(Solution) SCIE1046 Activity 4.2 Eutrophication

COURSE  

SCIE1046: Fundamental of Microbiology with Lab

1. About the Lab

Learning Objectives:

  • Understand the nitrogen cycle and its importance for living beings.
  • Understand the concept of eutrophication and harmful algal bloom, and the impact that it has on the ecosystem.
  • Analyze dissolved nitrogen levels in the water sample.
  • Understand the importance of sampling from different locations to get representative data.

Estimated Length: 30 to 35 minutes

 

MAKE THE CONNECTION

The background information in section 2 was adapted from the following Microbiology lecture course Tutorials:
2.2.3 Algae
3.2.4 Microbial Photosynthesis
3.2.5 Biogeochemical Cycles

 

2. Background Information

The following background information will be helpful as you prepare for the simulation.

2a. Introduction to Algae

Algae are autotrophic protists that can be unicellular or multicellular. The dinoflagellates, diatoms, golden algae, and brown algae are classified as TSAR (formerly within supergroup Chromalveolata). The red and green algae are classified under Archaeplastida. Algae are important ecologically, environmentally, and economically because they are responsible for the production of approximately 70% of the oxygen and organic matter in aquatic environments. They are at the base of many food webs. Some types of algae, even those that are microscopic, are regularly eaten by humans and other animals. Algae are also the source of agar, agarose, and carrageenan that are used as solidifying agents in the laboratory and in food production.

Although algae are not pathogenic, some species produce toxins. Algal blooms occur when algae grow quickly and produce dense populations. This can result in the release of large quantities of toxins that harm aquatic animals and humans. Additionally, the decomposition of these algae uses up oxygen and produces “dead zones” as organisms die in these zones from lack of oxygen.

 

TERM TO KNOW

This glossary term is important to know and will help you during the Activity.

Algal bloom

An overgrowth of algae that can be harmful because of the release of toxins or depletion of oxygen.

2b. Microbial Photosynthesis

Photosynthesis involves two major parts: the light reactions (also called light-dependent reactions) and the light-independent reactions (also called the Calvin cycle). The light reactions use light energy to produce the chemical energy to power light-independent reactions.

The table below summarizes the stages of photosynthesis in green plants, which will be explained in more detail below. Note that the light reactions produce ATP and NADPH that are used by light-independent reactions. Light-independent reactions then produce the molecules needed for light reactions to continue. Oxygen is released into the atmosphere and carbon dioxide is taken in from the atmosphere.

Stages of Photosynthesis in Green Plants
Location Inputs Outputs
Light reactions Thylakoid membranes Light energy, ADP,  (inorganic phosphate), ATP, NADPH,
Light-independent reactions Stroma (eukaryotes) , ATP, NADPH ADP, , organic molecules

The image below shows a simplified illustration of photosynthesis, indicating the inputs and outputs of each stage.