Biology; Chemistry; Physics: Post your doubts here!

[Awesome12]

I think you mean used in?
You set up a beaker with some snails, a CO2 absorbant (KOH), wire mesh, a tube leading out of the beaker to a capillary tube with a dye in it.
As oxygen is used up in beaker, low pressure is created and the dye in the capillary tube moves towards the beaker.

Why do we use snails in such experiments? Do they actively respire, or anything as such?

 

[Fate0]

Why do we use snails in such experiments? Do they actively respire, or anything as such?

Not really. Just that they're easily available. I've seen Insect Larvae being used aswell

 

[***amd***]

I think you mean used in?
You set up a beaker with some snails, a CO2 absorbant (KOH), wire mesh, a tube leading out of the beaker to a capillary tube with a dye in it.
As oxygen is used up in beaker, low pressure is created and the dye in the capillary tube moves towards the beaker.

we have to specify that it is oxygen which which is used.

View attachment 41172

FIRST PART OF EXPERIMENT
Blow the air in the test tube with the help of a blowing-pump. This is the air you inhale.
When the water will be displaced down and air will come in contact with potassium, it will burn using the OXYGEN gas present in air. The water level will rise.
Measure this rise in water level, 'A'
SECOND PART OF EXPERIMENT
(Set up the same apparatus and) Blow the air in the test tube with your mouth. This is your exhaled air.
Potassium will burn again when it comes in contact with air, using the OXYGEN, and the water level will rise.
Measure this rise in water level, 'B'.

We will observe that A > B because inhaling air contains more oxygen.

HEY! WAIT! ISNT IT THAT POTASSIUM BURNS IN WATER TOO? IF IT IS, THEN I GUESS WE SHOULD USE OIL INSTEAD OF WATER

 

[Awesome12]

we have to specify that it is oxygen which which is used.

Your experiment is complex. Bhai ka sab se betair tha

 

[***amd***]

Why do we use snails in such experiments? Do they actively respire, or anything as such?

its upon you you may yourself sit in the test tube if you want to

 

[***amd***]

Your experiment is complex. Bhai ka sab se betair tha

more complex = by a more genius person

 

[Fate0]

Here's the diagram if you're wondering. The colored liquid moves towards the test tube.

 

[Awesome12]

its upon you you may yourself sit in the test tube if you want to

 

[Awesome12]

View attachment 41246
Here's the diagram if you're wondering. The colored liquid moves towards the test tube.

Why is there a zinc gauze and NaOH solution?

 

[***amd***]

What is actually meant by the term 'control for an experiment'?

 

[***amd***]

Why is there a zinc gauze and NaOH solution?

NaOH (base) to absorb CO2
zinc to keep the maggots from drowning in.

 

[Fate0]

What is actually meant by the term 'control for an experiment'?

It's another version of the experiment with one/two things changing/opposite so that the observation and conclusion of this control experiment are actually opposite/different from the original one.

 

[***amd***]

It's another version of the experiment with one/two things changing/opposite so that the observation and conclusion of this control experiment are actually opposite/different from the original one.

you mean, for control the difference between the results of 2 experiment is essential, right?

 

[Fate0]

you mean, for control the difference between the results of 2 experiment is essential, right?

yes.
For example in this experiment, the control experiment will have everything same but the alive maggots are replaced by dead maggots.
So the dye will not move towards the test tube, hence an opposite result.

 

[ciesgetoveralready]

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

Q3 part a) i and ii. Will we have to crush the seed first and then carry the test?

 

[Awesome12]

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

Q3 part a) i and ii. Will we have to crush the seed first and then carry the test?

Yes, because otherwise the reducing sugar or starch may not be that accessible for the test

 

[Fate0]

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

Q3 part a) i and ii. Will we have to crush the seed first and then carry the test?

Crushing breaks down the cell membrane of the cells and releases the stored nutrients.

 

[***amd***]

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

Q3 part a) i and ii. Will we have to crush the seed first and then carry the test?

you have to break the testa of the seed so that starch can come out.

 

[kirann]

I think you mean used in?
You set up a beaker with some snails, a CO2 absorbant (KOH), wire mesh, a tube leading out of the beaker to a capillary tube with a dye in it.
As oxygen is used up in beaker, low pressure is created and the dye in the capillary tube moves towards the beaker.

yeah used in sorry bean seeds can also be used other than snails? :/

 

[***amd***]

yeah used in sorry bean seeds can also be used other than snails? :/

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