DNA: The Genetic Material Trivia Quiz

1. Which of the following things was identified as the transforming principle in Griffith experiment?

DNA

RNA

Proteins

Carbohydrates

The transforming principle in Griffith's experiment was identified as DNA. In his experiment, Griffith observed that when he injected a mixture of heat-killed disease-causing bacteria and live harmless bacteria into mice, the mice died. This showed that something in the heat-killed bacteria was able to transform the harmless bacteria into disease-causing ones. Later research by Avery, MacLeod, and McCarty confirmed that the transforming principle was DNA. This discovery played a crucial role in establishing DNA as the genetic material and paved the way for further understanding of genetics.

Explanation

The transforming principle in Griffith's experiment was identified as DNA. In his experiment, Griffith observed that when he injected a mixture of heat-killed disease-causing bacteria and live harmless bacteria into mice, the mice died. This showed that something in the heat-killed bacteria was able to transform the harmless bacteria into disease-causing ones. Later research by Avery, MacLeod, and McCarty confirmed that the transforming principle was DNA. This discovery played a crucial role in establishing DNA as the genetic material and paved the way for further understanding of genetics.

2. Which of the following has the self-repairing mechanisms?

DNA and RNA

DNA, RNA and protein

Only DNA

DNA and proteins

DNA has the self-repairing mechanism because it contains enzymes called DNA repair enzymes that can detect and correct errors in the DNA sequence. These enzymes can identify and remove damaged or incorrect nucleotides and replace them with the correct ones, ensuring the integrity of the DNA molecule. RNA and proteins do not have this self-repairing capability.

Explanation

DNA has the self-repairing mechanism because it contains enzymes called DNA repair enzymes that can detect and correct errors in the DNA sequence. These enzymes can identify and remove damaged or incorrect nucleotides and replace them with the correct ones, ensuring the integrity of the DNA molecule. RNA and proteins do not have this self-repairing capability.

3. How did Rosalind Franklin take pictures of the shape of DNA?

X-Ray diffraction

X-Ray microscopy Scanning

Electron Microscope

Electromagnetic radiation

Rosalind Franklin used X-Ray diffraction to take pictures of the shape of DNA. X-Ray diffraction is a technique that involves directing X-rays at a crystal and analyzing the pattern of the diffracted X-rays to determine the structure of the crystal. By using this technique, Franklin was able to capture images of the DNA molecule and provide crucial insights into its helical structure.

Explanation

Rosalind Franklin used X-Ray diffraction to take pictures of the shape of DNA. X-Ray diffraction is a technique that involves directing X-rays at a crystal and analyzing the pattern of the diffracted X-rays to determine the structure of the crystal. By using this technique, Franklin was able to capture images of the DNA molecule and provide crucial insights into its helical structure.

4. How did Rosalind Franklin's photo of DNA affect the work of Watson and Crick?

It was used to determine the physical structure of DNA

It was used to identify the four bases that make up DNA

It was used to determine the theory of independent assortment

It was used to show DNA was the molecule of inheritance

Rosalind Franklin's photo of DNA, known as Photo 51, played a crucial role in determining the physical structure of DNA. This photo provided key insights into the helical nature of DNA and the arrangement of its components. Watson and Crick used this information to develop their double helix model of DNA, which revolutionized our understanding of genetics and molecular biology.

Explanation

Rosalind Franklin's photo of DNA, known as Photo 51, played a crucial role in determining the physical structure of DNA. This photo provided key insights into the helical nature of DNA and the arrangement of its components. Watson and Crick used this information to develop their double helix model of DNA, which revolutionized our understanding of genetics and molecular biology.

5. When a DNA molecule is described as replicating bidirectionally, that means that it has two ......

Molecules.

Independently replicating segment.

Origins.

Replication forks.

When a DNA molecule is described as replicating bidirectionally, it means that the replication process occurs in two opposite directions from a central point. This results in the formation of two replication forks, which are the points where the DNA strands separate and new nucleotides are added to each strand. The replication forks move in opposite directions along the DNA molecule, allowing for the simultaneous synthesis of both strands.

Explanation

When a DNA molecule is described as replicating bidirectionally, it means that the replication process occurs in two opposite directions from a central point. This results in the formation of two replication forks, which are the points where the DNA strands separate and new nucleotides are added to each strand. The replication forks move in opposite directions along the DNA molecule, allowing for the simultaneous synthesis of both strands.

6. A nucleotide of DNA may contain ________.

Ribose, uracil, and a phosphate group

Deoxyribose, uracil, and a phosphate group

Deoxyribose, thymine, and a phosphate group

Ribose, thymine, and a phosphate group

not-available-via-ai

Explanation

not-available-via-ai

7. In double helix of DNA, the two DNA strands are .......

Coiled around each other

Coiled around a common axis

Coiled with different width

Coiled over protein sheath

The correct answer is "Coiled around a common axis". In the double helix structure of DNA, the two DNA strands are twisted around each other in a helical shape. This coiling occurs around a common axis, with the two strands running in opposite directions. This arrangement allows for the complementary base pairing between the strands, where adenine pairs with thymine and guanine pairs with cytosine, forming the genetic code. The coiling around a common axis also helps to stabilize the DNA structure and protect the genetic information it carries.

Explanation

The correct answer is "Coiled around a common axis". In the double helix structure of DNA, the two DNA strands are twisted around each other in a helical shape. This coiling occurs around a common axis, with the two strands running in opposite directions. This arrangement allows for the complementary base pairing between the strands, where adenine pairs with thymine and guanine pairs with cytosine, forming the genetic code. The coiling around a common axis also helps to stabilize the DNA structure and protect the genetic information it carries.

8. A segment of DNA has 120 adenine and 120 cytosine bases. The total number of nucleotides present in the segment is .....

120

240

360

480

The total number of nucleotides present in a DNA segment can be calculated by adding the number of adenine (A) bases and the number of cytosine (C) bases together. In this case, there are 120 adenine bases and 120 cytosine bases, so the total number of nucleotides is 120 + 120 = 240.

Explanation

The total number of nucleotides present in a DNA segment can be calculated by adding the number of adenine (A) bases and the number of cytosine (C) bases together. In this case, there are 120 adenine bases and 120 cytosine bases, so the total number of nucleotides is 120 + 120 = 240.

9. Nucleotides have a nitrogenous base attached to a sugar at the …....

1' carbon

2' carbon

3' carbon

5' carbon

Nucleotides have a nitrogenous base attached to a sugar at the 1' carbon. This is because the carbon atoms in the sugar molecule are numbered, with the 1' carbon being the carbon atom closest to the nitrogenous base. The attachment of the nitrogenous base to the 1' carbon is important for the formation of the phosphodiester bond that links nucleotides together in a DNA or RNA strand.

Explanation

Nucleotides have a nitrogenous base attached to a sugar at the 1' carbon. This is because the carbon atoms in the sugar molecule are numbered, with the 1' carbon being the carbon atom closest to the nitrogenous base. The attachment of the nitrogenous base to the 1' carbon is important for the formation of the phosphodiester bond that links nucleotides together in a DNA or RNA strand.

10. A nucleotide has ……….

Three phosphoric acid molecules

Two sugar molecules + phosphoric acid

One pentose sugar

Two phosphoric acid + nitrogenous base

A nucleotide is composed of three main components: a nitrogenous base, a sugar molecule, and a phosphate group. The sugar molecule in a nucleotide is a pentose sugar, which is a type of sugar with five carbon atoms. Therefore, the correct answer is "One pentose sugar."

Explanation

A nucleotide is composed of three main components: a nitrogenous base, a sugar molecule, and a phosphate group. The sugar molecule in a nucleotide is a pentose sugar, which is a type of sugar with five carbon atoms. Therefore, the correct answer is "One pentose sugar."

11. Each half turn of DNA molecule contains _______ nitrogenous bases.

5

10

20

25

Each half turn of a DNA molecule contains 10 nitrogenous bases. The DNA molecule consists of two strands that are twisted together in a double helix structure. Each strand is made up of a sequence of nitrogenous bases, which are adenine (A), thymine (T), cytosine (C), and guanine (G). These bases pair up with each other, with A always bonding with T and C always bonding with G. In each half turn of the DNA molecule, there are 10 pairs of nitrogenous bases, resulting in a total of 10 bases.

Explanation

Each half turn of a DNA molecule contains 10 nitrogenous bases. The DNA molecule consists of two strands that are twisted together in a double helix structure. Each strand is made up of a sequence of nitrogenous bases, which are adenine (A), thymine (T), cytosine (C), and guanine (G). These bases pair up with each other, with A always bonding with T and C always bonding with G. In each half turn of the DNA molecule, there are 10 pairs of nitrogenous bases, resulting in a total of 10 bases.

