Question

where in eukaryotic cells is dna found?
a. cytoplasm
b. ribosomes
c. nucleus
d. endoplasmic reticulum
what type of molecule is dna?
a. carbohydrate
b. lipid
c. amino acid
d. nucleic acid
what type of sugar is found in dna?
a. ribose sugar
b. deoxyribose sugar
c. phosphate sugar
d. nitrogenous sugar
what type of bond joins together the sugar - phosphate backbone of dna?
a. covalent bond
b. hydrogen bond
c. ionic bond
d. nitrogen bond
what type of bond joins together complementary base pairs?
a. covalent bond
b. hydrogen bond
c. ionic bond
d. nitrogen bond
which of the following is not found in a nucleotide?
a. nitrogenous base
b. phosphate group
c. sugar
d. gene
how many strands make up a dna molecule?
a. 1
b. 2
c. 3
d. 4

Explanation:

• First question: In eukaryotic cells, DNA is mainly located in the nucleus. The cytoplasm may have some DNA (e.g., mitochondrial DNA, but the main storage is nucleus). Ribosomes are for protein synthesis and have rRNA, not DNA. Endoplasmic reticulum is involved in protein and lipid synthesis and has no DNA.
• Second question: DNA is a nucleic acid. Carbohydrates are sugars (e.g., glucose). Lipids are fats. Amino acids are the building blocks of proteins.
• Third question: DNA has deoxyribose sugar. RNA has ribose sugar. There is no phosphate sugar or nitrogenous sugar in the context of DNA's sugar component.
• Fourth question: The sugar - phosphate backbone of DNA is joined by covalent bonds (phosphodiester bonds). Hydrogen bonds join complementary base pairs. Ionic bonds are due to electrostatic attraction between ions (not relevant here). There is no nitrogen bond in this context.
• Fifth question: Complementary base pairs (A - T, G - C) are joined by hydrogen bonds. Covalent bonds are in the sugar - phosphate backbone. Ionic bonds are not for base - pair joining. Nitrogen bonds are not relevant here.
• Sixth question: A nucleotide consists of a nitrogenous base, a phosphate group, and a sugar. A gene is a segment of DNA (a long chain of nucleotides), not a component of a single nucleotide.
• Seventh question: A DNA molecule is double - stranded (double helix structure).

Answer:

1. C. nucleus
2. D. nucleic acid
3. B. deoxyribose sugar
4. A. covalent bond
5. B. hydrogen bond
6. D. gene
7. B. 2