Question

Who isolated auxins from tips of coleoptiles of oat seedlings?
A. Darwin and Darwin
B. Went
C. Skoog et al.
D. Kurosawa

Answer 1

Hint: The plant hormones are described as chemical or signal molecules that are produced within the plants and are produced in extremely low concentrations but are highly specific in actions. These chemicals are important as they control all the different aspects of the plant growth.

Complete answer:
Plant hormones are natural chemicals that are produced by the cells of the plants. They are able to promote growth, development, maturation of fruits as well as reproduction. They are not considered as nutrients but they are produced in much smaller amounts but are highly specific in their mode of action.
The important plant hormones produced by the plants are abscisic acid, ethylene, gibberellins, auxins and cytokinin. Auxin are the compounds that influence the enlargement of cells, formation of buds and root initiation in plants. The auxins were the first group of plant growth regulators that was discovered by Dutch botanist, F.W. Went in 1928. He was successful in isolating auxin from the tip of oat coleoptiles in a gelatin block.
Went described the role of auxin as an important part in the growth of the plants. He showed that auxin appeared as a chemical messenger which diffuses from the tip of the coleoptiles. He was successful in identifying how a growth promoting chemical causes a coleoptile to grow towards the light source. He further, cut the tip of the coleoptiles and placed them in the dark over agar or gel blocks. He again administered the controlled coleoptiles to variations of the chemical and showed how it affected the movement of the coleoptiles towards the sources of light.
Darwin and Darwin worked on the coleoptiles and observed that they were affected as they bend towards the source of light and light was detected by the tip of the coleoptiles.
Skoog et al. demonstrated that ratio of cytokinin to auxin in the media affects the morphogenesis of roots and shoots in plant tissue cultures.

Therefore, the correct option is option B.

Note: The plant hormones are produced by the cells of the plants and are known to affect different regions of the cell producing the hormones. The first plant hormone that was isolated and was discovered by F.W. Went on the tips of the coleoptiles. He isolated the chemical named as auxin from the tips of the coleoptiles on an agar block.