Section 3: Chapter 6: Exchange

Question 1

What 3 structures do fish have for gas exchange?

Answer 1

• Gills.
• Gill filaments.
• Lamellae.

Question 2

What does the countercurrent flow of gas exchange in fish mean?

Answer 2

• Blood and water flow in opposite directions.

- Maintains steep diffusion gradient throughout fish.

Question 3

Do fish have a small or large SA:Vol ratio?

Answer 3

Small.

Question 4

What 3 ways can water move in and out of an insects tracheal system?

Answer 4

1) Down diffusion gradient.
2) Mass transport.
3) Volume changes in the tracheole ends (fill with water).

Question 5

What are the 3 structures in an insects tracheal system?

Answer 5

• Spiracles.
• Trachea.
• Tracheoles.

Question 6

How does gas exchange occur by mass transport in insects?

Answer 6

Muscles contract, squeezing mass amounts of air in or out of the trachea.

Question 7

Explain the role of water in the tracheoles of insects in their gas exchange.

Answer 7

• Anaerobic respiration occurs in muscles surrounding tracheoles, causing lactate to be produced.
• This lowers Ψ in the muscles so water leaves tracheole ends down conc. gradient via osmosis.
• More volume in tracheoles for air, so more can move in and diffuse to cells.

Question 8

In what ways is a plant adapted for gas exchange?

Answer 8

• Exchange takes place in gas stage.
• All cells close to oxygen and carbon dioxide supply.
• Large SA:Vol of leaves.
• Large SA of mesophyll cells.
• Lots of air spaces throughout mesophyll layer.

Question 9

What 4 structures to mammals have for gas exchange?

Answer 9

• Trachea.
• Bronchus.
• Bronchioles.
• Alveoli.

Question 10

What is the role of cartilage in the trachea and bronchi?

Answer 10

Prevents them from collapsing / keeps them open.

Question 11

What is a xerophyte?

Answer 11

Pants adapted to living in conditions with little water.

Question 12

How are insects adapted to limit water loss? (3 points)

Answer 12

• Waterproof coverings.
• Small SA:Vol ratio.
• Spiracles can close.

Question 13

How are xerophytes adapted to limit water loss? (5 points)

Answer 13

• Leaves can roll up - traps water vapour so no conc. gradient.
• Thick waxy cuticle.
• Hairy leaves - traps water vapour so no conc. gradient.
• Small SA:Vol ratio.
• Stomata in pits - traps water vapour.

Question 14

What is the structure of the lungs?

Answer 14

• Lobed.
• Series of bronchioles with alveoli on the ends.
• Protected by the rib cage.

Question 15

What is the structure of the trachea?

Answer 15

• Cartilage rings.

- Walls made up of muscle, epithelium and goblet cells.

Question 16

What is the structure of bronchi?

Answer 16

• Similar to trachea.
• Mucus to trap dirt, cilia to bring mucus up to throat.
• Small amount of cartilage rings.

Question 17

What is the structure of bronchioles?

Answer 17

• Walls lined with muscle and epithelial cells.

- Muscles = can constrict to control air flow in and out of alveoli.

Question 18

What is the structure of alveoli?

Answer 18

• Collagen and elastic fibres between bronchioles and alveoli.
• Lined with epithelium.
• Small and numerous amounts.

Question 19

What is the function of ciliated epithelium?

Answer 19

Moves mucus towards throat to be swallowed.

Question 20

What is the function of goblet cells?

Answer 20

Secrete mucus.

Question 21

Describe inspiration. (5 points)

Answer 21

1) RICE.
2) Diaphragm contracts and flattens.
3) Thorax volume increases.
4) Pressure decreases.
5) Air forced in.

Question 22

What is the mnemonic for inspiration?

Answer 22

RICE.

Question 23

Describe expiration. (5 points)

Answer 23

1) ERIC.
2) Diaphragm relaxes and pushed up.
3) Thorax volume decreases.
4) Pressure increases.
5) Air forced out.

Question 24

What is the mnemonic for expiration?

Answer 24

ERIC.

Question 25

What is a spirometer?

Answer 25

Measures lung volume by a person breathing in and out of an airtight chamber.

Question 26

What is meant by vital capacity?

Answer 26

Maximum volume of air a person can inhale or exhale in a single breath.

Question 27

What is meant by tidal volume?

Answer 27

Volume of air we breath in and out at rest.

