AS Biology Question

[kratos009]

Hey everyone,
I got two Biology questions. They were from the May/ June 2007 Paper 1.

1. Membranous sacs containing products of metabolism are formed by the endoplasmic reticulum in cells.
   Where are these products used?
   A. inside and outside the cell
   B. inside lysosomes only
   C. inside the cells only
   D. Outside the cell only

 the answer was A. could you explain to me what they mean by products of metabolism, do they mean metabolic wastes such as CO2? And if that is what they meant how and why are they used inside and outside the cells?

2. This molecule is a polymer of reducing sugars.
Which of the following procedures could be carried out in order to test for the presence of the
reducing sugars in this molecule?
1 add hydrolytic enzyme and then heat with Benedict’s reagent
2 dissolve in water, neutralise and then heat with Benedict’s reagent
3 boil with ethanol and then heat with Benedict’s reagent
4 boil with hydrochloric acid, neutralise and then heat with Benedict’s reagent

A 1 and 2
B 1 and 4
C 1, 2 and 4
D 1, 2, 3 and 4

The answer is B. I was just wondering how and why is Hydrochloric acid used for the breakdown of polymers?

Thank you very much

[nid404]

For the first one metabolism could be synthesis of proteins and lipids and so on too.....in fact if u study function of cell organelles

Smooth Endoplasmic Reticulum (SER). Series of membrane channels involved in synthesising and transporting materials, mainly lipids, needed by the cell.

Rough Endoplasmic Reticulum (RER). Similar to the SER, but studded with numerous ribosomes, which give it its rough appearance. The ribosomes synthesise proteins, which are processed in the RER (e.g. by enzymatically modifying the polypeptide chain, or adding carbohydrates), before being exported from the cell via the Golgi Body.


So they are used both within the cell and outside


for the 2nd one......HCl hydrolysis the glycosidic bond.

[kratos009]

Thanks a lot for answering so quickly

Oh right I get the first one. So lipids are used in the cells for energy reserves, while the proteins are exported out of the cell to form other useful substances like antibodies etc.
For the second one how does HCl hydrolyse the glycosidic bond? Is it like dilute HCl acid which has aspects of water which hydrolyses the glycosidic bond while the HCl acid acts as a sort of a catalyst? Would it be alright if you could explain the mechanism of the hydrolysis or find a link that explains it if its not too much to ask. Thanks a lot.

I also got another question from that paper

In mammals, some carbon dioxide is transported by red blood cells in combination with
haemoglobin.
What is the product of this combination?
A carbamino-haemoglobin
B carbonic acid
C carboxyhaemoglobin
D haemoglobinic acid

the answer is A. I don't find the question very clear, so are they saying how is CO2 transported if it remains as just CO2 or if otherwise I was just wondering isn't most of the CO2 that is transported in the red blood cell in the form of carbonic acid as the CO2 reacts with the water and is stored in the red blood cell during the transportation until it reaches the lungs where the reaction is reversed to form CO2 again?

Thanks, I hope that made sense

[nid404]

the mechanism of hydrolysis....will have to look for summin

and they are askin what is the compound that forms when CO₂ combines with Hb........it's called carbamino-heamoglobin...like how O2 forms oxyhaemoglobin...


By the way ur concept of loading and unloadin doesn't seem clear.....I'll look for a video tutorial......ur under the wrong impression that Hb carried CO2 in the form of carbonate ion

[nid404]

check this   http://www.youtube.com/watch?v=Qrvrs6RXxwY&feature=related

&& http://www.youtube.com/watch?v=wLPgxfBqtOM

[kratos009]

Thanks a lot. I think i understand how it works now. I still don't understand the mechanism of the hydrolysis so I would really appreciate it if you could find a link.

[nid404]

I'm lookin for  video tutorial cuz it explains best

[kratos009]

Hey guys,

1. Which agricultural practice will not provide an alternative to the use of ammonium nitrate as a
fertiliser to increase the productivity of wheat?
A growing wheat and another cereal crop in the same field in alternate years
B wheat and another cereal crop in the same field in alternate years
C ploughing animal waste such as dung into the soil
D using synthetic urea as a fertiliser

the answer was A. These type of questions come up occasionally in Biology multi-choice questions. I don't really understand how growing wheat and beans in the same field in alternate years provides an alternative source of ammonium nitrate. And i also don't really understand what is the difference between growing wheat and another cereal crop in the same field in alternate years and wheat and another cereal crop in the same field in alternate years. Could someone explain to me why one provides an alternative source of ammonium while the other doesn't?

2. Which function can be carried out by a mature red blood cell?

A active transport
B cell division
C phagocytosis
D protein synthesis

The answer was A. i was wondering how does red blood cell do active transport wehn hardly any organelles are present with the red blood cell. Wouldn't the red blood cell require lots of energy and thus require lots of mitochondria to be present? And even if it does do active transport which material does it use active transport on?

3. Some soil-borne fungi cause wilting in crop plants by growing within the xylem vessels.
Which process will be directly affected by these fungi?

A conduction in the apoplast
B development of root pressure
C stomatal movement
D uptake of water by root hairs

The answer was A. What do they mean by conduction of the apoplast? I thought the apoplast way was when the water travels through the cell walls so how does the fungi growing within the xylem vessel affect this apoplast process? And i thought that answer B would make more sense because wouldn't the growth of the fungi increase the resistance against water movement, therefore affecting the hydrostatic pressure between the roots and the leaf, and therefore the movement of the water would be restricted?

Thanks a lot.

[nid404]

check the first question again....check f there's a typo....the A & B option are the same

for the second one yes the RBC can carry out active transport..most eukaryotic cells have sodium pumps......i think the sodium pumps are discussed later ahead...i don't know whether the syllabus asks for that funtion...

Apoplast is the pathway through cell wall...when fungi form in the xylem, the side walls will get obstructed...hence conduction through apoplast will suffer

[kratos009]

Oh right thanks i understand the second and third question now. Yeah sorry there was a typo it should be:

1. Which agricultural practice will not provide an alternative to the use of ammonium nitrate as a
fertiliser to increase the productivity of wheat?
A growing wheat and another cereal crop in the same field in alternate years
B growing wheat and beans in the same field in alternate years
C ploughing animal waste such as dung into the soil
D using synthetic urea as a fertiliser

the answer was A. These type of questions come up occasionally in Biology multi-choice questions. I don't really understand how growing wheat and beans in the same field in alternate years provides an alternative source of ammonium nitrate. And i also don't really understand what is the difference between growing wheat and another cereal crop in the same field in alternate years and wheat and another cereal crop in the same field in alternate years. Could someone explain to me why one provides an alternative source of ammonium while the other doesn't? Huh?

Some further Biology questions .

1. Which enzyme rejoins sections of DNA in genetic engineering?

A DNA ligase
B DNA polymerase
C restriction enzyme
D reverse transcriptase

The answer was A. I was just wondering what happens to DNA polymerase after it links the sugar-phosphate group of the activated nucleotide  to the original backbone of the DNA. I'm not exactly sure what DNA ligase is used for and how it rejoins the DNA, could someone explain, Thanks.

2. What is the main effect of heroin on the body?

A It affects metabolic processes in the liver.
B It causes over reaction in muscles.
C It mimics natural neurotransmitters.
D It stimulates reflex pathways through the spinal cord.

The answer was C. I don't think i've covered the effects of heroin in my syllabus. Could someone explain what it means by 'mimics natural neurotransmitters.' thanks a lot.

[kratos009]

Don't worry about answering these guys. I think I've figured out why the answers are what they are... .