Chapter 12 Test - Biology

Adenine is the correct answer because it is the base abbreviated as "A". Adenine is one of the four nucleobases in the nucleic acids DNA and RNA. It pairs with thymine in DNA and with uracil in RNA. Adenine is an important component of genetic material and plays a crucial role in the functioning of DNA and RNA molecules.

The name of the base abbreviated "T" is thymine. Thymine is one of the four nucleotide bases found in DNA and RNA, along with adenine, cytosine, and guanine. It pairs with adenine in DNA and uracil in RNA. Thymine is essential for the proper functioning and replication of genetic material.

Cytosine is the correct answer because it is the base abbreviated as "C". Cytosine is one of the four bases found in DNA and RNA, along with adenine, guanine, and thymine (in DNA) or uracil (in RNA). It is a pyrimidine base, meaning it has a single-ring structure, and it pairs with guanine through hydrogen bonding in DNA and RNA molecules. Cytosine is crucial for the genetic code and plays a significant role in protein synthesis and gene expression.

Guanine is the correct answer because it is the base that is abbreviated as "G". Guanine is one of the four main bases found in DNA and RNA, along with adenine, cytosine, and thymine (in DNA) or uracil (in RNA). It plays a crucial role in the structure and function of nucleic acids, as it forms base pairs with cytosine. Guanine is also involved in various biological processes, such as protein synthesis and cell signaling.

During replication, the nucleotide sequence that would bond with the DNA sequence TATGA is ATACT. This is because in DNA replication, adenine (A) always pairs with thymine (T), and cytosine (C) always pairs with guanine (G). Therefore, the complementary sequence to TATGA would be ATACT, where A pairs with T, T pairs with A, G pairs with C, and A pairs with T.

The four bases found in DNA are G, C, A, and T. These bases are the building blocks of DNA and they pair up to form the double helix structure of DNA. G (guanine) pairs with C (cytosine), and A (adenine) pairs with T (thymine). This pairing is crucial for DNA replication and protein synthesis.

DNA polymerase is the correct answer because it is the main enzyme responsible for linking individual nucleotides into DNA molecules. DNA polymerase catalyzes the formation of phosphodiester bonds between adjacent nucleotides, creating the sugar-phosphate backbone of the DNA molecule. This enzyme is essential for DNA replication, repair, and synthesis during various cellular processes. DNA protease, ribose, and carbohydrase are not directly involved in the synthesis of DNA molecules and do not play a role in linking nucleotides together.

The two "backbones" of the DNA molecule consist of phosphates and sugars. The phosphate groups and deoxyribose sugars form a repeating pattern along the length of the DNA molecule. The phosphate groups provide a negative charge, while the sugars provide a backbone structure. These two components alternate to form the sturdy and stable structure of the DNA molecule. Adenines, thymines, guanines, and cytosines are the nitrogenous bases that are attached to the sugars and project inward, forming the rungs of the DNA ladder through hydrogen bonding.

A nucleotide is composed of three components: a sugar, a phosphate, and a nitrogenous base. The sugar can be either ribose or deoxyribose, depending on whether it is found in RNA or DNA respectively. The phosphate group is responsible for linking the nucleotides together, forming the backbone of the nucleic acid molecule. The nitrogenous base can be adenine, thymine, cytosine, or guanine, and it pairs with a complementary base in the opposite strand to form the double helix structure of DNA. Therefore, the correct answer is a phosphate.

Bases that are placed in specific pairings in DNA are said to be complimentary to each other. This means that they have a specific relationship where they can bind together in a specific way. In DNA, the bases adenine (A) pairs with thymine (T), and cytosine (C) pairs with guanine (G). These pairings are essential for the structure and function of DNA, as they allow for the accurate replication and transcription of genetic information.

Scientists had to show that DNA could carry and make copies of information in order to establish it as the genetic material in cells. This is because genetic material is responsible for storing and transmitting hereditary information, which requires the ability to carry and replicate genetic information accurately. This evidence was crucial in demonstrating that DNA possesses the necessary properties to serve as the genetic material.

