Holiday Question Thread

[Russ]

Come find out how much you remember of the term 1 material!

Not all the questions are written by me, they all come from my collection of tutoring notes/material (I don't keep track of where stuff comes from). None are from VCAA exams.

Whilst doing these bear in mind that I usually work through them with students, prompting as required so some of them are kinda tricky or require information that you're probably not required to know. They're good for practice though! I don't have a lot of MCQs but those are easy anyway, so let's get some practice in on the hard stuff!

If you post an answer to a SAQ I will do my best to give it a mark and feedback but that basically depends on how up to date with my uni lecture schedule I am (I'm at -12 right now).

MCQs

1. A protein was found to contain 100 amino acids. How many peptide bonds are present in this protein?

A. 50
B. 100
C. 99
D. 101

2. A major function of the mitochondrial inner membrane is the conversion of energy from electrons to the stored energy of the phosphate bond in ATP. To accomplish this function, this membrane must have all of the following features except

A. proteins to accept electrons from NADH
B. the electron transport chain of proteins.
C. high permeability to protons
D. proton pumps embedded in the membrane

3. An organism with a cell wall would have the most difficulty performing which process?

A. osmosis
B. diffusion
C. active transport
D. facilitated diffusion 

4. Plant walls are comprised of cellulose, whilst the cell walls of fungi are comprised of:

A. chitin
B. glycogen
C. protein
D. lipid

SAQs

1. Aspartame is a common sweetener in diet soft drinks. Research has observed a significantly higher incidence of cancer in those who drink diet soft drinks as opposed to those who drink the regular variety. Is it reasonable to draw the conclusion "aspartame causes cancer"; suggest one reason why it is and one reason why it is not. (2 marks)

2. Name the four classes of biomacromolecule. Name one function of each. Briefly describe the structure of each. Give one example of each. (4 marks)

3. Read the following passage (source) and explain why lack of protein causes accumulation of fluid in this way. (2 marks)

Kwashiorkor is a dangerous and widespread form of childhood malnutrition caused when diets are excessively high in carbohydrates and low in protein. A lack of protein in her diet caused her to develop an abnormal accumulation of fluid beneath the skin of her legs, stomach, and face.

4. What could you conclude about the function of a cell if it possessed large amounts of mitochondria or a flagellum? Give an example of each. (2 marks)

[HERculina]

THANKS RUSS! 
Here are my answers to these q.s:

MC:
1.c
2.c
3.a
4.a

SA:
1. +  It is reasonable to conclude that Aspartame causes cancer because the given evidence shows that in the presence of this sweetener, the rates of cancer has increased
+ It is unreasonable to conclude that Aspartame causes cancer because this hypothesis is not experimentally proven as other factors may have resulted in cancer (eg. another ingredient in diet soft drinks)

2. Four classes of biomolecules:
Lipids:
Structure - Generally made of fatty acids chain(s) and a glycerol backbone.
A function - Makes up the plasma membrane
Example - Phospholipids

Proteins:
Structure - Polypeptide Chain(s) of amino acids folded into a precise 3-Dimensional shape
A function - Catalyses important biological reactions inside the cell
Example - Enzymes

Polysaccharides (Carbohydrates):
Structure - Monosaccharide sugar units, usually glucose, repetitively linked together by glycosidic bonds
A function - Stores immediate energy
Example - Starch

Nucleic acids:
Structure - A molecule made of one nitrogenous base, one negative phosphate group and one 5-carbon sugar
A function - Contains information needed to code for proteins
Example - DNA (Deoxyribonucleic acid)

3. + The proteins missing in her diet could have helped synthesise carrier proteins which are essential in transporting solutes from the extracellular environment to the cytosol of the cells. Without carrier proteins, fluid would have easily accumulated in the surrounding environment
+ Proteins could have provided the amino acids required to build different enzymes. Without catalytic enzymes, reactions maintaining the balance of fluids out of the cells would be too slow and would not have any effect at all

4. If a cell possessed large amount of mitochondria, the cell could be a liver cell producing large amounts of usable ATP energy for the body
If a cell possessed large amounts of flagellum, it could be a sperm actively moving around so it can eventually reach a woman's egg for fertilization to take place.

[WhoTookMyUsername]

SPOILER ALERT :



1. C
2. not sure on this one but it doesn't need to have C (as no membranes do)
3. also not 100% sure on this one, but the use of 'performing' suggests it is not passive - C
4. A

SA
1. Aspartame has been shown to have a direct link with cancer and therefore correlates and provides strong support for the possible causality. Various reasons for not inc. Scientists can only support not prove hypothesis, though there is a correlation, there is no definite link and the apparent correlation could be a result of numerous factors.

