Science - 2019-20

BIO.2 a - Water Chemistry

The student will investigate and understand the chemical and biochemical principles essential for life. Key concepts include
a) water chemistry and its impact on life processes.

Bloom's Levels:  Analyze; Understand

Adopted: 2010

BIG IDEAS

  • Every living thing is mainly made up of water.

  • I can explain why produce prices are higher during times of drought.

UNDERSTANDING THE STANDARD

  • Water is essential for life on Earth. Water absorbs heat when it evaporates, allowing organisms to release excess heat. The solid form of water, ice, floats, preventing lakes and oceans from freezing solid. Water molecules are both cohesive and adhesive due to the nature of hydrogen bonding.
  • About two-thirds of the mass of a cell is made up of water, and most of the biochemical processes of life occur in water solutions. Water is able to dissolve many substances (due to polarity); therefore, the water inside and outside of cells is able to carry nutrients into and around cells and wastes away from cells. 
  • The pH scale ranges from 0 to 14. The pH of pure water is 7. Substances added to water can lower or raise the pH. A solution with a pH below 7 is acidic. A solution with a pH above 7 is basic. 
  • Organisms can tolerate only small changes in pH because every cell has a particular pH at which it functions best. For example, changes in pH cause changes in enzyme conformation, resulting in a change in activity. Most cells function best within a narrow range of temperature and pH. At very low temperatures, reaction rates are too slow. High temperatures or extremes of pH can irreversibly change the structure of proteins and alter their function. 
  • In multicellular organisms, the fluid within the cell and the fluids surrounding the cells have a characteristic and nearly constant pH. This pH is maintained in a number of ways, and one of the most important is through buffer systems.
  • Inside every cell is a concentrated mixture of thousands of different macromolecules forming a variety of specialized structures that carry out cell functions, such as energy production, transport, waste disposal, synthesis of new molecules, and storage of genetic material.
  • Cells can make a variety of macromolecules from a relatively small set of monomers. 
  • The primary functions of carbohydrate macromolecules are to provide and store energy. 
  • The primary functions of lipid macromolecules are to insulate, store energy, and make up cell membranes. 
  • Nucleic acids (DNA and RNA) control cell activities by directing protein synthesis. 
  • Proteins are polymers made by linking together amino acid monomers. Protein molecules that are assembled in cells carry out most of the cells’ work. The function of each protein molecule depends on its specific conformation. The sequence of amino acids and the shape of the chain are a consequence of attractions between the chain’s parts. Some proteins are structural (hair, nails). Others function in transport (hemoglobin), movement (muscle fibers and cytoskeletal elements), defense (antibodies), and regulation of cell functions (hormones and enzymes). 
  • Most life processes are a series of chemical reactions influenced by environmental and genetic factors. The chemical reactions that occur inside cells are directly controlled by a large set of protein molecules called enzymes, whose functions depend on their specific shapes. Each enzyme has a definite three-dimensional shape that allows it to recognize and bind with its substrate. In living cells, enzymes control the rate of metabolic reaction by acting as catalysts. 

ESSENTIALS

In order to meet this standard, it is expected that students will

a)  explain the importance of the chemical and physical properties of water that make it vital to life.

a-d)  explain how light is the initial source of energy for most communities.


KEY VOCABULARY

atom, nucleus, electron, element, isotope, compound, ionic bond, ion, covalent bond, molecule, van der Waals forces, cohesion, adhesion, mixture, solution, solute, solvent, suspension, pH scale, acid, base, buffer, monomer, polymer, carbohydrate, monosaccharide, polysaccharide, lipid, nucleic acid, nucleotide, ribonucleic acid (RNA), deoxyribonucleic acid (DNA), protein, amino acid

Updated: Dec 01, 2017