12. How many turns does a molecule of DNA consist of 2000 base pairs have?

20

100

200

400

A molecule of DNA consists of two strands that are twisted around each other in a double helix structure. Each turn of the helix contains approximately 10 base pairs. Therefore, a molecule of DNA with 2000 base pairs would have 200 turns, since 2000 divided by 10 is equal to 200.

Explanation

A molecule of DNA consists of two strands that are twisted around each other in a double helix structure. Each turn of the helix contains approximately 10 base pairs. Therefore, a molecule of DNA with 2000 base pairs would have 200 turns, since 2000 divided by 10 is equal to 200.

13. For a DNA molecule, which is not true?

A + G = C + T

A / T = G / C

(A +T) / (G + C) = 1

(A + G) / (C + T) =1

The statement (A + T) / (G + C) = 1 is not true for a DNA molecule. The correct ratio for the base pairs in DNA is A + T = G + C, not (A + T) / (G + C) = 1.

Explanation

The statement (A + T) / (G + C) = 1 is not true for a DNA molecule. The correct ratio for the base pairs in DNA is A + T = G + C, not (A + T) / (G + C) = 1.

14. DNA is composed of repeating units of ………

Ribonucleosides

Ribonucleotides

Deoxyribonucleosides

Deoxyribonucleotides.

DNA is composed of repeating units called nucleotides. These nucleotides consist of a sugar molecule (deoxyribose), a phosphate group, and a nitrogenous base. Therefore, the correct answer is deoxyribonucleotides, as they contain the deoxyribose sugar molecule that is characteristic of DNA. Ribonucleosides and ribonucleotides contain ribose sugar and are components of RNA, not DNA.

Explanation

DNA is composed of repeating units called nucleotides. These nucleotides consist of a sugar molecule (deoxyribose), a phosphate group, and a nitrogenous base. Therefore, the correct answer is deoxyribonucleotides, as they contain the deoxyribose sugar molecule that is characteristic of DNA. Ribonucleosides and ribonucleotides contain ribose sugar and are components of RNA, not DNA.

15. Which of the following nucleotide sequences contains 4 different types of bases?

GATGAATGT

GCCAGAUAA

UAGAGGUAA

TCAACTTACA

The nucleotide sequence "GCCAGAUAA" contains 4 different types of bases because it includes the nucleotides G, C, A, and U. The other sequences do not contain all 4 types of bases.

Explanation

The nucleotide sequence "GCCAGAUAA" contains 4 different types of bases because it includes the nucleotides G, C, A, and U. The other sequences do not contain all 4 types of bases.

16. Which of the following is true about the linkage between two adjacent nucleotides?

5’-phosphate group of one nucleotide unit is joined to the 3’-hydroxyl group of the other nucleotide.

3’-phosphate group of one nucleotide unit is joined to the 5’-hydroxyl group of the other nucleotide.

5’-phosphate group of one nucleotide unit is joined to the 5’-hydroxyl group of the other nucleotide.

3’-phosphate group of one nucleotide unit is joined to the 3’-hydroxyl group of the other nucleotide.

The correct answer is that the 5'-phosphate group of one nucleotide unit is joined to the 3'-hydroxyl group of the other nucleotide. This is known as a phosphodiester bond and it forms the backbone of DNA and RNA molecules. The phosphate group of one nucleotide is covalently bonded to the hydroxyl group of the sugar of the adjacent nucleotide, creating a strong and stable linkage between the nucleotides. This linkage allows for the formation of a linear chain of nucleotides, which is essential for the structure and function of DNA and RNA.

Explanation

The correct answer is that the 5'-phosphate group of one nucleotide unit is joined to the 3'-hydroxyl group of the other nucleotide. This is known as a phosphodiester bond and it forms the backbone of DNA and RNA molecules. The phosphate group of one nucleotide is covalently bonded to the hydroxyl group of the sugar of the adjacent nucleotide, creating a strong and stable linkage between the nucleotides. This linkage allows for the formation of a linear chain of nucleotides, which is essential for the structure and function of DNA and RNA.

17. In the transcription of RNA from DNA, which of the following statements is true?

The template strand DNA is identical to the sequence of the RNA transcript.

The template strand DNA is complementary to the sequence of the RNA transcript.

The template strand DNA is identical to the sequence of the complementary strand DNA.

The template strand DNA runs parallel to the sequence of the RNA transcript.

The correct answer is that the template strand DNA is complementary to the sequence of the RNA transcript. This means that the RNA transcript is formed by pairing complementary nucleotides to the template strand of DNA. The RNA transcript will have a sequence that is complementary to the template strand, but it will not be identical to it.

Explanation

The correct answer is that the template strand DNA is complementary to the sequence of the RNA transcript. This means that the RNA transcript is formed by pairing complementary nucleotides to the template strand of DNA. The RNA transcript will have a sequence that is complementary to the template strand, but it will not be identical to it.

18. What is the complementary DNA strand that is created from this template during replication? 3' T A C C G A T T G C A 5'

5’TAGGCATTGCA 3’

5’TGCAATGCCTA 3’

5’AUGGCUAACGU 3’

5’ATGGCTAACGT 3’

The complementary DNA strand is created by pairing each nucleotide with its complementary base. In DNA, adenine (A) pairs with thymine (T) and cytosine (C) pairs with guanine (G). Therefore, the complementary DNA strand for the given template sequence is 5’ATGGCTAACGT 3’.

Explanation

The complementary DNA strand is created by pairing each nucleotide with its complementary base. In DNA, adenine (A) pairs with thymine (T) and cytosine (C) pairs with guanine (G). Therefore, the complementary DNA strand for the given template sequence is 5’ATGGCTAACGT 3’.

19. Which association between complementary bases would require the most energy to break?

A:U

A:T

G:C

All require the same energy

The association between complementary bases G:C would require the most energy to break because it is connected by three hydrogen bonds, whereas A:T and A:U are connected by only two hydrogen bonds. The additional hydrogen bond in G:C makes it stronger and more stable, hence requiring more energy to break the bond.

Explanation

The association between complementary bases G:C would require the most energy to break because it is connected by three hydrogen bonds, whereas A:T and A:U are connected by only two hydrogen bonds. The additional hydrogen bond in G:C makes it stronger and more stable, hence requiring more energy to break the bond.

20. In a sample of double-stranded DNA, 20% of the nitrogenous bases are guanine (G). What is the percentage of the nitrogenous bases adenine (A) in the sample?

40%

30%

60%

20%

In a double-stranded DNA, the percentage of guanine (G) is 20%. Since DNA consists of two strands, the percentage of cytosine (C) would also be 20% as it pairs with guanine. This means that the total percentage of guanine and cytosine combined is 40%. As DNA follows the base pairing rule, the percentage of adenine (A) would be equal to the percentage of thymine (T). Therefore, the percentage of adenine would also be 40%. However, since the question specifically asks for the percentage of adenine (A) alone, we need to divide the 40% by 2, resulting in 20%. Therefore, the correct answer is 30%.

Explanation

In a double-stranded DNA, the percentage of guanine (G) is 20%. Since DNA consists of two strands, the percentage of cytosine (C) would also be 20% as it pairs with guanine. This means that the total percentage of guanine and cytosine combined is 40%. As DNA follows the base pairing rule, the percentage of adenine (A) would be equal to the percentage of thymine (T). Therefore, the percentage of adenine would also be 40%. However, since the question specifically asks for the percentage of adenine (A) alone, we need to divide the 40% by 2, resulting in 20%. Therefore, the correct answer is 30%.

21. Where is DNA NOT found?

In red blood cells

In viruses

In bacteria

In brain cells

Red blood cells do not contain a nucleus, which means they do not contain DNA. Unlike other cells in the body, red blood cells lose their nucleus during development in order to make space for more hemoglobin, the protein responsible for carrying oxygen. Therefore, DNA is not found in red blood cells.

Explanation

Red blood cells do not contain a nucleus, which means they do not contain DNA. Unlike other cells in the body, red blood cells lose their nucleus during development in order to make space for more hemoglobin, the protein responsible for carrying oxygen. Therefore, DNA is not found in red blood cells.

22. A molecule of DNA consists of 300 base pair. If the number of thymine base is 150. What is the number of the triple hydrogen bonds found in the molecule?

300

150

600

100

The number of triple hydrogen bonds in a DNA molecule is equal to the number of adenine-thymine base pairs. Since the number of thymine bases is given as 150, it means that there are 150 adenine bases in the molecule as well. Therefore, the number of triple hydrogen bonds in the molecule is also 150.

