1.
What is the genetic material which passes traits from one generation to the next?
Correct Answer
B. Protein, RNA, DNA
Explanation
Protein, RNA, and DNA are all involved in passing traits from one generation to the next. DNA carries the genetic information and serves as the template for the synthesis of RNA molecules. RNA, specifically messenger RNA (mRNA), carries the genetic information from the DNA to the ribosomes, where proteins are synthesized. Proteins, in turn, are the molecules that ultimately determine the traits expressed in an organism. Therefore, all three components - protein, RNA, and DNA - are essential for the transmission of traits from one generation to the next.
2.
Who studied pneumonia in mammals?
Correct Answer
A. Frederick Griffith
Explanation
Frederick Griffith studied pneumonia in mammals.
3.
How do the nitrogenous in DNA pair up?
Correct Answer
C. Adenine (A) with thymine (T) and guanine (G) with cytosine (C)
Explanation
The nitrogenous bases in DNA pair up in a specific way. Adenine (A) always pairs with thymine (T), and guanine (G) always pairs with cytosine (C). This is known as complementary base pairing, and it is a fundamental aspect of DNA structure and replication. The pairing of these bases allows for the accurate replication and transmission of genetic information.
4.
What are the two groups of Nitrogenous bases?
Correct Answer
Pyrimidines and Purines
Purines and Pyrimidines
Explanation
The two groups of nitrogenous bases are pyrimidines and purines. Pyrimidines include cytosine, thymine, and uracil, while purines include adenine and guanine. These bases are the building blocks of DNA and RNA molecules and play a crucial role in genetic information storage and transfer.
5.
What kind of bond holds nucleotides together?
Correct Answer
Phosphodiester bond
Phosphodiester bonds
Phosphodiester
Explanation
A phosphodiester bond is the type of bond that holds nucleotides together. It is formed between the phosphate group of one nucleotide and the sugar group of another nucleotide. This bond plays a crucial role in the structure of DNA and RNA molecules, as it forms the backbone of the nucleic acid chains. Multiple phosphodiester bonds connect the nucleotides in a linear sequence, creating a stable and continuous strand.
6.
What three parts does a nucleotide consist of?
Correct Answer
Nitrogenous base, sugar, phosphate group
Nucleoside, sugar, phosphate group
Nitrogenous base, pentose, phosphate group
Nucleoside, pentose, phosphate group
Explanation
A nucleotide consists of a nitrogenous base, a sugar, and a phosphate group. The nitrogenous base can be adenine, thymine, cytosine, or guanine. The sugar in DNA is deoxyribose, while in RNA it is ribose. The phosphate group is responsible for linking nucleotides together in a chain to form DNA or RNA molecules. The other options listed do not accurately describe the components of a nucleotide.
7.
Nucleic acids are polymers.
Correct Answer
A. True
Explanation
Nucleic acids are polymers because they are made up of repeating units called nucleotides. These nucleotides are linked together through phosphodiester bonds to form a long chain. This chain structure is characteristic of polymers, which are large molecules made up of repeating subunits. Therefore, it is correct to say that nucleic acids are polymers.
8.
What kind of bonds are between nitrogenous bases?
Correct Answer
Hydrogen
Hydrogen bonds
Explanation
The bonds between nitrogenous bases are hydrogen bonds. Hydrogen bonds form between the hydrogen atom of one molecule and an electronegative atom, such as nitrogen or oxygen, of another molecule. In the case of nitrogenous bases, hydrogen bonds form between the hydrogen atoms of one base and the nitrogen or oxygen atoms of another base. These hydrogen bonds play a crucial role in stabilizing the structure of DNA and RNA, as they hold the two strands of the double helix together.
9.
Who analyzed DNA base composition and studied molecular diversity among species?
Correct Answer
B. Erwin Chargaff
Explanation
Erwin Chargaff analyzed DNA base composition and studied molecular diversity among species. He discovered that the amount of adenine in DNA is always equal to the amount of thymine, and the amount of guanine is always equal to the amount of cytosine. This finding, known as Chargaff's rules, was crucial in understanding the structure and function of DNA. His work laid the foundation for the discovery of the double helix structure of DNA by Francis Crick and James Watson.
10.
