Qualification > Sciences
Biology Paper 1 and 3 help HERE ONLY!!!
annie_angel:
auxin is used as a herbicide for weeds...as they complete their lifecycle and turn into manure<-- [weeds]
too much auxin will make the plant grow and may kill it... :-\
well...whn sunlight hits the plant the AUXIN go on to the shaded part in the plant and make the plant absorb more water on da shaded side so makes it heavir and so the unshaded part of the plant...PLANT grows towards the SUNLIGHT...NOT THE AUXINS...and therefore grow this way
hope this helps... :)
nid404:
--- Quote from: goin4dakill on June 06, 2009, 07:32:13 pm ---try telling alot of people that. ha! and plus..thats why we have karma :) theres a time limit, u can only rep someone after two hours. seeeee? moderation!
Anyway...I need help on Auxins..
Tell me about them..and also..Where do they grow towards. I always thought they grew towards light.. but then in a past paper they said they grew away from light. Now also, in a past paper it also says that too many auxins will kill a plant.
--- End quote ---
Auxins r known as plant hormones. They grow in the root and shoot tips. It causes growth in plants. They have opposite effects in the shoot and root. In shoots auxins absorb more water whereas in roots they absorb less water. They are photosensitive.So when they r placed in light the auxins in the shoot move towards the shaded area and absorb more water here,causing imbalance and thus bending towards light(known as positive phototropism). whereas in roots when they move towards the shaded area(bottom part) it absorbs less water and it is heavier above than below and so it bends downwards,away from light(negative phototropism)
when excess Auxins r added to plants they cause rapid growth and respiration. The growth is incontrollable and the cells divide rapidly(like cancer for e.g....not literally) and result in death of the plant
Aodian:
--- Quote from: goin4dakill on June 06, 2009, 07:32:13 pm ---try telling alot of people that. ha! and plus..thats why we have karma :) theres a time limit, u can only rep someone after two hours. seeeee? moderation!
Anyway...I need help on Auxins..
Tell me about them..and also..Where do they grow towards. I always thought they grew towards light.. but then in a past paper they said they grew away from light. Now also, in a past paper it also says that too many auxins will kill a plant.
--- End quote ---
Auxins are negatively phototrophic.. They hate light.. So think of it like darth vader.. bear with me on this one.. Auxins accumulate on the "DARK SIDE" of the shoot.. As you know.. auxins are growth hormones that the plant secretes(can i use tat word) so accumulation on only one side of the plant the "DARK SIDE" will cause one sided growth.. The "DARK SIDE" of the plant grows more than the one exposed to light.. This causes one sided growth making the dark side grow more n longer causing it to bend towards the light...
whereas for geotropism.. Auxins are positively geotrophic.. Auxins will collect on the lower sides of the shoot tip and root tip due to gravity..
A high concentration of ausxins in the shoot stimulates one sided growth so it grows upwards towards the sky showing negative geotropism..
The auxins on the root collect on the lower side but they do not promote cell elongation.. they actually inhibit cell elongation so the upper side of the root grows longer than the lower side causing the root tip to bend downwards.. this shows positive geotropism in roots..
please do correct me if im wrong.. I dont wanna be giving out misleading information
hmh:
LMAO! 1 question and 4 answers so far.. I feel so gud tht billion of sweet people are here to help in each and every step we wanna take towards success... GRRRRRRR8 GOING GUYS!
goin4dakill:
WOW you guys are awesome!! And every explanation was unique..and no i def understand. And im kicking myself with laughter. Theres always a way to bring Star Wars into everything, right??? hahah
PLus REP..again
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