Biol-B301 Dark room Lab
Richard Salisbury
Biol-B301
Professor: Parul Khurana
22 March 2016
In the image above there is a small hole in the corner of the sterilized dish. This hole allows
oxygen and carbon dioxide to enter the dish at that point. Because of the large influx of air the
plant establishes aerotropism like qualities in which the plants grow towards the oxygen. Upon
the seed actually germinating the shoot originally grows in a positive gravitropic manner but
because of the aerotropism movement the plants stem creates a curve. The aerotropism
movement is caused by the initial perseception of the plant due to the greater stimulus of air. This
causes a transduction of hormones in which the uneven distribution of hormones is applied to the
stem causing cell elongation on the side furthest away from the hole. While the root sytem grows
in a negative gravitropic manner as any other situation because the dish is turned up on edge the
arrow in the image shows what edge the dish was resting on.
In the figure above the plant seems to be growing as if a normal plant would. The issue is that the
dish was turned up on edge. When the plant germinated the root system initially grew into the
media due to the nutrients and vitamins that the media contains. The root then turns in a
downward direction also known as a negative gravotropic movement. As the root grows further
