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:

"Nanotechnology has enabled numerous advances in communications, medicine, energy, and agriculture. But as the proliferation of nanomaterials ramps up, unintended consequences are becoming increasingly visible. A recent study examined the effects of silver nanoparticles on soils supporting the growth of maize. Findings revealed a 30% decrease in the relative abundance of members of the archaea community, which are important for nitrogen cycling in soil, vital for plant growth. Nanosilver also increased the abundance of certain possibly phytopathogenic fungi, possibly by eliminating bacteria that normally keep these harmful fungi in check. Finally, increased root growth seems unsustainable because it is probably caused by these stress factors, and not by beneficial effects. While this study was limited to relatively small, pot experiments, the findings suggest that the microbiome is an essential inclusion for studying the long-term effects of nanomaterials on the environment..."

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.

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 removal is a critical part of the wastewater treatment process. and one of the most efficient ways to remove nitrogen from water is anaerobic ammonium oxidation (anammox). Anammox is a process mediated by bacteria that — via several biochemical steps — converts ammonium to nitrogen gas. Understanding how external factors like nutrient availability impact these organisms can help us optimize and maintain these systems. A recent study found that the anammox bacterial communities are resilient to short-term starvation. The community structure changed slightly, and the bacteria increased expression of important nutrient transporters and energy metabolism genes. Expression of key genes associated with anammox reactions were also increased in response to starvation. The anammox bacteria showed fewer differences in transcriptional patterns after starvation than heterotrophs, suggesting that the anammox bacteria had greater transcriptional resilience than the heterotrophs..."

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:

"Salt marsh ecosystems perform multiple “ecosystem services”. For example, they clean the water, protect coastlines against storm surges, and support fisheries. Sediment microbes in these ecosystems are known to mediate cycling of important nutrients, but their effects on marsh plant productivity are unclear. To learn more, a new study analyzed the sediment and root microbiomes of a dominant marsh plant, _Spartina alterniflora_. The sediment of taller _S. alterniflora_ had greater microbial biomass and faster organic matter mineralization than that of shorter plants, suggesting that the sediment microbes helped support plant productivity. The sediment and root-adjacent (rhizosphere) microbiomes of taller plants were also more diverse. Among _S. alterniflora_ of all sizes, root microbes were less diverse than sediment and rhizosphere microbes, implying that the roots were colonized by highly competitive microorganisms..."

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