Science - 2019-20

BIO.2 c-d - Enzymes, Photosynthesis, & Respiration

The student will investigate and understand the chemical and biochemical principles essential for life. Key concepts include
c) the nature of enzymes;
d) the capture, storage, transformation, and flow of energy through the processes of photosynthesis and respiration.

Bloom's Levels:  Analyze; Understand

Adopted: 2010


  • Living organisms acquire the energy they need for life processes through various metabolic pathways (photosynthesis and cellular respiration).

  • I can choose medications to treat my medical conditions.
  • I can choose a location and layout of a greenhouse for the school.


  • 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. 
  • The breakdown of nutrient molecules enables all cells to store energy in specific chemicals that are used to carry out the life functions of the cell.
  • Plant cells and many microorganisms use solar energy to combine molecules of carbon dioxide and water into complex, energy-rich organic compounds and release oxygen into the environment.
  • The process of photosynthesis provides a vital connection between the sun and the energy needs of living systems. During photosynthesis, cells trap energy from sunlight with chlorophyll, found in chloroplasts, and use the energy, carbon dioxide, and water to produce energy-rich organic molecules (glucose) and oxygen. Photosynthesis involves an energy conversion in which light energy is converted to chemical energy in specialized cells. These cells are found in autotrophs such as plants and some protists. 
  • During cell respiration, eukaryotic cells “burn” organic molecules with oxygen in the mitochondria, which releases energy in the form of ATP, carbon dioxide, and water. 
  • Photosynthesis and cell respiration are complementary processes for cycling carbon dioxide and oxygen as well as transferring energy in ecosystems.
  • Cells release the chemical energy stored in the products of photosynthesis. This energy is transported within the cell in the form of ATP. When cells need energy to do work, certain enzymes release the energy stored in the chemical bonds in ATP. 


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

c) describe the structure of enzymes and explain their role in acting as catalysts to control the rate of metabolic reactions.

d) recognize the equations for photosynthesis and respiration and identify the reactants and products.

     describe the role of ATP in the storage and release of chemical energy in the cell.

     explain the interrelatedness of photosynthesis and cell respiration.

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


autotroph, heterotroph, adenosine triphosphate (ATP), photosynthesis, pigment, chlorophyll, thylakoid, photosystem, stroma, NADP^+, light-dependent reactions, ATP synthase, Calvin cycle

Updated: Dec 01, 2017