biological molecules 1 exam qs Flashcards
Explain five properties that make water important for organisms
A metabolite in condensation
A solvent so (metabolic) reactions can occur
high latent heat of vaporisation so provides a cooling effect
High (specific) heat capacity so buffers changes in temperature;
Cohesion (between water molecules) so supports columns of water
Describe the structure of glycogen
Polysaccharide of α-glucose]
(Joined by) glycosidic bonds
Suggest how glycogen acts as a source of energy
Hydrolysed (to glucose);
Glucose used in respiration
Explain how cellulose molecules are adapted for their function in plant
cells.
Long and straight chains;
2. Become linked together by many hydrogen bonds to form
fibrils;
3. Provide strength (to cell wall)
Name the group represented by COOH.
Carboxyl;
Describe how an ester bond is formed in a phospholipid molecule.
Condensation (reaction)
Between of glycerol and fatty acid
Give two ways in which ATP is a suitable energy source for cells to use
Releases relatively small amount of energy
doesn’t leave cells
Give two ways in which the hydrolysis of ATP is used in cells.
To provide energy for other reactions
To add phosphate to other substances and make them more
reactive
Describe the induced-fit model of enzyme action and how an enzyme acts
as a catalyst.
Substrate binds to the active site
Active site changes shape (slightly) so it is complementary to
substrate
Reduces activation energy
A competitive inhibitor decreases the rate of an enzyme-controlled
reaction.
Explain how.
inhibitor similar shape to substrate;
2. Fits/binds to active site;
3. Prevents enzyme-substrate complex forming;
Describe how the structure of a protein depends on the amino acids it
contains.
Structure is determined by position of amino acid
2. Primary structure is sequence/order of amino acids;
3. Secondary structure formed by hydrogen bonding (between amino
acids);
4. Tertiary structure formed by interactions (between R groups);
5. Creates active site in enzymes
Describe the chemical reactions involved in the conversion of polymers to
monomers and monomers to polymers.
Give two named examples of polymers and their associated monomers to
illustrate your answer.
A condensation reaction joins monomers together and forms a
bond and releases water;
2. A hydrolysis reaction breaks a bond between
monomers and uses water;
* amino acid and polypeptide, protein
* nucleotide and polynucleotide, DNA or RNA
Describe the difference between the structure of a triglyceride molecule and the
structure of a phospholipid molecule.
In phospholipid, one fatty acid
replaced by a phosphate
A quantitative Benedict’s test produces a colour whose intensity depends on the
concentration of reducing sugar in a solution. A colorimeter can be used to
measure the intensity of this colour.
The scientist used quantitative Benedict’s tests to produce a calibration curve of
colorimeter reading against concentration of maltose.
Describe how the scientist would have produced the calibration curve and used
it to obtain the results in Figure 4.
Make maltose solutions of
known concentrations
2. (Use colorimeter to) measure
colour of each solution and plot calibration
curve described;
3. Find concentration of sample from
calibration curve;
the scientists used a data logger to measure the length of the root rather than a ruler.
Suggest one reason why they used a data logger and explain why this was important in
this investigation.
To increase accuracy because reduces risk of human error;
