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

Aids, how get a aids

how get a aids

Determine the nutritious meals to the elderly, Determine the nutritious mea...

Determine the nutritious meals to the elderly? The various considerations to be kept in mind for providing nutritious meals to the  elderly are highlighted herewith. Due

Define excretion of toxin and act as precursor- carbohydrate, Define Excret...

Define Excretion of toxins and Act as precursors? Excretion of toxins: Glucuronic acid, a metabolite of glucose, combines with chemical and bacterial toxins and some normal met

Cell, The scientist who described cells as “many little boxes” was

The scientist who described cells as “many little boxes” was

What do you mean by descending aorta, Q. What do you mean by Descending Aor...

Q. What do you mean by Descending Aorta?  The descending aorta begins at the level of the fourth thoracic vertebra. It is defined through the cardiac shadow on the CXR, as it l

Show the error detection and editing function, Q. Show the Error Detection ...

Q. Show the Error Detection and Editing Function? Error Detection and Editing Function: Consciousness helps us avoid acting solely through habit. It allows us to make novel res

Explain syndrome x as a effect of obesity, Explain Syndrome X as a Effect o...

Explain Syndrome X as a Effect of Obesity? People with intra-abdominal obesity with high waist- to- hip ratio are more prone to develop the metabolic syndrome X. This is charac

What is the procedure of uristix, What is the Procedure of Uristix 1. C...

What is the Procedure of Uristix 1. Collect the urine. 2. Remove one strip from bottle and replace cap. 3. Completely immerse reagent areas of the strip in urine and remo

Male reproductive disorders, MALE REPRODUCTIVE DISORDERS Generally, ab...

MALE REPRODUCTIVE DISORDERS Generally, about 5-10% of cattle bulls reaching sexual maturity would be suffering from poor reproductive efficiency or sterility. Crossbreeding ha

Nutrition intervention, Nutrition intervention Nutrition intervention, ...

Nutrition intervention Nutrition intervention, the third step of  the nutrition care process, is a specific set of activities and associated materials used  to address the prob

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