Explanation

The number of triple hydrogen bonds in a DNA molecule is equal to the number of adenine-thymine base pairs. Since the number of thymine bases is given as 150, it means that there are 150 adenine bases in the molecule as well. Therefore, the number of triple hydrogen bonds in the molecule is also 150.

23. A molecule of DNA consists of 200 base pair. What is the number of the free phosphate groups found in the molecule?

200

400

10

2

A molecule of DNA consists of two strands, each made up of a long chain of nucleotides. Each nucleotide contains a phosphate group, a sugar molecule, and a nitrogenous base. Therefore, for a molecule of DNA with 200 base pairs, there would be 200 phosphate groups. However, since each phosphate group is shared between two nucleotides, there would be half as many free phosphate groups. Therefore, the number of free phosphate groups found in the molecule would be 2.

Explanation

A molecule of DNA consists of two strands, each made up of a long chain of nucleotides. Each nucleotide contains a phosphate group, a sugar molecule, and a nitrogenous base. Therefore, for a molecule of DNA with 200 base pairs, there would be 200 phosphate groups. However, since each phosphate group is shared between two nucleotides, there would be half as many free phosphate groups. Therefore, the number of free phosphate groups found in the molecule would be 2.

24. In the DNA molecule, the width of the A=T is always …….. ring/(s)

1

2

3

4

The width of the A=T ring in the DNA molecule is always 3.

Explanation

The width of the A=T ring in the DNA molecule is always 3.

25. In the figure below, if A is a phosphate group, B is a ribose sugar and C is a nitrogenous base, then D have to be …..

C - H

C - C

C – OH

C = H

In a DNA molecule, the phosphate group (A) is attached to the ribose sugar (B) and the nitrogenous base (C). The ribose sugar has a hydroxyl group (-OH) attached to it. Since the question asks for the identity of D, it can be deduced that D refers to the hydrogen atom (H) attached to the carbon atom (C) in the ribose sugar. Therefore, the correct answer is C = H.

Explanation

In a DNA molecule, the phosphate group (A) is attached to the ribose sugar (B) and the nitrogenous base (C). The ribose sugar has a hydroxyl group (-OH) attached to it. Since the question asks for the identity of D, it can be deduced that D refers to the hydrogen atom (H) attached to the carbon atom (C) in the ribose sugar. Therefore, the correct answer is C = H.

26. If you know that the percentage of (A) in one strand of a DNA molecule is 10% and that of (T) on the same strand is 20%. What is the percentage (C) in the double helix molecule?

10%

40%

35%

70%

The percentage of (A) and (T) in a DNA molecule always add up to 100%. Since the percentage of (A) is 10% and the percentage of (T) is 20%, the remaining percentage must be allocated to (C) and (G). Therefore, the percentage of (C) in the double helix molecule is 35%.

Explanation

The percentage of (A) and (T) in a DNA molecule always add up to 100%. Since the percentage of (A) is 10% and the percentage of (T) is 20%, the remaining percentage must be allocated to (C) and (G). Therefore, the percentage of (C) in the double helix molecule is 35%.

27. What is the correct mode of DNA replication?

Conservative

Semi-conservative

Each strand is a patchwork of original and new DNA

Dispersive

In DNA replication, the correct mode is semi-conservative. This means that during replication, each new DNA molecule consists of one original strand and one newly synthesized strand. This was proven by the Meselson-Stahl experiment, where they labeled the parental DNA with a heavy isotope and the newly synthesized DNA with a light isotope. After multiple rounds of replication, the DNA was analyzed and it was found that the DNA molecules were a mix of heavy and light isotopes, supporting the semi-conservative mode of replication.

Explanation

In DNA replication, the correct mode is semi-conservative. This means that during replication, each new DNA molecule consists of one original strand and one newly synthesized strand. This was proven by the Meselson-Stahl experiment, where they labeled the parental DNA with a heavy isotope and the newly synthesized DNA with a light isotope. After multiple rounds of replication, the DNA was analyzed and it was found that the DNA molecules were a mix of heavy and light isotopes, supporting the semi-conservative mode of replication.

28. What is the reaction in DNA replication catalyzed by DNA ligase?

Formation of a covalent bond between the 3’-OH of one DNA fragment and the 5’-phosphate of the next fragment

Addition of new nucleotides to the leading strand

Addition of new nucleotide to the lagging strand

Base pairing of the template and the newly formed DNA strand

DNA ligase catalyzes the formation of a covalent bond between the 3'-OH of one DNA fragment and the 5'-phosphate of the next fragment. This process is crucial in DNA replication as it joins the Okazaki fragments on the lagging strand and seals any nicks or gaps in the DNA backbone. By forming this bond, DNA ligase helps to ensure the integrity and continuity of the newly synthesized DNA strand.

Explanation

DNA ligase catalyzes the formation of a covalent bond between the 3'-OH of one DNA fragment and the 5'-phosphate of the next fragment. This process is crucial in DNA replication as it joins the Okazaki fragments on the lagging strand and seals any nicks or gaps in the DNA backbone. By forming this bond, DNA ligase helps to ensure the integrity and continuity of the newly synthesized DNA strand.

29. For the following figure to be the building unit of DNA and not of RNA, The structure ……. Should be …….

A / Phosphate group

B / Ribose sugar

C / Adenine

C / Thymine

The structure that should be present in the building unit of DNA and not RNA is Thymine. Thymine is one of the four nucleotide bases found in DNA, while RNA contains Uracil instead of Thymine. Therefore, the presence of Thymine indicates that the structure is specific to DNA and not RNA.

Explanation

The structure that should be present in the building unit of DNA and not RNA is Thymine. Thymine is one of the four nucleotide bases found in DNA, while RNA contains Uracil instead of Thymine. Therefore, the presence of Thymine indicates that the structure is specific to DNA and not RNA.

30. In the following figure, write the sequence of the structural letters with respect to each of the following: leading strand / cannot work from 3`end toward 5`end / lagging strand / joins the short pieces of DNA.

A / B / C / D

C / B / D / A

D / B / C / A

C / A / D / B

The correct answer is C / B / D / A. In DNA replication, the leading strand is synthesized continuously in the 5' to 3' direction, so the structural letter C represents the leading strand. The lagging strand is synthesized in short fragments called Okazaki fragments, which are later joined together. Therefore, the structural letter B represents the lagging strand. The short pieces of DNA on the lagging strand are joined by an enzyme called DNA ligase, so the structural letter D represents the joining of the short pieces. Finally, the structural letter A represents the inability to work from the 3' end toward the 5' end, which is a characteristic of DNA replication.

Explanation

The correct answer is C / B / D / A. In DNA replication, the leading strand is synthesized continuously in the 5' to 3' direction, so the structural letter C represents the leading strand. The lagging strand is synthesized in short fragments called Okazaki fragments, which are later joined together. Therefore, the structural letter B represents the lagging strand. The short pieces of DNA on the lagging strand are joined by an enzyme called DNA ligase, so the structural letter D represents the joining of the short pieces. Finally, the structural letter A represents the inability to work from the 3' end toward the 5' end, which is a characteristic of DNA replication.

31. Some Mice were killed in Griffith's experiment after injection with ….

Nonliving S-type

Living R-type

Living S-type + nonliving R-type

Living R-type + nonliving S-type

In Griffith's experiment, some mice were killed after injection with a combination of living R-type bacteria and nonliving S-type bacteria. This suggests that the living R-type bacteria were able to transform the nonliving S-type bacteria into a deadly form. This transformation is known as bacterial transformation and was a key discovery in understanding how genetic material can be transferred between bacteria.

Explanation

In Griffith's experiment, some mice were killed after injection with a combination of living R-type bacteria and nonliving S-type bacteria. This suggests that the living R-type bacteria were able to transform the nonliving S-type bacteria into a deadly form. This transformation is known as bacterial transformation and was a key discovery in understanding how genetic material can be transferred between bacteria.

32. The ratio between the amount of DNA in the uterine cells and that in the kidney cells is ….

2 : 1

1 : 1

3 : 1

1 : 2

The ratio between the amount of DNA in the uterine cells and that in the kidney cells is 1 : 1. This means that both types of cells have the same amount of DNA.

Explanation

The ratio between the amount of DNA in the uterine cells and that in the kidney cells is 1 : 1. This means that both types of cells have the same amount of DNA.

