All organisms must regulate by turning genes on and off in different cells at different times. a. True
b. False

a. True

Explanation:

The genome can be defined as the complete set of genetic information of an organism which is responsible to produce all the biological components required to carry out its metabolic functions (i.e., development, growth, reproduction, etc). These genes are transcriptionally expressed to produce mRNAs which are subsequently used to synthesize specific proteins (i.e., enzymes and structural proteins) by the process of translation. All organisms (i.e., either unicellular or multicellular organisms) exhibit specific gene expression programs by which such genes are regulated over time. Within the cell, gene regulation is essential to carry out biological processes ranging from development and differentiation to cell cycle arrest. These gene expression programs are acutely regulated via genetic (e.g., transcription factor binding) and epigenetic (e.g., DNA methylation) mechanisms, which work together in order to turn on/off genes during development.

volcanoes (an event in the geosphere) release a large amount of particulate matter into the atmosphere. these particles serve as nuclei for the formation of water droplets (hydrosphere). rainfall (hydrosphere) often increases following an eruption, stimulating plant growth (biosphere).

he forelimbs below belong to four species that descended in a direct line from the ancestral mammal shown above. of the four descendants shown, which species most likely appeared earliest in evolutionary history?