Which describes a promoter? a. the first part of an operon that regulates where, when, and to what level a gene is expressed b. the part of an operon that, if attached by a repressor protein, suppresses the expression of a gene c. a cluster of genes that are expressed or repressed as a group d. an enzyme that dna unzip prior to transcription

List two modern organisms that have pentameral symmetry

What molecule does hemoglobin decay into over time

Agroup of students is studying convection currents. they fill two identical balloons with the same amount of helium. one balloon is placed in a freezer and the other in an area with warm air. after 10 minutes, the balloons are released from a height of 1 meter. which of the following do the students most likely observe? question 8 options: the cold balloon expands and rises. the warm balloon shrinks and sinks. the balloons rise at the same rate. both balloons are the same size. the ballons both rise. the cold ballon is larger than the warm balloon. the warm balloon expands and rises. the cold balloon shrinks and sinks.