Biology; Chemistry; Physics: Post your doubts here!

[sameer Ul Haq]

Ionic substances have high Melting & boiling points and conduct electricity while Covalent substances have low melting & boiling points and do not conduct Electricity. Ionic bonds are formed between Metal and Non-metal while covalent bonds are formed between Non-metals and Non-metals

 

[A*****]

Ionic substances have high Melting & boiling points and conduct electricity while Covalent substances have low melting & boiling points and do not conduct Electricity. Ionic bonds are formed between Metal and Non-metal while covalent bonds are formed between Non-metals and Non-metals

*Ionic substances conduct electricity in molten or aqueous form...u need to mention this...while covalent substances don't conduct electricity in any state.

 

[MysticLightning]

Could someone please provide me with an explanation of how bacteria is used to produce cheese and yogurt?

 

[A*****]

Would anyone happen to have a precise explanation to the production of cheese and yogurt using bacteria?

YOGHURT:
*Warm milk and add the culture of bacteria.
*Bacteria respires anaerobically and converts milk lactose to lactic acid.
*Lactic acid causes milk protein(casein) to curdle, producing yoghurt.

CHEESE:
*Milk is fermented to lactic acid by bacteria.
*This causes the milk protein to curdle.
*Curdled milk + fats in the milk are removed and acted upon by a mixture of both bacteria and fungi to produce cheese.
*Different types of cheese can be prepared by varying the conditions.

 

[A*****]

Can someone plz help me with this...

 

[Talha Jameel]

Can someone plz help me with this...

View attachment 61802

For first part, you have to write down 2 values of where graph intersects the x axis

 

[A*****]

For first part, you have to write down 2 values of where graph intersects the x axis

Sorry I was asking about the (e) part

 

[cool.fireboy24]

you have to find the variables which make the equation eqqual to x3+10x-80

If we write 4-x in the place of y you would find that it results in x3+10x-80 showing that y=4-x is the equation

 

[Nour29]

Can someone send feb/mar 2017 question papers pleasee

 

[THE YELLOW FLASH]

Hello guys. I am new to this thread and I wanted to ask if anyone has Physics and Chemistry Past Papers in a form of e-book. Please reply and share it will be a great help
-Thank You

 

[MnMz Mohammad-M]

hey,

can somebody solve this question for physics on 0625/63/o/n/16

the questions starts with something like that --> Plan an experiment which will enable you to compare the strengths of different samples of thin paper

its the last question.

please solve it in a brief and detailed way...
and plz use the mark scheme

 

[ZainJamro]

Here's my Question
How does transpiration stream increase the production of protein?

 

[A*****]

Here's my Question
How does transpiration stream increase the production of protein?

Transpiration brings nitrates dissolved in solution up the plant....those nitrates are used to manufacture amino acids, which in turn are used to synthesis more proteins...
Hope it helped

 

[Zeerak 420]

"The best removal of stains is maintained by providing the optimum temperature for enzymes, presoaking to leave time for the enzymes to digest, putting the suitable amount of the powder", can someone briefly explain the presoaking and powder part?

Also, why is water needed for activating enzymes in germination of seeds?

 

[whyareallnamestaken]

"The best removal of stains is maintained by providing the optimum temperature for enzymes, presoaking to leave time for the enzymes to digest, putting the suitable amount of the powder", can someone briefly explain the presoaking and powder part?

Also, why is water needed for activating enzymes in germination of seeds?

Detergent powders contain enzymes which digest the protein in food/blood stains. Increasing the enzyme concentration would speed up the process of protein digestion.

Pre-soaking is required because enzymes need aqueous mediums to function (hydrolytic breakdown).

In germination, you need water for the same reason. Enzymes allow break down to happen through hydrolysis, which quite obviously requires water.

 

[BlitzyDay]

"The best removal of stains is maintained by providing the optimum temperature for enzymes, presoaking to leave time for the enzymes to digest, putting the suitable amount of the powder", can someone briefly explain the presoaking and powder part?

Also, why is water needed for activating enzymes in germination of seeds?

For germination to occur, you need water to break down the stored food inside the cotyledon - enzymatic activity (hydrolysis) and also for the permeability of the seed coat for oxygen uptake.

 

[Gippi89]

Can someone provide me with some stuff to enhance my organic chemistry ....

 

[anumali5]

I actually wanted to ask about the ATP paper Of biology, I'm having my paper after 2 days and yet I'm not prepared for my exam. Would please help me out to find a convenient way to prepare my exam in a better and easy way and as well as in short time too. thanks.

 

[Superintelligent]

AOA

The O'level syllabus for Biology does not mention whether the individual stages of cell division (meiosis and mitosis) are required or not. Can someone tell whether I should study them or not?

 

[A*****]

AOA

The O'level syllabus for Biology does not mention whether the individual stages of cell division (meiosis and mitosis) are required or not. Can someone tell whether I should study them or not?

No they aren't important, nor is there any question regarding them in the past papers...u just need to know the differences bw mitosis and meiosis which includes the pairing of homologous chromosomes etc.