Tag: zoology

Questions Related to zoology

The purine bases of DNA are

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

  1. U and G

  2. A and G

  3. A and C

  4. None of the above

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Correct Option: B
Explanation:

Purines and pyrimidines, make up the two groups of nitrogenous base which plays on important role in structural backbone of DNA. Adenine and guanine are purines, while cytosine and thymine are pyrimidines. Purines pairs with pyrimidines, by formation of H-bonds. Adenine attaches to thymine, by two hydrogen bonds, while cytosine and guanine forms three hydrogen between them.

The two strands of DNA in the double helix is connected by ___________.

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

  1. Covalent bonding

  2. Ionic bonding

  3. Hydrogen bonding

  4. Hydrophobic interactions

  5. Teritary structure

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Correct Option: C
Explanation:

Genetic information is carried in the linear sequence of nucleotides in DNA. Each molecule of DNA is a double helix formed from two complementary strands of nucleotides held together by hydrogen bonds between G-C and A-T base pairs.

Hence, C is the correct option. 

The distance between two DNA strands is 

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

  1. 20$\mathring{A}$

  2. 34$\mathring{A}$

  3. 3.4$\mathring{A}$

  4. 2$\mathring{A}$

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Correct Option: A
Explanation:

According to the Watson Crick double helical model of DNA, the diameter of DNA molecule is 20 angstrom. Hence, the distance between two DNA strand is 20 angstroms.
So, the correct answer is option A.

The histone occupies the major groove of a DNA at an angle of

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

  1. $60^{\circ}$

  2. $90^{\circ}$

  3. $45^{\circ}$ to helix axis

  4. $30^{\circ}$ to helix axis

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Correct Option: D
Explanation:

DNA is acidic. For its compaction, it requires basic (histone) proteins. The histone proteins, are positively charged and occupy the major grooves of DNA at an angle of 30° to helix axis. 

Therefore, the correct answer is option D.

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

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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

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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.