Chapter 6 - Exchange

Question 1

what are the features of a specialised exchange surface? (5)

Answer 1

• large SA:Vol
• thin, short DP
• selectively permeable
• movement of environmental medium to maintain DG
• transport system to maintain DG

Question 2

What is the calculation for diffusion?

Answer 2

surface area x difference in concentration
_________________________________

     length of diffusion pathway

Question 3

How are single celled organisms able to survive with no transport system?

Answer 3

large SA:Vol
simple diffusion
no part too far from external substances

Question 4

what is the main factor in conflict with gas exchange in terrestrial organisms?

Answer 4

water conservation

Question 5

list the structures of insects gas exchange system in order from smallest to largest (4)

Answer 5

fluid filed ends
tracheoles
trachea
spiracles

Question 6

How do gases move in/out of the tracheal system? (3)

Answer 6

• along a diffusion gradient, oxygen used by surrounding cells
• mass transport, muscle contraction
• fluid filled ends, water enters surrounding cells by osmosis during times of activity meaning a lower vol. of water in the system leaving a shorter diffusion pathway for gas exchange in times of high metabolic activity

Question 7

What are the limitations of the tracheal system? (2)

Answer 7

• rely solely on diffusion

- needs short diffusion pathway therefore limits insect size

Question 8

state the structures of the gills from largest to smallest

Answer 8

gill bar
gill filaments
gill lamella

Question 9

What is the importance of the counter-current exchange system for diffusion?

Answer 9

• maintains a constant favourable diffusion gradient for oxygen to diffuse into the blood e.g. when blood with little oxygen meets water with little oxygen the oxygen still diffuses down the gradient into the blood

Question 10

how do gases enter/exit the leaf of a plant (the process)?

Answer 10

diffusion

Question 11

how are leaf tissues gas exchange systems similar to that of an insect? (2)

Answer 11

• cells not far from external air, short DP

- diffusion takes place in gas phase, more rapid

Question 12

State an adaptation of a leaf for rapid diffusion

Answer 12

stomata -short DP
air spaces throughout mesophyll
large SA of mesophyll = large SA

Question 13

state the structures of a leaf from top to bottom (5)

Answer 13

waxy cuticle
upper epidermis
mesopyhll
air spaces
lower epidermis

Question 14

How are stomata adapted for limiting water loss?

Answer 14

when flacid due to low water potential stomata close, when turgid they remain open

Question 15

state 3 adaptations of insects to reduce water loss

Answer 15

• small SA:Vol
• waterproof coverings
• spiracles, open/close

Question 16

adaptations of non-xerophitic plants to limit water loss? (2)

Answer 16

• waxy cuticle

- close stomata

Question 17

adaptations of xerophytes? (5)

Answer 17

• thick cuticle
• rolling up of leaves
• hairy leaves
• stomata in pits/grooves
• reduced SA:Vol e.g. cactus

Question 18

state the structures of the lungs passed through by air entering the lungs (mouth onwards) (4)

Answer 18

trachea
bronchus
broncheole
alveoli

Question 19

why must the lungs be located inside the body?

Answer 19

• air not dense enough to support the delicate structure

- significant water loss, body would dry out

Question 20

describe the structure of the trachea

Answer 20

flexible airway supported by ‘c’ shaped cartilage, lined by goblet cells

Question 21

describe the structure of the bronchi

Answer 21

less cartilage as bronchi get smaller

Question 22

describe the structure of bronchioles

Answer 22

muscle walls able to constrict, lined with epethelial cells

Question 23

describe the structure of alveoli

Answer 23

air sacs with collagen and elastic fibres between to allow it to expand and recoil

Question 24

state the 3 sets of muscle involved with the mechanism of breathing

Answer 24

• internal intercostal muscles
• external intercostal muscles
• diaphragm

Question 25

describe the diaphragm

Answer 25

sheet of muscle separating thorax from abdomen

Question 26

outline the process of inspiration (6)

Answer 26

- external contract, internal relax - ribs pull upwards and outwards - volume of thorax is increased - diaphragm contracts and flattens - reduction of pressure in lungs - atmospheric pressure is then greater than in lungs = air flows into lungs

Question 27

adaptations of alveoli for diffusion into blood (5)

Answer 27

- red blood cells slowed as they move through capillaries - more time for diffusion - red blood cells flattened against walls of capillaries - thin walls of both - shorter DP - both have large SA - constant ventilation, constant heartbeat maintains DG

Question 28

state the risk factors for lung disease (5)

Answer 28

- smoking - air pollution - genetics - infections - occupation (chemicals)

Question 29

what is the difference between a correlation and a causation?

Answer 29

``` correlation = change of one variable reflected by change in other variable causation = one variable is the result of the change in the other variable ```

Question 30

state the major parts of the digestive system (5)

Answer 30

``` oesophagus stomach ileum large intestine rectum (salivary glands) (pancreas) ```

Question 31

what is the difference in function of the ileum and the large intestine?

Answer 31

ileum: - food digested - absorbs products of digestion large intestine: - absorbs water

Question 32

outline the process of carbohydrate digestion (chemical). (5)

Answer 32

- saliva enters mouth from salivary glands, mixes with food through chewing (contains salivary amylase, breaks down starch to maltose) - acid in stomach denatures salivary amylase - food passes into ileum, mixes with pancreatic juice containing pancreatic amylase - muscles in intestine push food along ileum - membrane-bound disaccharidase maltase hydrolyses maltose to alpha glucose

Question 33

what is the term used to describe enzymes that hydrolyse carbs?

Answer 33

carbohydrases

Question 34

what the the two other types of hydrollytic enzymes other than maltase for carbs?

Answer 34

sucrase | lactase

Question 35

what is the optimum pH for amylase?

Answer 35

around neutral

Question 36

outline the process of lipid digestion (3)

Answer 36

- bile salts split lipids into micelles - process called emulsification - increases SA for action of lipases

Question 37

name of protein enzymes?

Answer 37

peptidases

Question 38

name the 3 types of peptidases

Answer 38

endopeptidases exopeptidases dipeptidases

Question 39

state adaptations of the exchange surface of the ileum + function of adaptation (5)

Answer 39

- villi, SA - microvilli, SA - thin walls, DP - muscle walls for movement//mixing, DG - capillary network, DG

Question 40

how are amino acids absorbed in the ileum?

Answer 40

co-transport using sodium and co-transport carrier proteins

Question 41

outline how lipids are absorbed (5)

Answer 41

- micelles associated with bile salts - contact epethelial cells and break down releasing monoglycerides and fatty acids (lipid soluble) pass through PB-L - transported to ER reform into triglycerides - continue to Golgi where they become associated with cholesterol and lipoproteins to form chylomicron - excytosis out of cell into lymphatic capillaries which drain into blood