Biology; Chemistry; Physics: Post your doubts here!

[Yazka Shathir]

http://olevel.sourceforge.net/papers/5054/5054_s13_qp_21.pdf
Question number 9 part (iii) kinetic energy calculation
I used KE= 1/2mv2 to find the answer.
But if we use Workdone = energy transfered ( workdone = f*d ) the answer appears to be different. 1800 J
can someone explain why i cant use workdone=energy transformed theory here.
why don't i get the same answer for kinetic energy in both the methods?
thanks

 

[Zuhsid]

http://olevel.sourceforge.net/papers/5054/5054_s13_qp_21.pdf
Question number 9 part (ii) kinetic energy calculation
I used KE= 1/2mv2 to find the answer.
But if we use Workdone = energy transfered ( workdone = f*d ) the answer appears to be different. 1800 J
can someone explain why i cant use workdone=energy transformed theory here.
why don't i get the same answer for kinetic energy in both the methods?
thanks

Isnt it part (a),(iii)?? or am i mistaken?

 

[Zuhsid]

http://olevel.sourceforge.net/papers/5054/5054_s13_qp_21.pdf
Question number 9 part (ii) kinetic energy calculation
I used KE= 1/2mv2 to find the answer.
But if we use Workdone = energy transfered ( workdone = f*d ) the answer appears to be different. 1800 J
can someone explain why i cant use workdone=energy transformed theory here.
why don't i get the same answer for kinetic energy in both the methods?
thanks

May i ask, how did you get 1800J?

 

[Kamihus]

http://olevel.sourceforge.net/papers/5054/5054_s13_qp_21.pdf
Question number 9 part (ii) kinetic energy calculation
I used KE= 1/2mv2 to find the answer.
But if we use Workdone = energy transfered ( workdone = f*d ) the answer appears to be different. 1800 J
can someone explain why i cant use workdone=energy transformed theory here.
why don't i get the same answer for kinetic energy in both the methods?
thanks

You must have got 1800 by using its weight. The force needed to move it is not equal to the weight of the object, that's why you're answer is different.

 

[AAAYY***]

any one help me with question 13

 

[black widow]

well
for the first beaker amalyse is slowly denatured, after 30 minutes, it is completely denatured and thus positive test for starch indicating no digestion of starch
for the second time, 35 degrees celcius is the optimum temp so greater amylase activity, all starch digested immediately, so no starch remaining thus negative test for starch
for third one, amylase activity slow due to low temp, and starch digested after some time
for fourth one, amylase activity stops due to very low temp, and no starch digestion

 

[AAAYY***]

The answer is A
EXPLANATION: at 90 C, amylase enzymes get denatured, at 35 C the amylase works the best(optimum temperature) and hence the colour change immediately, while 20 C the reaction is slow but the colour change does happen. And at 10 C amylase enzymes are inactive.
P.S use the elimination method to eliminate incorrect options and then choose the best of the remaining

thankyou

 

[AAAYY***]

your welcome

any tips for atps ??? am stuck with biology

 

[AAAYY***]

what is atps?????? idk

paper 6 alternative to practical

 

[AAAYY***]

unfortunately, i have done my igcse's and now im in IB

ohhh its okay

 

[AAAYY***]

PAPER -6
Yeah ive done them in Biology gcse

yaaa but am studying gce

 

[AAAYY***]

YEAH, they were a bit awkward. All I did was practice all the past-papers, know all definitions, learn all the diagrams -including labelings (esp chapters that include classification of the animal.plant,etc kingdoms......)
i dont remember much regarding the chapter names.......

in the end conclusion past papers

 

[AAAYY***]

yaaa but i didnt do O levels, i did IGCSE

okay forget

 

[AAAYY***]

question 38 and question 8

 

[Zuhsid]

question 38 and question 8

8:C
As a protein solution will only react to a protein test(biuret test) and change to purple...... and the iodine test(for starch) and Benedict test(for reducing sugars) will remain the same color; their original colors(brown and blue) -----> all in all, this is a fact

38:C
Homozygous means that both the alleles are same, heterozygous means that both the alleles are different...... As the first plant is has a genotype RR(example).... and the other is ww(example).... the F1 generation is entirely made up of genotype Rw(as red is dominant, so all floers are red)...... when crossed among each other, the theoretical offsprings (F2 generation) should be: RR, Rw, Rw, ww..... therefore, as red is dominant(it exerts its affect)(it would come first in the ratio), there should be 3 red flowers and one white, hence the ratio should be: 3:1....but as we got 12 red and 6 white, the ratio simplifies to 2:1!!!

Hope it helps!!!

 

[raynalist]

negative acceleration means deceleration.

 

[raynalist]

learn all experiments you have done.work out the previous past exams.most popular question are on plant nutrition,blood,eye,genetics

 

[Salman Shah Jee]

Hye!! Can anyone explain budding and grafting(reproduction in plants).......i m nt getting it!!!!!!!!!!
any link will also be helpfull....thnkx

 

[AAAYY***]

question 3 part d and question

 

[Zuhsid]

question 3 part d and question

As yo9u may know, epidermal cells are the outer most layer of a leaf.... so its basic function is to protect the various cells(like spongy/palisade mesophyll cells) and thus lets thus lets them conduct their function easily; photosynthesis!! -------> this is the main reason!!

Is there something else after "and question"???

Hope it helps!!!