*Biology Paper 5 tips*

[Student12]

Student12 now you give me an example..

LOOL umm...
- As u mentioned Rate of photosynthesis varies with intensity of light. Independent : Light .. Dependent : Rate of Photosynthesis
- Effect of CO2 on rate of photosynthesis. In. : CO2 and Dependent: Rate of photosynthesis ( How to vary.. Take 5 conc. & maintain each Co2 with the probe.. For dependent: Time to collect known amount of gas)
- The lower epidermis has more stomata per unit area than upper epidermis. Independent: upper or lower and dependent is No. of stoamta per unit area. (Can u explain this one?)
And at this point going through past papers i realized that whenever we write the procedure we write the independent & dependent variables that how they vary! Right?
- As the Light increases the number of pollen grains present in the atmosphere will increase and then decrease as light decreases. Independent: In incrased or decreased light intensity ( it changes so independent) Depenedent: No. of pollen grains.. it depends on independent.
- Ethanol increases membrane permebility more than an increase in temprature. Independent: Temperature and Conc. of ethanol Dependent: light absorbance (why not permability?)
-Effect of temperature on Rate of Light Dependent rxn. Independent: Temperature Dependent is Effect of temperature.
- Leaf Discs from shade leaves will photosynthesis at a higher rate in low light intensity than leaf discs from sun leaves. Ind. : Light intensity cuz its varying and dependent is Time taken for discs to rise depending on experiment.
-Effect of an Organo-mercury compound on mitosis were investigated in a cell culutre of human WBC. Independent: conc. of organo lalala and dependent is Frequency of type of mitosis.. in question.

Correct me please if im wrong in any?

 

[Student12]

Student12 now you give me an example..

No one would care asking in return.. and u actually made me go through past papers

 

[comrade]

why did u choose those 10 are the others out of syllabus or what

I have no idea. The booklet mentions only ten practicals. You can check it by clicking on the link.

 

[knowitall10]

LOOL umm...
- As u mentioned Rate of photosynthesis varies with intensity of light. Independent : Light .. Dependent : Rate of Photosynthesis
- Effect of CO2 on rate of photosynthesis. In. : CO2 and Dependent: Rate of photosynthesis ( How to vary.. Take 5 conc. & maintain each Co2 with the probe.. For dependent: Time to collect known amount of gas)
- The lower epidermis has more stomata per unit area than upper epidermis. Independent: upper or lower and dependent is No. of stoamta per unit area. (Can u explain this one?)
And at this point going through past papers i realized that whenever we write the procedure we write the independent & dependent variables that how they vary! Right?
- As the Light increases the number of pollen grains present in the atmosphere will increase and then decrease as light decreases. Independent: In incrased or decreased light intensity ( it changes so independent) Depenedent: No. of pollen grains.. it depends on independent.
- Ethanol increases membrane permebility more than an increase in temprature. Independent: Temperature and Conc. of ethanol Dependent: light absorbance (why not permability?)
-Effect of temperature on Rate of Light Dependent rxn. Independent: Temperature Dependent is Effect of temperature.
- Leaf Discs from shade leaves will photosynthesis at a higher rate in low light intensity than leaf discs from sun leaves. Ind. : Light intensity cuz its varying and dependent is Time taken for discs to rise depending on experiment.
-Effect of an Organo-mercury compound on mitosis were investigated in a cell culutre of human WBC. Independent: conc. of organo lalala and dependent is Frequency of type of mitosis.. in question.

Correct me please if im wrong in any?

Excellent mashAllah! You're perfectly right!
For Ethanol and Memberane Permeability:
We are looking at light absorbance because the more permeably the membrane, the more light will pass..we can't test membrane permeabilty through naked-eye can we?
and for the number of stomata thing...
usually, it's covering the lower and upper with a layer of wax.
For example: We're going to see the mass loss in a leaf with constant temp, light intensity, and....all of those factors.
So it's not a matter of the dependant or independent unless we're testing something.. so if there's greater mass loss when the upper surface is covered, more stomata are present at the bottom. if there's greater mass loss when the lower surface is covered, then there are more stomata on the upper epidermis..get it?