A nucleotide is composed of three main components: a 5-carbon sugar, a nitrogen base, and a phosphate group. These components are essential for the structure and function of nucleotides. However, an amino acid is not a part of a nucleotide. Amino acids are the building blocks of proteins and are not involved in the structure of nucleotides. Therefore, the correct answer is "an amino acid".

In eukaryotes, the DNA is found in the nucleus. The nucleus is a membrane-bound organelle that contains the genetic material of the cell, which includes the DNA. This DNA carries the instructions for the cell's functions and is responsible for the inheritance of traits. The nucleus also regulates the activities of the cell and protects the DNA from damage. Therefore, it is correct to say that all the DNA (except for mitochondria and chloroplasts) is found in the nucleus in eukaryotes.

Rosalind Franklin's work on X-ray diffraction on DNA provided important clues to developing a model of DNA. X-ray diffraction is a technique used to study the structure of materials by analyzing how X-rays interact with them. Franklin's X-ray diffraction images of DNA provided crucial information about its helical structure and dimensions. Her work was instrumental in the discovery of the double helix structure of DNA by James Watson and Francis Crick.

After DNA replication is completed, two copies of DNA are produced. This is because DNA replication is a process in which the DNA molecule unwinds and each strand serves as a template for the synthesis of a new complementary strand. As a result, two identical copies of the original DNA molecule are formed, each consisting of one original strand and one newly synthesized strand.

Transformation is the correct answer because it refers to the process by which one strain of bacterium is apparently changed into another strain. In transformation, bacteria can take up and incorporate foreign DNA from their surroundings, leading to genetic changes and the appearance of new traits in the transformed strain. Transcription, duplication, and replication are not accurate terms to describe this specific process of bacterial strain change.

Chargaff's rule of base pairing states that in DNA, the amount of adenine (A) is equal to the amount of thymine (T), and the amount of cytosine (C) is equal to the amount of guanine (G). This means that A pairs with T and C pairs with G in DNA. Therefore, the correct answer is A = T, C = G.

The correct answer is weak hydrogen bonds between nitrogenous bases. The two strands of DNA are held together by hydrogen bonds formed between the nitrogenous bases. These bases, adenine (A), thymine (T), cytosine (C), and guanine (G), pair specifically with each other (A with T and C with G) through these weak hydrogen bonds. This bonding allows for the complementary base pairing that is essential for DNA replication and transcription.

Bacteriophages are viruses that specifically infect bacteria. They are composed of genetic material, either DNA or RNA, enclosed in a protein coat. Bacteriophages attach to the surface of bacteria and inject their genetic material into the bacterial cell, taking over the cellular machinery to replicate themselves. Eventually, the bacteriophage particles are released, causing the bacterial cell to burst and release more phages to infect other bacteria. Therefore, the correct answer is viruses.

During DNA replication, the two strands are called leading and lagging. The leading strand is synthesized continuously in the 5' to 3' direction, while the lagging strand is synthesized discontinuously in the opposite direction, creating short fragments called Okazaki fragments. This occurs because DNA polymerase can only add nucleotides in the 5' to 3' direction. The leading and lagging strands work together to ensure the accurate and efficient replication of the DNA molecule.

The dead S, living R group produced a conclusive result in Griffith's experiment. This is because when the living R bacteria were injected into the mice along with the heat-killed S bacteria, the mice in this group still died. This showed that the genetic material from the dead S bacteria was able to transform the harmless R bacteria into a deadly form. Therefore, the dead S, living R group provided conclusive evidence of bacterial transformation.

In eukaryotic chromosomes, DNA is tightly coiled around proteins called histones. Histones play a crucial role in organizing and compacting DNA within the nucleus. They help to maintain the structure and stability of chromosomes by forming a complex called chromatin. This coiling and packaging of DNA allow for efficient storage and replication of genetic information. DNA polymerase is an enzyme involved in DNA replication, nucleotides are the building blocks of DNA, but neither of them specifically refers to the proteins that DNA is coiled around in eukaryotic chromosomes.

