Answer:
b) spontaneous reverse mutation
Explanation:
Spontaneous mutations are produced by natural biological processes, while induced mutations are produced by mutagenic agents that trigger nucleotide errors in the DNA sequence. In the first phase of the experiment, Sally generated an induced mutation by using 5-bromouracil. The resulting strain required a constant supply of tryptophan to grow.
A reverse mutation restores the wild-type phenotype modified by a forward mutation, thereby reversing the phenotypic alteration to its original state. In a second step of the experiment, the colonies grew without the supply of tryptophan, thereby evidencing that the mutation was reversed in the original colony.
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The answer is :
B. A eukaryotic cell's nucleus contains the DNA or the genetic material of the cell.
The DNA has the necessary information for the cell's construction and the control of the synthesis tasks done by the cell. The nucleus is protected by the nuclear membrane. It surrounds the nucleus with a membrane with many pores.
Explanation:
The nucleus is a membrane-enclosed organelle located in most eukaryotic cells. The nucleus is the largest organelle in the cell and includes most of the cell's genetic information (mitochondria also contain DNA, called mitochondrial DNA, but it proceeds up just a small portion of the cell's overall DNA content. Inside its fully enclosed nuclear membrane, it contains the preponderance of the cell's hereditary material. This material is designed as DNA molecules, along with a family of proteins, to form chromosomes.
Cells are the basic unit of life
