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what are the most important topics to study for paper 1? any help please?
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fetus is not the same as the child.Can anyone please explain this one point?
I read in a book that the plasmodium which causes Malaria can pass form the mother to the fetus via the placenta. But in one question, the mark scheme said that malaria cannot pass directly from parents to child?
9700/11/M/J11 Q. 36.
Help me please!
magnification = observed size (ruler) / (divide) actual sizejust tell me the way ...
fetus is not the same as the child.
The fetus is the unborn child, but a child is ... the born child?Excuse me?
The fetus is the unborn child, but a child is ... the born child?
I think they mean "child" as in the disease can pass through breastfeeding and not through the placenta...however I think the answer is b) malaria not because it's "correct" but because of elimination, i.e the other answers are incorrect. Also, they say "parent", not "mother", so sickle-cell is obv. incorrect as it require both parents to have the gene for sickle-cell..
Sickle cell anemia - genetic / hereditary and so can be passed from parent to child
TB / Cholera - bacterium and so can be transferred through the placenta? Not sure.
The fetus is the unborn child, but a child is ... the born child?
I think they mean "child" as in the disease can pass through breastfeeding and not through the placenta...however I think the answer is b) malaria not because it's "correct" but because of elimination, i.e the other answers are incorrect. Also, they say "parent", not "mother", so sickle-cell is obv. incorrect as it require both parents to have the gene for sickle-cell..
Sickle cell anemia - genetic / hereditary and so can be passed from parent to child
TB / Cholera - bacterium and so can be transferred through the placenta? Not sure.
hey...i have a question.A tree carries out photosynthesis and provides organic compounds for other organisms in aforest. It takes carbon dioxide from and returns oxygen to the atmosphere. It takes water from thesoil into its roots and its leaves lose water to the atmosphere. Many other organisms live in thetree.Which term applies to the description of the tree?AecosystemBhabitatCnicheDtrophic levelthis question came twice in the exam in oct nov 2009 and oct nov 2012 but in both cases answer was different.can anyone explain this to me?
What could be produced in a terminating step during the bromination of propane (Attached)
OMG ... by mistakeThis a thread for Biology MCQ's brother!
But viruses can...AND...if they are asking whether the disease can pass through breastfeeding, what about TB and cholera? I mean bacteria cannot pass through breast feeding!!!
But viruses can...
Because it'd be weaker if there were no covalent bondshttp://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w10_qp_12.pdf
Q8. the answer is C but why is the 4th statement correct
Q7 Turgid plant tissue is placed in a solution which has the same solute potential as the contents ofthe cells. The diagram shows a cell after one hour.Which equation describes the value of the pressure potential for this cell?A pressure potential = solute potential of the cellB pressure potential = solute potential of the external solutionC pressure potential = water potential of the cellD pressure potential = zerowhy is the answer D? its from winter 03
Q13 How does increasing substrate concentration affect the rate of an enzyme-catalysed reaction in the presence of a competitive inhibitor? A) The rate of the reaction decreases. B) The rate of the reaction decreases initially and then recovers. C) The rate of the reaction increases. D) The rate of the reaction is not affected. why is the answer C? please help
Because it'd be weaker if there were no covalent bonds
It's asking for things affecting the tensile strength of collagen - collagen is strong because of its helical structure (more hydrogen bonds), and the small R group means that when individual strands of collagen are placed parallel to each other, the hydrogen bonds would be stronger than if the R group was large (the ratio of hydrogen bonds to individual atoms would be larger if the R group was smaller); the covalent bonds affect the tensile strength because they prevent the strand from breaking when a force is exerted on them. If there were no covalent bonds, it'd be much, much weaker because when there's a bunch of strands and hundreds of covalent bonds to make a single, say, hair, it'd be very easy to tear -- those bonds add up, and so the more bonds there are between molecules, the stronger things get.
At least, that's what I think.
Q7 - The pressure potential is basically the pressure exerted by the water on the cell wall, and as more water enters the cell, the pressure potential increases. By default, the pressure potential is 0 (cell contents); if excess water entered the cell, the cell would be turgid, and so the pressure potential would be greater than 0. If water left the cell, it would be plasmolysed, and so the pressure potential would be less than 0. But since the solute potential of the surroundings of the cell is the same as the solute potential of the inside of the cell, it should generally follow that the water potential is also the same. Since the water potential is the same, it is an isotonic solution - no water leaves or enters the cell, in net. As a result, the pressure potential is 0.
Q13 - For this, try to look at what would happen when there is no competition from an inhibitor, aka a normal enzyme-catalysed reaction. Increasing the substrate concentration would increase the rate of the reaction, naturally, because there are more molecules (a la the kinetic model). Now, if you add a competitive inhibitor, with a normal amount of substrate, the rate would decrease. However, increasing the substrate concentration would result in the rate of reaction increasing, because even though there is a competitive inhibitor, there is a higher number of substrate and so it would increase. I think.
However, if it were a non competitive inhibitor, it would not affect the rate, because the active site would be distorted.
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