C would be the correct answer.
Answer:
The Thymus is a unique gland which protects the body against autoimmunity when the immune system act against itself.Hence the Thymus plays a significant role the dual systems i.e.,the lymphatic system (body’s defensive mechanism) and the endocrine system
Explanation:
The Thymus is special gland located anteriorly to the chest directly behind the sternum and in between the lungs. Active until puberty and gradually shrinks to become fat after puberty.
Function: Prior to birth and during childhood thymus engage in producing and maturation of T-lymphocytes or T-cells a particular type of white blood cells which defence the body against infectious disease germs.Though the organ does not function throughout the life span but it plays a significant role protecting the body against autoimmunity refers to an immune system works against itself .Therefore the thymus plays a key role in lymphatic system and an endocrine system.
Secretion:Thymus secretes Thymosin a hormone it instigates the development of T-Cells ( disease resisting cells) Thymosin stimulates the development of T-Cells until a human attains its puberty.
At the age of 75 thymus becomes a fatty tissue.
Answer:
The correct answer would be - Characteristics can be lost in evolution.
Explanation:
The new evidence helps in developing a new hypothesis. In this case, new evidence proved that the Chondrichthyes diverged after the evolution of bone had started instead of before the evolution started. This process called atavism where an ancestral genetic trait reappears after having lost. This leads to loss of the traits in the evolution
This can take place by knocking the mutation out to overriding the gene by the old gene or overriding the new trait by the old trait during the evolution period.
The question is incomplete. The complete question is as follows:
Which of the following mutations is most likely to cause a phenotypic change?
A) a duplication of all or most introns
B) a large inversion whose ends are each in intergenic regions
C) a nucleotide substitution in an exon coding for a transmembrane domain
D) a single nucleotide deletion in an exon coding for an active site
E) a frameshift mutation one codon away from the 3' end of the nontemplate strand
Answer: D) a single nucleotide deletion in an exon coding for an active site
Explanation:
Deletion or insertion of a single nucleotide in an axon coding for an active site is called frameshift mutation.
The sequence of codons is read during translation, in order to synthesize a amino acids chain and form a protein from the nucleotide sequence. Frameshift mutations occur when the usual codon sequence is broken by the deletion or addition of one or more nucleotides. For example, if only one nucleotide is removed from the axon sequence during the RNA splicing process, then there will be a disrupted reading frame for all codons before and after the mutation. This may result in several incorrect amino acids being introduced into the protein. Disruption in protein sequence will cause phenotypic change.
Hence, the correct option is D) a single nucleotide deletion in an exon coding for an active site
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