Biology Paper 3 2013

[minastirid]

What do we have to know particularly?

 

[mustafaata1]

revise frm study guide to save time and solve latest papers e.g(2010-2012) both june and nov

 

[aaaamfa]

revise frm study guide to save time and solve latest papers e.g(2010-2012) both june and nov

plzz could u explain me the connections between auxin acculmation and positive phototroprism
any help would be appreciated.

 

[mustafaata1]

plzz could u explain me the connections between auxin acculmation and positive phototroprism
any help would be appreciated.

do u hv a study guide for bio?

 

[aaaamfa]

do u hv a study guide for bio?

no, i dont understand if u are done with ur prepartions then plzz help:
the notes which refer to say that:

Auxins are growth hormones in a plant. When they are distributed unequally, some parts of the plant grow faster than others, causing it to bend/change direction.
In positive phototropism auxins accumulate where the shoot is darkest, causing the dark side to grow rapidly, making the plant bend towards the light.
In negative phototropism the auxins also accumulate at the darker side, but this time they restrain growth there, making the shoot grow away from light.
In negative geotropism, auxins accumulate at the lower side of the shoot, therefore the lower side grows faster and then the shoot bends away from gravity.
In positive geotropism, auxins accumulate on the lower side of the root, but it restrains growth there, causing it to bemd toward gravity.
Synthetic plant hormones can be used to kill weeds, which have broad leaves. If another plant is nearby that is wanted has broad leaves,

 

[aaaamfa]

So you have a plant, and the sun is on the right. The left side of the plant is the darker side. Auxins accumulate on the darker side i.e. the left, causing that side to elongate more than the right. So the plant eventually bends to the right to face the sun.
Good luck

okay understood thank you so much

 

[mustafaata1]

no, i dont understand if u are done with ur prepartions then plzz help:
the notes which refer to say that:

Auxins are growth hormones in a plant. When they are distributed unequally, some parts of the plant grow faster than others, causing it to bend/change direction.
In positive phototropism auxins accumulate where the shoot is darkest, causing the dark side to grow rapidly, making the plant bend towards the light.
In negative phototropism the auxins also accumulate at the darker side, but this time they restrain growth there, making the shoot grow away from light.
In negative geotropism, auxins accumulate at the lower side of the shoot, therefore the lower side grows faster and then the shoot bends away from gravity.
In positive geotropism, auxins accumulate on the lower side of the root, but it restrains growth there, causing it to bemd toward gravity.
Synthetic plant hormones can be used to kill weeds, which have broad leaves. If another plant is nearby that is wanted has broad leaves,

Now see,
there is a shoot, on the tip of shoot there r auxins all around the shoot tip, the region/side of the tip of shoot where sunlight is falling, there at that side auxins r killed, means there r still auxins on the other side(where light is not falling) so as we know dat auxins help to grow plants, so as they r present on the dark side the dark side will start to grow, when dark side will grow and bright side will not grow due to absence of auxins the shoot or the tip of shoot will bend toward the bright one side, which means it bent towards the side on which light was falling, this is called positive phototropism, phot means light and tropism means movement which plant made due to the light

 

[aaaamfa]

Now see,
there is a shoot, on the tip of shoot there r auxins all around the shoot tip, the region/side of the tip of shoot where sunlight is falling, there at that side auxins r killed, means there r still auxins on the other side(where light is not falling) so as we know dat auxins help to grow plants, so as they r present on the dark side the dark side will start to grow, when dark side will grow and bright side will not grow due to absence of auxins the shoot or the tip of shoot will bend toward the bright one side, which means it bent towards the side on which light was falling, this is called positive phototropism, phot means light and tropism means movement which plant made due to the light

thank u