2. Lipids - Major component of cellular membranes.
Usually contain hydrophobic head and tail or hydrophilic head and hydrophobic tail.
Proteins - Reaction control - enzymes - ATP synthaze - Folded chain of amino acids, can take different structures and properties. Each amino acid contains a Central Carbon, a hydrogen, an amino group, a carboxyl group and a variable R group
Polysaccharide - Source of chemical energy storage within cells - Starch -  consists of a chain of monosaccharides folded in a variety of ways.
Nucleic Acids - Code for proteins - Dna - Constructed of nucleotides, each containing a phosphate group, a sugar and a nitrogenous base

3. Protein in diet is necessary for homeostasis and normal bodily function. The lack of proteins will mean a lack in the vital ability to carry out and regulate body functions through enzymes, hormones, structural components and other protein functions. This will render the child unable to satisfactorily regulate fluid accumulation and will thus be unable to prevent the buildup of these bodily fluids.

4. Large amounts of mitchondria would indicate a high energy requirement such as liver cells which require large amounts of energy to sustain reactions.
A flagellum would indicate motility as flagellum/flagella are often in present in free cells such as sperm or some bacteria.











Thanks Russ!

[shinny]

Re: both your answers so far for Q3, I assume Russ was looking for something far simpler. Tip regarding short answer questions for unit 3 is that they invariably come back only to a few separate princples; SA:V ratio, diffusion gradients and the stimulus-response model to name a few common ones. Basically I just made a checklist of them and whenever I was stuck, I would just go through the list and see what fits and could explain what's going on in the stimulus material.

[34590]

Did you write these questions?

The multiple Choice questions are great...

[HERculina]

hey russ, was the answer to MC Q.3 ?

[Russ]

3B
Cell wall is a barrier to influx of molecules but active transport and facilitated diffusion utilize particular channels that circumvent that problem. Osmosis is a specific subset of diffusion (as well as having some channels) so diffusion, in general, is affected the most.

For SAQ3, I was hoping for the answer that less protein in the body means that there will be less osmotic pressure holding the water within the capillaries. More movement of water out of the circulatory system into tissues will produce edema and the affects noted.

[HERculina]

oh ok thanks russ
but i still dont get question 3 of MC:
first of all, how is the cell wall a barrier when all cell walls are freely permeable.
and can you give an example of the particular channels active transport and facilitated diffusion use (are you talking about protein channels)
and because its a cell wall of AN ORGANISM I assumed it was some sort of unicellular organism (bacteria, fungi, a protist) - wouldn't they rely on diffusion of substances to obtain their nutrients
im a bit confused here :|

[WhoTookMyUsername]

For SAQ3, I was hoping for the answer that less protein in the body means that there will be less osmotic pressure holding the water within the capillaries. More movement of water out of the circulatory system into tissues will produce edema and the affects noted.

i don't understand this answer, are you saying the protein conc. affects osmotic gradients to this extreme effect?

[shinny]

For SAQ3, I was hoping for the answer that less protein in the body means that there will be less osmotic pressure holding the water within the capillaries. More movement of water out of the circulatory system into tissues will produce edema and the affects noted.

i don't understand this answer, are you saying the protein conc. affects osmotic gradients to this extreme effect?

Yep. It's simple diffusion principles. If the solute (in this case, dissolved proteins) decreases, the water will shift out of the blood and into the tissues.

[HERculina]

Ohhh i think i get that. so less proteins in diet = less proteins flowing around = high water conc. outside cells = water will flow into cells
BUT
i dont get how they causes accumulation of fluid (it seems like less accumulation to me)
AND
what is edema? 

[Kaille]

Protein is required in blood for keeping fluid in blood vessels. When fluid seeps of out of the blood to deliver nutrients to tissues, it relies on the solute concentration of the protein to draw it back into the blood vessels. The lack of protein in the diet does not provide this concentration gradient, therefore the fluid remains in the tissues, hence the accumulation of fluids in tissue.

[WhoTookMyUsername]

For SAQ3, I was hoping for the answer that less protein in the body means that there will be less osmotic pressure holding the water within the capillaries. More movement of water out of the circulatory system into tissues will produce edema and the affects noted.

i don't understand this answer, are you saying the protein conc. affects osmotic gradients to this extreme effect?

Yep. It's simple diffusion principles. If the solute (in this case, dissolved proteins) decreases, the water will shift out of the blood and into the tissues.

I would have thought their would be a lack of protein in the all cells of the body, therefore not effecting the overall osmotic gradient?

[Russ]

The osmotic gradient is between the capillary and connective tissue. Whilst there will be deficiencies in general, the circulatory system will be the most affected

what is edema?

The American spelling of oedema, which is an accumulation of fluid in tissue

e, VVVVVVVVVVVVVV
fine use specific names then

[shinny]

For SAQ3, I was hoping for the answer that less protein in the body means that there will be less osmotic pressure holding the water within the capillaries. More movement of water out of the circulatory system into tissues will produce edema and the affects noted.

i don't understand this answer, are you saying the protein conc. affects osmotic gradients to this extreme effect?

Yep. It's simple diffusion principles. If the solute (in this case, dissolved proteins) decreases, the water will shift out of the blood and into the tissues.

I would have thought their would be a lack of protein in the all cells of the body, therefore not effecting the overall osmotic gradient?

There's many proteins in the body, but at the end of the day, albumin, a protein found only in the blood is probably the only protein really worth considering in terms of calculating osmotic gradients. Albumin is essentially just a heavy-weight protein whose only job is to maintain these osmotic gradients.