Q: Answer the following question given this paragraph: Q: Several neuropeptides, relatively short chains of amino acids, serve as neurotransmitters that operate via metabotropic what? Choices: - lipids - membranes - organelles - receptors A:
A: receptors

Q: Answer the following question given this paragraph: Birth Prior to birth, the lungs are filled with amniotic fluid, mucus, and surfactant. As the fetus is squeezed through the birth canal, the fetal thoracic cavity is compressed, expelling much of this fluid. Some fluid remains, however, but is rapidly absorbed by the body shortly after birth. The first inhalation occurs within 10 seconds after birth and not only serves as the first inspiration, but also acts to inflate the lungs. Pulmonary surfactant is critical for inflation to occur, as it reduces the surface tension of the alveoli. Preterm birth around 26 weeks frequently results in severe respiratory distress, although with current medical advancements, some babies may survive. Prior to 26 weeks, sufficient pulmonary surfactant is not produced, and the surfaces for gas exchange have not formed adequately; therefore, survival is low. Q: Prior to birth, the lungs are filled with amniotic fluid, mucus, and what else? Choices: - blood - plasma - air - surfactant A:
A: surfactant

Q: Answer the following question given this paragraph: The Precambrian Supereon (4.6 billion544 million years ago) is the first major division of the geologic time scale. The first living cells may have evolved around 4 billion years ago. By 1 million years ago, the first multicellular eukaryotes had evolved. The Precambrian ended with the first of six mass extinctions that occurred during Earth's history. Q: The first living cells may have evolved around how long ago? Choices: - 900,000 years - 6 billion years - 2.2 billion years - 4 billion years A:
A: 4 billion years

Q: Answer the following question given this paragraph: Most muscles are skeletal muscles, which are attached to bones by tendons. Skeletal muscles work in pairs to move bones back and forth at joints. Q: By what are skeletal muscles attached to bones? Choices: - joints - ligaments - veins - tendons A:
A: tendons