33. During DNA replication, a separation occurs between …..

Cytosine and guanine

Uracil and thymine

Sugar and phosphate

Adenine and cytosine

During DNA replication, a separation occurs between cytosine and guanine. This is because during replication, the DNA double helix unwinds and the two strands separate. Cytosine and guanine are complementary base pairs, meaning they always pair together. Therefore, during replication, the cytosine on one strand will pair with guanine on the other strand, and vice versa. This separation allows for the synthesis of new DNA strands using the separated strands as templates.

Explanation

During DNA replication, a separation occurs between cytosine and guanine. This is because during replication, the DNA double helix unwinds and the two strands separate. Cytosine and guanine are complementary base pairs, meaning they always pair together. Therefore, during replication, the cytosine on one strand will pair with guanine on the other strand, and vice versa. This separation allows for the synthesis of new DNA strands using the separated strands as templates.

34. The enzyme deoxyribonuclease hydrolyses ……… completely.

Proteins and RNA

Proteins

RNA

DNA

The correct answer is DNA because deoxyribonuclease is an enzyme that specifically hydrolyzes DNA. It breaks down the DNA molecule into smaller fragments by breaking the phosphodiester bonds between the nucleotides. This enzyme does not hydrolyze proteins, RNA, or any other molecule besides DNA. Therefore, the correct answer is DNA.

Explanation

The correct answer is DNA because deoxyribonuclease is an enzyme that specifically hydrolyzes DNA. It breaks down the DNA molecule into smaller fragments by breaking the phosphodiester bonds between the nucleotides. This enzyme does not hydrolyze proteins, RNA, or any other molecule besides DNA. Therefore, the correct answer is DNA.

35. The nitrogenous base of the nucleotide is linked to the sugar molecule at its carbon atom number ……

1’

3’

4’

5’

The nitrogenous base of the nucleotide is linked to the sugar molecule at its carbon atom number 1. This is because carbon atom number 1 in the sugar molecule is attached to the nitrogenous base, forming a covalent bond. This bond is important for stabilizing the structure of the nucleotide and allowing it to participate in the formation of DNA and RNA molecules.

Explanation

The nitrogenous base of the nucleotide is linked to the sugar molecule at its carbon atom number 1. This is because carbon atom number 1 in the sugar molecule is attached to the nitrogenous base, forming a covalent bond. This bond is important for stabilizing the structure of the nucleotide and allowing it to participate in the formation of DNA and RNA molecules.

36. …… is a pyrimidine base that makes a triple hydrogen bond.

Adenine

Guanine

Cytosine

Thymine

Cytosine is a pyrimidine base that forms a triple hydrogen bond. Adenine and guanine are purine bases, while thymine is also a pyrimidine base but it forms only a double hydrogen bond. Therefore, the correct answer is cytosine.

Explanation

Cytosine is a pyrimidine base that forms a triple hydrogen bond. Adenine and guanine are purine bases, while thymine is also a pyrimidine base but it forms only a double hydrogen bond. Therefore, the correct answer is cytosine.

37. The enzyme ……… adds a new nucleotide in the direction of 5`to 3` of the strand which is synthesizing.

DNA helicase

DNA polymerase

Reverse transcriptase

DNA ligase

DNA polymerase is the correct answer because it is the enzyme responsible for adding new nucleotides during DNA synthesis. It adds nucleotides in the 5' to 3' direction, meaning it adds them to the growing strand in the same direction as the replication fork is moving. DNA helicase unwinds the DNA strands, reverse transcriptase synthesizes DNA from an RNA template, and DNA ligase joins together Okazaki fragments during DNA replication.

Explanation

DNA polymerase is the correct answer because it is the enzyme responsible for adding new nucleotides during DNA synthesis. It adds nucleotides in the 5' to 3' direction, meaning it adds them to the growing strand in the same direction as the replication fork is moving. DNA helicase unwinds the DNA strands, reverse transcriptase synthesizes DNA from an RNA template, and DNA ligase joins together Okazaki fragments during DNA replication.

38. How many nucleotides are there in a DNA strand that comprises 150 nitrogenous bases?

450

300

150

75

The number of nucleotides in a DNA strand is equal to the number of nitrogenous bases. Since the question states that the DNA strand comprises 150 nitrogenous bases, the correct answer is 150.

Explanation

The number of nucleotides in a DNA strand is equal to the number of nitrogenous bases. Since the question states that the DNA strand comprises 150 nitrogenous bases, the correct answer is 150.

39. Which of the following DNA segments is complement to the segment 5'-G-T-C-3?'

5’-T-A-G-3’

3’-C-A-G-5’

5’-C-A-G-3’

3’-T-A-G-5’

The complementary strand of DNA is formed by pairing the nucleotides in a specific way. Adenine (A) pairs with Thymine (T), and Guanine (G) pairs with Cytosine (C). Therefore, the complementary strand to 5'-G-T-C-3' would be 5'-C-A-G-3'.

Explanation

The complementary strand of DNA is formed by pairing the nucleotides in a specific way. Adenine (A) pairs with Thymine (T), and Guanine (G) pairs with Cytosine (C). Therefore, the complementary strand to 5'-G-T-C-3' would be 5'-C-A-G-3'.

40. What is the percentage of guanine base in a DNA sample comprises 22% of thymine base?

44%

33%

11%

28%

The percentage of guanine base in a DNA sample can be determined by subtracting the percentage of thymine base from 100%. Since the thymine base comprises 22% of the DNA sample, the guanine base would make up the remaining percentage. Therefore, the percentage of guanine base in the DNA sample would be 100% - 22% = 78%. However, since the question is asking for the percentage of guanine base only, the correct answer is 28%.

Explanation

The percentage of guanine base in a DNA sample can be determined by subtracting the percentage of thymine base from 100%. Since the thymine base comprises 22% of the DNA sample, the guanine base would make up the remaining percentage. Therefore, the percentage of guanine base in the DNA sample would be 100% - 22% = 78%. However, since the question is asking for the percentage of guanine base only, the correct answer is 28%.

41. The genetic material of a Bacteriophage is …..

DNA double strands

DNA single strand

RNA

Any of the previous

The genetic material of a Bacteriophage is DNA double strands. Bacteriophages are viruses that infect bacteria, and their genetic material is composed of double-stranded DNA. This DNA carries the instructions for the replication and assembly of new bacteriophages inside the host cell. This is different from other types of viruses, such as retroviruses, which have RNA as their genetic material. Therefore, the correct answer is DNA double strands.

Explanation

The genetic material of a Bacteriophage is DNA double strands. Bacteriophages are viruses that infect bacteria, and their genetic material is composed of double-stranded DNA. This DNA carries the instructions for the replication and assembly of new bacteriophages inside the host cell. This is different from other types of viruses, such as retroviruses, which have RNA as their genetic material. Therefore, the correct answer is DNA double strands.

42. How many turns do a molecule of DNA which consists of 2000 bases have?

20

200

100

400

A molecule of DNA consists of two strands that are twisted together to form a double helix structure. Each strand is made up of nucleotides, which are the building blocks of DNA. In this case, the DNA molecule consists of 2000 bases, which means there are 2000 nucleotides on each strand. Since the two strands are twisted together, they make one complete turn for every 10 base pairs. Therefore, a DNA molecule with 2000 bases would have 200 turns. However, the question asks for the number of turns for a single molecule of DNA, so we divide the total number of turns by 2. Therefore, a molecule of DNA with 2000 bases would have 100 turns.

Explanation

A molecule of DNA consists of two strands that are twisted together to form a double helix structure. Each strand is made up of nucleotides, which are the building blocks of DNA. In this case, the DNA molecule consists of 2000 bases, which means there are 2000 nucleotides on each strand. Since the two strands are twisted together, they make one complete turn for every 10 base pairs. Therefore, a DNA molecule with 2000 bases would have 200 turns. However, the question asks for the number of turns for a single molecule of DNA, so we divide the total number of turns by 2. Therefore, a molecule of DNA with 2000 bases would have 100 turns.

43. RNA is the genetic material of …..

Bacteria

Beans

HIV-virus

Bacteriophage

RNA is the genetic material of HIV-virus. HIV is a retrovirus, meaning it uses RNA as its genetic material instead of DNA. The RNA of HIV is used to synthesize DNA through the process of reverse transcription, which allows the virus to integrate its genetic material into the host cell's DNA. This integration is a crucial step in the replication and spread of the virus within the host's body. Therefore, HIV-virus is the correct answer.

Explanation

RNA is the genetic material of HIV-virus. HIV is a retrovirus, meaning it uses RNA as its genetic material instead of DNA. The RNA of HIV is used to synthesize DNA through the process of reverse transcription, which allows the virus to integrate its genetic material into the host cell's DNA. This integration is a crucial step in the replication and spread of the virus within the host's body. Therefore, HIV-virus is the correct answer.

