Chemical Basis for life

Water is the most abundant molecule found in living organisms.  Most mammals, in fact are approximately 70% water by weight.  About two-thirds of this water is present inside cells.  The other one-third is present outside cells (e.g., in blood plasma or other body fluids).  Why is water so important to cells?

• Water is stored in the cells to be used when the organism gets thirsty.
• Almost all the chemical reactions in life processes occur in solutions with water.
• Water determines which proteins are translated from the cellular DNA.
• The main structural component found in plasma membranes and cell walls is water.

Tags

NGSS.HS-LS2-3

In order to change from a solid to a liquid to a gas, water must absorb a large amount of heat energy.  
Water can absorb a large amount of energy while producing only small changes in temperature because water has a 

• low particle density.
• high particle density.
• high specific heat.
• low specific heat.

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NGSS.MS-PS1-4

NGSS.MS-PS3-4

All living organisms contain carbon atoms.  Which of the following is an important characteristic of carbon?

• Carbon atoms can bond with many other kinds of atoms to form very stable molecules.
• Carbon atoms can bond with any other atom, but they cannot form bonds with other carbon atoms.
• Carbon atoms are very stable and do not easily form bonds with other atoms.
• Carbon atoms are highly reactive and form unstable bonds with any available atom.

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NGSS.HS-PS1-2

Nucleic acids are one of the four major macromolecules.  The main functions of nucleic acids are to

• store and transport energy and structural components in the cell.
• act as enzymes, cell signals, and structural support for the cell.
• carry genetic material and create structures inside the cell.
• aid in development, the immune system, and blood clotting.

Protein molecules are composed of long chains of __________ .

• ribosomes
• RNA
• amino acids
• DNA

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NGSS.HS-LS1-6

Organic macromolecules called __________ are insoluble in water, are often found in biological membranes and other waterproof coverings, and have the ability to store energy for extended periods of time.

• carbohydrates
• lipids
• proteins
• nucleic acids

Water molecules are ____________ due to _________ bonding. This property helps water molecules to stick to each other and allows for the movement of water from plant roots up to plant leaves.

• cohesive; ionic
• cohesive; hydrogen
• adhesive; hydrogen
• adhesive; covalent

Tags

NGSS.MS-PS1-1

Which reaction is responsible for the production of lipids, when glycerol is joined to three fatty acids?

• dehydration
• hydrolysis
• hydrophilic
• hydrophobic

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NGSS.HS-LS1-6

Lakes and oceans are able to stabilize air and land temperatures because

• the temperature of water changes significantly instead of the temperature of the air and land.
• the salt in the water bodies is able to absorb large amounts of heat.
• the water is able to release large amounts of heat into the air when necessary.
• water is able to absorb large amounts of heat without significantly changing its temperature.

Tags

NGSS.HS-ESS2-5

The attraction between hydrogen and oxygen atoms in different water molecules is known as a(n)

• ionic bond.
• hydrogen bond.
• covalent bond.
• dispersion force.