Describe how you would use a biochemical test to show that a solution contained a non-reducing sugar,
such as sucrose. [3] - ,first reducing sugars test; boil with dilute HCl acid then Neutralise with
NaHCǑ, add benedict and heat to 95 degrees C brick red ppt forms if reducing sugar is present
...
Describe how you would use a biochemical test to show that a solution contained a non-reducing sugar,
such as sucrose. [3] - ✔✔,first reducing sugars test; boil with dilute HCl acid then Neutralise with
NaHCǑ, add benedict and heat to 95 degrees C brick red ppt forms if reducing sugar is present
Describe a chemical test you could carry out to show that a piece of coconut contains lipids. [3] - ✔✔
(Crush in) ethanol / alcohol; Add (to) water (Order of adding is critical for this point); Emulsion / white
colour
Explain what is meant by a polymer. [1] - ✔✔Molecule) made up of many identical/similar
molecules/monomers/ subunits;
Name the reaction which occurs when starch is broken down into maltose. [1] - ✔✔Hydrolysis
What is the formula for lactose? [2] - ✔✔C12 ; H22Ō1
Describe how β-glucose molecule differs from a molecule of α-glucose. [1] - ✔✔H at top right end
(instead of OH) / OH at bottom (carbon 1)
Show two ways in which the structure of cellulose is different from the structure of starch. [2] - ✔✔
Starch 1,4 and 1,6 bonds / branching Cellulose 1,4 bonds / no 1,6 bonds / straight; starch All glucoses
/monomers same way up cellulose Alternate glucoses upside down; starch Helix / coiled/compact
cellulose Straight; Starch monomer Alpha glucose Cellulose monomer Beta glucose
Describe the structure of starch and explain how its structure is related to its function. [3] - ✔✔Formed
from α glucose; Joined by condensation/ by the removal of a water molecule/ glycosidic bonds; Between
(carbons) 1 and 4 (and 1 and 6); Coiled chain; compact; (Allows) storage of large amount in a small
space; Insoluble so has no effect on osmosis/water potential; Branches; (Allows) rapid
breakdown/release of glucose / hydrolysis;
,The structure of a phospholipid molecule is different from that of a triglyceride. Describe how. [2] - ✔✔
triglyceride has three fatty acids and phospholipid has two; no phosphate group present in triglyceride
but present in phospholipid.
What is an unsaturated fatty acid? [1] - ✔✔Some / two carbons with only one hydrogen / (double
bonds) between carbon atoms / not saturated with hydrogen;
Describe the structure of cellulose and explain how its structure is related to its function. [3] - ✔✔
Alternate β-glucose rotated 180o, long straight chains, Many hydrogen bonds join (polysaccharide)
chains/molecules to each other / makes microfibrils / gives tensile strength;
Which elements are found in proteins? [1] - ✔✔Carbon, hydrogen, oxygen, nitrogen (sometimes
sulphur)
Describe how you would use a biochemical test to show that a solution contained protein. [2] - ✔✔
Biuret / alkali + copper sulphate; Lilac/purple/mauve/violet;
Which bonds are found in a)Primary structure [1]b)Secondary structure [1] c)Tertiary structure [2] - ✔✔
a)Peptide b) Hydrogen (and peptide) c)Ionic, disulphide bridges, hydrophobic interactions (hydrogen and
peptide)
Explain how a change in the primary structure of a globular protein may result in a different three-
dimensional structure. [3] - ✔✔Sequence of amino acids changes; tertiary structure changes/folds in a
different way; bonds form in different places (not peptide);
Describe how two-way chromatography is carried out. [2] - ✔✔Run chromatogram then turn through
90/right angle; With a different solvent;
,Explain the advantage of using two-way chromatography to separate short polypeptides. [2] - ✔✔
Spreads spots/polypeptides out more/ make sure spot only contains one substance;
Explain how inhibitors affect the rate of enzyme-controlled reactions. [6] - ✔✔Statement about two
types, competitive and non-competitive; Competitive: Similar shape to substrate;Inhibitor can
enter/bind with active site (of enzyme);Non-competitive: Affect/bind to enzyme other than at active
site; Distorts shape of active site; Inhibitors: Prevent entry of/binding of substrate to active site;
Therefore fewer/no enzyme-substrate complexes formed;
Describe and explain how an increase in temperature affects the rate of an enzyme controlled reaction.