44. If half the amount of DNA present in a cell of Horse's scrotum is (X), then the liver cell contains …… of DNA.

½ (X)

2(X)

(X)

4(X)

Since the question states that half the amount of DNA in a horse's scrotum cell is represented by (X), we can infer that the liver cell contains twice the amount of DNA, which is represented by 2(X).

Explanation

Since the question states that half the amount of DNA in a horse's scrotum cell is represented by (X), we can infer that the liver cell contains twice the amount of DNA, which is represented by 2(X).

45. One of the following was not among the results shown by Franklin …….

DNA is twisted into a spiral or helix.

The bases lie perpendicular to the length of the fiber.

The sugar-phosphate backbone is on the outside of the helix with the bases on the inside.

Number of purine bases are equal to the number of pyrimidine ones.

The correct answer is "Number of purine bases are equal to the number of pyrimidine ones." This statement is not among the results shown by Franklin. Franklin's X-ray diffraction images of DNA provided evidence for the helical structure of DNA, with the DNA molecule twisted into a spiral or helix. The bases in DNA were found to lie perpendicular to the length of the fiber, and the sugar-phosphate backbone was determined to be on the outside of the helix with the bases on the inside. However, Franklin's work did not provide information about the specific ratio or equality of purine and pyrimidine bases in DNA.

Explanation

The correct answer is "Number of purine bases are equal to the number of pyrimidine ones." This statement is not among the results shown by Franklin. Franklin's X-ray diffraction images of DNA provided evidence for the helical structure of DNA, with the DNA molecule twisted into a spiral or helix. The bases in DNA were found to lie perpendicular to the length of the fiber, and the sugar-phosphate backbone was determined to be on the outside of the helix with the bases on the inside. However, Franklin's work did not provide information about the specific ratio or equality of purine and pyrimidine bases in DNA.

46. All of the following enzymes are involved in the DNA replication except …..

DNA polymerase

Deoxyribonuclease

DNA ligase

DNA helicase

Deoxyribonuclease is not involved in DNA replication. DNA polymerase is responsible for synthesizing new DNA strands, DNA ligase joins the Okazaki fragments on the lagging strand, and DNA helicase unwinds the DNA double helix. Deoxyribonuclease, on the other hand, is an enzyme that breaks down DNA molecules by hydrolyzing the phosphodiester bonds between nucleotides. It is not involved in the process of DNA replication.

Explanation

Deoxyribonuclease is not involved in DNA replication. DNA polymerase is responsible for synthesizing new DNA strands, DNA ligase joins the Okazaki fragments on the lagging strand, and DNA helicase unwinds the DNA double helix. Deoxyribonuclease, on the other hand, is an enzyme that breaks down DNA molecules by hydrolyzing the phosphodiester bonds between nucleotides. It is not involved in the process of DNA replication.

47. A sample of DNA contains 400 purines nucleotides. What is the amount of pyrimidine nucleotides?

200

400

600

800

Since DNA consists of two types of nucleotides, purines and pyrimidines, the total number of purines and pyrimidines should be equal. Therefore, if the sample of DNA contains 400 purines nucleotides, it should also contain 400 pyrimidine nucleotides.

Explanation

Since DNA consists of two types of nucleotides, purines and pyrimidines, the total number of purines and pyrimidines should be equal. Therefore, if the sample of DNA contains 400 purines nucleotides, it should also contain 400 pyrimidine nucleotides.

48. The following figure illustrates the replication of prokaryotic DNA which comprises a ---------- origin(s) of replication.

Single

Double

Triple

Quadruple

Prokaryotic DNA replication involves the synthesis of a new DNA strand using an existing one as a template. In prokaryotes, replication starts at a single origin of replication, where the DNA strands separate and replication machinery is assembled. This single origin serves as the starting point for the replication process.

Explanation

Prokaryotic DNA replication involves the synthesis of a new DNA strand using an existing one as a template. In prokaryotes, replication starts at a single origin of replication, where the DNA strands separate and replication machinery is assembled. This single origin serves as the starting point for the replication process.

49. The following table represents the percentages of the bases in four different samples of DNA. Which samples prove the base pairing in DNA?

(1) and (2)

(2) and (3)

(1) and (3)

(2) and (4)

The base pairing in DNA is a fundamental principle in genetics. It states that adenine (A) always pairs with thymine (T), and cytosine (C) always pairs with guanine (G). By examining the percentages of the bases in different samples of DNA, we can determine if the base pairing is occurring. In this case, samples (1) and (3) prove the base pairing in DNA because the percentages of A and T are similar, as well as the percentages of C and G. This suggests that A is pairing with T and C is pairing with G in these samples.

Explanation

The base pairing in DNA is a fundamental principle in genetics. It states that adenine (A) always pairs with thymine (T), and cytosine (C) always pairs with guanine (G). By examining the percentages of the bases in different samples of DNA, we can determine if the base pairing is occurring. In this case, samples (1) and (3) prove the base pairing in DNA because the percentages of A and T are similar, as well as the percentages of C and G. This suggests that A is pairing with T and C is pairing with G in these samples.

50. What does the X dots pattern in Franklin's photo of DNA indicate?

The molecule consists of two strands

The DNA is helical

The presence of sugar-phosphate backbone

The presence of phosphate groups

The X dots pattern in Franklin's photo of DNA indicates that the DNA is helical. This is because the X-shaped pattern is a characteristic of a helix structure, where the two strands of DNA twist around each other in a spiral shape. The presence of the X dots pattern suggests that the DNA molecule has a helical structure.

Explanation

The X dots pattern in Franklin's photo of DNA indicates that the DNA is helical. This is because the X-shaped pattern is a characteristic of a helix structure, where the two strands of DNA twist around each other in a spiral shape. The presence of the X dots pattern suggests that the DNA molecule has a helical structure.

51. Which is(are) the real method(s) representing the model of DNA replication?

A

B

C

A and B

The correct answer is B because it is the only option that represents a real method of DNA replication. Option A is not a real method, and option C is not mentioned as a method of DNA replication. Therefore, the only valid choice is B.

Explanation

The correct answer is B because it is the only option that represents a real method of DNA replication. Option A is not a real method, and option C is not mentioned as a method of DNA replication. Therefore, the only valid choice is B.

52. Which of the following enzymes is involved in repairing DNA depurination?

DNA helicase

DNA polymerase

DNA ligase

Deoxy-ribonuclease

DNA ligase is the correct answer because it is the enzyme responsible for repairing DNA depurination. Depurination is the loss of a purine base (adenine or guanine) from the DNA molecule, resulting in an apurinic site. DNA ligase catalyzes the formation of phosphodiester bonds between adjacent nucleotides, sealing the gap created by the missing base. This repair process helps maintain the integrity and stability of the DNA molecule. DNA helicase unwinds the DNA double helix, DNA polymerase synthesizes new DNA strands, and deoxyribonuclease breaks down DNA molecules.

Explanation

DNA ligase is the correct answer because it is the enzyme responsible for repairing DNA depurination. Depurination is the loss of a purine base (adenine or guanine) from the DNA molecule, resulting in an apurinic site. DNA ligase catalyzes the formation of phosphodiester bonds between adjacent nucleotides, sealing the gap created by the missing base. This repair process helps maintain the integrity and stability of the DNA molecule. DNA helicase unwinds the DNA double helix, DNA polymerase synthesizes new DNA strands, and deoxyribonuclease breaks down DNA molecules.

53. When does the damage in DNA molecule cannot be fixed?

If a Guanine base is broken down from the molecule.

If an Adenine base is broken down from the molecule.

If any purine base is broken down from the molecule.

If both bases on the two strands are altered at the same time.

If both bases on the two strands are altered at the same time, the damage in the DNA molecule cannot be fixed. This is because the repair mechanisms in the cell are unable to accurately determine the original sequence of the bases and restore them to their correct positions. As a result, the altered bases may lead to mutations or errors in DNA replication, which can have detrimental effects on the cell's functioning and potentially lead to diseases or cell death.

Explanation

If both bases on the two strands are altered at the same time, the damage in the DNA molecule cannot be fixed. This is because the repair mechanisms in the cell are unable to accurately determine the original sequence of the bases and restore them to their correct positions. As a result, the altered bases may lead to mutations or errors in DNA replication, which can have detrimental effects on the cell's functioning and potentially lead to diseases or cell death.

54. Depurinated bases in single-stranded DNA undergoing replication can lead to mutations because,1-In the absence of information from the complementary strand, the DNA repair can add an incorrect base at the apurinic site. 2-When this strand is replicated; DNA polymerase copies the 'blank' apurinic position by incorporating a random base.

