Tag: zoology

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

The base pairs of DNA are correctly shown as

  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
Reveal answer Fill a bubble to check yourself
C Correct answer
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.

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

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

  1. $200 \mathring{A}$
  2. $100 \mathring{A}$
  3. $20 \mathring{A}$
  4. $50 \mathring{A}$
Reveal answer Fill a bubble to check yourself
C Correct answer
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.
Multiple choice zoology structure of chromosome, cell cycle and cell division structure of dna nucleic acid heredity and inheritance


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

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
B Correct answer
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'.

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

Which of the following is TRUE regarding sense and antisense strands?

  1. Both the strands are present on RNA

  2. Both the strands are present on DNA

  3. Sense strand is on DNA and antisense on RNA

  4. Sense strand is on RNA and antisense on DNA
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Both sense and antisense strands are present in DNA as these act as antisense strand acts as a template during transcription and sense strand has the same sequence as mRNA in the nucleus.

So, the correct option is B.

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

In which of the following DNA sequences the sequence of nucleotides is the same when one strand is read left to right and the other strand is read right to left?

  1. RFLP

  2. RAPD

  3. VNTR

  4. Palindromic sequence
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
A palindromic sequence is a sequence made up of nucleic acids within double helix of DNA or RNA that is the same when reading from 5' to 3' on one strand and 5' to 3' on the other, complementary strand. 
So, the correct answer is 'Palindromic sequence'.
Multiple choice zoology structure of chromosome, cell cycle and cell division structure of dna nucleic acid heredity and inheritance

The double-helix structure of DNA was described by

  1. Watson

  2. J.D. Watson and F. H. C. Crick

  3. Maurice Wilkins

  4. All of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The structure of DNA was deciphered by Watson and Crick in 1953 on the basis of X-ray diffraction data generated by Wilkins, Astbury and Franklin. Wilkins, Watson and Crick were awarded Nobel prize for their model in 1962.
So, the correct answer is option D.

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

The characteristic feature of Z-DNA is

  1. Left handed

  2. Right handed

  3. 12 base pairs in each turn

  4. Both A and C
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

DNA duplex of Watson and Crick is right handed and is called as B-DNA. Z-DNA is left handed double helix, which contains zigzag backbone of phosphodiester bonds and 12 base pairs per turn. The diameter of Z-DNA is 18 $\mathring A$ as against B-DNA diameter of 20 $\mathring A$.
So, the correct answer is option D.

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

Which of the following has higher surface area (SA) to volume (V) ratio?

  1. Red blood cell

  2. Nails

  3. DNA

  4. Human Hair
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Surface area to volume ratio increases as the size of an object decreases. DNA, being a molecular structure, has a significantly higher surface area to volume ratio compared to cellular structures like red blood cells or macroscopic objects like hair and nails.