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OCR F211/F212 AS Biology Retake 2016

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it asked how RNA was used in the production of viral proteins.

i think you just had to talk about transcription

Yeah but virus are not living organisms and have no DNA for transcription to occur. It cannot replicate without the host as it cannot mske its own proteins I think. Our teacher suggested it was overlapping A2 content because she was surprised to see that in?

Reply 741

milutin767

What did you say about lily for 1 mark? The one about not being in its original habitat? I sad climate change in central africa, too hot so the mud is dry
something like that

Reply 742

milutin767

Can't be overlapping A2 content but I'm sure you'd get credit for mentioning reverse transcriptase but you don't need that
just mentioning transcription and the host/virus from the question stem

Reply 743

badhand45

Original post by milutin767

Can't be overlapping A2 content but I'm sure you'd get credit for mentioning reverse transcriptase but you don't need that
just mentioning transcription and the host/virus from the question

But because virus dont have ribosomes they can't do protein synthesis. Ah well maybe because it was a suggest question you didn't need to know thst. But because most people doing it have done A2 and our teacher whos an examiner said she wouldn't be surprised if there was synoptic links. But you know what ocr are like hahq

Reply 744

CurleysWife

Original post by badhand45

The virus uses the organelles and enzymes in the host's cells to produce new copies of itself. Suggest the role of the viral RNA in the production of viral proteins.

That was the question.

Reply 745

badhand45

Original post by CurleysWife

The virus uses the organelles and enzymes in the host's cells to produce new copies of itself. Suggest the role of the viral RNA in the production of viral proteins.

That was the question.

I wrote "RNA converted to DNA by reverse transcriptase, this converted DNA is used in protein synthesis and therfore transcribes the viral proteins" something alomg those lines

Reply 746

CurleysWife

Original post by badhand45

I wrote "RNA converted to DNA by reverse transcriptase, this converted DNA is used in protein synthesis and therfore transcribes the viral proteins" something alomg those lines

You'll probably get an alternative answer mark because that information is A2, which is not on the AS spec and technically we aren't meant to know that yet.

Reply 747

CurleysWife

THIS IS JUST WHAT I THOUGHT THE ANSWERS WERE, FEEL FREE TO EDIT/ADD ANY WRONG OR ALTERNATIVE ANSWERS.

1a)
i) X = C, Y = O, Z = hydroxyl group
ii) Draw beta glucose iii) Bond: 1,4-glycosidic bond ; disaccharide: maltose
1b) Glycogen is an animal energy storage polysaccharide made up of alpha glucose joined together by 1,4-glycosidic bonds. It has branches due to 1,6-glycosidic bonds which allow hydrolysis at many branches for a faster rate of break down of glycogen into glucose for respiration. It is insoluble in water as it cannot form hydrogen bonds with water, and therefore does not affect the water potential of cells, can therefore be stored in cells easily.
1c) beta pleated sheets, hydrogen, tertiary, chains, quaternary
2a) active artificial
2b)
i) Viral mRNA uses host cells ribosomes to carry out transcription to produce viral proteins, process also uses tRNA.
ii) Mutation in RNA causes a change to nucleotide base sequence, which causes different amino acids to be coded for, changing primary structure. Different primary structure causes coiling and folding at different parts of secondary structure as hydrogen bonds are formed differently. This therefore affects the tertiary structure of the protein, as bonds are formed differently (disulfide bonds, covalent bonds etc).
iii) Less teachers taking sick leave and therefore won't be paid when not working.
2c) lower, higher longer, shorter
2d) T-killer cells: locate and destroy infected cells by releasing hydrogen peroxide into them. T-helper cells: release cytokines to attract B-lymphocytes T-memory cells: remain in the blood to provide immunological memory, and will divide into T-helper cells and T-killer cells upon repeat infection.
3a)
i) Add copper sulfate to solution, positive result will cause colour change from pale blue to lilac.
ii) (NOT SURE ON THIS)
3b) (NOT SURE ON ANY OF THIS)
3c) These are examples of coenzymes and cofactors. They bind to the active site of the enzyme before the substrate binds. They link together series of enzyme-catalysed reactions. Examples include coenzyme A, NAD, FAD. (Not sure how to get 5 marks).
4a) Organism survives on damp soil, however due to climate change the soil has dried out and therefore the organism cannot grow here.
4b)
i) 1: genetic diversity, 2: habitat diversity
ii) allows us to develop medicines for human illnesses.
iii) Plant diversity means that the crops will be more able to survive changes within the environment, whereas monocultures are unlikely to be able to survive these changes. Therefore, if there are any changes within the environment, then they will only lose some produce rather than all of their produce with a monoculture.
4c) Use a stratified sample using a continuous belt transect. The environmental gradient would be from damp soil to dry soil (gradual change). Count all of the lilies in each quadrat and plot the number onto a graph which shows change in population against change in moisture. Repeat this experiment twice in order to increase reliability of findings.
4d)
i) CITES
ii) Rio convention
4e) Continuous variation describes the quantitative differences between organisms. There are very many intermediates between two extremes and there are no clearly distinguishable categories. Size of this organism is an example of this because it is a quantitative measurement with very many intermediates between two extremes.
5)
- Tar enters lines and settles on the walls of the airways and alveoli, increasing diffusion distance for oxygen to enter the blood and for carbon dioxide to leave. - Tar stimulates goblet cells to become enlarged and secrete excess mucus.
- Tar paralyses and destroys cilia, meaning that mucus cannot be wafted away, causing a buildup of mucus in the airways and lungs.
- Mucus containing trapped pathogens is not swept away, and pathogens divide within mucus. Presence of pathogens means lungs are more susceptible to infections.
- Tar contains carcinogens such as benzopyrene which enters the nucleus of cells and causes a mutation in the DNA. This leads to uncontrollable mitosis and causes a mass of cells to be produced called a tumour. This is known as lung cancer.
6a)
i) Fungi
ii) Does it have autotrophic nutrition?
iii) Does it have fertilised eggs that develop into blastula?
6b)
i) Phylum, class, order, family
ii) Slime moulds more closely related to plants and fungi. Evidence of classification may be that it has saprophytic nutrition, cell walls made of cellulose/chitin. Multinucleate cytoplasm.
iii) (NOT SURE ON THIS).
7a) Draw alanine.
7b)
i) Saturated fats are used in synthesis of LDLs (protein, cholesterol, saturated fats). LDLs decrease activity of receptors on liver, therefore less cholesterol taken up from blood into liver.
ii) Increased blood cholesterol causes deposition on artery walls and damages the walls. Specialised phagocytes called monocytes repair damage, which causes growth of smooth muscle and deposition of fatty materials onto artery wall. This leads to formation of a plaque, which develops into an atheroma. This decreases width of artery lumen, increasing hydrostatic pressure of blood. This is atherosclerosis.
7c) It is a competitive inhibitor for enzymes that break down fats in the small intestines.
8a) Concentration.
8b + c) Unsure on these... I thought the statements were correct lol.
8d) Freezing retards bacterial enzymes and slows down reproduction rate of bacteria. This means that extracellular digestion cannot occur/occurs at a much slower rate and therefore food can be stored for a much longer period of time without becoming spoilt.

