Cell differentiation occurs when various genes are expressed to a different extent in different cells. what does it mean for a gene to be "turned off," or not expressed?

Match the following. match the items in the left column to the items in the right column. 1. foreshocks process used to locate the epicenter of an earthquake 2. magnitude newer magnitude scale that measures the amount of moved (displaced) rock along a fault to determine the strength of an earthquake 3. mercalli intensity scale measure of the total amount of energy released during an earthquake 4. moment magnitude scale areas on active faults where a major earthquake hasn't occurred in a long time 5. richter scale mini-quakes that usually occur before a major earthquake 6. seismic gaps scale that measures the effects or severity of an earthquake 7. triangulation scale of magnitude based on the size of seismic waves produced by an earthquake

Living cells cannot use heat to provide the activation energy for biochemical reactions because which choice(s) complete the sentence correctly? a) answer choice ii. eliminate b) answer choices ii and iv. c) answer choice iii and iv. d) all answers can complete the sentence.

Where do the respiratory and circulatory systems meet? a. in the heart b. in the muscles c. in the lungs d. in the brain