OCR AS Biology (F211) - Jan 2013.

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All you need to know is that the chloride shift keeps the ph the same(as a buffer) during the point where carbonic acid(H2CO3) dissociates into H+(acidic) and HCO3(hydrogen carbonate), and then chloride moves out as H+ associates to Hb

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The haemoglobin is the buffer, forming haemoglobinic acid, not the chloride ions. The chloride keeps the charge the same.

Reply 1181

rachhhhhh

Original post by JamesNeedHelp2

Does anyone have the june 2012 f211 mark scheme? Thanks

Here's the mark scheme :smile:

F211_MS_June12-1.pdf122.6KB

Reply 1182

Tom_hess

Original post by Emmaaawhite

You have enough hypotheses to have a hypothesis kill-list, im impressed :wink:

Are you on Skype? Because it says you're offline :redface:

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Reply 1183

own

Original post by JamesNeedHelp2

Yh i need this too :smile:

Original post by rachhhhhh

Does anyone have a list of definitions of words/terms we will need to know?

Thanks

KEY DEFINITIONS (from text book)
-Magnification- The degree to which the size of an image is larger than the object itself. Numerically, it is the image size divided by the actual size of the object, measured by the same units.

-Resolution- Is the degree to which it is possible to distinguish between two objects that are very close together. The higher the resolution, the greater the detail you can see.

-Micrometre- Is equal to one millionth (10-6) of a metre. It is the standard unit for measuring cell dimensions.

-Nanometre- is 10-9 of a metre. It is a useful unit for measuring the size of organelles within cells and the size of large molecules.

-Staining- In microscopy refers to any process that helps to reveal or distinguish different features. In light microscopy, stains may be colour of fluorescent dyes. In electron microscopy they are metal particles or metal salts.

-Cytoskeleton- Refers to the network of protein fibres found within cells that give structure and shape to the cell, an also moves organelles around inside cells.

-Organelle- The term organelle refers to a particular structure of a cell that has a specialized function. Some organelles are membrane-bound others are not. All perform a particular role in the life processes of the cell.

-The phospholipid bilayer- is the basic structural component of plasma membranes. It contains of two layers of phospholipid molecules. Proteins are embedded in this layer.

-Fluid mosaic – refers to the model of the cell membrane structure. The lipid molecules give fluidity and proteins in the membrane give it a mosaic (patchwork) appearance. The molecules can move about.

-Cell signalling- Cells communicate with one another by signals. Many molecules act as signal – some signal during processes taking place inside cells; others signal from one cell to others. Cytokines are an example of cell signals.

-Diffusion- is the movement of molecules from a region of high concentration of that molecule to a region of lower concentration of that molecule down a concentration gradient.

-Active transport- refers to the movement of molecules or ions across membranes, which uses ATP to drive protein ‘pumps’ within the membrane.

-Solute- a substance that dissolves in a liquid.

-Solvent- a liquid that dissolves substances.

-Solution- a liquid containing dissolved substances.

-Cell cycle- describes the events that take place as one parent cell divides to produce two new daughter cells which then each grow to full size. For some unicellular organisms, this is called the life cycle.

-Mitosis- refers to the process of nuclear division where two genetically identical nuclei are formed from one parent cell nucleus.

-Clones- genetically identical cells or organisms derived from one parent.

-Differentiation- refers to the changer occurring in cells of a multicellular organism so that each different type of cell becomes specialised to perform a specific function.

-Tissue- A collection of similar cells that carry out a specific function.

-Organ- A collection of tissues that work together to carry out a specific function.

-Exchange surface- is a specialised area that is adapted to make it easier for molecules to cross from one side of the surface to the other.

-Gaseous exchange- Is the movement of gases by diffusion between an organism and its environment across a barrier such as the alveolus wall.

-Inspiration and Expiration- are the terms used to describe breathing in and breathing out.

-Transport- Is the movement of oxygen, nutrients, hormones, waste and heat around the body.

-Heart- is a muscular pump that creates pressure to propel the blood through the arteries and around the body.

-Cardiac cycle- is the sequence of events in one heartbeat.

-Sinoatrial node- SAN is the heart’s pacemaker. It is a small patch of tissue that sends out waves of electrical excitation at regular intervals to initiate contractions.

-Purkyne tissue- is specially adapted muscle fibres that conduct the wave of excitation from the AVN down the septum to the ventricles.

-Open circulatory system- the blood is not always kept in vessels.

-Closed circulatory system – the blood always remains within vessels.

-Blood- is held in the heart and blood vessels.

-Tissues fluid- bathes the cells of individual tissues.

