AS Biology P1 MCQs Preparation Thread

[rogue94]

Plz sum1 help me with mcQ 13 of may June 2010 variant 12

the field of view is circular so you will use the formula for area of a circle which is = pi x raidus^2. To find this out, you need to calculate the radius. From the figure, 40 divisions on eyepiece graticule are equal to 0.1 mm or 100 um. As the radius is equal to 50 divisions, so the actual size of radius is 125 (use ratios). Hence, the answer is C.

 

[XPFMember]

There are only two graphs that could come.
One is this ECG one. And the other where they ask us to identify when the atrio-ventricular and semi-lunar valves close.

View attachment 12844
P is the atrial systole.
QRS is ventricular systole.
T is the start of ventricular diastole.
That's all you need to know!

2.
View attachment 12845

Opens Closes
Closes Opens. Rote-learn it for short-time's sake.

JazakAllah khairen!!! thnx a lott!!!!!!!!!!!
may Allah give u success in both worlds ...aameen!!!!!!!!!!

 

[rogue94]

There are only two graphs that could come.
One is this ECG one. And the other where they ask us to identify when the atrio-ventricular and semi-lunar valves close.

View attachment 12844
P is the atrial systole.
QRS is ventricular systole.
T is the start of ventricular diastole.
That's all you need to know!

2.
View attachment 12845

Opens Closes
Closes Opens. Rote-learn it for short-time's sake.

What about the graph for change in volume of blood in left ventricle during one cardiac cycle. Could that come too?

 

[Jaf]

Can someone please EXPLAIN The following questions (I have the marking schemes so I am not asking for answers but explanations):

May/June 2010, question 23
October/November 2010, Questions 39 and 40

I want someone to explain how you reach the answers.

Thanks!

 

[Nibz]

What about the graph for change in volume of blood in left ventricle during one cardiac cycle. Could that come too?

I don't know which graph are you talking about.

 

[geek101]

Can someone please EXPLAIN The following questions (I have the marking schemes so I am not asking for answers but explanations):

May/June 2010, question 23
October/November 2010, Questions 39 and 40

I want someone to explain how you reach the answers.

Thanks!

variants?

 

[Capricedcapri]

Each division in the stage micrometer is 0.1 mm. So from the diagram we can see that 40 division in the eye piece graticule is equal to 1 division in the stage micrometer. So 1 division in the eye piece graticule= 0.1/40= 0.0025mm. Each small division in the eyepiece graticule is 0.0025 mm.
Then find the diameter of the field- there are 100 division in the eye piece graticule, so 0.0025*100=0.25 mm= 250 micrometer.
They asked for the area, and we know the formula to calculate the area of a circle is pi*r^2 (pi r square or pi*r*r)
The find the radius of the field which is 250/2= 125
so pi*125*125= 4*10^4
Hence answer is C

Thank you soo much!!

 

[Capricedcapri]

the field of view is circular so you will use the formula for area of a circle which is = pi x raidus^2. To find this out, you need to calculate the radius. From the figure, 40 divisions on eyepiece graticule are equal to 0.1 mm or 100 um. As the radius is equal to 50 divisions, so the actual size of radius is 125 (use ratios). Hence, the answer is C.

Thank you soo much !!

 

[malik234]

may/june2010/11
mcq no.28 n 30 ?

 

[Soldier313]

There are only two graphs that could come.
One is this ECG one. And the other where they ask us to identify when the atrio-ventricular and semi-lunar valves close and open.

View attachment 12844
P is the atrial systole.
QRS is ventricular systole.
T is the start of ventricular diastole.
That's all you need to know!

2.
View attachment 12845

Opens Closes
Closes Opens. Rote-learn it for short-time's sake.

tx soo much for this!

 

[Nibz]

tx soo much for this!

No problem =)
Sorry for being rude the other day.

 

[Soldier313]

No problem =)
Sorry for being rude the other day.

it's okay

 

[sarahnafea]

Can someone PLEASE answer me? Why are the 4 levels of protein structure involved in maintaing the specificity of an enzyme when an enzyme is limited to a tertiary structure?? Much appreciated.

 

[Soldier313]

Can someone PLEASE answer me? Why are the 4 levels of protein structure involved in maintaing the specificity of an enzyme when an enzyme is limited to a tertiary structure?? Much appreciated.

an enzyme is a protein therefore it has all the levels of protein structure (although nt all enzymes have a quarternary structure)
therefore obviously 2 proteins (enzymes) which have diff primary structure will have diff specificity
2 proteins (enzymes) which have diff secondary structure (ie one may be alpha helix while the other beta pleated) will have diff specificity

and so on with tertiary n quaternary

in short u cant expect 2 enzymes with same tertiary structure while diff primary structure to have the same specificity

hope u understood

 

[oldfashionedgirl]

Can someone please EXPLAIN The following questions (I have the marking schemes so I am not asking for answers but explanations):

May/June 2010, question 23
October/November 2010, Questions 39 and 40

I want someone to explain how you reach the answers.

Thanks!

which variant?

 

[Jaf]

variants?

Moola, sorry! Variant 1 for both

 

[Jaf]

Moola, sorry! Variant 1 for both

Oops. Sorry*

I hate typing on phones!

 

[geek101]

Oops. Sorry*

I hate typing on phones!

someones answered them!

 

[Soldier313]

people the ans fr this is B....i understand the second column, however for the first isn't it water potential increases? I mean isn't that how the hydrostatic pressure is built up..... bcoz of high water potential in sieve tube elements in leaves, which will allow the mass flow to occur?

 

[oldfashionedgirl]

Some help? Please?

On question 33. Answer is A.

http://www.xtremepapers.com/papers/...nd AS Level/Biology (9700)/9700_w10_qp_12.pdf