We are currently struggling to cover the operational costs of Xtremepapers, as a result we might have to shut this website down. Please donate if we have helped you and help make a difference in other students' lives!
Click here to Donate Now (View Announcement)
check youtube/google and use your syllabus to find the most relevant video/notes, there were few links i posted regarding biology tutorials either in this thread or anotherCan someone help me with serial sample and series dilution. Please provide me the step by step procedure for doing this
hmm well okacheck youtube/google and use your syllabus to find the most relevant video/notes, there were few links i posted regarding biology tutorials either in this thread or another
The first question states that the magnification used is 400x. Which is very low to be able to see any cell contents except the nucleus.Guys new here but I have this question that has REALLY bugged me. It's from Summer 2010, Question Paper 11, Question 2. The answer is C, and the examiner report
says,
"The relative difficulty of this item was due to many candidates failing to appreciate that animal cells are very
difficult to see clearly using a light microscope and that the organelles are far too small to see."
But it makes no sense to me since we learn that light microscopes CAN distinguish organelles larger than 0.2 micrometers or 200 nanometers, and organelles like mitochondria, lysosomes, etc. (Searching on google "size of cell organelles" and following the first link can show that.) Can someone care to explain? Or did CIE mess up here (which is what I think happened)? Thank you.
EDIT:
Just saw another question in summer 2012, which was:
A microscope has a resolution of 200 nm. Which of the following organelles would not be
resolved using this microscope?
A chloroplasts
B lysosomes
C mitochondria
D ribosomes
The answer is of course D, but this imples that A B and C all CAN be resolved using a light microscope, which seems to contradict the answer in the question I'm confused about. Any input would be appreciated.
The first question states that the magnification used is 400x. Which is very low to be able to see any cell contents except the nucleus.
In the second question you have "resolution" given, 200nm resolution means that anything with size smaller than 200nm will not be seen. In this case it is only the ribosomes which have an average 25nm diameter
I think that section was removedare details of IVF in the syllabus? I found long questions on it in past papers but the detail is not mentioned in our books... is it out? Its not mentioned in the syllabus like it was before....but its not mentioned in the "Out of syllabus" content at the end of the syllabus.
In interphase obviously no appearance as chromatids as chromatin not yet coiled up and not yet shorter and thicker.Interphase has 886 number of cells , prophase has 73 number of cells , metaphase has 16 number of cells , anaphase has 14 number of cells and telophase has 11 number of cells . What percentage of cells contain chromosomes that appears as two chromatids ? ANS:8.9%. Anyone can explain how to do ?
oh ok thxIn interphase obviously no appearance as chromatids as chromatin not yet coiled up and not yet shorter and thicker.
In anaphase, centromeres have replicated, chromatid pairs no loger exist.
In prophase and metaphase only are the chromatids seen in pairs.
So 73+16/1000=8.9
Someone answer him. I have the same queryin P5, is method of serial/ any dilution as written in marking schemes enough? or do we have to write in detail, the entire method??
i'm giving 34. But leaving it open is what i was taught..Have my 33 practical tomorrow. All seems set except one confusion. When making plan diagrams, what do I do at the "boundary" of the image I'm drawing? I'm referring to situations where they ask us to make the bottom 1/4 of an image for example. That would be a perfect rectangle or a square so should there be an external boundary within which I make the diagram? Or in cases like the attached picture. When drawing the plan diagram, do I seal the edges or leave it open? I'm referring to the highlighted top right area. Thank you.
For almost 10 years, the site XtremePapers has been trying very hard to serve its users.
However, we are now struggling to cover its operational costs due to unforeseen circumstances. If we helped you in any way, kindly contribute and be the part of this effort. No act of kindness, no matter how small, is ever wasted.
Click here to Donate Now