Which of the following elements helps in maintaining the structure of ribosomes?
AI-generated explanation. Check against your textbook.
Explanation:
Magnesium (Mg2+) helps maintain the structure of ribosomes by stabilizing rRNA and ribosomal subunits, which is essential for proper protein synthesis. This is in line with NCERT, which notes the importance of Mg2+ in ribosome stability during translation. The other elements—Zinc, Copper, and Molybdenum—are involved in different cellular functions (enzymes and electron transport) but are not described as maintaining ribosome structure in NCERT.
🧠 Did You Know?
Ribosomes require divalent cations like magnesium to maintain their shape and function during protein production.
💡 NCERT Memory Line:
Magnesium stabilizes ribosomal structure for translation.
The concept of "Omnis cellula-e cellula" regarding
cell division was first proposed by:
AI-generated explanation. Check against your textbook.
Explanation:
The correct option is 3, Rudolf Virchow. He stated the concept “omnis cellula e cellula,” meaning every cell arises from pre-existing cells, adding to the cell theory. NCERT credits Schleiden and Schwann with the idea that cells are fundamental units of life, while Virchow added that new cells come from existing ones. Aristotle is not part of the modern cell theory and suggested spontaneous generation, which is not accepted in NCERT biology. Therefore, the phrase “omnis cellula e cellula” is attributed to Virchow and explains how cell division occurs in living organisms.
🧠 Did You Know?
Virchow’s addition completed the cell theory by emphasizing the origin of new cells from old cells during division.
💡 NCERT Memory Line:
Omnis cellula e cellula — every cell arises from pre-existing cells (Virchow).