Reply 748

EllieO

Original post by sabahk

What was the answer to that animal kingdom taxonomic level question? And mechanism that stops fat breakdown ...last question?

One of my teachers thinks you had to talk about competitive inhibitors, like oristol(spell?) acts as an inhibitor for lipase which breaks down fats, but I wrote some bs about removing water!

And I have no clue about the one that was like why is the 3 domain classification favour above the 5 kingdoms method of classification!

Reply 749

badhand45

Do you think if you wrote carbon and oxygen for the first question you would lose marks? I know in some of the mark schemes it will only allow the atomic symbol?

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Reply 750

GetOverHere

Original post by badhand45

Do you think if you wrote carbon and oxygen for the first question you would lose marks? I know in some of the mark schemes it will only allow the atomic symbol?

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I think because it gave you a displayed formula and told you to fill in the gap, you were obliged to give the chemical symbol as opposed to the name. However I'm sure it'd be fine, though surely it's easier to put a C or an O rather than carbon and oxygen

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Reply 751

badhand45

Original post by GetOverHere

Because in some questions it specifically says chemical symbol. Whereas that one just said name the atom or group. So im not sure what it wanted specifically

Reply 752

GetOverHere

Original post by badhand45

Because in some questions it specifically says chemical symbol. Whereas that one just said name the atom or group. So im not sure what it wanted specifically

Well, I would've thought the chemical symbol would be more appropriate seeing as X, Y and Z were placeholders for carbon, oxygen and hydrogen in a displayed formula.

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Reply 753

badhand45

Original post by GetOverHere

Well, I would've thought the chemical symbol would be more appropriate seeing as X, Y and Z were placeholders for carbon, oxygen and hydrogen in a displayed formula.

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Well thats what I thought. But said name the atom or atom group. But as it didn't really specify which one it wanted. Least id get one mark for saying OH (hydroxyl) haha

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Reply 754

laksi

any prediction for f214 and f215 ?

Reply 755

laksi

got this prediction from student room what do you think ?
F214:
Excretion
- ornithine cycle
- (possibly) cause of respiratory acidosis
- detoxification
- selective reabsorbtion

Photosynthesis
- experiments (most likely an application question)

Communication
- maintaining a resting potential
- local currents
- myelination (benefits)
- adrenaline (use of first and second messengers)
- control of heart rate

Respiration
- coenzymes (used where)
- oxidative phosphorylation & evidence for
- anaerobic respiration
- respiratory substrates

Reply 756

rsmith1234

will the grade boundary for f212 be crazy high this year??