2 The importance of water

Question 1

how do the following properties of water aid survival:

• high latent heat of vapourisation
• high SHC
• ice being less dense than water?

Answer 1

• evaporation is an effective cooling mechanism
• large amounts of E required to raise temperature ∴ creates thermally stable environment for aquatic organism ∴ less heat used to regulate core temperature
• surface provides habitat for organisms; water beneath is insulated and does not freeze

Question 2

how do the following properties of water aid survival:

• polar
• transparency

Answer 2

• solvent/transport medium/cohesion/adhesion

- underwater photosynthesis

Question 3

what cell does cholera act on?

Answer 3

enterocytes

small intestine + appendix

Question 4

how does cholera cause dehydration?

Answer 4

toxin enters cell –> transported to G.A.

incr. andenylate cyclase enzymes
incr. concentration of cAMP (100x)

phosphorylation of CF transmembrane conductance regulator (CFTR - Cl- channel proteins)

Cl- ions leave cells into intestinal lumen –> H(2)O follows by osmosis –> rapid loss of fluids

Question 5

what are the components of oral rehydration methods?

Answer 5

water

NaCl

glucose

mineral ions (e.g. K+)

Question 6

what is hyponatraemia?

Answer 6

a low electrolyte concentration in the blood

Question 7

how does salt cause hypertension?

Answer 7

salt in blood plasma –> lowers water potential

water moves out of tissues into blood

increases blood volume

∴ blood pressure increases

Question 8

what is the definition of osmosis?

Answer 8

the movement of water across a partially permeable membrane from an area of high water potential to an area of low water potential into/out of the cytoplasm of the cell as a consequence of the random movement of individual water molecules

Question 9

how does high water potential cause haemolysis/cytolysis/turgidity?

Answer 9

movement of water molecules into a cell down the water potential gradient

exerts a higher pressure on the CSM

CSM ruptures

(in plant cells, water contained by cell wall ∴ protoplast presses up against cell wall)

Question 10

how does low water potential cause crenation/plasmolysed?

Answer 10

movement of water molecules out of a cell down the water potential gradient

reduces pressure on CSM

cell becomes crenated

Question 11

what is blood plasma?

Answer 11

a straw-coloured non-cellular mammalian biofluid

Question 12

what are the contents of blood plasma?

Answer 12

water

mineral ions

plasma proteins

Question 13

what is the function of water in blood plasma?

Answer 13

transportation of dissolved substances

thermoregulation

regulation of blood pressure and volume

Question 14

what is the function of mineral ions in blood plasma?

Answer 14

osmotic balance

pH buffering

regulation of membrane permeability

ion-specific roles

Question 15

give an example of a plasma protein and its function

Answer 15

serum albumin

• regulates osmotic balances
• pH buffering
• Ca2+ transport

fibrinogen + prothrombin
- blood clotting

immunoglobulins
- antibodies for i.r.

Question 16

what is the composition of lymph?

Answer 16

lymphocytes

small proteins

lipids

low G/O(2)/a.a.

high CO(2)

Question 17

what is the role of lymph?

Answer 17

circulatory

lymph nodes used to filter pathogens and foreign substances from lymph fluid

Question 18

what are the functions of carbohydrates?

Answer 18

energy store

energy source

cell markers

Question 19

what is the basic formula for a monosaccharide?

Answer 19

C(x)(H2O)y

Question 20

what are the monosaccharides used to make the following disaccharides:

• maltose
• lactose
• sucrose?

Answer 20

• a. glucose + a. glucose
• a. glucose + galactose
• a. glucose + sucrose

Question 21

what is the bond formed between two monosaccharides?

Answer 21

covalent a. 1,4 glycosidic bond

condensation reaction ∴ H2O formed

Question 22

what is the test for reducing sugars?

Answer 22

Benedict’s solution + heat

forms precipitate - blue -> green -> yellow -> brick red

Question 23

what is the test for non-reducing sugars?

Answer 23

add HCl and boil

add Na(2)CO(3)

then Benedict’s solution + heat

forms precipitate - blue -> green -> yellow -> brick red

Question 24

what are the three common polysaccharides?

Answer 24

starch

glycogen

cellulose

Question 25

what are the differences between amylose and amylopectin?

Answer 25

amylose forms a helix; amylopectin forms branches amylopectin has a. 1,6 glycosidic bonds; amylose only has a. 1,4 amylopectin is soluble; amylose is insoluble

Question 26

where is glycogen found?

Answer 26

skeletal muscles and liver

Question 27

what is the composition of cellulose?

Answer 27

B. 1,4 glycosidic bonds between glucose monomers

Question 28

what is the difference between a. and B. glucose?

Answer 28

C1 on molecule -OH group ABBA

Question 29

what is the range for normal blood glucose?

Answer 29

3.89 - 5.83 mmol dm-3

Question 30

what is the function of clinistix/diastix?

Answer 30

glucose biosensors

Question 31

how is the glucose concentration of urine monitored?

Answer 31

pad with peroxidase dipped in sample peroxidase breaks down H(2)O(2) to O(2) H(2)O O(2) oxidises reagent on pad --> colour change Clinistix: pink } light --> dark in Diastix: blue } presence of glucose

Question 32

how is the glucose concentration of blood monitored?

Answer 32

pad with glucose dehydrogenase has blood smeared on it glucose dehydrogenase converts glucose to gluconolactone reaction produces a signal --> converted to electrical current by transducer --> quan. result dependent glucose concentration

Question 33

what is the definition of a solvent?

Answer 33

a liquid that dissolves a solid

Question 34

what is the definition of a solute?

Answer 34

a solid that dissolves in a liquid

Question 35

what is the definition of a solution?

Answer 35

a combination of solvent and solution

Question 36

what is the definition of water potential?

Answer 36

a measure of the ability of water molecules to move freely in solution

Question 37

why does normal urine still contain some proteins?

Answer 37

can be filtered through glomerulus if small enough can be produced in genitourinary tract

Question 38

what is the level of protein in urea that indicates proteinuria?

Answer 38

>150mg in 24 hours

Question 39

what is the level of protein in urea that indicates nephritic syndrome?

Answer 39

>3.5g in 24 hours

Question 40

how is urine tested for the presence of proteins?

Answer 40

pad containing chromagen dipped in sample some have pH buffers/indicators (e.g. tetrabromoethanol) yellow = absence of proteins green -> blue = incr. concentration of proteins (incr. pH)