IGCSE EDEXCEL BIOLOGY PAPER 1 12TTH MAY...are you ready?!

i hate bio so i'm not 100% confident but hopefully i'll be ok. How are the rest of you feeling about it?

if there are questions related to genes i will tear the paper!!!!!

haha yeah i like genes. I hate kidneys and anything to do with plants though!

how can you like genes? it sucks! and kidney is really awesome. i love that chapter related to nephrons but plants suck!

Any predictions about what you think will be on it?

i get the dominant resessive allele stuff but i had to self teach myself most of it but evolution, natural selection and genetic modification are quite hard for me. I cant stand kidneys because of how confusing they are!

what dont you understand about these topics? you just have to remember the key words for each process. i will write down an answer that would get 6 marks for these processes and hopefully you can learn from them. memorise them and regurgitate them in the exam if they come up and thats a free 6 marks.

2.75 Describe the role of ADH in regulating the water content of the blood

If a person is sweating or hasn’t drunk enough water, the pituitary gland in the hypothalamus detects the lack of water, stimulating it to release anti-diuretic hormone (ADH) which is carried to the kidneys via the blood stream. ADH increases the permeability of the collecting duct so water is selectively reabsorbed back into the blood. The urine produced is then more concentrated and has a lower volume- this prevents dehydration.

3.30 Describe the process of evolution by means of natural selection

Evolution is the formation of a new species from an original species. At first there is genetic variation. A mutation will occur in one of the animals. There will be competition for resources (e.g. mates/food), the animal with the beneficial mutation will survive because it has a select advantage. It then mates and reproduces and the offspring will have the characteristic as genes are inherited. These offspring will also have better chance of survival so they live longer and reproduce more. The process continues (evolution) and over a long period of time the mutation becomes a common gene in a species because those without it cannot compete and go extinct- this is survival of the fittest.

5.12 Describe the use of restriction enzymes to cut DNA at specific sites and ligase enzymes to join pieces of DNA together/5.13 Describe how plasmids and viruses can act as vectors, which take up pieces of DNA, then insert this recombinant DNA into other cells

Restriction enzymes are used to cut DNA sequences at specific sites in the DNA to be inserted and the vector DNA. Ligase enzymes join the two pieces of together to produce a recombinant DNA. A plasmid or virus is used as a vector to insert the recombinant DNA in other cells.

I've got this exam tmrw too! if anything I pray this exam paper isnt like the January 2015 one, as that was A LOT harder than the past few years!!

I haven't seen the jan 2015 paper :O

But I'm about as prepared as I'm going to be at this point in time.
Good luck everyone!

I just have pre-exam nerves because biology is my first one, but i'm as ready as i'll ever be. I'm dreading the cormmss questions though... :/

Still haven't revised reproductive cycle, brain or the water cycle/nitrogen cycle or temperature regulation, is this possible to do before tomorrow i am freaking out