[5] - ✔✔Rate of reaction increases; Increasing temperature increases rate of movement of molecules/
kinetic energy; Collide more often/substrate enters active site more often/more enzyme-substrate
complexes formed; Up to optimum; Rate of reaction decreases; High temperatures cause
denaturation/loss of tertiary structure/3D structure; By breaking specified bonds (not peptide bond);
Active site altered/substrate cannot bind/fit/
An enzyme catalyses only one reaction. Explain why [2] - ✔✔(Enzyme has) active site; Only substrate
fits (the active site);
Describe the induced fit model of enzyme action. [2] - ✔✔Active site / enzyme not complementary;
Active site changes (shape) / is flexible; (Change in enzyme allows) substrate to fit / E-S complex to form;
Describe one way that the lock and key model is different from the induced fit model. [1] - ✔✔Active
site does not change (shape) / is fixed (shape) / is rigid / does not wrap around substrate / (already) fits
the substrate / is complementary (before binding);
Explain why the rate of reaction of an enzyme is low away from its optimum pH. [3] - ✔✔(change in pH)
leads to breaking of bonds holding tertiary structure/ changes charge on amino acids;
enzyme/protein/active site loses shape/denatured; substrate will not bind with/fit active site; fewer/no
ES complexes formed;
, A protein molecule contains 150 amino acids. What is the total number of peptide bonds in this
molecule? [1] - ✔✔149
How do you calculate magnification? [1] - ✔✔M= I (Image)/ A (actual size)
Describe the ways in which prokaryotic cells and eukaryotic cells differ. [3] - ✔✔Prokaryotic cells do not
have a nucleus / have genetic material in cytoplasm; DNA in loop / ring; Not associated with proteins /
do not have chromosomes /chromatin / do not divide by mitosis; Smaller ribosomes; No membrane-
bound organelles; Such as mitochondria / lysosomes / endoplasmic reticulum / Golgi / chloroplasts;
Prokaryotic cells may have mesosomes; Prokaryotic cells smaller; May be enclosed by capsule;
What is the function of: a)Ribosome b)Smooth ER c)Golgi apparatus d) Chloroplast e)Mitochondria [5] -
✔✔a)Protein synthesis b)Lipid synthesis and transport c)Processing and packaging proteins for
secretion d)Photosynthesis e)Aerobic respiration to produce ATP
Explain the advantages and limitations of using a transmission electron microscope [5] - ✔✔
Advantages: Small objects can be seen; TEM has high resolution as wavelength of electrons shorter;
Limitations: Cannot look at living cells as cells must be in a vacuum; must cut section / thin specimen;
Preparation may create artefact; Does not produce 3D or colored image;
Why an electron microscope can be used to produce images [2] - ✔✔EM gives high resolution due to
short wavelength of electrons;
Explain how viruses cause damage to cells. [3] - ✔✔uses / breaks up / digests host nuclear / genetic
material (allow references made to DNA /RNA instead of nuclear /genetic); virus DNA / genetic material
inserted into hosts DNA / chromosome / genetic material; host cells amino acids are used to synthesize
viral proteins; cell lysis; by enzyme (produced by expressing a virus gene); toxin production;
Describe and explain how cell fractionation and ultracentrifugation can be used to isolate mitochondria
from a suspension of animal cells. [5] - ✔✔Cell homogenisation to break open cells; 1. Accept suitable
method of breaking open cells. Filter to remove (large) debris / whole cells; 2. Reject removes cell walls.
Use isotonic solution to prevent damage to mitochondria / organelles; Keep cold to prevent / reduce
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller jessyqueen. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $22.57. You're not tied to anything after your purchase.
