Which statement describes an activity of a decomposer?*

The calcium concentration in the root cells of certain plants is higher than in the surrounding soil. Calcium may continue to enter the root cells of the plant by the process of*

Homeostasis is maintained in a single-celled organism by the interaction of*

Within which structure of an animal cell does DNA replication take place?*

The shape of a protein is originally determined by the*

Plant cells can synthesize energy-rich organic molecules, and later break them down to extract that energy for performing life processes. These activities require direct interaction between the*

Selective breeding has been used for thousands of years to*

A deletion of a DNA segment alters a gene in a single skin cell of an individual. Which statement best describes a result of this mutation?*

Some goats have been genetically modified with a human gene that codes for a blood anticlotting factor. The anticlotting factor can then be extracted from the goat milk and used during surgery. To produce these genetically modified goats, scientists most likely*

Which characteristic is necessary for natural selection to occur in a species?*

Researchers use a variety of techniques to learn more about the function of a specific gene in an organism. In one type of experiment, called a loss-of-function experiment, the gene being investigated is eliminated. In a gain-of-function experiment, extra copies of the gene being investigated are inserted. The cell process most directly affected in both experiments is*

Plants are green because they contain the protein chlorophyll. A bucket was left on the lawn for one week. When the bucket was removed, the grass under the bucket had turned from green to a yellowish white color. This change is due to the interaction between the grass and*

Which statement describes a function of the human male reproductive system?*

Exposure to toxins during early stages of pregnancy is more likely to cause birth defects than exposure in late pregnancy because*

Although a liver cell and a muscle cell in a human developed from the same single cell, their appearance and functions are different. This is because the liver cell*