-Lymph- is held within the lymphatic system.

-Bohr effect- refers to a change in shape of the oxyhaemoglobin curve when carbon dioxide is present- this causes the oxyhaemoglobin to release oxygen more readily.

-Xylem- transports water up the plant.

-Phloem- transports sugars and other assimilates up and down the plant.

-Water potential- is the total potential energy of the water molecules in a
system. It is a measure of how likely it is that water will be lost from the system by diffusion down its water potential gradient.

-Cohesion- is the attraction of water molecules for one another.

-Adhesion- is the attraction of water molecules to the walls of the xylem.

-Symplast pathway- Moves water through the cell cytoplasm.

-Apoplast pathway- Moves water through the cell walls and between cells.

-Transpiration- is the loss of water by evaporation from the aerial parts of a plant.

-Xerophyte- is a plant that is adapted to reduce water loss so that it can survive in very dry conditions.

-Translocation- is the transport of assimilates through the plant, in the phloem tissue.

-Source- releases sucrose into the phloem.

-Sink- removes sucrose from the phloem.

There may be spelling mistakes or other as i tend to type quite quickly but anyway these are the ones in the key definitions boxes in the book (roughly) :smile:

It may be an idea to look through the specification as well just for a double check, because homologous pair came up but that is not in the definitions.
Hope it helps!

(edited 11 years ago)

Reply 1184

rachhhhhh

Original post by own

I have a list of all the 'key definitions' boxes from the book, if you want that? :smile:

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Yes please, that would be great!

Reply 1185

Tom_hess

Original post by JamesNeedHelp2

To be fair, those 'respectable' scientists where once students too.

Yeah, it becomes a chicken and egg argument, how did they become respected if nobody trusted their hypotheses? :redface:

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Reply 1186

Dugald

I don't know about anyone else, but I feel pretty confident for this exam now. There is not really anything on the specification that I don't know. I'm not sure what to do with myself because I should be frantically revising but I feel like I have already got it all covered. Anyone else the same?

Reply 1187

Tom_hess

Original post by Dugald

Yeah, the only part I don't remember is when they ask "what is the diameter of a prokaryotic ribosome" and sizes which you have to learn by heart:s

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Reply 1188

Yasmine Cherfi

Original post by Tom_hess

Yeah, the only part I don't remember is when they ask "what is the diameter of a prokaryotic ribosome" and sizes which you have to learn by heart:s

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Prokaryotic ribosome??

Reply 1189

own

Original post by rachhhhhh

Yes please, that would be great!

Yeah its above ^^^^ post, its quite obvious :smile:

Reply 1190

SuperMushroom

Original post by Yasmine Cherfi

Prokaryotic ribosome??

The ribosomes in Prokaryotes are much smaller than the ones in Eukaryotes,
Hence they might ask for length which i think is 0.5NM dont count me on that tho :biggrin:

Reply 1191

rachhhhhh

Original post by own

Yeah its above ^^^^ post, its quite obvious :smile:

Haha yeah I noticed, thank you so much! :smile:

Reply 1192

Tom_hess

Original post by SuperMushroom

The ribosomes in Prokaryotes are much smaller than the ones in Eukaryotes,
Hence they might ask for length which i think is 0.5NM dont count me on that tho :biggrin:

Yeah, I did this in a past paper, they give you quite a bit of leeway, for example, they asked for a eukaryotic ribosome, it's about .20 nm? And I said 10, they allowed between .7-.40nm!

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Reply 1193

SuperMushroom

Original post by Tom_hess

I dont think much on Cells will come up on this test,
Considering it was a huge question on it in the june 2012 exam :smile:

Reply 1194

Tom_hess

Original post by SuperMushroom

I dont think much on Cells will come up on this test,
Considering it was a huge question on it in the june 2012 exam :smile:

I'm a wizard at protein synthesis, I hope that comes up in maybe a 6 mark question? *dribbles* xD

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Reply 1195

SuperMushroom

Original post by Tom_hess

I'm a wizard at protein synthesis, I hope that comes up in maybe a 6 mark question? *dribbles* xD

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If that comes up i will also be very happy!
Such easy marks, i think i will lose marks on things such as explaining trends in tables, stuff like that.

Just hoping i get an A in this test! :smile:

Reply 1196

t()m

Can some one please explain the lymphatic system and what would actually be asked and the answer..?

Also can some one give model answer for Bohr shift and fetal haemaglobin questions ?

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Reply 1197

t()m

Also just thinking this might be helpful.

Reliability : replicate for repeat

Accuracy: use smaller measurements (increments) on devises

Validity: can't remember of top of head is a list in book ...

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