A + T = G + C
Correct Answer
B. False
Explanation
The equation A + T = G + C represents the base pairing rule in DNA, where adenine (A) always pairs with thymine (T) and guanine (G) always pairs with cytosine (C). Therefore, the equation is true and the given answer, False, is incorrect.
11.
Who used X-ray crystallography?
Correct Answer
C. Maurice Wilkins and Rosalind Franklin
Explanation
Maurice Wilkins and Rosalind Franklin used X-ray crystallography. X-ray crystallography is a technique used to determine the atomic and molecular structure of a crystal by directing X-rays through it and analyzing the resulting diffraction pattern. Wilkins and Franklin used this technique to study the structure of DNA, which eventually led to the discovery of its double helix structure by James Watson and Francis Crick.
12.
Eukaryotic DNA replication is faster than prokaryotic DNA replication.
Correct Answer
B. False
Explanation
Eukaryotic DNA replication is not faster than prokaryotic DNA replication. In fact, prokaryotic DNA replication is generally faster than eukaryotic DNA replication. This is because prokaryotic cells have a simpler and more streamlined replication process compared to eukaryotic cells. Prokaryotes have a single origin of replication, while eukaryotes have multiple origins. Additionally, eukaryotes have larger genomes and more complex DNA packaging, which further slows down the replication process. Therefore, the statement that eukaryotic DNA replication is faster than prokaryotic DNA replication is false.
13.
What is the enzyme that releases tortional stress by cutting DNA, allowing rotation of DNA< and putting it back together?
Correct Answer
Topoisomerase
Explanation
Topoisomerase is the enzyme that cuts DNA and releases tortional stress, allowing the rotation of DNA strands. It functions by breaking the phosphodiester bonds in the DNA backbone, allowing the strands to rotate and relieve the tension. After the rotation, the enzyme reseals the DNA strands, effectively putting them back together. This process is essential for DNA replication, transcription, and other DNA-related cellular processes.
14.
What untwists the double helix at the replication forks and breaks hydrogen bonds holding the strands together?
Correct Answer
Helicases
Helicase
Explanation
Helicases are enzymes that play a crucial role in DNA replication. They are responsible for unwinding and separating the double helix structure of DNA at the replication forks. By breaking the hydrogen bonds that hold the two strands of DNA together, helicases create a single-stranded template for DNA polymerase to synthesize new complementary strands. Therefore, helicases are essential for the accurate and efficient replication of DNA.
15.
What keeps the DNA strands apart (maintains single-strandedness)?
Correct Answer
single-strand binding protein
SSBP
single-stranded binding protein
Explanation
Single-strand binding protein (SSBP) is responsible for maintaining the single-strandedness of DNA strands. It binds to the single-stranded DNA, preventing the two strands from reannealing or forming a double helix structure. This binding stabilizes the single-stranded DNA and protects it from degradation or damage. SSBP plays a crucial role in DNA replication, recombination, and repair processes by keeping the DNA strands apart and allowing other proteins, such as DNA polymerase, to interact with the single-stranded DNA template.
16.
DNA can only be synthesized in one direction.
Correct Answer
A. True
Explanation
DNA can only be synthesized in one direction due to the nature of the DNA polymerase enzyme. This enzyme can only add new nucleotides to the 3' end of the growing DNA strand. Therefore, DNA replication occurs in a 5' to 3' direction, with the leading strand being synthesized continuously in the same direction as the replication fork, and the lagging strand being synthesized discontinuously in the opposite direction. This process ensures the accurate replication of the DNA molecule.
17.
DNA polymerases add nucleotides only to the free 5' end of a growing strand.
Correct Answer
B. False
Explanation
only to the free 3' end
18.
A primase consists of 10-12 nucleotides of...
Correct Answer
B. RNA
Explanation
Primase is an enzyme responsible for synthesizing short RNA primers during DNA replication. These primers serve as starting points for DNA polymerase to begin the synthesis of new DNA strands. Therefore, the correct answer is RNA, as primase synthesizes RNA primers.
19.
Leading strand synthesis moves away from the replication fork and is discontinuous while lagging strand synthesis moves toward the replication fork and is continuous.
Correct Answer
B. False
Explanation
opposite
20.
A complex of proteins that replaces RNA nucleotides with DNA nucleotides is called.....