The two answers are correct.

The two answers are wrong.

The first answer is correct while the second is wrong.

The first answer is wrong while the second is correct.

When a single-stranded DNA undergoes replication and contains depurinated bases, mutations can occur. This is because in the absence of information from the complementary strand, DNA repair mechanisms may add an incorrect base at the apurinic site. Additionally, during replication, DNA polymerase may copy the "blank" apurinic position by incorporating a random base. Both of these processes can lead to mutations in the replicated DNA strand. Therefore, both statements are correct in explaining why depurinated bases in single-stranded DNA undergoing replication can lead to mutations.

Explanation

When a single-stranded DNA undergoes replication and contains depurinated bases, mutations can occur. This is because in the absence of information from the complementary strand, DNA repair mechanisms may add an incorrect base at the apurinic site. Additionally, during replication, DNA polymerase may copy the "blank" apurinic position by incorporating a random base. Both of these processes can lead to mutations in the replicated DNA strand. Therefore, both statements are correct in explaining why depurinated bases in single-stranded DNA undergoing replication can lead to mutations.

55. A turn in DNA molecule has 10 thymine nitrogenous bases. How many guanine bases does the turn contain?

Zero

5

10

20

In DNA, thymine always pairs with adenine, while guanine always pairs with cytosine. Since the question states that there are 10 thymine nitrogenous bases in the turn, it implies that there are no guanine bases present. Therefore, the correct answer is zero.

Explanation

In DNA, thymine always pairs with adenine, while guanine always pairs with cytosine. Since the question states that there are 10 thymine nitrogenous bases in the turn, it implies that there are no guanine bases present. Therefore, the correct answer is zero.

56. Gene (X) composed of 14 pairs of nitrogenous bases. From the below table detect the number of cytosine bases in the gene.

18

25

36

43

not-available-via-ai

Explanation

not-available-via-ai

57. The following diagram shows an experiment where the researcher used E. coli bacteria to be grown in nutritive medium (X) which contains ¹⁵N then he isolated a bacterial cell its genome contains ¹⁵N only and put it in a nutritive medium (Y) which contains ¹⁴N only. The percentage of DNA molecules containing ¹⁴N only in the second generation is …….

Zero %

50%

75%

100%

When the researcher isolated a bacterial cell with a genome containing only 15N and placed it in a nutritive medium containing only 14N, the DNA replication process would result in the synthesis of new DNA strands. These new DNA strands would consist of a mixture of 14N and 15N, as the 15N from the original genome would be used as a template. In the second generation, each DNA molecule would have one strand of 14N and one strand of 15N, resulting in a 50% composition of DNA molecules containing 14N only.

Explanation

When the researcher isolated a bacterial cell with a genome containing only 15N and placed it in a nutritive medium containing only 14N, the DNA replication process would result in the synthesis of new DNA strands. These new DNA strands would consist of a mixture of 14N and 15N, as the 15N from the original genome would be used as a template. In the second generation, each DNA molecule would have one strand of 14N and one strand of 15N, resulting in a 50% composition of DNA molecules containing 14N only.

58. What are the characteristics of rough pneumococci strain?

Non-capsulated and pathogenic

Non-capsulated and non-pathogenic

Capsulated and pathogenic

Capsulated and non-pathogenic

Rough pneumococci strains are characterized by being non-capsulated and non-pathogenic. This means that they do not have a protective capsule surrounding them and they do not cause disease or infection.

Explanation

Rough pneumococci strains are characterized by being non-capsulated and non-pathogenic. This means that they do not have a protective capsule surrounding them and they do not cause disease or infection.

59. During DNA replication ....

The lagging strand requires a slight delay before undergoing replication.

The leading strand requires a slight delay before undergoing replication.

The DNA ligase unwinds the DNA double helix.

The complementary strand (in the 5'-3' order) for the DNA segment AGC will be GCA.

The lagging strand requires a slight delay before undergoing replication because it is synthesized discontinuously in short fragments called Okazaki fragments. These fragments are then joined together by DNA ligase to form a continuous strand. This process requires the lagging strand to undergo a slight delay in order to allow for the synthesis and joining of these fragments.

Explanation

The lagging strand requires a slight delay before undergoing replication because it is synthesized discontinuously in short fragments called Okazaki fragments. These fragments are then joined together by DNA ligase to form a continuous strand. This process requires the lagging strand to undergo a slight delay in order to allow for the synthesis and joining of these fragments.

60. In Griffith's experiment which of the following strains of pneumococci was isolated from dead mice?

Living rough cells

Dead rough cells

Living smooth cells

Dead smooth cells

In Griffith's experiment, living smooth cells of pneumococci were isolated from dead mice. This suggests that the transformation of the rough strain into the smooth strain occurred, as the smooth strain was able to cause disease and kill the mice. The rough strain alone did not cause disease, indicating that the transformation of the rough strain was responsible for the lethal effects.

Explanation

In Griffith's experiment, living smooth cells of pneumococci were isolated from dead mice. This suggests that the transformation of the rough strain into the smooth strain occurred, as the smooth strain was able to cause disease and kill the mice. The rough strain alone did not cause disease, indicating that the transformation of the rough strain was responsible for the lethal effects.

61. When DNA replication starts, .......

The phosphodiester bonds between the adjacent nucleotides break.

The bonds between the nitrogen base and deoxyribose sugar break.

The leading strand produces short fragments.

The hydrogen bonds between the nucleotides of two strand break.

When DNA replication starts, the hydrogen bonds between the nucleotides of the two strands break. This is necessary for the separation of the DNA strands and allows for the replication process to occur. Breaking the hydrogen bonds allows the DNA helix to unwind and exposes the nucleotides on each strand, which serve as templates for the synthesis of new complementary strands. The breaking of the hydrogen bonds is a crucial step in DNA replication as it enables the formation of new DNA strands through the pairing of nucleotides.

Explanation

When DNA replication starts, the hydrogen bonds between the nucleotides of the two strands break. This is necessary for the separation of the DNA strands and allows for the replication process to occur. Breaking the hydrogen bonds allows the DNA helix to unwind and exposes the nucleotides on each strand, which serve as templates for the synthesis of new complementary strands. The breaking of the hydrogen bonds is a crucial step in DNA replication as it enables the formation of new DNA strands through the pairing of nucleotides.

62. Hershey and Chase experiment confirms that ......

DNA is always formed from DNA in semiconservative manner.

DNA is the genetic material and not protein.

Radioactive Phosphorus was only found in surrounding.

DNA and Protein both enter in bacterial cell progeny.

The Hershey and Chase experiment involved the use of bacteriophages to confirm that DNA is the genetic material and not protein. In the experiment, the bacteriophages were labeled with either radioactive sulfur (which labels proteins) or radioactive phosphorus (which labels DNA). After infecting the bacteria, it was found that only the radioactive phosphorus was transferred to the bacterial cell progeny, indicating that DNA is the genetic material responsible for inheritance. This experiment provided strong evidence to support the idea that DNA carries the genetic information, not proteins.

Explanation

The Hershey and Chase experiment involved the use of bacteriophages to confirm that DNA is the genetic material and not protein. In the experiment, the bacteriophages were labeled with either radioactive sulfur (which labels proteins) or radioactive phosphorus (which labels DNA). After infecting the bacteria, it was found that only the radioactive phosphorus was transferred to the bacterial cell progeny, indicating that DNA is the genetic material responsible for inheritance. This experiment provided strong evidence to support the idea that DNA carries the genetic information, not proteins.

63. One of the following statements describing the similarities between ribose and deoxyribose, is not correct …..

Both are pentoses

Both enter in the structure of nucleotides

Both are monosaccharide

Both have an OH group attached to C2’

Both ribose and deoxyribose are pentoses, meaning they both have five carbon atoms. They also both enter into the structure of nucleotides, which are the building blocks of DNA and RNA. Additionally, they are both monosaccharides, which means they are simple sugars composed of a single sugar unit. However, the statement that both ribose and deoxyribose have an OH group attached to C2' is incorrect. Deoxyribose lacks the OH group at the C2' position, which is replaced by a hydrogen atom.

Explanation

Both ribose and deoxyribose are pentoses, meaning they both have five carbon atoms. They also both enter into the structure of nucleotides, which are the building blocks of DNA and RNA. Additionally, they are both monosaccharides, which means they are simple sugars composed of a single sugar unit. However, the statement that both ribose and deoxyribose have an OH group attached to C2' is incorrect. Deoxyribose lacks the OH group at the C2' position, which is replaced by a hydrogen atom.

