Certain species that defy expectations of sexual gender are important in helping biologists understand reproductive mechanisms. Not all species fit perfectly into the definitions of specific species concepts like the morphology or biological species concepts. The reproductive mechanisms for numerous species of lizards, fungi, and microbes differ drastically from mammalian mechanisms of reproduction. Certain species will reproduce sexually but do not fail to produce offspring even in the absence of the opposite sex. This is common in lizards that will lay eggs with no need for fertilization from the male counterpart. The viability of the offspring are high. Other traits that defy the biological species concepts include hybrids that are able to produce fertile and viable offspring with other hybrids but somehow, unable to cross with the parental species. These are instances in which the expectations from sexes and reproductive success are unable to fit perfectly into the human made concepts to understand nature.
You are here
Speciation is the evolutionary process by which new species arise. Although the definitions of what a species is does vary, the mechanisms by which these differences among species arise is consistent. Two types of speciation are sympatric and allopatric speciation. In sympatric speciation, a single species diverges to become two distinct species due to sexual preferences, a separation by a reproductive barrier, or polyploidy. Over time, a single area may have a population experience distruptive selection. For example, a group of beetles that breed within flowers of a plant, but if the plant has a mutation and produces a new colored flower, one that would attract certain beetles, the separation and preference causes the species to diverge. This is an example of pre-zygotic, behavioral isolation. In allopatric speciation, a separation, a geographic barrier between a once united group may cause the species to diverge. For example, in a pool that dries up and creating smaller pools, the fish that were once together are now separated geographically. Over time, the fish will exert a preference for their own kind if re-united. This too, is an example of speciation of a single species, now separated by preferences due to evolution.
Speciation is a concept created by humans to organize life, but nature exists as it is without need to be understood. The concept of a species can therefore, be defined in a variety of ways. A few common ways that species are understood by humans include the biological concept, the morphological, phylogenetic, and ecological concepts. The biological concept defines a species as a group of organisms that can produce fertile and viable offspring, but excludes asexual species, extinct species, and species that create viable and fertile offspring. The morphological concept defines species as having similar development and morphology (shape). Phylogenetic concept tracks the genetic evolutionary relationships between the species. The ecological species defines species by their niches. The different concepts help to understand species, but they are often imperfect and cannot include all life in the categories that humans have created.
A single carbon bonded to four groups has eight electrons, a full octet. If one of the groups attatched to the carbon is a leaving group, and is capable of removing an electron from the carbon along with itself, a carbo-cation is formed. This carbo-cation will have six electrons. However, when the ectrons are taken by the carbon from one of the groups, this creates a carbo-anion, which will still have eight electrons attatched to itself. If electrons in one bond of the groups is split between the carbon and the leaving group, a free radical is formed. Free radicals that left the carbon leave the carbon with seven electrons.
There are several theories on why animals must sleep. Some of these theories include the "repair and restoration theory," "evolutionary theory," and "information consolidation theory." The repair and restoration theory suggests that physiological processes are restored and revitalized when organisms sleep. This also ties into the other theories, which are likewise all interconnected. The evolutionary theory suggests that sleep is an adaptation. According to this theory, when food supply was short, in order to conserve energy, organisms developed the adaptation to sleep. The information consolidation theory, similar to the repair and restoration theory, suggests that sleep helps process information gathered from the day. It also helps with processing information during periods of being awake. However, these theories do not fully capture why it is necessary to sleep, and some biologists have made claims that sleep is one of evolution's biggest flaws.This is because sleeping organisms are more prone to attack while they are asleep.
An acid base extraction involves looking at a mixture and separating the two solvents within to extract pure compounds.The compounds, when mixed with two different solvents of different densities will separate into two layers. After the compounds are mixed and layers are formed in test tubes, the two phases are separated via pipet. Once the solvents are evvaporated, the separated, we get a yield of the solid compounds. Once the solids are aquired, purification may be done by recrystalization to remove any impurities.
