Phototropism - root and shoot morphogenesis, Biology

Assignment Help:

Phototropism - Root and Shoot Morphogenesis

 Paratonic growth movement of part of a plant in response to light, e.g. bending of stems of indoor plants towards a window, brought about by increased elongation of cells in growth region at tip of stem on shaded side. Coleoptiles of dark grown Avena seedlings bend towards light, when we provide unilateral light. The tip is found to be playing a role. Actually the tip is site of auxin production. If the tip is removed there is no response to unilateral light. But an agar block containing auxins can substitute for the tip and coleoptile would bend towards the light as if it had not been decapitated. The coleoptile bends towards light because of unequal elongation of cells on two sides. The cells on the darker side elongate faster than those cells on two sides exposed to light.

Generally accepted that effect is due to greater concentration of auxin on dark side than on side facing light but some recent evidence suggests asymmetric distribution of some co-factor that influences auxin effect. Shoots always bend and grow towards light. It is an adaptive mechanism, no doubt. Here, also the auxin is agents that mediate light control just as in coleoptile. One question that needs to be asked is whether the extent of phototropism is proportional to the duration of exposure to light. Secondly, whether the magnitude of curvature is proportional to the energy content of the inducing light.


Related Discussions:- Phototropism - root and shoot morphogenesis

Pollutants, These are solid, liquid or gaseous substance present in the atm...

These are solid, liquid or gaseous substance present in the atmosphere in such concentrations, as may be or tend to be injurious to human beings or other living creatures, plants a

General reproduction, write about the asexual reproduction in mucor

write about the asexual reproduction in mucor

Supenisory nursing round, Supenisory Nursing Round: Supervisory rounds...

Supenisory Nursing Round: Supervisory rounds are tours or excursions into areas where patients are cared for where personnel operate, where intra and inter departmental commun

Descent of the testis, Descent of the Testis The testis develops on ...

Descent of the Testis The testis develops on the posterior abdominal wall at the mesonephric ridge. To reach the adult position in the scrotum, it must decent. A fibrous cor

Explain wind pollinated flowers, Wind pollinated flowers are: 1. Small, ...

Wind pollinated flowers are: 1. Small, brightly coloured, producing large number of pollen grains 2. Small, producing large number of dry pollen grains 3. Large producing

What is punnett squares in genetics, What is Punnett Squares in genetics? ...

What is Punnett Squares in genetics? The probability, or likelihood, that a certain phenotypic or genotypic trait will appear in offspring can be predicted and diagrammed using

Explain food applications of dextran, Food Applications Dextran can be ...

Food Applications Dextran can be used in food products, as it is capable of moisture retention and inhibition of crystallization of sugar. The properties of dextran as gelling

Why do male and female gametes diffrent from each other, Q. Concerning thei...

Q. Concerning their size and basic morphology how and why do the male and the female gametes differentiate from each other? The female gametes are big cells full of vitellus (n

What characteristics of fatty acids are false, what characteristics of fatt...

what characteristics of fatty acids are false? (Dissolves in water, used for energy storage, used to build lipids, found in triglycerides, found in steroids)?

Heat removal of gutta percha-endodontics principles, Heat removal of Gutta ...

Heat removal of Gutta percha: -    Heated plugger. -    Touch-N-Heat or system B used to thermo soften and remove gutta-percha from root canal systems. -    The cross-sectional

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd