Download Hormone such as testosterone/estrogen that could influences sex

SBI4U – Biochemistry
Name: ___ANSWER – PERIOD 3____________________________________
Total:
/71
Evaluation Allocation
Achievement Category
Knowledge/Understanding (K/U)
Thinking & Inquiry (I)
Communication (C)
Making Connections (MC)
Marks Received
/33
/16
/16
/6
Achievement Level
Part A Multiple Choice (20 marks) (K/U) Using the test page provided, answer questions #120 on the SCANTRON CARD provided. Make NO MARKS on this test page.
Part B Modified True/False (5 marks) (K/U) Indicate whether the sentence or statement is true
or false. If false, change the italicized term or phrase to make the statement true in the space
provided.
1)
Nuclear medicine takes advantage of the properties of isotopes in order to construct
images that can be used in the diagnosis of disease __________________________
2)
Buffers often consist of a strong acid associated with a strong base.
___________weak acid and conjugate base_______________________
3)
The production of smaller molecules from a larger one, releasing energy in the
process is called a catabolic reaction.
______________________________________________________________
4)
During labour, the hypothalamus is considered to be the regulator/effector of the
feedback response . _____control centre___________________________
5)
Phospholipids are constructed by three fatty acids joining to glycogen.
______2 fatty acids and glycerol___________________________________
Part C Fill in the Blank (16 x ½ = 8 marks) (K/U)
6)
Amino acids are the building blocks for making __proteins_____________. There
are 20 amino acids in most organisms. 12 of these amino acids are termed ___nonessential____________ because the body can make these on its own. The other 8
amino acids are termed ___essential________________ since the organism must
rely upon these in their diet. The basic structure of an amino acid consists of two
functional groups, a __carboxyl__________ on one end and a __amino__________
on the other end. Amino acids differ in structure from one another in their ____Rside chain_________________. When amino acids are repeatedly added in a long
chain, a ___polypeptide_________________ is formed.
7)
Carbohydrates are the most common organic materials of Earth. They contain
hydrogen and oxygen in a _____2:1____________________ ratio. Carbohydrates
are classified into three groups. The monosaccharides are partly classified by the
number of carbons in their backbone. For example five-carbon sugars are called
_____pentoses____________________ while six-carbon sugars are called
_____hexoses____________________. When two or three monosaccharides join
together they are called ___oligosaccharides______________________. The bond
that links them together is called a(n) ___glycosidic______________________
linkage. When only two sugars bond together they are called a
___disaccharide______________________. When several hundred to several
thousand sugars link together they are called a(n)
__polysaccharide_______________________. These substances are important
either for energy storage such as ____glycogen/starch_____________________ or
structural support such as ______cellulose/chitin___________________.
SBI4U – Biochemistry
Part D Short Answer (16 marks) (C)
8)
Using the diagram, answer the following questions:
a) Fully name the macromolecule subclass that this molecule would belong
to. Also include the broad category of macromolecule this specific
structure would belong to. (eg. Nucleic acid – DNA). Explain the rationale
for your selections.
(3 marks)
Lipids – Steroids (Sterols)
Interlocking carbon rings; high H to O ratio
b) Name and circle two chemical groups found on the diagram above.
(2 marks)
ketone, methyl, and hydroxyl (from left to right on diagram)
c) Describe a function that this subclass of molecule would serve in a living
organism. (2 marks)
Hormone such as testosterone/estrogen that could influences sex characteristic changes; cholesterol - cell
membrane composition to maintain fluidity
9)
Name the family of macromolecules that the following molecules would belong
to, and then indicate their subclass. (4
marks)
a)
c)
___protein – amino acid___
b)
__protein – alpha helix__
d)
___carb - monosaccharide___
___lipid - triglyceride____
Using molecule d), demonstrate a reaction that would break this molecule into
its components. Show all chemical structures produced and be sure to NAME
ALL reactants used & products made. You may use the designation “R” to
represent hydrocarbon chains in the interest of time. (5 marks)
See classroom copy
SBI4U – Biochemistry
Part E Thinking and Inquiry (16 marks) (I) Answer the following questions on a sheet
of lined paper.
10)
State one similarity and one difference between the following: (4 marks)
a) hydrogen bond and covalent bond
Similarity – attractive forces, both involve attractions to other atoms
Difference – intermolecular (hydrogen) vs intramolecular (covalent), weak (hydrogen) vs stronger (covalent)
b) amylose and glycogen
Similarity – both polysaccharides or carbohydrates, both have 2H: 1O ratio, both used for energy storage
Difference – glycogen has branches and amylose does not, glycogen is animal starch and amylase is a plant
starch
11)
Clearly differentiate between negative and positive feedback. Explain why
negative feedback is more common/preferable in living organisms. (3 marks)
Negative feedback involves generating a response that negates/nullifies/counteracts the presence of a stimulus
bringing the parameter back within a narrow range. Positive feedback when the response acts to magnify the
presence of a stimulis. Many bodily processes can occur only within a narrow range (pH, temperature), so this is
critical for survival.
