Biology; Chemistry; Physics: Post your doubts here!

[kirann]

why the test tube is washed with tap water, then with distilled water and then with hydrogencarbonate indicator to investigate gaseous exchange during photosynthesis, i cant get the logic behind in washing the testube with three diff solutions

 

[kirann]

perhaps no, coz they do not respire unless they are germinating.
insteadd, bean seedlinds might be used.

ok can germinating bean seeds be used? and boiled seeds as a control?

 

[kirann]

why the test tube is washed with tap water, then with distilled water and then with hydrogencarbonate indicator to investigate gaseous exchange during photosynthesis, i cant get the logic behind in washing the testube with three diff solutions

***amd*** can you answer this as well?

 

[***amd***]

ok can germinating bean seeds be used? and boiled seeds as a control?

germinating seeds can not be used for control.
and for boiled seeds, that doesnt make any sense, coz seeds are not going to respire unless they need to germinate. you may use dead snails. or just nothing at all

 

[***amd***]

***amd*** can you answer this as well?

can you post the whole of Q?

 

[funky brat]

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!

Wasting time since the morning, Going to study in an hour.

 

[funky brat]

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) .

We remove chlorophyll not starch.

 

[Anonymous321]

Question plis?

Is it some universal law that we only use metre values in formulas

http://papers.xtremepapers.com/CIE/Cambridge International O Level/Physics (5054)/5054_w10_qp_41.pdf

Q1.c (iii) They've given us a formula to calculate something from values obtained from previous answers. But they haven't specified which unit to use (cm or m)?
Even though in the previous part (in which we obtained that value), they are accepting BOTH cm and m....

Also where would we place the eye in 1(a) (ii). the marking scheme is vague about this :|

 

[kirann]

what is the use of nitrates, calcium, phosphorus an magnesium in plants?

 

[Laibaaa]

Q) How can we demonstrate the presence of stomata in a leaf?

 

[peacce]

what is the use of nitrates, calcium, phosphorus an magnesium in plants?

magnesium= it is a component of chlorophyl,
nitrates: Component of chlorophyl,aminoacids and prteins
Calcium: cell formation (root and shoot tips)
phosphurus: for release of energy

 

[ciesgetoveralready]

what is the use of nitrates, calcium, phosphorus an magnesium in plants?

Nitrates for synthesis of proteins which forms aminoacids for aid in growth and repair.
Magnesium for synthesis of chlorophyll.
Dont know about the other two. Probably related to growth

 

[ciesgetoveralready]

what is the use of nitrates, calcium, phosphorus an magnesium in plants?

http://www.bbc.co.uk/schools/gcsebi...y_pre_2011/greenworld/plantmineralsrev1.shtml

 

[wasted]

Lame question but when we're drawing a graph, can we label the y and x axis numbers outside the grid? and do we HAVE to use the whole grid?

 

[kirann]

Q) How can we demonstrate the presence of stomata in a leaf?

pick up a fresh leaf with a pair of forceps and hold the leaf below the surface of the water. the water should be approx 75 degree c
observe carefully, you will notice the formation of bubbles, which indicates presence of stomata.

 

[Lilly2318]

PPL i need good notes for Locomtion and teeth. kindly help!

 

[Laibaaa]

pick up a fresh leaf with a pair of forceps and hold the leaf below the surface of the water. the water should be approx 75 degree c
observe carefully, you will notice the formation of bubbles, which indicates presence of stomata.

Why do bubbles form?

 

[kirann]

Why do bubbles form?

cux stomata controls exchange of gases

 

[Fate0]

Lame question but when we're drawing a graph, can we label the y and x axis numbers outside the grid? and do we HAVE to use the whole grid?

You cannot number outside the grid.
Your graph should cover atleast 3/4 of the total space, if not all.

 

[kirann]

how can we show phloem carries material from leaves to other parts of plant?