This discussion is now closed.

Check out other Related discussions

A2 OCR Practical Biology

Im guessing the other thread has been taken down so im gonna start a new thread, buh lets be a bit more careful this time!

can someone just post a list of things to learn in GENERAL nothing too specific, and explain to me how to draw a plan diagram????? i need microscope help!

xxxxx

Reply 1

daisy_chain

Generally just respiration and photosynthesis for the first section (there have been loads of questions to do with yeast in past papers). Also make sure you know all the tests for starch, reducing and non reducing sugars etc.

For the microscope work i would revise things like the kidneys, pancreas, and plant tissues. Rules for microscope diagrams are to only draw about three cells, fairly large, with clear pencil lines (not sketchy), don't shade, and label clearly.

I'm just going by what i've seen on past papers for what to revise, so if anyone else can think of something i havent mentioned then please post it. Hope that helped :smile:

Reply 2

Jack_1707

independent variable in 1st column, dependent in second and rate in third

i would revise respiration and homeostasis as that seems to be the trend in past exams

(edited 3 years ago)

Reply 3

Ehmo

Same as above, except it's blates not the kidneys, that's come up the last two times.

Reply 4

Silent-Star

Mass panic, only now got chance to revise for this exam! Had courswork and other exams. Panicing loads!
anyone got a kinda list of what sort of things to learn?
scared!

Reply 5

Jack_1707

only if it tells you to do so
but i doubt it will as of the time constraints
for an improvemnent to the experiment mention the need to do repeats

(edited 3 years ago)

Reply 6

Jack_1707

Silent-Star

Mass panic, only now got chance to revise for this exam! Had courswork and other exams. Panicing loads!
anyone got a kinda list of what sort of things to learn?
scared!

its a practical exam and so revision isnt that necessary
just remind yorself of central concepts eg repiration/homeostasis etc.

Reply 7

Silent-Star

Jack_1707

its a practical exam and so revision isnt that necessary
just remind yorself of central concepts eg repiration/homeostasis etc.

I hope you're right :biggrin:

ty anyway!

Reply 8

jennifer.re

Everyone seems to be freaking out so here's some revision for you all. I'll start with Enzymes, since my teacher said that if you go into the exam not knowing them inside out then you are stupid. :smile:

Enzymes
Enzymes are 'biological catalysts' as they speed up chemical reactions. The shape of the active site allows the substrate to fit perfectly. The enzyme has a specific shape and structure, and is unchanged by the process.

Activiation Energy
Many reactions require an initial amount of energy. However, when a substrate binds to the active site its shape slightly changes, so the activation energy needed is lower. Therefore some reactions can take place at lower temperatures, as there is little need to gain energy from higher temperatures.

Effects Upon Rate
Substrate concentration - Higher concentration means a higher rate, until the maximum possible rate is reached. This is called Vmax.
Temperature - Lower temperature means a lower rate. As temperature increases, so does rate until a certain point. At these very high temperatures the enzyme is vibrating fast due to the high levels of kinetic energy converted from the heat energy. The enzyme vibrates so much that their bonds break, causing it to denature. Enzymes within the human body work best at body temperature, 37'C.
pH - Most enzymes work best in fairly neutral conditions (pH 7). However, some enzymes have other optimum pHs, such as protease pepsin, which is found in the stomach. As it works in acidic conditions it has a very low optimum pH.

Inhibitors
Competitive Reversible - Attaches briefly to active site, preventing the substrate from doing so. Can be reversed.
Non-Competitive Reversible - Briefly attaches to a different part of the enzyme, causing it to change shape and distorting its active site. Therefore the substrate can not bind to the enzyme. Can be reversed.
Non-Competitive Irreversible - As above, the inhibitor attaches to a part of the enzyme, distorting the active site. However, this is a permanent effect.
Competitive Irreversible - The inhibitor binds to the active site of the enzyme permenantly.

If anyone has any corrections, additions or suggestions then fire away. Also if anyone has any preference on what I cover next, leave a comment. :smile:

Reply 9

logic123

i reckon it will be on the kidney tommorow not enzymes tbh, they have came up to often.,

Reply 10

Swayum

I would like to reiterate what the OP said: don't get specific, particularly with teachers' comments/predictions.

Here's some advice:

Go through the past mark schemes and memorise the generic points. For all the 5 or 8 mark questions, they ALWAYS accept 3 generic points that come up every single year, so you can score those without any work. For example, if asked how to improve the experiment, instantly just write down more trials and you'll get a mark. There are others like that.

Don't worry about the results too much, if you mess up, just ask for them. Most of the marks go out for drawing your table right - remember to put the independent variable on the left, units at the top and not in every cell, same number of decimal places, neatness etc and you'll already have most of the marks.

Good luck :smile:

Reply 11

samburke

the post above is correct, look through the mark schemes, jan 07 for example.. you get 7 marks or so for a table with labels, titles and units... and the drawing side of things you get a mark for using continuous lines, a mark for no shading and for each label you get a mark for a description.

I think that biological molecules might be a good bet, especially carbohydrates.

Reply 12

sausagewallet

has anyone got a cheeky link to any past papers/mark schemes that i can have a look at i've lost the ones that were given to me.

Reply 13

jennifer.re

logic123

i reckon it will be on the kidney tommorow not enzymes tbh, they have came up to often.,

Kidney has come up for the past two years.

Reply 14

ibbstertrickster

I reckon, pure speculation that it'll be on respiration and pancreas. Yeah, just revise all the standard improvement etc stuff.. and revise:
Photosynethsies, respiration... in relation to enzymes

and Have a look at the pancreas.. islets of langerhans (alpha, beta) and exocrine.

Maybe have a look at meiosis too.