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

Wilkins X-ray diffraction showed the diameter of the DNA helix is

  1. 10 $\mathring { A }$
  2. 20 $\mathring { A }$
  3. 30 $ \mathring { A }$
  4. 40 $ \mathring { A }$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Wilkins X -ray diffraction showed the diameter of the DNA helix is around 20 $\mathring A$.  According to Maurice Wilkins, the structure of DNA of all species comprises two helical chains each coiled round the same axis, and each with a pitch of 34 angstroms and a radius of 10 angstroms. According to another study, when measured in a particular solution, the DNA chain measured 20 to 26 angstroms wide, and one nucleotide unit measured 3.3 long. Although each individual repeating unit is very small, DNA polymers can be very large molecules containing millions of nucleotides.
So, the correct answer is option B.

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

The back bone in the structure of DNA molecule is made up of

  1. Pentose sugar and phosphate

  2. Hexose sugar and phosphate

  3. Purine and pyrimidine

  4. Sugar and phosphate
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

DNA is a polymer of deoxyribonucleotides. The deoxyribonucleotides are made up of phosphoric acid and deoxyribonucleosides. The deoxyribonucleosides are made up of deoxyribose sugars and nitrogenous bases. The deoxyribonucleotides are joined to each other with the help of 3', 5' phosphodiester bonds forming the backbone of single DNA chain. In a molecule of DNA, two such chains are present attached with each other with the help of hydrogen bonds between the nitrogenous bases of deoxyribonucleotides.

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

The DNA molecule has uniform diameter due to

  1. Double strandedness.

  2. Presence of phosphate.

  3. Specific base pairing between purine and pyrimidine.

  4. None of the above.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

DNA molecule has uniform diameter due to specific base pairing between purine and pyrimidine. In DNA, the bases adenine and guanine form hydrogen bonds with their complementary pyrimidines; thymine and cytosine, respectively, this is called as complementary base pairing.

Most DNA molecules consist of two biopolymer strands coiled around each other to form a double helix. The two DNA strands are known as polynucleotides since they are composed of simpler units called nucleotides. Each nucleotide is composed of a nitrogen-containing nucleobase either guanine (G), adenine (A), thymine (T), or cytosine (C) as well as a monosaccharide sugar called as deoxyribose and a phosphate group.
So, the correct answer is option C.

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

The two long polynucleotide chains of DNA are held together by

  1. Hydrogen bonds

  2. Covalent bonds

  3. Metallic bonds

  4. Ionic bonds

  5. Polar covalent bonds
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

DNA is a double helical molecule made of two antiparallel strands of nucleotides which is linked by hydrogen bonds between complementary base pairs. DNA carries the genetic instructions used in the growth, development, functioning and reproduction of all known living organisms. Adenine (A) pairs with Thymine (T) via two hydrogen bonds. Guanine (G) pairs with Cytosine (C) via three hydrogen bonds. Hence option A is correct.

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

The DNA strands are anti-parallel because of

  1. H bonds

  2. Phospho-diester bonds

  3. Disulphide bonds

  4. Phosphate bonds
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The DNA strands runs anti-parallel, due to phosphodiester bonds. A phosphodiester bond occurs when exactly two of the hydroxyl groups in phosphoric acid react with hydroxyl groups on other molecules to form two ester bonds. Phosphodiester bonds are central to most life on Earth, as they make up the backbone of the strands of DNA. In DNA and RNA, the phosphodiester bond is the linkage between the 3' carbon atom of one sugar molecule and the 5' carbon atom of another, deoxyribose in DNA and ribose in RNA. Strong covalent bonds form between the phosphate group and two 5-carbon ring  two ester bonds. Due to this bond the DNA strands run anti-parallel.

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

In the DNA molecule,

  1. The proportion of adenine in relation to thymine varies with the organism.
  2. There are two strands which run antiparallel one in $5'\rightarrow 3'$ direction and other in $3'\rightarrow 5'$.

  3. The total amount of purine nucleotides and pyrimidine nucleotides is not always equal.
  4. There are two strands which run parallel in the $5'\rightarrow 3'$ direction.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

DNA (Deoxyribonucleic Acid) is composed of two polynucleotide strands (the polymers of nucleotides), which form what looks like a ladder. The nitrogenous bases in DNA store the instructions for making polypeptide chains, essentially coding for every feature of the entire organism. The two polynucleotide strands run 'antiparallel' to each other, with nitrogenous bases projecting inwards. The term 'antiparallel' means that the strands run in opposite directions, parallel to one another. The antiparallel strands twist in a complete DNA structure, forming a double helix.

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

In the speculation concering the origins of life, one theory states that the combination of purines, pyrimidines, sugars, and phosphates is called as______________.

  1. Nucleotides

  2. Nucleosides

  3. Carbohydrates

  4. Fats

  5. Proteins
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Nucleotides are formed by the combination of purines or pyrimidines (nitrogenous bases), sugars (pentose), and phosphates. Nucleosides lack the phosphate group, making option A the correct answer.

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

If one strand of DNA sequence is - 5'-GAATTG-3' - then the sequence of the opposite strand is

  1. 5'-CAATTC-3'

  2. 5'-CTTAAC-3'

  3. 5'-GAATTG-3'

  4. 5'-GTTAAG-3'

  5. 5'-TAATTC-3'
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A DNA strand is complementary. This means adenine pairs with thymine and cytosine pairs with guanine in the opposite strand. The given strand has a sequence 5'-GAATTG-3'. Hence the complementary strand will have a sequence 5'-CAATTC-3'. Thus the correct answer is option A.

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

DNA is directly involved in the synthesis except that of

  1. DNA

  2. Protein

  3. tRNA

  4. mRNA
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
DNA is genetic material found in the living cell. It helps to carry characters from one generation to the other. The process by which the DNA replicated and forms another DNA molecule is known as replication. Parent strand of the DNA strand act as a template for synthesis of another DNA molecule.
Transcription is the process by which DNA is converted into RNA. The enzyme RNA polymerase plays an important role in transcription. The sequence of the nitrogenous base on the DNA acts as a template and determines the sequence of the nitrogenous base on the RNA. The RNA formed by the DNA are messenger RNA, t- RNA and ribosomal RNA.
Protein is formed by the m-RNA by process of translation.
So, the correct answer is option B.
Multiple choice zoology structure of chromosome, cell cycle and cell division structure of dna nucleic acid heredity and inheritance

A $340\overset{o}{A}$ long segment of DNA molecule has $20$ thymine nitrogenous bases, what will be the number of guanine nitrogen bases in the same segment?

  1. $10$
  2. $40$
  3. $30$
  4. $160$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
Option (C) 30

$ 34A = 10 $ nucleotides
$ 340A = 100 $ nuclotides
$ A = T = 20 $
$ 100-40 = 60 $ nucleotides
$ G = C = 60 $
Hence $ G = 60/2 = 30 $ nuclotides