Question

The 70S ribosomes occur in one of the following.

• A. Bacterial cells, endoplasmic reticulum and mesosome.
• B. Bacterial cells, mitochondria and chloroplasts.
• C. Nucleus, mesosome and mitochondrion.
• D. Chloroplasts, Golgi complex and mitochondria.

Hint:

Remember that 70S ribosomes are typically found in prokaryotic cells and in organelles of eukaryotic cells that have a prokaryotic origin (mitochondria and chloroplasts).

Answer 1

The Correct Option is B

Step 1: Understanding 70S ribosomes.
70S ribosomes are found in prokaryotic cells like bacteria and in certain organelles in eukaryotic cells, such as mitochondria and chloroplasts. These ribosomes are smaller than the 80S ribosomes found in the cytoplasm of eukaryotic cells.
Step 2: Analyzing the options.
(A) Bacterial cells, endoplasmic reticulum and mesosome: The endoplasmic reticulum does not contain 70S ribosomes, and the mesosome is a structure in bacterial cells, but not a consistent location for ribosomes.
(B) Bacterial cells, mitochondria and chloroplasts: Correct — 70S ribosomes are found in bacteria, mitochondria, and chloroplasts, as these organelles have evolved from ancestral prokaryotes.
(C) Nucleus, mesosome and mitochondrion: The nucleus does not contain 70S ribosomes.
(D) Chloroplasts, Golgi complex and mitochondria: The Golgi complex does not contain 70S ribosomes, so this option is incorrect.
Step 3: Conclusion.
The correct answer is (B) Bacterial cells, mitochondria and chloroplasts. These are the places where 70S ribosomes are located.