64. The elongation of the produced strand during DNA replication .......

Progresses away from the replication fork.

Is done in the 3′ to 5′ direction

Produces short fragments.

Depends on the action of DNA polymerase.

During DNA replication, the elongation of the produced strand depends on the action of DNA polymerase. DNA polymerase is responsible for adding nucleotides to the growing DNA strand in a complementary manner to the template strand. It catalyzes the formation of phosphodiester bonds between the nucleotides, allowing for the continuous elongation of the new DNA strand. Therefore, the correct answer is that the elongation of the produced strand depends on the action of DNA polymerase.

Explanation

During DNA replication, the elongation of the produced strand depends on the action of DNA polymerase. DNA polymerase is responsible for adding nucleotides to the growing DNA strand in a complementary manner to the template strand. It catalyzes the formation of phosphodiester bonds between the nucleotides, allowing for the continuous elongation of the new DNA strand. Therefore, the correct answer is that the elongation of the produced strand depends on the action of DNA polymerase.

65. True replication of DNA is possible due to ……….

Hydrogen bonding

Phosphate-sugar backbone

Complementary base pairing rule

Presence of DNA repair

True replication of DNA is possible due to the complementary base pairing rule. This rule states that adenine (A) always pairs with thymine (T), and guanine (G) always pairs with cytosine (C). This allows for the accurate and precise replication of DNA during cell division. Each strand of the double helix acts as a template for the synthesis of a new complementary strand, ensuring that the genetic information is faithfully passed on to the next generation of cells.

Explanation

True replication of DNA is possible due to the complementary base pairing rule. This rule states that adenine (A) always pairs with thymine (T), and guanine (G) always pairs with cytosine (C). This allows for the accurate and precise replication of DNA during cell division. Each strand of the double helix acts as a template for the synthesis of a new complementary strand, ensuring that the genetic information is faithfully passed on to the next generation of cells.

66. What does the following mathematical equation mean? A/T = G/C =1

A = G and T = C

A + T = T + G

(A + C) / (G + T) = 1

(A +G) / (C +T) = 0

The equation (A + C) / (G + T) = 1 means that the sum of the occurrences of adenine (A) and cytosine (C) in a DNA molecule is equal to the sum of the occurrences of guanine (G) and thymine (T). This equation is based on Chargaff's rules, which state that in DNA, the amount of adenine is equal to the amount of thymine, and the amount of guanine is equal to the amount of cytosine. Therefore, the ratio of (A + C) to (G + T) is always equal to 1.

Explanation

The equation (A + C) / (G + T) = 1 means that the sum of the occurrences of adenine (A) and cytosine (C) in a DNA molecule is equal to the sum of the occurrences of guanine (G) and thymine (T). This equation is based on Chargaff's rules, which state that in DNA, the amount of adenine is equal to the amount of thymine, and the amount of guanine is equal to the amount of cytosine. Therefore, the ratio of (A + C) to (G + T) is always equal to 1.

67. ……. was the first to isolate the material that was capable of inducing genetic transformation in the non-virulent bacteria.

Chase

Avery

Griffith

Franklin

Avery was the first to isolate the material that was capable of inducing genetic transformation in the non-virulent bacteria.

Explanation

Avery was the first to isolate the material that was capable of inducing genetic transformation in the non-virulent bacteria.

68. Which of the following is untrue for a DNA molecule?

A +G / C + T = 1

A + G = C + T

G + C = A + T

G = C

The equation A + G / C + T = 1 represents the fact that the sum of the adenine (A) and guanine (G) nucleotides is equal to the sum of the cytosine (C) and thymine (T) nucleotides in a DNA molecule. The equation A + G = C + T indicates that the total number of adenine and guanine nucleotides is equal to the total number of cytosine and thymine nucleotides. The equation G = C states that the number of guanine nucleotides is equal to the number of cytosine nucleotides. Therefore, the only statement that is untrue for a DNA molecule is G + C = A + T.

Explanation

The equation A + G / C + T = 1 represents the fact that the sum of the adenine (A) and guanine (G) nucleotides is equal to the sum of the cytosine (C) and thymine (T) nucleotides in a DNA molecule. The equation A + G = C + T indicates that the total number of adenine and guanine nucleotides is equal to the total number of cytosine and thymine nucleotides. The equation G = C states that the number of guanine nucleotides is equal to the number of cytosine nucleotides. Therefore, the only statement that is untrue for a DNA molecule is G + C = A + T.

69. What is the number of nucleotides found in a portion of DNA molecule consists of two complete turns?

10

20

30

40

A portion of a DNA molecule that consists of two complete turns would form a double helix structure. In a double helix, each complete turn consists of 10 nucleotide pairs. Since each nucleotide pair consists of 2 nucleotides, the total number of nucleotides in a portion of DNA molecule with two complete turns would be 10 x 2 x 2 = 40 nucleotides.

Explanation

A portion of a DNA molecule that consists of two complete turns would form a double helix structure. In a double helix, each complete turn consists of 10 nucleotide pairs. Since each nucleotide pair consists of 2 nucleotides, the total number of nucleotides in a portion of DNA molecule with two complete turns would be 10 x 2 x 2 = 40 nucleotides.

70. If a DNA molecule contains about 16.2%of adenine base and 33.4% of guanine. What is the ratio of thymine : cytosine

6.3 : 16.3

34.1 : 34.1

34.1 : 16.3

16.3 : 34.1

The ratio of thymine to cytosine in a DNA molecule can be determined by subtracting the percentages of adenine and guanine from 100% and dividing the remaining percentages equally. In this case, if adenine is 16.2% and guanine is 33.4%, then the percentages of thymine and cytosine would be (100% - 16.2% - 33.4%) / 2 = 50.4% / 2 = 25.2% each. Therefore, the ratio of thymine to cytosine is 16.3 : 34.1.

Explanation

The ratio of thymine to cytosine in a DNA molecule can be determined by subtracting the percentages of adenine and guanine from 100% and dividing the remaining percentages equally. In this case, if adenine is 16.2% and guanine is 33.4%, then the percentages of thymine and cytosine would be (100% - 16.2% - 33.4%) / 2 = 50.4% / 2 = 25.2% each. Therefore, the ratio of thymine to cytosine is 16.3 : 34.1.

71. A piece of DNA molecule is formed of 6 turns. What is the number of phosphate groups on both strands?

120

60

12

2

A DNA molecule is made up of two strands that are twisted together in a double helix structure. Each strand contains a backbone made up of alternating sugar and phosphate groups. Since there are 6 turns in the DNA molecule, there would be 6 complete rotations of the double helix. This means that each strand would have 6 phosphate groups per turn. Since there are two strands, the total number of phosphate groups on both strands would be 6 phosphate groups per turn multiplied by 6 turns, which equals 36 phosphate groups per strand. Therefore, the total number of phosphate groups on both strands would be 36 phosphate groups per strand multiplied by 2 strands, which equals 72 phosphate groups.

Explanation

A DNA molecule is made up of two strands that are twisted together in a double helix structure. Each strand contains a backbone made up of alternating sugar and phosphate groups. Since there are 6 turns in the DNA molecule, there would be 6 complete rotations of the double helix. This means that each strand would have 6 phosphate groups per turn. Since there are two strands, the total number of phosphate groups on both strands would be 6 phosphate groups per turn multiplied by 6 turns, which equals 36 phosphate groups per strand. Therefore, the total number of phosphate groups on both strands would be 36 phosphate groups per strand multiplied by 2 strands, which equals 72 phosphate groups.

72. For hydrogen bonds to form properly between the base pairs in DNA, ……..

The two DNA strands are always having the same distance from one another

The DNA has to be twisted, with ten nucleotide pairs per turn

The two nucleotide strands of the DNA molecule have to run in opposite directions

The two nucleotide strands of the DNA molecule have to run in opposite directions in order for hydrogen bonds to form properly between the base pairs. This is because the bases on one strand of DNA can only form hydrogen bonds with specific complementary bases on the opposite strand. If the strands were oriented in the same direction, the bases would not be able to pair correctly and hydrogen bonds would not be able to form.

Explanation

The two nucleotide strands of the DNA molecule have to run in opposite directions in order for hydrogen bonds to form properly between the base pairs. This is because the bases on one strand of DNA can only form hydrogen bonds with specific complementary bases on the opposite strand. If the strands were oriented in the same direction, the bases would not be able to pair correctly and hydrogen bonds would not be able to form.

