Question

Which of the following was given by Robert Brown?
A. Brownian motion of molecules within the cell
B. Structure of cell
C. Structure of chromatin fibers
D. All of the above

Answer 1

Hint: Robert Brown is a Scottish scientist known for his great contributions by his descriptions related to cell nuclei. He is known for his theory of continuous motion of minute particles in solution.

Complete answer:
Robert Brown a Scottish Botanist gave many fundamental theories regarding cell nuclei, the motion of molecules that later called Brownian motion, the distinction between angiosperms and gymnosperms. Also, he had major contributions to the field of botany and taxonomy.
Option A is that the Brownian motion of molecules within the cell was given by Robert Brown. The Brownian motion refers to the irregular motion of molecules within the cell. He stated that molecules are in a continuous zig-zag type of motion due to vibrations or unequal bombardments. The name Brownian motion is after Robert Brown who discovered it.
Option B is the structure of the cell. In 1893 Matthias Jakob Schleiden and Theodor Schwann worked on cell theory to discover the structure of the cell. In this discovery, Robert Brown contributed by revealing the presence of the nucleus as the controlling unit of the cell.
Option C is the structure of chromatin fibers. Kornberg and Thomas in 1974 gave the Nucleosome-Solenoid Model of Chromatin fibers that became to be the most accepted model. Robert Brown contributed in only discovering the presence of the nucleus but he did not give the structure of contents present inside it.
Option D is that all of the above is correct. But option B and C do not come under the work of Robert Brown.

Therefore, the correct answer is option A.

Note: Robert Brown did most of his studies in the field of Botany. He discovered the Brownian motion first by observing the continuous random motion of pollen grain in a solution when he was studying the fertilization mechanism in plants. Also, from the fertilization even of pollen into ovule he discovered vacuoles moving from pollen towards ovule and he named these vacuoles as the nucleus.