The two strands of DNA run antiparallel to one another because they are oriented in opposite directions. In DNA, one strand runs in the 5' to 3' direction, while the other runs in the 3' to 5' direction. This antiparallel arrangement allows for the complementary base pairing between the strands, where adenine pairs with thymine and guanine pairs with cytosine. This arrangement is crucial for DNA replication and transcription processes.

Hershey and Chase's work showed that genes are probably made of DNA. This conclusion was based on their experiments with bacteriophages, which are viruses that infect bacteria. They labeled the DNA of the bacteriophages with radioactive phosphorus and the protein coat with radioactive sulfur. After infecting the bacteria, they found that the radioactive phosphorus was transferred to the bacterial cells, indicating that DNA was the genetic material being passed on. This experiment provided strong evidence that DNA, not protein, is the carrier of genetic information in organisms.

Prokaryotic cells are single-celled organisms that lack a nucleus and other membrane-bound organelles. They have a simpler structure compared to eukaryotic cells. One major difference is that prokaryotic cells have a much smaller amount of DNA. This is because they lack a nucleus where the DNA is stored and instead have a single circular chromosome located in the cytoplasm. In contrast, eukaryotic cells have a nucleus and multiple linear chromosomes, resulting in about 1/1000 times more DNA compared to prokaryotic cells.

Alfred Hershey and Martha Chase used radioactive markers in their experiments to provide evidence that DNA was the genetic material in cells. They conducted an experiment with bacteriophages, viruses that infect bacteria. They labeled the DNA of the bacteriophages with radioactive phosphorus and the protein coat with radioactive sulfur. After infecting the bacteria, they found that the radioactive DNA was transferred into the bacterial cells, while the protein coat remained outside. This demonstrated that DNA, not protein, was responsible for transmitting genetic information, supporting the idea that DNA is the genetic material in cells.

Griffith is the correct answer because he was the scientist responsible for the discovery of bacterial transformation. In his experiment, Griffith observed that a harmless strain of bacteria could be transformed into a deadly strain when exposed to heat-killed bacteria of the deadly strain. This transformation suggested that there was a transfer of genetic material between the two strains, which laid the foundation for further research on DNA and genetic transformation. Watson and Crick are known for their discovery of the structure of DNA, Avery for his work on DNA as the genetic material, and Franklin for her contributions to understanding DNA structure through X-ray crystallography.

In the Hershey-Chase experiment, sulfur-35 was used to tag proteins while phosphorus-37 was used to tag DNA. This choice of radioactive elements allowed the researchers to track the location and transfer of these components within the phages. By using different tags for proteins and DNA, the experimenters were able to determine that DNA, not proteins, is the genetic material that is passed on during phage infection.

DNA replication is a process where a new DNA molecule is synthesized using an existing DNA molecule as a template. It occurs in both directions on both strands of the double helix. However, the replication process is more straightforward on one strand, known as the leading strand, where DNA synthesis occurs continuously. On the other strand, known as the lagging strand, DNA synthesis occurs discontinuously in small fragments called Okazaki fragments. These fragments are later joined together by enzymes to form a complete DNA strand. Therefore, DNA replication happens smoothly on one strand but is more complicated on the other strand.

The sugar-phosphate backbone is held together with covalent bonds. Covalent bonds involve the sharing of electrons between atoms, which creates a strong and stable connection. In the case of the sugar-phosphate backbone, the covalent bonds form between the phosphate group of one nucleotide and the sugar molecule of the adjacent nucleotide. This bond is essential for maintaining the integrity and stability of the DNA molecule, as it allows for the formation of a continuous chain of nucleotides.

In prokaryotes, DNA molecules are located in the nucleoid region. Unlike eukaryotic cells, prokaryotes do not have a true nucleus. Instead, the DNA is found in a region called the nucleoid, which is a concentrated area within the cell where the genetic material is located. The nucleoid region is not surrounded by a membrane like a nucleus, but it is still the site where DNA replication, transcription, and other genetic processes take place in prokaryotic cells.

The sugar-phosphate backbone is a description of the structure of DNA, as it refers to the alternating sugar and phosphate molecules that form the backbone of the DNA molecule. The other options, including double helix, nucleotide polymer, and adenine-guanine pairs, all accurately describe aspects of the structure of DNA.