Tag: genetics: inheritance

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Questions Related to genetics: inheritance

Multiple choice biology inherited changes linkage and crossing over linkage and recombination genetics: inheritance

A DNA molecule measures 204 nm in length; 35% of the molecule has AT base pairs. Find out the number of H-bonds existing between the two strands of DNA.

  1. 1590

  2. 159

  3. 1410

  4. 141
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

DNA length 204 nm = 600 base pairs (0.34 nm/bp). 35% AT = 210 AT pairs (2 H-bonds each = 420). 65% GC = 390 GC pairs (3 H-bonds each = 1170). Total = 420 + 1170 = 1590.

Multiple choice biology inherited changes linkage and crossing over linkage and recombination genetics: inheritance

A human male is heterozygous for two autosomal genes A & B and homozygous dominant for 3rd autosomal gene C. The individual is having sry gene (S) on its Y-chromosome. What will be the probability of sperms to carry abcS condition? 

  1. $\frac{1}{4}$
  2. $\frac{1}{8}$
  3. $0$
  4. $\frac{1}{16}$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The human male is heterozygous for A and B, and homozygous dominant for C, with genotype Aa Bb CC S (plus Y). To produce a sperm carrying the abcS condition, the sperm must receive recessive alleles a and b, but the individual is homozygous dominant for C (meaning only allele C is present, never c). Therefore, the probability of producing a sperm with the allele c is 0, making the overall probability 0.

Multiple choice biology inherited changes linkage and crossing over linkage and recombination genetics: inheritance

Assume that the occurrence of nitrogen bases in adjacent positions in a DNA strand is random. Identify the minimum number of nucleotides in a DNA strand where GAAT can occur once on the basis of probability

  1. 512

  2. 256

  3. 4096

  4. 1024
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The probability of a specific 4-nucleotide sequence occurring at any position is (1/4)^4 = 1/256. To expect this sequence to occur once, you need 256 positions. Thus, 256 nucleotides are required.

Multiple choice biology inherited changes linkage and crossing over linkage and recombination genetics: inheritance

In an organism punk is a sex-linked recessive trait and black hair heterozygous female is mated to white male which is not spotted, the phenotypic ratio of the offspring would be :

  1. 1/4 spotted black; 1/4 pink spotted white; 1/4 unspotted black; 1/4 uspotted white

  2. 1/2 spotted black; 1/2 pink spotted white

  3. 3/4 pink spotted black; 1/4 pink spotted white

  4. 3/4 unspotted black; 1/4 pink spotted white
Reveal answer Fill a bubble to check yourself
A Correct answer