Tag: zoology

Questions Related to zoology

The DNA strands are antiparallel because of the presence of

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

  1. H-bonds

  2. Peptide bonds

  3. Disulphide bonds

  4. Phosphate-diester bonds

  5. None of the above

Show answer
Correct Option: A
Explanation:

When DNA strands run in opposite direction one strand from 5 prime to 3 prime and another strand from 3 prime to 5 prime is called as antiparallel. The 5 prime end have phosphate in 5$^{th}$position of sugar and 3 prime end have a hydroxyl group on 3$^{rd}$ position of sugar. DNA strands are antiparallel because of the presence of hydrogen bond. Hydrogen bond binds the complementary bases (purine and pyrimidine)

In DNA, adenine pairs with

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

  1. Guanine

  2. Thymine

  3. Cytosine

  4. Uracil

Show answer
Correct Option: B
Explanation:

The nitrogenous bases present in the DNA are purines and pyrimidines. The purines are adenine and guanine. The pyrimidines are thymine and cytosine. The purines are double ring structure while the pyrimidines are the single ring made up of carbon and nitrogen. Purines pair with the pyrimidines by hydrogen bonds. Adenine pairs with thymine by two hydrogen bond while the cytosine pairs with the guanosine by three hydrogen bonds.

So, the correct answer is option B.

DNA is composed of repeating units of

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

  1. Ribonucleosides

  2. Deoxyribonucleosides

  3. Ribonucleotides

  4. Deoxyribonucleotides

Show answer
Correct Option: A
Explanation:
DNA is a chain of polynucleotide which are joined by the phosphodiester bonds. The nucleotide consists of a deoxyribose sugar, nitrogenous bases, and phosphate.The two nucleotide is linked by the phosphodiester bond. It is formed by the linkage between the 3' carbon atom of one sugar molecule and the 5' carbon atom of another. Two hydroxyls (OH) groups on the phosphate molecule bind to the 3’ and 5’ carbons on two independent pentose sugars to form a bond.
So, the correct answer is option D.

Major and minor grooves can be seen in

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

  1. Polypeptide

  2. RNA

  3. DNA

  4. Chromatin

Show answer
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$^o$. At major grooves, the base pairs are far apart while at minor groove the base pairs are closer. Major grooves have base pairs at a distance the DNA binding protein can easily interact with the bases.
So, the correct answer is option A.

Base pairs present in one turn of DNA are

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

  1. $12$

  2. $11$

  3. $10$

  4. $9$

Show answer
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 distance between base pairs is 3.4 A$^o$. The total length of one turn of DNA is 34 A$^o$. The total number of the base pair in each turn is 34/3.4 = 10.
So, the correct answer is option C.

The similarity between bacterial and eukaryotic DNA is that both are

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

  1. Circular

  2. Single stranded

  3. Double stranded

  4. All the above

Show answer
Correct Option: C
Explanation:
Nucleic acids are DNA and RNA. DNA is a genetic material which is mainly present in the nucleus of the cell in eukaryotes like mammals. The genetic material is covered by a nuclear membrane. In prokaryotes like bacteria the genetic material lie freely in the cytoplasm. The region where the nucleic acid are present is known as nucleoid. The similarity between bacterial and eukaryotic DNA is that both are double stranded DNA.
So, the correct answer is option C.

Length of one turn of DNA is

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

  1. $34 \mathring{A}$

  2. $3.4 \mathring{A}$

  3. $0.34 \mathring{A}$

  4. $20 \mathring{A}$

Show answer
Correct Option: A
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$^o$. So the total length of one turn of DNA is 10 x 3.4 =  34 A$^o$.
So, the correct answer is option A.

The two strands of DNA are held together by bonds of

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

  1. Nitrogen

  2. Oxygen

  3. Hydrogen

  4. Carbon

Show answer
Correct Option: C
Explanation:
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, uracil, 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 C.

DNA is very long. It is accommodated in small sized nucleus by

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

  1. DNA-ase digestion

  2. Super coiling

  3. Elimination of repetitive DNA

  4. Deletion of non-essential genes

Show answer
Correct Option: B
Explanation:

DNA is very long. It is accommodated in the small-sized nucleus by super coiling. The enzyme topoisomerase helps in the supercoiling of the DNA which helps in packaging and some biological process. The super coiled DNA is uncoiled during the process of transcription and translation. During transcription the enzyme helicase cuts the phosphate backbone and separates the two super coiled DNA strands while the topoisomerase balances the strain and prevents the recoiling of the DNA.

So, the correct answer is option B.

A $68nm$ length double stranded DNA has 24 adenine nucleotices. What must be the number of guanine nucleotides?

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

  1. $48$

  2. $72$

  3. $76$

  4. $176$

Show answer
Correct Option: D
Explanation:

Length of $3.4 nm $ includes $10$ base pairs.So, $68 nm $ will include $200$ base pairs that is $400$ bases.

A=T AND G=C,
A+T+G+C=$400$,
$24$+$24$+$2G$=$400$.,
$2G$ = $352$.
So, Guanine nucleotides would be $176$.
Hence, the correct answer is option D.