Final answer:
The growth hormone (GH) is the hormone responsible for increasing energy production, stimulating protein synthesis, and accelerating tissue repair. It causes cells to switch their energy source from glucose to fatty acids, helping preserve glucose and support growth and repair needs.
Step-by-step explanation:
The hormone that increases energy production by cells, stimulates protein synthesis, and speeds up the repair of damaged tissues is the growth hormone (GH). GH is produced by the anterior portion of the pituitary gland and has a major role in bodily growth, protein synthesis, and cellular replication. It acts both directly by accelerating protein synthesis in skeletal muscle and bones and indirectly by activating insulin-like growth factor 1 (IGF-1), which in turn promotes the formation of new proteins in muscle cells and bone.
Growth hormone switches the energy source of most cells by stimulating lipolysis, which releases fatty acids into the blood, leading to a glucose-sparing effect. It means most tissues will preferably use fatty acids over glucose for energy, preserving glucose for tissues like the brain that are more dependent on glucose. This shift is essential during periods of growth or repair when energy needs are heightened.
In summary, option 4, growth hormone, is the correct answer to the question about which hormone is responsible for these functions.