Which question could be answered using dna as a molecular clock? how old is a dinosaur bone? how long ago was a dinosaur track left in the mud? how long ago did two species of birds share an ancestor? how old was a bird when it died?

How long ago did two species of birds share an ancestor?

Explanation:

Molecular clocks estimates the time of divergence of two species or populations from each other. The process compares the total number of different nucleotide present in genome of two organisms. The average rate at which the specific gene evolves tells about the dates of evolutionary branch points. By comparing the total number of different nucleotides present in genome of two birds species, molecular clock can answer "How long ago did two species of birds share an ancestor?"

interphase

the period of cell growth when the cell synthesizes new molecules and organelles. the cell is not dividing and it constitutes the majority of the time spent in the cell cycle

prophase

changes occur in the nucleus and cytoplasm. the chromatin condenses to form structures (sister chromatids) visible with a light microscope and the mitotic spindle begins to form, but the nucleus is still in tact

prometaphase

the nuclear envelope fragments and the spindle microtubules attach to the kinetochores of the sister chromatids

metaphase

all the cell's duplicated chromosomes are lined up at an imaginary plane equidistant between the poles of the mitotic spindle

anaphase

begins when sister chromatids separate from each other and ending when a complete set of daughter chromosomes arrives at each of the two poles of the cell

telophase

the daughter nuclei form at the two poles of a cell

cytokinesis

the division of a cytoplasm to form two separate daughter cells. usually occurs during telophase during mitosis. this and mitosis make up to mitotic (m) phase of the cell cycle