Tag: structure of chromosome, cell cycle and cell division

Questions Related to structure of chromosome, cell cycle and cell division

DNA strands are joined by

zoology structure of chromosome, cell cycle and cell division structure of dna nucleic acid heredity and inheritance

  1. Oxygen bonds

  2. Hydrogen bonds

  3. Carbon bonds

  4. Nitrogen bonds

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Correct Option: B
Explanation:
Double helical structure of DNA was proposed by Watson and Crick. DNA is made up of a nitrogenous base, phosphate, and sugar. It has deoxyribose sugar which has hydrogen at second carbon. The nitrogenous bases present in the DNA are purines and pyrimidines. Purines are double ring while pyrimidines are single ring structure. Adenine and guanine are purines while thymine and cytosine are pyrimidines. A purine is attached to pyrimidine by hydrogen bond. Adenine is attached to thymine by two hydrogen bonds while three hydrogen bond is present between guanine and cytosine.
So, the correct answer is option B.

Sugar found in DNA is

zoology structure of chromosome, cell cycle and cell division structure of dna nucleic acid heredity and inheritance

  1. Dextrose

  2. Levulose

  3. Glucose

  4. Deoxyribose

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Correct Option: D
Explanation:
DNA has deoxyribose sugar while RNA has ribose sugar. The deoxyribose sugar has hydrogen at second carbon while the ribose sugar has the hydroxyl group at the second carbon of the hexose ring. Ribose sugar is a monosaccharide which has five carbon atom. C$ _5$H$ _{10}$O$ _5$ is the chemical formula of ribose and it is a pentose sugar. 
So, the correct answer is option D.

The distance between two complementary strands of DNA almost remains the same because 

zoology structure of chromosome, cell cycle and cell division structure of dna nucleic acid heredity and inheritance

  1. Hydrogen bonds between the complementary nitrogen bases of the two chains

  2. Hydrophobic interactions between nitrogen bases

  3. Base pairing between purines and pyramidines

  4. All the above

Show answer
Correct Option: D
Explanation:

The distance between two complementary strands always remains the same because there are hydrogen bonds between the nitrogen bases of two strands restricting movement. The bonds are formed correctly on the opposite ie the bonds are between purines and pyrimidines.

Also, these interactions between nitrogen bases are hydrophobic.
So, the correct option is D.

The strands of DNA are associated with the help of

zoology structure of chromosome, cell cycle and cell division structure of dna nucleic acid heredity and inheritance

  1. Hydrogen

  2. Carbon

  3. Oxygen

  4. Nitrogen

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Correct Option: A
Explanation:

DNA has a double stranded structure where, the purines are linked to pyrimidines with the help of hydrogen bonds. Adenine is linked to thymine by two hydrogen bonds while, cytosine is linked to guanine by three hydrogen bonds.

In DNA, guanine pairs with

zoology structure of chromosome, cell cycle and cell division structure of dna nucleic acid heredity and inheritance

  1. Cytosine

  2. Thymine

  3. Uracil

  4. Adenine

Show answer
Correct Option: A
Explanation:

According to the base pair rule, purine pairs with pyrimidine. Hence, guanine pairs with cytosine by formation of three hydrogen bonds.

In the structure of DNA, one-nucleotide purine base joins with pyramid type by which bond?

zoology structure of chromosome, cell cycle and cell division structure of dna nucleic acid heredity and inheritance

  1. Aster

  2. Weak hydrogen

  3. Glycosidic

  4. Peptide

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Correct Option: B
Explanation:

Answer is option B i.e. "Weak hydrogen"
DNA is made up of nucleotide. Nucleotides join up with one another based on chemical compatibility of their nitrogen bases that are held together by weak hydrogen bond. In DNA, this hydrogen bond helps in stabilizing the nucleic acid structure.

For two closely related species, the DNA would be

zoology structure of chromosome, cell cycle and cell division structure of dna nucleic acid heredity and inheritance

  1. Completely different

  2. Somewhat different

  3. Very different

  4. Very similar

  5. Identical

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Correct Option: D
Explanation:

Species that are very closely related have very similar DNA with only minor differences. They are related through a common ancestor. 

The base pairs of DNA are correctly shown as

zoology structure of chromosome, cell cycle and cell division structure of dna nucleic acid heredity and inheritance

  1. A $\equiv $ T and C = G

  2. A = T and C = G

  3. A = T and C $\equiv $ G

  4. A $\equiv $ T and C $\equiv $ G

Show answer
Correct Option: C
Explanation:

In DNA, purines pairs with pyrimidines. Adenine pairs with Thymine with double hydrogen bond and Guanine pairs with Cytosine with the help of triple hydrogen bond.

Diameter of DNA is/Wilkin's X-ray diffraction showed DNA diameter to be

zoology structure of chromosome, cell cycle and cell division structure of dna nucleic acid heredity and inheritance

  1. $200 \mathring{A}$

  2. $100 \mathring{A}$

  3. $20 \mathring{A}$

  4. $50 \mathring{A}$

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Correct Option: C
Explanation:
DNA has the double helical structure where the two strands are tightly coiled over each other. B- DNA has right-handed helix with the major and minor groove. The diameter of the DNA is 20 A$^o$. The number of base pairs in one turn is 10 and the distance between base pairs is 3.4 A$^o$. The total length of one turn of DNA is 34 A$^o$.
So, the correct answer is option C.


Two nucleotides in a strand are linked through H-bond form a dinucleotide.

zoology structure of chromosome, cell cycle and cell division structure of dna nucleic acid heredity and inheritance

  1. True

  2. False

Show answer
Correct Option: B
Explanation:

  • The two strands of the double helix DNA have base pairing between complementary purines and pyrimidines. Adenine pairs with Thymine or vice versa by two hydrogen bonds and Guanine pairs with Cytosine or vice versa by three hydrogen bonds. 
  • The two nucleotides on the same strand are linked through phosphodiester bond between 5' phosphate group of one mononucleotide and 3' OH group of other mononucleotide, to form a dinucleotide.
Hence, the statement given in the question is incorrect.
So, the correct answer is 'False'.