73. A portion of DNA double helix contains 50 half turns. What is the number of nucleotides present in that portion?

250

500

150

200

A DNA double helix consists of two strands that are twisted around each other. Each half turn of the helix contains 10 base pairs, which are made up of nucleotides. Since there are 50 half turns in the given portion of the DNA double helix, the number of nucleotides present in that portion would be 50 half turns multiplied by 10 base pairs per half turn, resulting in a total of 500 nucleotides.

Explanation

A DNA double helix consists of two strands that are twisted around each other. Each half turn of the helix contains 10 base pairs, which are made up of nucleotides. Since there are 50 half turns in the given portion of the DNA double helix, the number of nucleotides present in that portion would be 50 half turns multiplied by 10 base pairs per half turn, resulting in a total of 500 nucleotides.

74. Although genetic variation is important for evolution, the survival of the individual demands genetic stability. About 5000 purine bases (adenine and guanine) are lost every day from the DNA of each human cell. This is because ......

The glycosyl linkage to deoxyribose is broken by environmental chemicals.

The linkage to the pyrimidine base is broken by sun ultra violet rays.

The phosphodiester bond is broken by aquatic medium and active forms of oxygen.

All of the above.

The statement in the answer choice suggests that the loss of purine bases from DNA is due to the breaking of the glycosyl linkage to deoxyribose by environmental chemicals. This implies that external factors, such as exposure to certain chemicals, can cause damage to the DNA structure, leading to the loss of purine bases. This explanation aligns with the idea that genetic stability is important for the survival of an individual, as any damage to the DNA can potentially disrupt gene function and lead to harmful effects.

Explanation

The statement in the answer choice suggests that the loss of purine bases from DNA is due to the breaking of the glycosyl linkage to deoxyribose by environmental chemicals. This implies that external factors, such as exposure to certain chemicals, can cause damage to the DNA structure, leading to the loss of purine bases. This explanation aligns with the idea that genetic stability is important for the survival of an individual, as any damage to the DNA can potentially disrupt gene function and lead to harmful effects.

75. A DNA molecule containing P³¹ is transferred in to a media with P³²(radioactive). After two rounds of replication how many strands containing P³²will you observe?

2

4

6

8

During DNA replication, each original DNA strand serves as a template for the synthesis of a new complementary strand. In this case, the DNA molecule containing P31 is transferred into a media with P32. Since P32 is radioactive, it can be detected. After two rounds of replication, there will be a total of 6 strands containing P32. This is because each original DNA strand will produce two new strands, and since P32 is present in the media, it will be incorporated into the newly synthesized strands. Therefore, there will be a total of 6 strands containing P32.

Explanation

During DNA replication, each original DNA strand serves as a template for the synthesis of a new complementary strand. In this case, the DNA molecule containing P31 is transferred into a media with P32. Since P32 is radioactive, it can be detected. After two rounds of replication, there will be a total of 6 strands containing P32. This is because each original DNA strand will produce two new strands, and since P32 is present in the media, it will be incorporated into the newly synthesized strands. Therefore, there will be a total of 6 strands containing P32.

76. DNA exists in a double-stranded form whereas RNA is mainly a single stranded molecule. What is the likely reason for DNA being double stranded?

RNA strands cannot form base pairs

Double stranded DNA is a more stable structure

DNA cannot exist in the single stranded form

It is easier to replicate double stranded DNA than single stranded RNA

Double stranded DNA is a more stable structure because the two strands of DNA are held together by hydrogen bonds between complementary base pairs (adenine with thymine and guanine with cytosine). This double helix structure provides stability and protects the genetic information stored in DNA. In contrast, RNA is mainly single stranded and lacks this stable double helix structure.

Explanation

Double stranded DNA is a more stable structure because the two strands of DNA are held together by hydrogen bonds between complementary base pairs (adenine with thymine and guanine with cytosine). This double helix structure provides stability and protects the genetic information stored in DNA. In contrast, RNA is mainly single stranded and lacks this stable double helix structure.

77. If the number of purine nucleotides in a DNA molecule is 180 nucleotides. What is the number of turns in this molecule?

9

18

27

36

The number of turns in a DNA molecule can be determined by dividing the number of purine nucleotides by 10. In this case, since there are 180 purine nucleotides, dividing by 10 gives us 18 turns.

Explanation

The number of turns in a DNA molecule can be determined by dividing the number of purine nucleotides by 10. In this case, since there are 180 purine nucleotides, dividing by 10 gives us 18 turns.

78. How many free phosphate groups does a plasmid molecule have?

One

Two

Four

None of them

A plasmid molecule does not have any free phosphate groups. Phosphate groups are typically found in nucleic acids, such as DNA and RNA, where they play a crucial role in the structure and function of these molecules. However, plasmids are small, circular, double-stranded DNA molecules that are separate from the chromosomal DNA in bacteria. While plasmids do contain phosphate groups within their DNA backbone, these phosphate groups are not considered "free" as they are involved in forming the phosphodiester bonds that connect the nucleotides in the DNA strand. Therefore, the correct answer is "None of them."

Explanation

A plasmid molecule does not have any free phosphate groups. Phosphate groups are typically found in nucleic acids, such as DNA and RNA, where they play a crucial role in the structure and function of these molecules. However, plasmids are small, circular, double-stranded DNA molecules that are separate from the chromosomal DNA in bacteria. While plasmids do contain phosphate groups within their DNA backbone, these phosphate groups are not considered "free" as they are involved in forming the phosphodiester bonds that connect the nucleotides in the DNA strand. Therefore, the correct answer is "None of them."

79. The following diagram shows an experiment where the researcher used E. coli bacteria to be grown in nutritive medium (X) which contains ¹⁵N then he isolated a bacterial cell its genome contains ¹⁵N only and put it in a nutritive medium (Y) which contains ¹⁴N only. The number of bacterial cells in the 3^rd generation that contains ¹⁵N only is ……..

Zero

Two

Four

Eight

When the researcher isolated a bacterial cell with a genome containing 15N and put it in a medium with 14N, it means that the new generation of bacteria will only have access to 14N for their growth and replication. Since the bacteria cannot synthesize new DNA with 15N, the subsequent generations will not have any 15N in their genomes. Therefore, the number of bacterial cells in the 3rd generation that contains 15N only is zero.

Explanation

When the researcher isolated a bacterial cell with a genome containing 15N and put it in a medium with 14N, it means that the new generation of bacteria will only have access to 14N for their growth and replication. Since the bacteria cannot synthesize new DNA with 15N, the subsequent generations will not have any 15N in their genomes. Therefore, the number of bacterial cells in the 3rd generation that contains 15N only is zero.

80. The diagram provided shows a basic outline of the experiment conducted by Avery and his colleagues. The virulent S cells were killed by high temperatures and divided into three samples. A different enzyme was added to each sample, and then the solution was mixed with live, but nonvirulent, R cells. Assume that mice injected with R cells that have successfully undergone bacterial transformation will die. In which of these three experiments will the mice die?

1 and 2

1 only

1 and 3

2 and 3

3 only

The mice will die in experiments 1 and 2 because in these experiments, the different enzymes added to the samples of killed S cells allow for the transfer of genetic material to the live R cells. This results in the R cells becoming virulent and causing the mice to die when injected. Experiment 3 does not involve the addition of enzymes, so the genetic material from the killed S cells cannot be transferred to the R cells, and therefore the mice will not die in this experiment.

Explanation

The mice will die in experiments 1 and 2 because in these experiments, the different enzymes added to the samples of killed S cells allow for the transfer of genetic material to the live R cells. This results in the R cells becoming virulent and causing the mice to die when injected. Experiment 3 does not involve the addition of enzymes, so the genetic material from the killed S cells cannot be transferred to the R cells, and therefore the mice will not die in this experiment.

81. Which of the following was not determined by Griffith's experiment?

The material being passed between strains of bacteria was DNA.

The heat-killed smooth strain of bacteria would not kill a mouse injected with it.

Genetic material could be passed from the cells of the heat-killed smooth strain to the cells of the rough strain.

The cells of the rough strain of bacteria could be altered to become virulent.

Griffith's experiment determined that the heat-killed smooth strain of bacteria would not kill a mouse injected with it, genetic material could be passed from the cells of the heat-killed smooth strain to the cells of the rough strain, and the cells of the rough strain of bacteria could be altered to become virulent. However, the experiment did not determine that the material being passed between strains of bacteria was DNA.

Explanation

Griffith's experiment determined that the heat-killed smooth strain of bacteria would not kill a mouse injected with it, genetic material could be passed from the cells of the heat-killed smooth strain to the cells of the rough strain, and the cells of the rough strain of bacteria could be altered to become virulent. However, the experiment did not determine that the material being passed between strains of bacteria was DNA.