Before there was any life on earth, which gas was absent from earth's ancient atmosphere?

A. nitrogen

B. ammonia

C. oxygen

D. methane

What is the ultimate source of genetic variability?

Mendel's law of independent assortment has its basis in which of the following events of meiosis I? alignment of pairs of homologous chromosomes along the middle of the cell synapsis of homologous chromosomes crossing over of homologous pairs of

How much higher is the avidity of IgM compared to IgG assuming that both isotypes have the same affinity? A) 2-fold B) 5-fold C) IgG had the same avidity as IgM D) 10-fold

A pure line of guinea pigs with genotype a/a; b/b is crossed to a pure line with genotype a/a; b/b. the f1 male and female guinea pigs are crossed to each other to generate the f2.

What the cell of the fish?

How might more than one agent of physical weathering operate in the same place

What is the primary source of energy for food chains in an ecosystem? decomposers producers consumers the sun

How do you calculate how much energy is transferred from one trophies level to the next

How does seafloor spreading move plates?

In what ways do humans use diatoms?