12)
A student investigated the action of saliva on a suspension of starch and on a
suspension of cellulose by setting up the following test tubes:
A)
B)
C)
D)
E)
2 mL of starch suspension
2 mL of cellulose suspension
2 mL of saliva
2 mL of starch suspension + 2 mL of saliva
2 mL of cellulose suspension + 2 mL of saliva
The pH of each test tube was 7.5. The test tubes were maintained in a
water bath at 37oC for 10 minutes. A Benedict’s test for simple sugars was
then carried out on the contents of each test tube.
Benedict’s solution is blue. In the presence of a simple sugar (mono- or
disaccharide), Benedict’s will turn a red colour.
The following observations were recorded:
Test Tube
A
B
C
Observation
Blue
Blue
Blue
D
E
Brick Red
Blue
I) Interpret the observations, making general conclusions about saliva’s
ability (2 marks)
Saliva can break down starch but not cellulose.
II) Explain why test tubes A, B, and C were set up? (2 marks)
They were set up as controls for a basis of comparison. They show that
Neither saliva or starch/cellulose on their own are capable of producing simple sugars. It shows that the result in
D and E is due to the enzyme and not something else
IV) Explain and compare the results of test tubes D and E. Refer to the
molecular structure of polysaccharides in your response. (3 marks)
Saliva possesses an enzyme called salivary amylase that can hydrolyze the starch into simple sugars.
Starches possess alpha glycosidic linkages while cellulose possess beta glycosidic linkages (and has every
other glucose flipped upside down)
Because of this cellulose polysaccharide chains can get very close to each other and can hydrogen bond,
humans don’t have an enzyme that can invade this structure. Starch, with its structure, tends to form a helical
structure that has space so that an enzyme can hydrolyze the linkage.
V) How does your answer in IV) impact how humans use these molecules
in their bodies? (2 marks)
Cellulose – used as roughage to scrape intestinal lining and pull out mucus – prevents constipation
Starch – can be used as an energy source
SBI4U – Biochemistry
Part F Making Connections (6 marks) (MC) Answer only TWO of the following on the
back of this test.
1. Imagine that polypeptide X is a key molecule involved with the formation of an
transport protein need to get glucose into the cells following a meal. By mistake,
the amino acid serine gets replaced by the amino acid leucine at one spot in the
amino acid sequence. Examine the structures below. Speculate as to what
effect this change could have on the protein’s operation. Be sure to connect
ideas to protein structure. (3 marks)
SERINE
LEUCINE
Serine is a polar amino acid and leucine is non-polar based upon their R-side chains. When a protein takes on its 3-D
shape, serine would H-bond in its tertiary structure or face towards the outside towards water (to H-bond). If replaced by
leucine, this amino acid is non-polar and therefore critical R- side chain interactions that maintain shape or stability of the
molecule might not occur. This could affect the ability of the molecule to do its function.
2. A molecule called “dopa” is used in the treatment of Parkinson’s disease. During
research, two chemical structures with the same formula and organization of
bonds are isolated. The only difference is at the asterisked group where the
molecule on the left has the group projecting out towards you, while the molecule
on the right has the group projecting away from you. Would there be any concern
with giving either one of these molecules to a patient? Explain. (3 marks)
Isolated forms of dopa
These two molecules are isomers and even though they have the same molecular formula, the small difference in
orientation of the bonds could make a difference with how bodily processes handle things. This is based on the idea that
structure determines functional characteristics. For example, we saw examples in class where the one isomer was
preferred by bodily processes to give desirable results while the other lead to defects (eg. Thalidomide)
3. You are a fish researcher studying a native species cell membrane from
Antarctica. How would you expect the membrane composition to be different
than species of fish near the equator? Explain. How would this adaptation help
the fish to survive? (3 marks)
Cell membranes are composed of a phospholipid bilayer. This membrane is kept in a fluid state by the presence of
unsaturated fatty acids. The double bonds create kinks maintaining space between the molecules to keep it fluid. In the
cold, molecules move closer together and this could lead to solidification (freezing). By having more unsaturated fatty
acids, this would help to keep the membrane in a fluid state allowing for better permeability of the membrane.
4. Imagine that Maria (or any other person) was admitted into hospital suffering from
acidosis of the blood. One treatment is to dissolve baking soda (NaHCO3) into
water and administer through an IV. Explain why this treatment is logical.
(3 marks)
Baking soda will dissolve and make bicarbonate ions in solution. These ions are conjugate bases of the normal blood
buffer system. These bases will neutralize the excess acidity bringing the pH back to normal.