Edexcel IGCSE Biology Paper 3 26th May 2010?

How did it go for you guys?

The question on the limpets was annoying...but the rest was pretty easy...I think! :s-smilie:

Scroll to see replies

Reply 1

Worrier12345

Yeah, I thought it was alright. :smile:

Do you know that question on the last page (I think) which asked to describe and explain how the relationship between the number of bubbles and light intensity? Did you write about enzymes being denatured?

Reply 2

polarbears1

it was good! just the day before we had done a past paper with many of those questions!
what was the question on light intensity? ive forgotten already! :rolleyes:

Reply 3

Worrier12345

igohardondis

no thats more temprature

light intensity affects width of stomata allowing more gas through so more bubblez

Yeah, I know but at a higher light intensity, the plant's rate of transpiration was slower than at a medium light intensity. So the higher light intensity had somehow managed to decrease the rate of transpiration...

Reply 4

Hellz_Bellz!

I can't actuall remember the light intensity question? xD

What did you guys write for the limpet experiment? I wrote about using a quadrat but i doubt thats right =/

Reply 5

polarbears1

Hellz_Bellz!

I can't actuall remember the light intensity question? xD

What did you guys write for the limpet experiment? I wrote about using a quadrat but i doubt thats right =/

I also wrote about using a quadrat and when i checked in a biology book it seemed right! :smile:

I can't remember the light intensity one either, anyone help? :s-smilie:

Reply 6

Hellz_Bellz!

I don't think there are enough books provided for the iGCSEs - especially the sciences. I did the Physics last year and had to take like 20 books out of the library in order to learn all the stuff from the syllabus.

Weird thing is...I got an A* o_o I thought I was gonna get a D!

What do you guys thing you're gonna get on the Biology iGCSE?!!

Reply 7

username459260

Hellz_Bellz!

I can't actuall remember the light intensity question? xD

What did you guys write for the limpet experiment? I wrote about using a quadrat but i doubt thats right =/

I don't think quadrat is correct - quadrat's are used to measure the number of organisms in a certain area - BUT the area of rock is unlikley to be bigger than 1m by 1m and thats probably what a quadrat would measure - even if it is bigger, it would be MORE accurate to count the number of limpets - after all they are not tiny - they can be seen easily - it would not take along time to count this.

however, i would presume both methods would get the marks

oh and by the way - quadrats would measure even surfaces - rocks dont have an even surface area

What do you guys think?

Reply 8

Hellz_Bellz!

You could be right, but the fact is I stated a way of counting the average number of limpets on rock so I should get the points! If not, the examiners are bastards! =P

Reply 9

username459260

Hellz_Bellz!

You could be right, but the fact is I stated a way of counting the average number of limpets on rock so I should get the points! If not, the examiners are bastards! =P

True, but if you stated an incorrect, unreliable method, how could they give you the marks?

Reply 10

otrivine

for the limpet question i put that first you should collect some limpets in the beach and then i wrote that they should be the same so that the experiment can be a fair test. After that, i put you could use a big ruler to see if the distance of the sea affects the limpets. After that i put that the experiment must be repeated of a mimimum of 3 times SO THAT THE RESULTS ARE RELIABLE. i put that you can collect a data and then from the results you can draw a gragh to see if the distance of the beach affects the limpets.

i hope thats right!

Reply 11

otrivine

i said that the distance should be 5cm- 10cm around that values

Reply 12

otrivine

can you please tell me if this is right? :smile:

thank you

Reply 13

badboyharris1

for the limpet question u definately needed a question. Drawing a graph will not get u any marks otrivine!!

Biology experiment design questions are marked in this way

C - concentration, how many quatrats and limpets
O- origin, where u have placed the quadrats
R - reliability, repeat the experiment
M -mesurement , how are ur mesuring it, counting, weighing??
S - standard - making the trials the same etc..

(5 Marks) EASY

Reply 14

otrivine

hello but you cannot really use a qudrant becuase thats for meausring grass to see how many plants there are but you have to use a for dfferent distances and from there you can see if it affects the population of limpets and from that information you can draw a graph and you have to repeat the experiment of a minimum of three times for the experiment to be reliable bobby¬!!!!!! im sure we are both right

Reply 15

Cappuccinoes

otrivine

hello but you cannot really use a qudrant becuase thats for meausring grass to see how many plants there

That’s not right. Quadrats aren't just for use on grass and you can use them to investigate the number of many different organisms in an area, not just plants. The organisms, however, must not be moving quickly otherwise it would be very difficult to count the number of organisms within the quadrat accurately. If you've ever seen limpets, you'll know they stick to rocks and usually stay there for a long time, so in this case you could use a quadrat.

More importantly though, why on earth did you write this?

otrivine

for the limpet question i put that first you should collect some limpets in the beach

The question asked us to design an experiment that would investigate the number of limpets on rocks which were different distances away from the sea. If you simply said "the beach", then you've investigated the wrong habitat.

Reply 16

otrivine

noo im sure i will get some marks for it because there are many ways of doing it and also beach and sea means the same thing !!! also, you cant really use quadrants as they only measure how many plants are in a place by counting them . There are many ways of doing this experiment!!

Reply 17

Cappuccinoes

otrivine

Again, quadrats are not only for counting plants. It says so in the first paragraph about quadrats on Wikipedia if you don't believe me: "A quadrat is a square (of either metal, wood, or plastic) used in ecology to isolate a sample, usually about 1m2 or 0.25m2. The quadrat is suitable for sampling plants, slow-moving animals (such as millipedes and other insects), and some aquatic organisms."

"Beach" and "sea" do not mean the same thing. The sea is the water and the beach is the name for a shoreline with sand, pebbles or stones. But that's irrelevant. The question asked us how we might investigate the population sizes of limpets on rocks. By saying "collect limpets in a beach" you've tested the wrong habitat :frown:

Reply 18

otrivine

but will i get some maRKS for it as i put repeating the experiment like that and other things will i get the marks . thank you for your help!

Reply 19

otrivine

thank you for your help and can i ask you will i get some marks becuase i put repeating experiment you can then collect data e.t.c i hope i will get marks at least 4 . thanks again and can i ask what do you think the percentage is to get an A* for both of the paPERS?