10. Which of the following molecules are found in substantial quantities in both the cell membrane and DNA?
Answer: C
Phosphate groups are found in substantial quantities in both the cell membrane and DNA.
Phosphate groups play a crucial role in the structure of DNA and are also a key component of phospholipids, which make up the cell membrane.
A) Nitrogenous bases
Nitrogenous bases are essential components of DNA, contributing to its genetic coding. However, they are not found in cell membranes, which do not contain nitrogenous bases as part of their structure, making this option incorrect.
B) Steroids
Steroids are a class of lipids that can be found in cell membranes, contributing to membrane fluidity and stability. However, they are not part of DNA structure, which makes this option incorrect as well.
C) Phosphate groups
Phosphate groups are integral to both DNA and cell membranes. In DNA, they form the backbone of the nucleotide structure, while in cell membranes, they are part of phospholipids, which are crucial for membrane formation and function. This makes option C the correct choice.
D) Lipids
While lipids are a significant component of cell membranes, they are not directly involved in the structure of DNA. DNA does not contain lipids, which makes this option incorrect.
Conclusion
Phosphate groups are uniquely present in both the structure of DNA and the cell membrane, fulfilling critical roles in these biological structures. In contrast, the other options either pertain solely to one of the structures or do not have a presence in both, confirming that phosphate groups are the only correct answer.