BIO145 Week 4

the totality of an organism’s chemical processes

• respiration
• photosynthesis
• circulation
• metabolism

Select the reactant

Select the product

Aquatic plants and algae in freshwater systems undergo this process, converting sunlight into chemical energy and producing oxygen as a byproduct.

All living organisms in freshwater systems, including plants, animals, and microorganisms, undergo ​ (a)   to generate energy by breaking down organic compounds and consuming oxygen.

• respiration
• photosynthesis

Bacteria and fungi break down organic matter in the presence of oxygen through ​ (a)   This process plays a key role in nutrient cycling and the breakdown of dead organic material.

• aerobic decomposition.
• anaerobic decomposition

With ​ (a)   , certain bacteria facilitate the decomposition of organic matter, producing substances such as methane and hydrogen sulfide. This process is prevalent in sediments at the bottom of freshwater bodies.

• anaerobic decomposition
• aerobic decomposition

Match the following to the proper definition

• Nitrogen fixation

• bacteria convert nitrate back into nitrogen gas or other nitrogen compounds, completing the nitrogen cycle. This helps regulate nitrogen levels in the ecosystem.

• Nitrification

• bacteria convert ammonia (produced by decomposition and excretion) into nitrite and then into nitrate. This process is important for the nitrogen cycle in freshwater systems.

• Denitrification

• Certain bacteria can convert atmospheric nitrogen into forms usable by plants in a process called nitrogen fixation. This is crucial for the availability of nitrogen, an essential nutrient in freshwater ecosystems

Define exergonic reactions

• Exergonic reactions release energy.
• Exergonic reactions create energy.
• Exergonic reactions have no effect on energy.
• Exergonic reactions absorb energy.

Define endergonic reactions

• Chemical reactions that require an input of energy to proceed
• Processes that occur spontaneously without energy input
• Reactions that do not require energy to proceed
• Chemical reactions that release energy