Tag: botany

Joseph Priestley discovered that plants produce oxygen.
Jean Senebier discovered that the source of this carbon is carbon dioxide. 
Sachs discovered that starch grains are produced in plant leaves and  these are the first visible product of the process of photosynthesis. 
Jan Ingenhousz discovered that light plays a major role in photosynthesis. 

• Most of the experimental work in photosynthesis has been done on Chlorella. Through photosynthesis it multiplies rapidly, requiring only carbon dioxide, water, sunlight and a small number of minerals to reproduce. 
• It is easy to culture and it is easy to understand the photosynthetic process in chlorella cells.
•  Based on the above advantages most of the photosynthetic work was conducted in chlorella compared to hydrilla, spinach leaves, and Chlamydomonas. 

The correcr answer is ' Sachs ' . Sachs stated that green parts in the plants produces glucose which is later stored as starch and this starch is the first visible product of photosynthesis . in 1865 Sachs proved that chlorophyll was confined to special bodies only , which was later termed as Chloroplasts .

Van Helmont concluded that plants get their food from water. Van Helmont wanted to prove plants use materials from the soil to perform photosynthesis and done an experiment and proved that.

Since DNA polymerase requires a free 3' OH group for initiation of synthesis, it can synthesize in only one direction by extending the 3' end of the preexisting nucleotide chain. Hence, DNA polymerasemoves along the template strand in a 3'–5' direction, and the daughter strand is formed in a 5'–3' direction.

Isolation of the Genetic Material (DNA):

Nucleic acid is the genetic material, which is present in all living organisms. In majority of organisms, this is present in the form of deoxy-ribonucleic acid (DNA). DNA must be present into pure form, i.e., free from other macro-molecules (like proteins, RNA, enzymes, etc.) in order to cut the DNA with restrictor enzymes.

Isolation of genetic material (DNA) is carried out in the following steps:

(a) Since the DNA is enclosed within the membranes, so, in order to release DNA along with other macro-molecules such as proteins, polysaccharides and lipids, bacterial cells/plant or animal tissues are treated with the enzyme lysozyme (bacteria), cellulose (plant cells), chitinase (fungus), respectively.

(b) RNA can be removed by the treatment with ribonuclease, whereas proteins can be removed by the treatment with protease.

(c) Other molecules can be removed by appropriate treatments and ultimately purified DNA will precipitate out, after the addition of chilled ethanol. This can be seen as collection of fine threads in the suspension.

So, the correct answer is “Precipitation of DNA”.