Biology; Chemistry; Physics: Post your doubts here!

[Mahnoorfatima]

Theres this question in Nov 2006 in which it says suggest one way by which a flower might be able to aviod self pollination. I've written that the ovum (female rep cell) and the pollen(male rep. cell) should mature at different times. Is it correct?

 

[ciesgetoveralready]

Now can somebody please help me too? I want to know how to prepare a slide? step by step. Thankyou very much.

 

[ciesgetoveralready]

Theres this question in Nov 2006 in which it says suggest one way by which a flower might be able to aviod self pollination. I've written that the ovum (female rep cell) and the pollen(male rep. cell) should mature at different times. Is it correct?

I think its correct but its written in the redspot book not in the cie marking scheme :/

 

[asadalam]

Guys is labelling of insect parts in our syllabus anymore?

 

[Laibaaa]

Thank you so much. I got it!
Yeah I will answer your Slide question, gimme a few minutes.

 

[Laibaaa]

Now can somebody please help me too? I want to know how to prepare a slide? step by step. Thankyou very much.

But what are you preparing? Pollen grain or animal/plant cell or epidermis or what?

 

[Awesome12]

Now can somebody please help me too? I want to know how to prepare a slide? step by step. Thankyou very much.

 

[peacce]

Now can somebody please help me too? I want to know how to prepare a slide? step by step. Thankyou very much.

http://maxpapers.com/wp-content/uploads/2012/10/5090_s13_ms_61.pdf scroll to the last part

 

[ciesgetoveralready]

But what are you preparing? Pollen grain or animal/plant cell or epidermis or what?

Both i guess?

 

[ciesgetoveralready]

View attachment 41231

Thanks a million!

 

[Mahnoorfatima]

Now can somebody please help me too? I want to know how to prepare a slide? step by step. Thankyou very much.

If you wan't to look at the chloroplasts of a plant then the following steps are:
1) Cut a leaf with the help of a scalpel till the mid rib.
2) Soak it dry so that it won't interfere with the actual image being seen in the microscope.
3) Place the leaf on the slide and over it place the coverslip at an angle to prevent air bubbles.
4) Stain the leaf with iodine before placing the coverslip.
5) Place the slide on a microscope and hold by clips on the stage
6) Focus light on the microscope
7) Observe the image first under low power then high power with care(in the high power)
8) Draw the structure that you see.
Source: Pure RATTA from the pure! Good luck and pray for me!

 

[Mahnoorfatima]

Guys is labelling of insect parts in our syllabus anymore?

I don't think so because I havent come across any such question while reading the ATP since 2000. So I guess no.

 

[peacce]

Germination related atps?

 

[kirann]

Its H2O for oxygen with the ratio of hydrogen to oxygen is 2:1.
So Hydrogen is 20, then oxygen evolved will be half of it acc to the ratio.
20/2 is 10cm3. Hope that helped a lil x

can you give another example other than h2O?

 

[Fate0]

Germination related atps?

http://papers.xtremepapers.com/CIE/Cambridge International O Level/Biology (5090)/5090_w10_qp_61.pdf Q3
http://papers.xtremepapers.com/CIE/Cambridge International O Level/Biology (5090)/5090_w10_qp_62.pdf Q2

 

[ciesgetoveralready]

If you wan't to look at the chloroplasts of a plant then the following steps are:
1) Cut a leaf with the help of a scalpel till the mid rib.
2) Soak it dry so that it won't interfere with the actual image being seen in the microscope.
3) Place the leaf on the slide and over it place the coverslip at an angle to prevent air bubbles.
4) Stain the leaf with iodine before placing the coverslip.
5) Place the slide on a microscope and hold by clips on the stage
6) Focus light on the microscope
7) Observe the image first under low power then high power with care(in the high power)
8) Draw the structure that you see.
Source: Pure RATTA from the pure! Good luck and pray for me!

Thankyou so much! haha yes IA. May Allah bless all of us with what we deserve and make it all easy for us

 

[kirann]

View attachment 41181
can anybody plz explain

funky brat can u help me with this question?

 

[Fate0]

funky brat can u help me with this question?

Eliminate the answers.
It cant be (a) because if X was more reactive than Cu and Mg then it should also displace Zn. But they have said that the deposit is in 2 tubes only.
It cant be (c) because if X was more reactive than Na and Mg then it should displace Zn and Cu aswell.
It cant be (d) because if X was more reactive than Mg then it should also displace Cu.

(b) is the correct answer because if X is after Na and Mg in reactivity series but before Cu and Zinc it will only displace those two.

 

[Laibaaa]

Okay this is probably a stupid question but this has been bothering me since day1.

When testing for importance of chlorophyll in a leaf,
we first remove chlorophyll from the leaf by putting it in ethanol. This means that the leaf doesn't have chlorophyll and can not photosynthesise.
Then no starch should be there right? But when we test with iodine, it says blueblack colour :/
Do check this question;

http://papers.xtremepapers.com/CIE/Cambridge International O Level/Biology (5090)/5090_s08_qp_6.pdf
On pg8, Q2) .

 

[ciesgetoveralready]

How are you all preparing for the Bio ATP tomorrow? Considering that everyone's done maximum pastpapers and still in the process of doing....what else will you guys do? Please help!