Question 28

What is meant by breathing rate?

Answer 28

The number of breaths in a minute. Measured with a spirometer.

Question 29

What is meant by residual volume?

Answer 29

Volume of air always present in lungs.

Question 30

What is meant by expiratory reserve volume?

Answer 30

Additional volume of air that can be exhaled on top of tidal volume.

Question 31

Name the 7 main parts of your digestive system.

Answer 31

- Salivary glands. - Oesophagus. - Stomach. - Ileum. - Large intestine - Pancreas. - Rectum.

Question 32

What is the function of the oesophagus?

Answer 32

Carries food from mouth to stomach.

Question 33

What is the function of the stomach?

Answer 33

- Digest food. | - Produces enzymes to digest proteins.

Question 34

What is the function of the ileum?

Answer 34

- Digest food. - Absorbing products into bloodstream. - Large SA because of folds (villi and microvilli).

Question 35

What is the function of the large intestine?

Answer 35

Absorbs water.

Question 36

What is the function of the rectum?

Answer 36

Stored faeces until removed from anus via digestion.

Question 37

What is the function of the salivary glands?

Answer 37

Secretes amylase (which hydrolyses starch into maltose).

Question 38

What is the function of the pancreas?

Answer 38

Secretes pancreatic juice (contains protease, lipase and amylase).

Question 39

What are the 3 main digestive enzymes and what do they hydrolyse?

Answer 39

1) Carbohydrase - carbohydrates --> monosaccharides. 2) Lipase - Lipids --> Glycerol + fatty acids. 3) Protease - proteins --> amino acids.

Question 40

Describe lipid digestion.

Answer 40

1) Emulsification - split into tiny micelle droplets by bile salts in the liver. 2) Lipase in the pancreas hydrolyses the ester bonds in triglycerides to form fatty acids and a monoglyceride.

Question 41

What is emulsification? Why is it important?

Answer 41

- Breaking up lipids into small micelle droplets. | - Increases SA so lipase can work faster.

Question 42

What are the 3 proteins used in protein digestion?

Answer 42

- Endopeptidase. - Exopeptidase. - Dipeptidease.

Question 43

What does endopeptidase do?

Answer 43

Hydrolyses peptide bonds between amino acid forming peptide molecules.

Question 44

What does exopeptidase do?

Answer 44

Hydrolyses the peptide bonds on the end of peptide molecules to release dipeptides and amino acids.

Question 45

What does dipeptidase do?

Answer 45

- Hydrolyse bond between dipeptides (2 amino acids). | - Part of the epithelial cells on ileum lining.

Question 46

Describe starch / maltose digestion.

Answer 46

1) Saliva from salivary gland mixes with food. 2) Salivary amylase - hydrolyses glycosidic bonds - starch --> maltose. Also contains salts to keep pH neutral. 3) Food enters acidic stomach - amylase denatures. 4) Food enters small intestine - mixes with pancreatic juice. 5) Pancreatic amylase - remaining starch --> maltose. Also contains alkaline salts. 6) Food enters ileum - membrane-bound maltase hydrolyses the maltose into a-glucose.

Question 47

Describe sucrose digestion.

Answer 47

Sucrase hydrolyses glycosidic bond --> glucose + fructose.

Question 48

Describe lactose digestion.

Answer 48

Lactase hydrolyses glycosidic bond --> glucose + galactose.

Question 49

How do villi increase absorption in the ileum?

Answer 49

- Increase SA for diffusion. - Thin walls - decrease diffusion distance. - muscles - can move to maintain diffusion gradient. - Well supplied with blood vessels - carry away absorbed mols - maintaining diffusion gradient. - Microvilli - increase SA.

Question 50

What process' absorbs amino acids and monosaccharides?

Answer 50

Diffusion and co-transport.

Question 51

How are triglycerides absorbed?

Answer 51

- Micelles break down when come into contact with epithelial cells lining ileum. - Micelle releases monoglycerides and fatty acids that can easily diffuse into epithelial cells. - Taken to endoplasmic reticulum and turned back to triglycerides. - Taken to golgi apparatus, bind with cholesterol and lipoproteins to form chylomicrons. - Chylomicrons leave epithelial cells by exocytosis into lacteals (capillaries in villus). - Chylomicrons hydrolysed by enzyme in endothelial cells so triglycerides can leave and diffuse into cells.