Which of the following terms is used to describe several planets orbiting a star?

a constellation

the universe

a galaxy

a solar system

Dr. bad has developed a way to damage the atp-binding cassette transporter (abc transporter) on a cell. the cell's abc transporter can no longer bind and use atp when it's transporting substances. which of the following statements best describes how this damage would effect the transport of substances in the affected cell? (choice a) substances at a low concentration outside the cell would be more rapidly transported into the cell, where there is a high concentration. (choice b) substances at a high concentration outside the cell would not be transported into the cell, where there is a low concentration. (choice c) equilibrium would be established between all substances inside and outside of the cell. (choice d) substances at a low concentration outside the cell would not be transported into the cell, where there is a high concentration.

Are the earth's ocean floor and continents the same age geologically? why or why not?

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