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:Explain the need for nitrogen fixation and how it is accomplishedIdentify foods in which prokaryotes are used in the processingDescribe the use of prokaryotes in bioremediationDescribe the beneficial effects of bacteria that colonize our skin and digestive tracts

By the end of this section, you will be able to:Understand the nutritional adaptations of plantsDescribe mycorrhizaeExplain nitrogen fixation

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:

"Deep-sea hydrothermal vents are extreme environments that typically form along mid-ocean ridges. Although hundreds of vent systems have been identified, those south of 14°S on the Mid-Atlantic Ridge remain relatively unexplored. To learn more, a recent study investigated the microbes inhabiting the newly discovered Deyin-1 vent in this area. Analysis of 219 metagenome-assembled genomes (MAGs) revealed a highly diverse and variable community. Most of the dominant microbes appeared capable of using reduced sulfur and hydrogen as primary energy sources, and many of the microbes seemed to use multiple energy pathways, indicating adaptability to fluctuating conditions. Multiple types of bacteria were also predicted to participate in the same metabolic pathways, suggesting functional redundancy within the community. Furthermore, the genome sequences suggested that a large proportion of microbes could both make their own food and consume other organisms..."

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 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.

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:

"Mosses are ubiquitous in northern ecosystems. Their critical ecological roles include insulating soils, maintaining soil moisture, and mediating carbon and nitrogen cycles. Like all plants, mosses associate with microbes and some of them are key contributors to nitrogen dynamics through their nitrogen fixation functions. To better understand the importance of moss host species and environmental factors in structuring these microbial communities, researchers studied 26 boreal and tundra moss species across 24 sites in Alaska. They found that both host species and host evolutionary history predicted moss microbiome composition, and microbe nitrogen fixation rates also varied by host species. To a lesser extent, light availability and temperature also influenced the composition and function of moss microbes. Finally, they identified putative nitrogen-fixing bacteria specific to some moss hosts, including some outside well-studied cyanobacterial clades..."

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

How nitrogen is recycled in our biosphere in the nitrogen cycle, including nitrogen fixation.