At what point does a fetus have a heartbeat

What must happen before meiosis can begin? a. four gametes must be produced b. the four tetrads must be pulled apart c. dna doubles and produces sister chromatids d. the cell membrane pinches together

Anita thinks that she has heterozygous alleles for red hair.if she is correct, which of these diagrams best illustrates anitas alleles pf red hair

If bacteria are much too small to see, what is one reason why can we see colonies in the petri dishes that have plenty of food to eat after only a few days?