In a biogeochemical cycle, a chemical element spends time in different places, called

Which of these correctly describes the difference between processes that take place in prokaryotic and eukaryotic cells?

Our planet has experienced five major extinctions in the four billion year history of life. the first, 450 million years ago, occurred shortly after the evolution of the first land-based plants and 100 million years after the cambrian explosion. the second extinction occurred 350 million years ago, causing the formation of coal forests. next earth experienced two mass extinctions during the triassic period, between 250 and 200 million years ago. the fifth mass extinction occurred 65 million years ago, ending the reptilian dominance of the earth. according to richard leakey, the sixth mass extinction is happening right now. leakey suggests that we, the human race, are the cause. each year, at our hand, approximately 50,000 species vanish from earth. he believes that man is destroying earth at a rate comparable with the impact of a giant asteroid. leakey's statistics indicate that 50% of earth's species will become extinct within the next 100 years assuming leakey's hypothesis of a sixth mass extinction to be true, how will we expect the model to change? a) a sharp spike in the graph approximately 100 million years from now b) a dip in the graph, followed by a sharp spike about 100 million years from now c) a sharp spike in the graph immediately following the "0" location of the x axis d) a plateau following the "0" mark on the x axis, followed by a gradual rise to a new peak

Suppose a point mutation, such as a change from an adenine to a guanine, occurs in the genome of a human sperm cell. the mutation could occur in any region of a gene. the effect of the mutation on the phenotype of the offspring will be determined by where the mutation occurs and its effect on the final gene product. in which of the following scenarios could the mutation alter the phenotype of the offspring? select all of the scenarios that apply the mutation occurs in the promoter and affects the rate of gene transcription. the mutation results in a new, dominant allele the mutation occurs in a portion of an intron not responsible for exon splicing the mutation occurs in a gene that controls development and alters differentiation of a cell type during development. the mutation occurs in a codon and alters the function of the final protein e mutation occurs in a codon, and the amino acid sequence of the final protein is unchanged.