Which of the Following Characterizes the History of Impacts on Earth

question 24

Multiple Choice

Which of the following characterizes the history of impacts on Earth as deduced by impact history on other terrestrial planets?

• A)All major impacts occurred in the first 100 million years after the solar system formed.
• B)Impacts continued at a fairly constant rate throughout the 4.5 billion year history of the solar system.
• C)Impacts were more intense in the early history of the earth but have continued at about half the rate of bombardment since about 4.4 billion years ago.
• D)Impact rates were very high in the early history of the earth,but dropped off after about the first 1 billion years of Earth history to a nearly constant rate since that time.

---

Definitions:

Phosphofructokinase (PFK)

An important enzyme in the glycolytic pathway, regulating the rate of glucose breakdown by converting fructose-6-phosphate into fructose-1,6-bisphosphate.

Glucose-6-phosphate

A glucose sugar phosphorylated at the 6th carbon, playing a critical role in energy metabolism and the glycogen storage pathway.

Fructose-1,6-bisphosphate

A fructose sugar phosphorylated on carbons 1 and 6, an important intermediate in glycolysis which breaks down sugar for energy production in cells.

Aerobic Respiration

A metabolic process in which cells convert biochemical energy, typically from carbohydrates, into ATP, with the consumption of oxygen.