The quality of the images on the two panels are notably different. The left is more vibrant and clearly shows the plants. However, the right side is slightly blurry and had less vivid coloring. This could be due to a different time of day during which the shots of the two panels were taken. At an earlier hour, or a sunnier day, the lighting could contribute to better displaying the subjects as they were captured in the left panel that had better coloring. Another factor that could have gone into this was the type of camera or settings on the camera that may cause the two colorings to become different. On top of that, the humitidy of the greenhouse could play a role in condensation around the lens. If the photographer did not clear the lens, it might have caused the images to become blurry in the right panel. The angles of the subjects are also different in the two panels. The left panel displays the plants facing straight forward, while the right panel looks slightly downward onto the plants. The way that the camera was directed at the subjects or the different heights of the person taking the photos could have been different. Someone taller could be looking downward on the plants, while someone who was shorter could have taken the photos directly facing them as they were taken in the left panel. The labeling of the images are different as well. Instead of simply labeling the images A, B, and C as it is done in the left panel, the right panel differs in that is labels the images from top to bottom, "A." then "B." then "C." This could have been miscommunicated in the methods or was not specifically mentioned. Another difference regarding the labels is the distance of the letters from the left side of the images. In the left panel, the letters are closer to the edge of the photos than in the right panel, which places the labels further from the left side of the images. The size of the subjects are also different in the two panels. This could be due to the distance of the photographer from the subjects. For the left panel, the subjects appear closer to the camera than the subjects on the right side panel. The table on which the plants lie are also not included in the image on the left, which also makes the subjects appear closer. The images of the right also feature some other plants on the side that are not the subject plant in each photo. Furthermore, the images on the right panel also capture the pot in which the plant was held as opposed to the images on the left panel, which also crops out most of the pot so that the soil and only some of the plant pot can be seen. This could be due all to the distance of the photographer from the subjects of the images.
There are several theories to why animals must sleep. Some of these theories include the "repair and restoration theory," "evolutionary theory," and "information consolidation theory." The repair and restoration theory suggests that the physiological processes are restored and revitalized when organisms sleep. This also ties into the other theories, which are likewise interconnected. The evolutionary theory suggests that sleep was an adaptation that was helpful in reducing activity when energy needed to be conserved due to lack of food in the environment. Information consolidation, similarly to the repair and restoration theory, suggests that sleep helps process information gathered from the day, and plays a role in helping processing information from the following period of being awake. However, these theories do not fully capture why it is necessary to sleep, and some biologists have made claims that sleep is one of evolution's biggest flaws, because sleeping organisms are prone to threats such as predators.
Predicting the energy level of an electron when activated by a photon is possible using the conservation of energy. If the energy before is equal to the energy after the interaction with the photon, then the respective energies become as follows: Ei+Ephoton=Ef. To calculate which energy levels are involved in this interaction, the information would need to be provided. The size of the boundry to which the electron is bound must be provided since the other factors are constants. The equation for the energy of an electron at an energy level n, is therefore En=(h^2)(n^2)/8mL^2, where h is planks constant of 6.626X10^-34J*s, n is the energy level, m is the mass of an electron (9.11X10^-31), and L is the provided length. Solving for the initial energy, then the energy of the photon will provide the final energy of the electron after interaction with the photon. To find the energy of the photon, the wavelength of the photon may be provided since the energy is E=hc/wavelength.
Dominance of an allele does not predict the outcome of allelic frequencies. Dominance simply refers to the outcome of a phenotype. The common misconception in terms of dominance is that dominance determines which of two alleles will persist. It is misconceived that a dominant allele will go into fixation, and cause the recessive allele to disappear in the population. In fact, dominance cannot determine whether or not alleles go into fixation. It is through selection that determines the outcome of allelic frequencies. If the dominant allele was selected for, in that case, the allele frequency of the dominant allele will increase, otherwise, if there is no positive selection for that allele, it will remain at a constant frequency. Likewise, recessive alleles may also be selected for and its frequency may also increase. To reiterate, dominance only determines the outcome of the phenotype, and if acted upon by negative selection, could potentially disappear from the population.