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what are the most important topics to study for paper 1? any help please?
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AS Biology P1 MCQs Preparation Thread
- Thread starter Soldier313
- Start date
fetus is not the same as the child.
magnification = observed size (ruler) / (divide) actual size
they should be in the same units (i.e metres)
magnification = 2500
therefore
2500 = observed size / actual size
substitute to get the actual size (as = observed / 2500), and then multiply that by 1 um (micrometre)
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The fetus is the unborn child, but a child is ... the born child?Excuse me?
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.
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nice expaination
- Messages
- 134
- Reaction score
- 117
- Points
- 28
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.
When the child is born, it may have the plasmodium inside it, hence suffer from malaria. Sickle cell anemia is an inherited disease and definitely cannot be the answer.
THIS IS A DAMN CONFUSING QUESTION...I mean Malaria can pass from the parents to child....URGH!!!
- Messages
- 134
- Reaction score
- 117
- Points
- 28
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.
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!!!
hey...i have a question.
A tree carries out photosynthesis and provides organic compounds for other organisms in a
forest. It takes carbon dioxide from and returns oxygen to the atmosphere. It takes water from the
soil into its roots and its leaves lose water to the atmosphere. Many other organisms live in the
tree.
Which term applies to the description of the tree?
A
ecosystem
B
habitat
C
niche
D
trophic level
this 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?
A tree carries out photosynthesis and provides organic compounds for other organisms in a
forest. It takes carbon dioxide from and returns oxygen to the atmosphere. It takes water from the
soil into its roots and its leaves lose water to the atmosphere. Many other organisms live in the
tree.
Which term applies to the description of the tree?
A
ecosystem
B
habitat
C
niche
D
trophic level
this 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?
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Its Niche(C) because the description above refers to the role played by the tree.
- Messages
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What could be produced in a terminating step during the bromination of propane
This a thread for Biology MCQ's brother!
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OMG ... by mistakeThis a thread for Biology MCQ's brother!
if u can help that will be good
Q7 Turgid plant tissue is placed in a solution which has the same solute potential as the contents of
the 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 cell
B pressure potential = solute potential of the external solution
C pressure potential = water potential of the cell
D pressure potential = zero
why is the answer D? its from winter 03
the 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 cell
B pressure potential = solute potential of the external solution
C pressure potential = water potential of the cell
D pressure potential = zero
why 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
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
http://papers.xtremepapers.com/CIE/...nd AS Level/Biology (9700)/9700_w10_qp_12.pdf
Q8. the answer is C but why is the 4th statement correct
Q8. the answer is C but why is the 4th statement correct
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!!!
- Messages
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- Reaction score
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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.
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.
Thank you
really appreciate it
one more question: Q26 from http://papers.xtremepapers.com/CIE/...nd AS Level/Biology (9700)/9700_s10_qp_11.pdf
what does the question ask? like water potential before or after translations has occurred?