Biology is designed for multi-semester biology courses for science majors. It is grounded on an evolutionary basis and includes exciting features that highlight careers in the biological sciences and everyday applications of the concepts at hand. To meet the needs of today’s instructors and students, some content has been strategically condensed while maintaining the overall scope and coverage of traditional texts for this course. Instructors can customize the book, adapting it to the approach that works best in their classroom. Biology also includes an innovative art program that incorporates critical thinking and clicker questions to help students understand—and apply—key concepts.

By the end of this section, you will be able to:Identify the macronutrients needed by prokaryotes, and explain their importanceDescribe the ways in which prokaryotes get energy and carbon for life processesDescribe the roles of prokaryotes in the carbon and nitrogen cycles

This resource is a video abstract of a research paper created by Research Square on behalf of its authors. It provides a synopsis that's easy to understand, and can be used to introduce the topics it covers to students, researchers, and the general public. The video's transcript is also provided in full, with a portion provided below for preview:

"Diazotrophs, microorganisms that “fix” atmospheric nitrogen into ammonia that plants can use, are important members of mangrove ecosystems. Diazotrophic community structure and nitrogen fixation rates are strongly regulated by the environment, but how they change with sediment depth remains unclear. To find out, a new study investigated biological nitrogen fixation in sediment cores taken from a mangrove ecosystem in China. The results showed that diazotroph diversity decreased with depth, and salinity was the main factor that influenced the diazotrophic community structure. Communities above vs. below 50 cm were markedly different. In sediments shallower than 50 cm, Anaeromyxobacter, Rubrivivax, Methylocystis, Dickeya and Methylomonas dominated, while Agrobacterium and Azotobacter dominated from 50 to 100 cm. The nitrogen fixation rate and the abundance of nitrogen fixation genes increased with depth, while the abundance of genes related to nitrification and denitrification decreased..."

The rest of the transcript, along with a link to the research itself, is available on the resource itself.

This resource is a video abstract of a research paper created by Research Square on behalf of its authors. It provides a synopsis that's easy to understand, and can be used to introduce the topics it covers to students, researchers, and the general public. The video's transcript is also provided in full, with a portion provided below for preview:

"Nitrogen is vital to aquatic ecosystems. But too much nitrogen, which can build up from fertilizer use or wastewater discharge, can be deadly. A recent study examined how two groups of nitrogen-removing bacteria interact in the hopes of discovering a synergy that can help remediate over-nitrified lakes. The two groups consisted of anammox bacteria, which feed on ammonium and release nitrogen gas and denitrifying bacteria, which do the same but feed on nitrates instead. Researchers locked the bacteria in bioreactors and monitored their activity for over a year as they fed on sediments from a nitrogen-rich lake. Findings revealed high nitrogen removal efficiencies of up to 86% for ammonium and 95% for nitrites with denitrifying and anammox bacteria showing signs of cooperation. For example, certain denitrifiers may provide amino acids and vitamins that support anammox bacteria..."

The rest of the transcript, along with a link to the research itself, is available on the resource itself.

This resource is a video abstract of a research paper created by Research Square on behalf of its authors. It provides a synopsis that's easy to understand, and can be used to introduce the topics it covers to students, researchers, and the general public. The video's transcript is also provided in full, with a portion provided below for preview:

"Glaciers and ice sheets may seem dead and empty to the naked eye, but the dust that coats them, cryoconite, is a hotspot for microbes and microbe-driven biogeochemical cycling. However, little is known about the geographical diversity in cryoconite microbial communities. Most cryoconite research focuses on polar microbial communities, and reports on Asia’s high mountain glaciers are rare. A recent metagenomics study found key metabolic and light harvesting differences between polar and Asian alpine cryoconite microbiota. The Asian cryoconite community had more abundant genes for denitrification, suggesting that denitrification is enhanced there compared to polar regions. While Asian cryoconite is dominated by multiple cyanobacterial lineages that possess phycoerythrin, a green-light harvesting protein, polar cryoconite is dominated by a single cyanobacterial species (_Phormidesmis priestleyi_) that lacks phycoerythrin..."

The rest of the transcript, along with a link to the research itself, is available on the resource itself.

This module provides an overview of the nitrogen cycle and the chemical changes that govern the cycle.