Biology; Chemistry; Physics: Post your doubts here!

[Fate0]

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

Tap water contains contaminents. We make sure that there are no contaminents left by washing with distilled water. And the hydrogen carbonate is used to check for presence of CO2 as it's yellow in presence of CO2 and red in absense.

 

[Fate0]

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

A sample of radioactive carbon is given to the plant.
The plant undergoes photosynthesis and sugar formed contain radiaoctive carbon.
The stem is then cut and exposed to X-Ray Photographic film.
It's found that the outer region in vascular bundles carry those sugars.
The outer region in vasuclar bundle is phloem.

There's also the Ringing Experiment.

 

[kirann]

A sample of radioactive carbon is given to the plant.
The plant undergoes photosynthesis and sugar formed contain radiaoctive carbon.
The stem is then cut and exposed to X-Ray Photographic film.
It's found that the outer region in vascular bundles carry those sugars.
The outer region in vasuclar bundle is phloem.

There's also the Ringing Experiment.

i was originally asking about the ringing experiment

 

[Fate0]

i was originally asking about the ringing experiment

A complete ring of bark is cut off including phloem and cambium from a stem. Place the twig in water with the exposed part underneath water.
Prepare another twig has a cut ring that has a cut ring above the water level
Observe the twigs
It is found that the twigs die and there's a swelling near the cut-off areas.
This is beacuase phloem does not reach the parts of the plants (roots) and is collected near the cut-off area.

 

[funky brat]

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

Nail varnish experiment.
The one in which we coat the epidermis with vaseline.

 

[Lilly2318]

Nail varnish experiment.
The one in which we coat the epidermis with vaseline.

can u fully explain and its reasons as well

 

[funky brat]

Which neurones are involved in the Knee-jerk reflex and why? Anyone?

 

[peacce]

Nail varnish experiment.
The one in which we coat the epidermis with vaseline.

Explain pls

 

[Dark Destination]

Which neurones are involved in the Knee-jerk reflex and why? Anyone?

Sensory and Motor neurons?

 

[Tuba noor]

can anybody plz tell me some imp topics for tommorrow's bio atp paper?

 

[funky brat]

Sensory and Motor neurons?

Why not relay?

 

[Lilly2318]

Which neurones are involved in the Knee-jerk reflex and why? Anyone?

do u have any notes for teeth

 

[Tuba noor]

can anybody plz tell me some imp topics for tommorrow's bio atp paper?

people plz help .....

 

[funky brat]

Explain pls

Nail varnish is to count the number of stomatas. The underside of the leave coated with thin layer of your favourite nail paint. layer removed when dry. Seen under microscope. Stomatas counted.

can u fully explain and its reasons as well

 

[Dark Destination]

Why not relay?

Relay, too.
Every action, involuntary or voluntary involves all three types of neurons i think.

 

[funky brat]

do u have any notes for teeth

No, I don't have them. Read from any book.

 

[peacce]

people plz help .....

No one can prdict this, however,focus on plants ,food tests, human eye ,diagrams labelling

 

[Dark Destination]

What are the most important topics for Bio atp?

 

[funky brat]

Relay, too.
Every action, involuntary or voluntary involves all three types of neurons i think.

Hmm. Every reflex action does. But the knee jerk does not.

 

[Mahnoorfatima]

Why not relay?

Relay is there as well. No??