.The arrow is pointing to what structure?(Not the molecule)
Sugar-phosphate backbone
Hydrogen ions
Base pairs
Ribosomes
The Correct Answer is C
- Sugar-phosphate backbone: This forms the vertical sides of the DNA ladder, not the horizontal rungs.
- Hydrogen ions: These are not structural components of DNA; hydrogen bonds hold base pairs together, but hydrogen ions themselves are not part of the DNA structure.
- Base pairs (nitrogenous base pairs): The horizontal rungs of the DNA ladder represent base pairs, formed by hydrogen bonding between complementary nitrogenous bases: adenine (A) pairs with thymine (T), and cytosine (C) pairs with guanine (G). These base pairs are critical for encoding genetic information and ensuring accurate replication. The arrow is not pointing to the entire DNA molecule, but specifically to the structural unit that connects the two strands
- Ribosomes: These are cellular organelles involved in protein synthesis, not part of DNA’s structure.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is B
Explanation
A. DNA: DNA contains the bases adenine (A), thymine (T), cytosine (C), and guanine (G). The presence of uracil (U) in the model rules out DNA, since uracil is unique to RNA.
B. RNA: The model shows nucleotides labeled G (guanine), U (uracil), and C (cytosine), which are components of RNA. The entire structure represents a strand of RNA being synthesized or processed.
C. Protein: Proteins are composed of amino acids, not nucleotide bases. The colored blocks labeled with letters (G, U, C) clearly indicate nucleotides, not amino acids.
D. Transfer RNA (tRNA): While tRNA is a type of RNA, the model depicts a linear strand of RNA bases rather than the folded cloverleaf structure characteristic of tRNA.
Correct Answer is D
Explanation
A. Stratified squamous epithelium: Found in areas subject to friction (skin, esophagus), not in alveoli.
B. Transitional epithelium: Found in the urinary bladder, specialized for stretching, not gas exchange.
C. Cuboidal epithelium: Found in kidney tubules and glandular tissue, not in alveoli.
D. Simple squamous epithelium: The alveoli of the lungs are lined with simple squamous epithelium. These cells are extremely thin and flat, allowing for rapid diffusion of gases (oxygen and carbon dioxide) between the alveolar air and the surrounding capillaries. Their delicate structure is essential for efficient gas exchange, which is the primary function of the lungs.
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