Explain two reasons how and why Alfred Wegener initially theorized that continents may have been joined at one time.

A muscle cramp is a sudden, painful contraction of a muscle, during which movement is difficult. What is happening at the cellular level during a muscle cramp? A. The proteins in the myofibrils become denatured, preventing relaxation. B.

What are the only organelles found in bacterial cells?

Which statement best supports the development of new wind farms? O Wind farms decrease carbon dioxide concentrations in the atmosphere. O Wind farms increase public dependence on burning fossil fuels for energy.

Which of the following explains why elements in column 17 (the halogens) are very reactive? Their atoms contain three energy levels. Their atoms need only one electron to complete their outer energy level. Their atoms have large masses.

A biologist marked 200 mice, by putting leg bands on them, out of a forest containing an unknown number of mice. The marked mice were then returned to the forest for 6 months to mix thoroughly.

Siamese cats have dark fur on their face, ears, legs and tail. On the core of their bodies they have lighter colored fur. The color of the fur is determined by an enzyme. On the cooler parts of the body the enzyme causes darker fur.

Which organs perform both mechanical digestion and chemical digestion of food?

What animals can eat chocolate

What do cells have in common

Summarize the similarities and differences of Prophase and Telophase.