Question

Which of the following cell organelles were discovered after the introduction of the electron microscope?
A. Mitochondria
B. Endoplasmic reticulum
C. Ribosomes
D. Both B and C

Answer 1

Hint: The electron microscope is a technique for obtaining high-resolution images of biological and non-biological specimens.

Complete answer:
Some cell organelles cannot be seen with light microscopes as they cannot achieve a high magnification. Organelles that can be seen under a light microscope are the nucleus, cytoplasm, cell membrane, chloroplasts, and cell wall. There are several different types of electron microscopes, including the transmission electron microscope (TEM), scanning electron microscope (SEM), and reflection electron microscope (REM.)

Option A: Mitochondria are also visible under a light microscope but a detailed study is not possible. Mitochondria were named by Carl Benda in 1898 from his study of cell internal structure and the first recorded information of mitochondria in plants in cells was created by Friedrich Meves.

Option B: The endoplasmic reticulum is a continuous membrane system that forms a series of flattened sacs within the cytoplasm of eukaryotic cells. It serves multiple functions, being important particularly in the synthesis, folding, modification, and transport of proteins. Organelles that can be seen under an electron microscope (highest magnification to more than 200,000X) are ribosomes, endoplasmic reticulum, lysosomes, centrioles, and Golgi bodies. Ribosomes, endoplasmic reticulum, lysosomes, centrioles, and Golgi bodies due to their smaller size were discovered after the introduction of an electron microscope.

Option C: Ribosomes cannot be seen with a light microscope but can be seen only using an electron microscope.

Therefore, the correct option is D) Both B and C.

Note: It is to be noted that combinations of TEM and SEM techniques have given rise to the scanning transmission electron microscope (STEM). Using STEM very high quality and precise images can be produced which help in extensive biological studies.