topic 1

Question 1

3 monosaccharides

Answer 1

glucose fructose galactose

Question 2

starch

Answer 2

energy store in plant cells
polysach of alpha glucose
amylose 1-4 glycosidic bonds so it is unbranched
amylopectin 1,4,1,6 branched
helical so compact for storage
large so cant leave the cell
insoluble in water so water potential of cell not affected

Question 3

glycogen

Answer 3

energy store in animal cells and is a polysaccharide of alpha glucose
1-4 2-6 glycosidic bonds so branched so its compact and can fit lots of molecules in a small area
branched also means more ends for hydrolysis so release glucose for respiration to make ATP for energy release large and insoluble so can’t leave cell and as its insoluble in water wp of cell unaffected

Question 4

cellulose

Answer 4

strength and structural support to plant cells and algal cell walls
polysach of B – 1,4 glycosidic bonds so unbranched chains that link parallel by hydrogen bonds forming microfibrils every other b glucose molecule is inverted in long straight unbranched chain and many hydrogen bonds link parallel strands to form microfibrils hydrogen bonds are also strong in high numbers so provide strength

Question 5

how to find quantity of sugar in a solution

Answer 5

make sugar dilutions of known concentrations heat volume of each sample with set volume of benedicts for same time and use colorimeter to measure absorbance of each known concentration plot calibration curve conc on x and absorbance on y and draw line of best fit then repeat benedicts with unknown samples

Question 6

Triglycerides

Answer 6

1 glycerol 3 FA 3 ester bonds there is a high ratio of C-H:C in HC chain so used in respiration to release more energy and insoluble in water so no effect on WP

Question 7

competitive inhibitor

Answer 7

as conc of comp inhibitor increases ROR decreases as it is a similar shape to the substrate it blocks the active sites so substate can’t bind so fewer E-SC

Question 8

non competitive inhibitor

Answer 8

as concentration of it increases, reaction rate decreases
it binds to the allosteric site changing the enzyme tertiary structure so active site is no longer complementary to substrate so substrate can’t bind so fewer E-SC – this is permanent so increasing substrate conc has no effect

Question 9

dna

Answer 9

hold genetic info for polypeptides

Question 10

rna

Answer 10

transfer genetic info from dna to ribosome

Question 11

How to nucleotides join to form polypeptides

Answer 11

condensation reaction between phosphate group and deoxyribose forming phosphodiester bonds

Question 12

dna structure

Answer 12

– polymer of nucleotides and each nucleotide is formed from a phosphate group a nitrogen containing base and phosphodiester bonds join adjacent nucleotides.2 polynuc chains held together by h bonds between specific comp base pairs and it is a double helix

Question 13

how does dna structure elated to function

Answer 13

two strands so both Can act as a template for semi conservative replication
hydrogen bonds between bases are weak so strands can be separated for replication
comp base pairing so accurate replication
many hydrogen bonds between bases so strong stable molecule
long molecule so it can store lots of genetic info

Question 14

semi conservative replication

Answer 14

dna helicase breaks hydrogen bonds between comp base pairs
unwinding the double helix both strands act s a template
free dna nucleotides attracted to exposed bases and join by specific comp base pairing
hydrogen bonds form between a and t and g and c
dna polymerase joins adjacent nucleotides on new strand via condensation
forming phosphodiester bonds

Question 15

why does DNA polymerase move in opposite directions along dna strands

Answer 15

dna has antiparallel strands
so shape of nucleotides on two ends different
dna polymerase is an enzyme with specific shaped active site
so can only bind to substrate with comp shape

Question 16

atp structure

Answer 16

ribose bound to a molecule of adenine and 3 phosphate groups
nucleotide derivative

Question 17

how is hydrolysis of ATP used in cells

Answer 17

coupled to energy requiring reactions within cells like active transport
inorganic phosphate released to phosphorylate other compounds making them more reactive

Question 18

how is atp resynth in cells

Answer 18

adp and pi to adp
condensation reaction removing water molecule
catalysed by auto synthase
during respiration and photosynthesis

Question 19

how do properties of ATP make it a suitable energy source

Answer 19

releases energy in small amounts
single reaction so only one bond hydrolysed to release energy
cannot pass out of cell

Question 20

how do hydrogen bonds occur between water molecules

Answer 20

water - polar
slightly negative charged oxygen attracted to slightly positively charged hydrogens atoms of other molecules

Question 21

water as metabolite

Answer 21

used in condensation hydrolysis photosynthesis

Question 22

water as a solvent

Answer 22

allows metabolic reactions to occur
allows transports pf substances like urea in the blood

Question 23

high specific heat capacity of water

Answer 23

buffers changes in temp
can Gain and lose a lot of heat without changing temp
good habitat for aquatic organisms as temp is more stable than land
helps organisms maintain constant internal body temp

Question 24

high latent heat of vaporisation

Answer 24

allows effective cooling via evap of small volume
so helps organisms maintain a constant internal body temp

Question 25

strong cohesion between water molecules

Answer 25

supports column of water like transpiration stream through xylem in plants
produce surface tension supporting small organisms

Question 26

Describe how proteins are digested in the human gut.

Answer 26

hydrolysis of peptide bond
exopeptidase hydrolyse terminal amino acid
endopeptidases break polypeptides into smaller peptide chains
Dipeptidases hydrolyse / break down dipeptides into amino acids.

Question 27

Explain how cellulose molecules are adapted for their function in plant cells.

Answer 27

long straight chains
link ed together by many hydrogen bonds to form fibrils
provide strength to cell wall