Ans.
HD (Huntington's disease) is a genetic neurological disorder that occurs due to damage and death of brain cells. it is caused by an autosomal dominant mutation in HTT (huntingtin) gene, having a trinucleotide repeat section that makes HTT protein.
The mutation leads to an increase in this nucleotide repeat count, associated with formation of altered or mutated huntingtin protein. These altered proteins show deleterious affect on brain cells and result in Huntington's disease.
Thus, the correct answer is 'option A). a mutated gene.'
Answer:
As a cell grows bigger, its internal volume enlarges and the cell membrane expands. Unfortunately, the volume increases more rapidly than does the surface area, and so the relative amount of surface area available to pass materials to a unit volume of the cell steadily decreases.
Answer:
B. Populations of amphibians in a few local areas have declined dramatically in the last few decades
Explanation:
The continuous, low-level extinction of species that has occurred throughout the World and at least six species of frogs have not been seen for one to three decades and also it has recently been discovered that some species of salamander-specific chytrid has gone into extinction