Correct Answer
A. DNA polymerase I
Explanation
DNA polymerase I is a correct answer because it is an enzyme that is involved in DNA replication and repair. It is responsible for removing RNA primers and replacing them with DNA nucleotides during DNA synthesis. DNA polymerase I has both 5' to 3' polymerase activity and 3' to 5' exonuclease activity, which allows it to remove the RNA primer and fill in the gap with DNA. DNA polymerase II and III are also involved in DNA replication, but they have different functions and are not specifically involved in replacing RNA nucleotides with DNA nucleotides.
21.
The lagging strand is synthesized as a series of segments called _______ ________, which are then joined together by DNA ligase.
Correct Answer
Okazaki fragments
Explanation
The lagging strand is synthesized discontinuously due to its antiparallel orientation to the leading strand. This means that it is synthesized in short fragments called Okazaki fragments. These fragments are synthesized in the 5' to 3' direction away from the replication fork. Once the fragments are synthesized, DNA ligase joins them together by catalyzing the formation of phosphodiester bonds between adjacent fragments. This process allows for the complete replication of the lagging strand during DNA replication.
22.
What joins the 3' end of DNA that replaces primer to rest of leading strand and joins Okazake fragments of lagging strand?
Correct Answer
DNA ligase
Explanation
DNA ligase is an enzyme that plays a crucial role in DNA replication and repair. It joins the 3' end of DNA that replaces the primer to the rest of the leading strand by catalyzing the formation of a phosphodiester bond. Additionally, DNA ligase also joins the Okazaki fragments of the lagging strand, which are short segments of DNA synthesized in the opposite direction of replication. This enzyme is essential for the completion of DNA synthesis and the maintenance of the integrity of the DNA molecule.
23.
DNA ligase requires energy.
Correct Answer
A. True
Explanation
DNA ligase is an enzyme that plays a crucial role in the process of DNA replication and repair. It functions by catalyzing the formation of phosphodiester bonds between adjacent DNA fragments. This process requires energy in the form of ATP (adenosine triphosphate) to drive the ligation reaction. Therefore, it is true that DNA ligase requires energy to carry out its function.
24.
What synthesizes new DNA strand by covalently adding nucleotides to the 3' end of a pre-existing DNA strand or RNA primer?
Correct Answer
C. DNA polymerase III
Explanation
DNA polymerase III synthesizes new DNA strands by covalently adding nucleotides to the 3' end of a pre-existing DNA strand or RNA primer. DNA polymerase I and II also have DNA synthesis activity, but they are not primarily responsible for the synthesis of new DNA strands in replication. DNA polymerase III is the main enzyme involved in DNA replication in prokaryotes and is responsible for the elongation of the leading and lagging strands during replication.
25.
What is the enzyme that cuts out RNA nucleotides?
Correct Answer
RNase H
Explanation
RNase H is an enzyme that specifically cleaves the RNA strand in an RNA-DNA hybrid, removing the RNA nucleotides. It is an endonuclease that hydrolyzes the phosphodiester bonds between the RNA and DNA molecules. This enzyme plays a crucial role in various biological processes, including DNA replication, repair, and transcription. By cutting out the RNA nucleotides, RNase H helps in the maturation of RNA molecules and ensures the fidelity of DNA replication and repair mechanisms.
26.
A complex of DNA and protein is called...
Correct Answer
B. Chromatin
Explanation
Chromatin is the correct answer because it refers to the complex of DNA and proteins found in the nucleus of a cell. It is the form in which DNA exists during most of the cell cycle, and it helps in the organization and packaging of DNA. Chromosomes, on the other hand, are condensed and visible structures formed from chromatin during cell division. Chromatid refers to one of the two identical copies of a chromosome that are joined at the centromere. Centromere is the region of a chromosome where the two chromatids are held together. "Cheerios" is not a relevant term in this context.
27.
Proteins that are responsible for the first level of DNA packing in chromatin are called.....
Correct Answer
Histones
Explanation
Histones are proteins that play a crucial role in the first level of DNA packing in chromatin. They help in organizing and condensing the DNA into a more compact structure by forming complexes known as nucleosomes. These nucleosomes consist of DNA wrapped around a core of histone proteins. Histones also play a role in regulating gene expression and providing stability to the chromatin structure. Therefore, histones are responsible for the initial packaging of DNA in chromatin.