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

Nursing care of common cold, Nursing Care of Common Cold: Relieve Nas...

Nursing Care of Common Cold: Relieve Nasal Congestion Clean the nasal passage to remove secretions. In  infants nasal aspirator can be used while  the older children can

What is the lasting form in the gametophyte, Q. What is the lasting form in...

Q. What is the lasting form in the gametophyte, pteridophytes or the sporophyte? How can it be compared to bryophytes? The lasting form in pteridophytes is the diploid (2n) spo

Are alleles segregate during meosis, Gregor mendel was an austrain augustia...

Gregor mendel was an austrain augustianian monk; his work most notably showed that. a. Alleles segregate during meosis b. Capital alleles are dominant c. The genetic material is pa

What is isozymes, ISOZYMES : an enzyme having different molecular forms bu...

ISOZYMES : an enzyme having different molecular forms but catalyzing the same reaction.

Consequences of aging, Consequences of Aging It is hard to enumerate ...

Consequences of Aging It is hard to enumerate the general consequences of aging in different animals. Gradual loss of reproductive ability, neuromuscular coordination and not

Instances of human diseases caused by bacteria, Q What are instances of hum...

Q What are instances of human diseases caused by bacteria? Some human diseases caused by bacteria are tuberculosis, pertussis, diphtheria, gonorrhea, bacterial meningitis, bubo

Into which classes are mollusc divided, Into which classes are mollusc divi...

Into which classes are mollusc divided? What are some representing beings of each class? The phylum Mollusca is separated into five major classes: pelecypods, or bivalves (Pele

Role of exercise in the management of diabetes mellitus, Role of exercise i...

Role of exercise in the management of diabetes mellitus Exercise is another important component of life style modification. Like diet control, regular exercise is important in

Peste des petits ruminants (ppr), Peste des petits ruminants (PPR) is an a...

Peste des petits ruminants (PPR) is an acute, highly contagious viral disease of goats and sheep caused by peste des petits ruminants (PPR) virus which belongs to the genus Morbil

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