I think it is repeatable, testable, observable
Vestigial structures. These are structural elements that once served a purpose but as the organism evolved now serves no purpose.
Answer:
A. single-gene
Explanation:
It is controlled by a single gene that has two alleles. The allele for a widow's peak is dominant over the allele for a hairline with no peak.
Be more specific please on this question
Answer:
Spindle fibers form a protein structure that divides the genetic material in a cell. The spindle is necessary to equally divide the chromosomes in a parental cell into two daughter cells during both types of nuclear division: mitosis and meiosis. During mitosis, the spindle fibers are called the mitotic spindle.
Explanation:
