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Biological Molecules Exam Study Guide Questions and Answers
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Biological Molecules Exam Study Guide Questions and Answers
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Biological Molecules Exam Study GuideQuestions and Answers
Name the covalent bond between two adjacent amino acids in a chain of amino acids. -
Answer-peptide
Name the type of reaction involved in breaking this bond and describe what happens in
this reaction. - Answer-1)hydrolysis
2)water is added
A student investigated how changing the pH affected the activity of pepsin.
• He used a blender to make a suspension of egg white (protein) in water.
• At the start of the investigation the suspension was cloudy.
• He prepared fixed concentrations of egg white suspension, acid and pepsin to add
to each of six test-tubes.
• He removed 0.1 cm3
of the mixture from each test-tube and used universal indicator
to measure the pH of each mixture.
(i) Identify three errors the student made in the preparation of his table before he
recorded
his results. - Answer-1)no units for 2nd column
2)amount rather than volume in 4th column
3)incorrect unit in final column
Identify a change the student could make to his procedure that would increase the
validity of the investigation. - Answer-equal volume in each tube
State the term that best describes the purpose of tube 6 - Answer-control
Another student suggested that he should repeat the investigation at least twice. How
would this have improved the investigation? - Answer-1)improve reliability
2)spread of results
On Fig. 1.1, draw a line to represent the effect of adding a fixed concentration of
pepstatin
on the rate of pepsin activity over the whole range of substrate concentrations. -
Answer-second line
Pepstatin acts as a competitive inhibitor of pepsin.
What can you conclude about the structure of pepstatin? - Answer-1)similar shape to
protein
2)complementary (shape) to (part of) active site
, Complete the table by indicating with a tick (✓) which of the compounds applies to each
statement. You may use more than one tick in a row.
1)Contains only the elements carbon hydrogen and oxygen
2)Insoluble in water
3)Contains glycerol
4)Contains ester bonds
5)Important in membrane structure
6)Contains fatty acids - Answer-1)triglyceride + cholesterol
2)all
3)triglyceride + phospholipid
4)triglyceride + phospholipid
5)phospholipid + cholesterol
6)triglyceride + phospholipid
Describe how to do the emulsion test for lipids and how a positive result would be
identified. - Answer-1)mix with ethanol and water
2)(goes) cloudy
Lipids form an essential part of a balanced diet. Some food, such as mycoprotein, is
produced by microorganisms. How might the lipid content of mycoprotein differ from
food that comes from animals? - Answer-1)Higher ratio of unsaturated to saturated
2)less saturated fat
3)more unsaturated
Hydrogen bonds also form between water molecules.
(i) Describe the formation of a hydrogen bond between two molecules of water and
explain why water can form these bonds - Answer-1)between O and H (of adjacent
molecules)
2) between delta+ (H) and delta- (O)
3) water molecule is polar
Hydrogen bonds allow water to act as a solvent. Why is the ability of water to act as a
solvent important for the survival of organisms?(2m) - Answer-1)organisms can take in
ions
2)able to dilute toxic substances
Amino acids form part of the structure of proteins.
(i) State the name given to the sequence of amino acids in a protein molecule. -
Answer-primary structure
Draw the general structure of an amino acid molecule in the space below. - Answer-
Collagen is an important fibrous protein which forms part of the wall of blood vessels. (i)
State one property of collagen that makes it a useful component of blood vessel walls. -
Answer-strength
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