Download App

Principles of Inheritance and Variation — BIOLOGY STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 ScienceBIOLOGYPrinciples of Inheritance and Variation3 Marks
Question
Explain the inheritance of Sickle Cell anaemia.
✓

Answer

Sickle-cell anaemia : This is an autosome linked recessive trait that can be transmitted from parents to the offspring when both the partners are carrier for the gene (or heterozygous). The disease is controlled by a single pair of allele, $Hb ^{ A }$ and $Hb ^{ S }$. Out of the three possible genotypes only homozygous individuals for $Hb ^{ S }\left( Hb ^{ S } Hb ^{ S }\right)$ show the diseased phenotype. Heterozygous $\left( Hb ^{ A } Hb ^{ S }\right)$ individuals appear apparently unaffected but they are carrier of the disease as there is 50 per cent probability of transmission of the mutant gene to the progeny, thus exhibiting sicklecell trait.
Image

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Explore more

More "3 Marks Question" from Principles of Inheritance and Variation→Principles of Inheritance and Variation — all question types→BIOLOGY STD 12 Science question papers→Gujarat Board STD 12 Science question papers→Gujarat Board question paper generator→

Similar questions

  1. Mature seeds of legumes are non-albuminous.Then, can it be considered that double fertilization does not occur in legumes? Explain your answer.
  2. Write one similarity and one difference between autogamy and geitonogamy.
→
Flowering plants have developed many devices to discourage self-pollination and to encourage cross-pollination. Explain three such devices.
→
Given below is a graph depicting organismic response to changing external conditions. According to their response the organisms are grouped into two types. Name the type which will show (i) Pattern A (ii) Pattern B.

→
Explain adaptive radiation. (Figure is not necessary)
→
What is molecular homology? Cite one example.
→
Suggest some important steps that you would recommend to be taken to improve the reproductive health standards in India.
→
One of the codons on mRNA is AUG. Draw the structure of tRNA adaptor molecule for this codon. Explain the uniqueness of this tRNA.
→
How did an American Company, Eli Lilly use the knowledge of rDNA technology to produce human insulin?

Or

How did Eli Lilly synthesise the human insulin? Mention one difference between this insulin and the one produced by the human pancreas.

Or

How did Eli Lilly Company go about preparing the human insulin? How is the insulin thus produced different from that produced by the functional human insulin gene?

→
Given below is the representation of amino acid composition of the relevant translated portion of b-chain of haemoglobin, related to the shape of human red blood cells.
  1. Is this representation indicating a normal human or a sufferer from certain related genetic disease? Give reason in support of your answer.
  2. What difference would be noticed in the phenotype of the normal and the sufferer related to this gene?
  3. Who are likely to suffer more from the defect related to the gene represented – the males, the females or both males and females equally? Andwhy?
→
Explain how biodiversity is important for human.
→