Biology; Chemistry; Physics: Post your doubts here!

[Suchal Riaz]

Can anyone explain me about what is a solenoid?

a coil.

 

[Zoya Shahab]

Solve b) i)

 

[Suchal Riaz]

Solve b) i)View attachment 21739

(i)
K.E=(mv²)/2
K.E=(75 kg)(4.0 m/s)² / 2
K.E= 600 J

 

[frozen sunlight]

Salams peoples
Have aliwl doubt
u know in bio when we study enzymes...the lock and key hypothesis..well....whats the key and whats the lock? O_O
diferent people tell me different things >.<

 

[fatima0000]

Salams peoples
Have aliwl doubt
u know in bio when we study enzymes...the lock and key hypothesis..well....whats the key and whats the lock? O_O
diferent people tell me different things >.<

Lock is enzyme to which the key, substrate fits after which the product is formed.
Like amylase is lock and starch which is the key fits to it and forms maltose, the product.

 

[frozen sunlight]

Lock is enzyme to which the key, substrate fits after which the product is formed.
Like amylase is lock and starch which is the key fits to it and forms maltose, the product.

likin some say that the enzyme is the key as it has an active site similar to the teeth of a key and it is specific to a substrate :/

 

[fatima0000]

likin some say that the enzyme is the key as it has an active site similar to the teeth of a key and it is specific to a substrate :/

Firstly, I havenot heard anyone saying that enzyme is key because it has teeth. Rather I know that it's simply a lock on which there is a groove-like depression and into this depression, the key fits which is substrate. So that's why it's true that enzymes are specific in shape as they only fit with their own substrate and not with any other subrate.

 

[frozen sunlight]

Firstly, I havenot heard anyone saying that enzyme is key because it has teeth. Rather I know that it's simply a lock on which there is a groove-like depression and into this depression, the key fits which is substrate. So that's why it's true that enzymes are specific in shape as they only fit with their own substrate and not with any other subrate.

Okay.........

 

[zohra`xo]

Can someone explain this MCQ to me please? The background count rate in a laboratory is 10 counts / min. The measured count rate from a radioactive source is 410 counts / min, which includes the background. The half-life of the source is 5 days. What is the measured count rate after 15 days? A 10 counts / min B 50 counts / min C 60 counts / min D 110 counts / min

 

[Suchal Riaz]

Can someone explain this MCQ to me please? The background count rate in a laboratory is 10 counts / min. The measured count rate from a radioactive source is 410 counts / min, which includes the background. The half-life of the source is 5 days. What is the measured count rate after 15 days? A 10 counts / min B 50 counts / min C 60 counts / min D 110 counts / min

the count rate - bg count rate = count rate of radioactive source.
so it is400. in 5 days it will be halves so 200 after five days, 100 after 10 days and 50 after 15 days.

 

[zohra`xo]

the count rate - bg count rate = count rate of radioactive source.
so it is400. in 5 days it will be halves so 200 after five days, 100 after 10 days and 50 after 15 days.

Oh! I was thinking of the question in the wrong way. Tysm!<3
*feels dum*

 

[Khadija_1234]

Hello,
I need help with all the experiments in physics
i mean, do you have to learn them or just understand the concepts?

and if anybody has notes of all the experiments, can i have them?

 

[Iridescent]

Test for silver(I) ions??

 

[Suchal Riaz]

Test for silver(I) ions??

add Hydrochloric acid, white precipitate of AgCl

 

[sweetiepie]

Hello,
I need help with all the experiments in physics
i mean, do you have to learn them or just understand the concepts?

and if anybody has notes of all the experiments, can i have them?

ATP Notes
http://www.xtremepapers.com/community/threads/atp-notes.20798/

 

[Khadija_1234]

Tha

ATP Notes
http://www.xtremepapers.com/community/threads/atp-notes.20798/

Thank you

 

[robinhoodmustafa]

Can anyone help me answer Question No. 3 in the Biology paper of June 2006? Any help is appreciated.

Paper 1?

 

[Muhammad Wasay]

hi everyone, i wanted to ask about chemistry, biology and physics paper 2.... you see all throughout my o levels (in the school) i have attempted all the questions in the section B. now i wanted to ask from a real pro, can i do this in the o levels final papers??
please help..

 

[aneeq247]

Paper 1?

nope, the atp paper

 

[farhan141]

Omg

hi everyone, i wanted to ask about chemistry, biology and physics paper 2.... you see all throughout my o levels (in the school) i have attempted all the questions in the section B. now i wanted to ask from a real pro, can i do this in the o levels final papers??
please help..

You mean there was choice and u still did all?