 

[knowitall10]

No one would care asking in return.. and u actually made me go through past papers

Well..I have to explain good if i choose to explain..otherwise i shouldn't answer if i knw my explanation will suck...

 

[Xainab]

Asalamalalikum

Thank youu for the amazing notes. I had this doubt, if you could solve it, please?

How do you get the values for E in Q 2 (b)(ii) of this paper: http://papers.xtremepapers.com/CIE/...nd AS Level/Biology (9700)/9700_w11_qp_53.pdf

Jazak Allah in advance

 

[afoo.666]

How do we calculate degree of freedom?

 

[knowitall10]

Asalamalalikum

Thank youu for the amazing notes. I had this doubt, if you could solve it, please?

How do you get the values for E in Q 2 (b)(ii) of this paper: http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w11_qp_53.pdf

Jazak Allah in advance

You're welcome..and wa iyaakkum
Cross 1 is the cross of two heterozygous cats, so the ratio is 9:3:3:1
Draw the rough cross yourself and match it with the results shown in the table... but i can't get the answer....although i did somehow a few days ago..

 

[Xainab]

You're welcome..and wa iyaakkum
Cross 1 is the cross of two heterozygous cats, so the ratio is 9:3:3:1
Draw the rough cross yourself and match it with the results shown in the table... but i can't get the answer....although i did somehow a few days ago..

I have tried every possible way. Not getting the answer. I think the ratio is not 9:3:3:1 but it is 1:1:1:1. I dont know.

 

[knowitall10]

I have tried every possible way. Not getting the answer. I think the ratio is not 9:3:3:1 but it is 1:1:1:1. I dont know.

the cross between two heterozygotes always results in the ratio 9:3:3:1
wait...i'm trying..cz i knw i got it one day, i actually explained it to my teacher...

 

[Xainab]

How do we calculate degree of freedom?

(n-1) is the general formula where n is the number of samples/ observations in your data set. So if your number of samples is 4, your degrees of freedom will be (4-1)=3

 

[Xainab]

the cross between two heterozygotes always results in the ratio 9:3:3:1
wait...i'm trying..cz i knw i got it one day, i actually explained it to my teacher...

Ok, I will be waiting. When you get it, please do post

 

[knowitall10]

Ok, I will be waiting. When you get it, please do post

Don't worry.. i'll post and i'll make sure i tag you... (I love your name btw )

 

[lionkill3r]

Ok, I will be waiting. When you get it, please do post

do you mind if i try to answer
In that cross the ratio of getting no tailed to tailed is 3:1 (no tail is dominant ). Since total number of observed is 40 +72 =112, to find tail it is (1\4) * 112 and to find no tail is (3\4)*112

 

[Xainab]

the cross between two heterozygotes always results in the ratio 9:3:3:1
wait...i'm trying..cz i knw i got it one day, i actually explained it to my teacher...

I got it, you were right. The ratio is 9:3:3:1. With tail will be 4/16 * 112 = 28 and without tail 12/16 * 112 = 84. Am i right?

 

[Xainab]

do you mind if i try to answer
In that cross the ratio of getting no tailed to tailed is 3:1 (no tail is dominant ). Since total number of observed is 40 +72 =112, to find tail it is (1\4) * 112 and to find no tail is (3\4)*112

Right.

 

[Xainab]

Don't worry.. i'll post and i'll make sure i tag you... (I love your name btw )

Thank youu

 

[knowitall10]

I got it, you were right. The ratio is 9:3:3:1. With tail will be 4/16 * 112 = 28 and without tail 12/16 * 112 = 84. Am i right?

yes!!!
Thanks man! You're a genius!! MashAllah!

 

[lionkill3r]

I got it, you were right. The ratio is 9:3:3:1. With tail will be 4/16 * 112 = 28 and without tail 12/16 * 112 = 84. Am i right?

That ratio is for dihybrid crosses, whereas this is a monohybrid cross :S

 

[knowitall10]

That ratio is for dihybrid crosses, whereas this is a monohybrid cross :S

It's not really monohybrid..the question says that the without tail allele is heterozygous..and they are male and female..so any two heterozygotes gives the ratio 9:3:3:1.