The Chemistry of Life

One of the accepted scientific theories describing the origin of life on Earth is known as chemical evolution. According to this theory, which of the following events would need to occur first for life to evolve?

• origin of genetic material

• formation of the plasma membrane

• onset of photosynthesis

• Synthesis of organic molecules

In a water molecule, hydrogen and oxygen share electrons to form a bond. Those shared electrons spend more time around the oxygen atom than the hydrogen atoms. As a result, the oxygen atom is

• very negative

• slightly negative

• very positive

• slightly positive

Tags

NGSS.HS-PS1-1

Which statement best explains why water is the most important substance for sustaining life on Earth?

• Water insulates Earth from the cold temperatures of outer space

• Water moderates Earth's climate by absorbing large amounts of heat

• Water builds organic molecules out of its living parts

• Water contains stored energy that powers chemical reactions

Tags

NGSS.HS-ESS2-5

Water in the blood helps carry nutrients and gases required for survival throughout the body. Which characteristics of water allows for this action?

• Water expands when it freezes

• Water dissolves many compounds

• Water has a neutral pH

• Water maintains temperature

Water is essential for life. Its special properties make water the most important molecule in plant life. Which of the following properties of water allows it to move from the roots to the leaves of a plant?

• Water exhibits cohesive behavior

• Water is able to moderate temperature

• Water expands as it freezes

• Water is an excellent solvent

Tags

NGSS.MS-ESS2-4

Biological macromolecules are organic compounds. Which three elements are found in these organic compounds?

• Nitrogen, chlorine, and phosphorus

• Nitrogen, hydrogen and oxygen

• Carbon, hydrogen, and oxygen

• Carbon, hydrogen and neon

Which of the following statements about macromolecules is correct?

• Nucleic acids often act as catalysts in biochemical reactions.

• Proteins are used in cellular respiration to produce cellular energy.

• Lipids are nonpolar, used for long term energy storage, and are commonly found in cell membranes.

• Carbohydrates can store genetic information and are found in the cell nucleus.

A molecule is found to have carbon, hydrogen, oxygen, and nitrogen. Which macromolecule category does it most likely fit?

• Carbohydrates

• Lipids

• Proteins

• Nucleic acids

Which of the following organic molecules is most closely related to nucleic acids?

• proteins

• nucleotides

• Lipids

• monosaccharides

Which of the following organic molecules is most closely related to carbohydrates?

• proteins

• nucleotides

• Lipids

• monosaccharides