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Plant species belonging to divergent branches of the evolutionary tree are known to have independently evolved caffeine production. According to scientists at Western Michigan University, caffeine-producing plants have taken a number of different biochemical routes to synthesize the stimulant. Coffee, tea, cocoa, orange, and guaraná plants make caffeine using an array of enzymes and substrates, the researchers reported in PNAS this week (September 20).

Ah, spring. Grass growing, flowers blooming, trees budding. For those with allergies, though, this explosion of new life probably inspires more dread than joy. So what's behind this annual onslaught of mucus? Eleanor Nelsen explains what happens when your immune system goes rogue.

Sulston worked alone, in silence, hunched over a microscope for eight hours a day. By studying and drawing worms of various ages, he figured out the ancestor and descendants of each of their cells. It was a monumental piece of science. Sulston mapped the complete history of an individual, the comprehensive family tree of a single body. "We had the entire story of the worm's cells from fertilized egg to adult," he later said, upon accepting the Nobel Prize for his work.

n Wednesday, it happened again. Yohannes Haile-Selassie of the Cleveland Museum of Natural History and his colleagues reported finding a jaw in Ethiopia that belonged to an ancient human relative that lived some time between 3.3 and 3.5 million years. They argue that the jaw belongs to an entirely new species, which they dubbed Australopithecus deyiremeda.

tutorial video with pre and post test questions on evolution

Have you ever seen a tree with a big, twisted knot growing out of it? That's just one way that plants can show signs of cancer. Quick Questions explains.

Welcome to the HealthStats Indicator Report Categorized Index. This categorized index provides a selection menu in the form of an explorer type hierarchical folder tree and is organized by topic or subject area. These menu selections are used to navigate to the system's various indicator reports. Listed below are the most general categorized index menu sections. After selecting one of these general category sections, a page will be presented which will allow the folder's sub items to be shown and selected.

The origin of viruses remains mysterious because of their diverse and patchy molecular and functional makeup. Although numerous hypotheses have attempted to explain viral origins, none is backed by substantive data. We take full advantage of the wealth of available protein structural and functional data to explore the evolution of the proteomic makeup of thousands of cells and viruses. Despite the extremely reduced nature of viral proteomes, we established an ancient origin of the "viral supergroup" and the existence of widespread episodes of horizontal transfer of genetic information. Viruses harboring different replicon types and infecting distantly related hosts shared many metabolic and informational protein structural domains of ancient origin that were also widespread in cellular proteomes. Phylogenomic analysis uncovered a universal tree of life and revealed that modern viruses reduced from multiple ancient cells that harbored segmented RNA genomes and coexisted with the ancestors of modern cells. The model for the origin and evolution of viruses and cells is backed by strong genomic and structural evidence and can be reconciled with existing models of viral evolution if one considers viruses to have originated from ancient cells and not from modern counterparts.

The purpose of this case is to teach introductory college biology students the basic process of mitosis, focusing on the fundamental cellular processes that occur during each of the stages-prophase, prometaphase, metaphase, anaphase, telophase and cytokinesis. It would also be appropriate for AP Biology students. The case is framed around solving a murder. The murder plot involves a naturally-occurring poison derived from Yew trees, known as paclitaxel. Paclitaxel is a mitotic inhibitor that works by inhibiting the depolymerization of microtubules so that the cell is arrested in metaphase. At the end of the case, students will be able to describe the basic process of mitosis, including the fundamental processes that occur in each stage. The discovery of paclitaxel led to the development of the chemotherapeutic drug, Taxol ®, and the case concludes by having students think about the correlations between poisons and chemotherapies. The case involves the use of videos, one of which was made by the author for this case, and can be used in a flipped classroom.

hat is color blindness? A color festival. No. Color blindness or color deficiency is a vision problem. Now, our eyes have light sensitive cells called rods and cones. Can I put ice cream on these cones? You are just unbelievable. Rods are responsible for black and white vision. They do not detect color. Whereas, cones detect color. There are three types of cones. One cone perceives red light, another perceives green and the third perceives blue. Together, these cones help us to see the whole spectrum of colors. Now in some cases, when one or more types of cones do not work properly, it causes color blindness. People with such deficiency have difficulty in distinguishing between certain colors or shades. For example, in red-green color blindness, the apple tree may appear like this.

Squirrels are frequent and beloved residents of college campuses throughout the United States, but oftentimes less welcomed by campus maintenance officials who report squirrels nesting in buildings, interfering with airflow from heating and cooling units, and destroying gutters. In this laboratory case, students act as members of a fictitious "squirrel task force" appointed by their campus administrators to provide recommendations for how to manage their school's squirrel population.  Students work in groups to assess the habitat suitability of their campus for squirrels by identifying and measuring trees that provide seasonal food for squirrels, and by identifying desirable hunting perches for common squirrel predators.  Students conduct squirrel surveys in designated campus zones to calculate the number of squirrels per acre on their campus and compare it with mean squirrel densities reported in forested areas and at a rival institution.  Students then compile and synthesize class data to provide management recommendations for university maintenance officials for either increasing or decreasing campus squirrel populations. Originally developed for an undergraduate wildlife biology course, the case could also be used in a lower-division biology or environmental studies course.

Over the past few decades, genetic research has revealed two deep truths about people. The first is that all humans are closely related-more closely related than all chimps, even though there are many more humans around today. Everyone has the same collection of genes, but with the exception of identical twins, everyone has slightly different versions of some of them. Studies of this genetic diversity have allowed scientists to reconstruct a kind of family tree of human populations. That has revealed the second deep truth: In a very real sense, all people alive today are Africans.

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