressing the acidity or alkalinity of a solution on a logarithmic scales which 7 is neutral, lower values are more acidic and higher values are more alkaline (equivalent to -log10[H+])

Question 39

What are protease?

Answer 39

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

Question 40

What is the rib cage?

Answer 40

The bony frame formed by the ribs round the chest

Question 41

What are salivary amylase?

Answer 41

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

Question 42

What are the salivary glands?

Answer 42

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

Question 43

What is the spiracle?

Answer 43

Tiny pores that allow gases to enter and leave the trachea (and water vapour to leave as well). They are opened and closed by a valve

Question 44

What is the stomach?

Answer 44

A muscular sac with an inner layer that produces enzymes. It’s role is to store and digest foods, especially proteins

Question 45

What are sucrase?

Answer 45

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

Question 46

What is the tracheae?

Answer 46

A large internal network of tuned in insects with supported rings to prevent them collapsing

Question 47

What are tracheoles?

Answer 47

These tubes extend from the trachea and extend throughout all the body tissues of the insect to allow atmospheric air to be brought directly to respiring tissues

Question 48

What is ventilation?

Answer 48

The process in which air is constantly moved in and out of the lungs to maintain diffusion of gases across the alveolar epithelium, also known as breathing

Question 49

What are villi?

Answer 49

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