Writing in Biology

I am currently taking statistics 240. We have covered topics such as descriptive statistics, simple linear regression and we have just started probability. We have also discussed the difference between qualitative and quantitative statistics, and whether or not they are discrete or continuous. Statistics may be represented in many ways, such as graphs and tables. There may be bar graphs, line graphs, and pie charts. Histograms and boxplots also provide details on the distribution of the data. Range, median, mode, mean and standard deviation are useful measures of the data and provide a variety of details about it, such as its general distribution. Chi-Square tests may be used, along with p-value, in order to determine whether there is a relationship between two sets of data. Simple linear regression may be used to determine whether or not two sets of date are correlated. By looking at the regression line and "r" it may be determined if there is a positive, negative, strong or weak correlation. Of course it is important to remember that correlation does not equal causation and there be a number of lurking variables which may effect the data, and make the correlation exist.

For our experiment, we will be studying the effects of starvation on Pholcidae spiders and demonstrate how their feeding time can be measured. Pholcidae spiders are cold-blooded and use a low amount of energy when not hunting for prey they remain still in their location to conserve energy and rely on low supply food to maintain metabolic rate. Though low food supply is needed for energy Pholcidae spiders will readily eat any available food when provided though the size of prey will be measured as Pholcidae will only hunt prey it can easily dominate.  

Fruit flies under anesthetic will be used because it ensures that they cannot fly away from the spider and allows capture from cellar spider for feeding. Flies and cellar spiders will be kept in Tupperware containers that allow observations to be observed more clearly through clear containers. Each container will have one cellar spider and variance in the number of fruit flies but the size of the fruit fly will remain small as cellar spiders only predicate flies they can dominate. The importance of this procedure was to ensure the time of feeding could be measured accurately. To measure the amount of time is spent on hunting fruit flies cellar spiders will be timed until fruit flies were attacked completely and could be declared dead.

I took ResEcon statistics in the Fall semester of my Sophomore year. Unfortunately, I do not remember a lot about statistics. I remember some units that the class went through, but I do not recall specific details. I remember talking about the difference between independent and dependent variables. The independent variable in an experiment does not depend on another variable, whereas the dependent variable varies according to the independent variable. We also learned about different methods of sampling. These include stratified random, simple random, cluster, and systemic sampling. Sampling techniques vary depending on the type of experiment that is performed; some sampling techniques are efficient for certain experiments depending on the size or range of the variables being tested. We also focused on graphs and statistical analysis. The ability to interpret statistical graphs is very important in biology as most of the results are displayed in graphs, scatter plots, and tables. This includes understanding how to find and interpret residuals, correlation, and linear regression. I do not remember specific detail about these concepts. We learned about how to use p value and degrees of freedom. I remember that a P value lower than .05 means that the difference between two averages is significant. The class also spent a good amount of the semester on probability. Overall, my memory of the material we learned in statistics class is hazy so reviewing the basics will be beneficial to this class.  

Ommochrome pigments are a type of pigment that is present in a large variety of arthropods. The pigment is present in both the eye and the body of the arthropod. The current hypothesis is that the color of the pigment is important to the pathway for color changing insects. Crab-spiders are unusual due to their ability to have reversible color changes. They are able to go from white to yellow and back to white again. The color change in the crab-spiders was originally attributed to the carotenoid pigment (commonly produced by plants which provides the yellow/orange coloration) but the pigments responsible for the spider’s color change was later found to be ommochromes. The color mimetism that the spiders are able to replicate is able to fool the discrimination ability of bees. Bees and other flowering visiting insects are known prey to the spiders and due to the close match between spider and flower, it is suggested that the color change is a predatory adaptation. Data and research is still being gathered and conducted between the spiders and birds to test if the color change may also be the result of a defensive mechanism.

 

In our research project we are looking at the affect of radiation on spiders, how they make their webs, where they make their webs, and etc.  One way to collect data would be to set up three different groups of spiders. The first group is the control group they will not be exposed to cellular radiation at all.  The next group is the radiation group that will be exposed to an operating cellphone that is on and using cellular data.  The last group will be exposed to a cellphone but the cellphone will be put into airplane mode and therefore shutting off cellular data.  This data will show the affect of radiation on spiders if there is any, and it will tell us if the cell phone radiates radiation when in airplane mode or only when cellular data is on. 

Within a developing embryo, three germs layers give rise to the various structures of the body. First of which is the endoderm. This is the inner layer of skin within the embryo that gives rise to the lining of most digestive and respiratory tracks. The endoderm is responsible for the glandular material associated with the digestive and respiratory tracks as well. The layer behind the endoderm is the mesoderm. Mesodermal derivations include the appendicular muscles, various connective tissues, and blood vessels. Lastly, the outer germ layer of the embryo is the ectoderm. This layer is responsible for the formation of the epidermis, the nervous system and the neural crest cells. Neural crest cells are a unique cell formed by the remanence of the neural fold after it closes over and establishes the neural tube. The neural crest cells travel through the body and establish the foundation for the visceral skeleton, pigment and photoreceptive cells, sensory and postganglionic neurons, and the dentine producing cells of teeth. Without these germ layers, the remaining structures of the body would be compromised and we would essentially be blobs of flesh and muscle.

Observation of a colony from the pasteurized plate, under a phase contrast microscope at 1000x, showed endospores inside rod shaped bacterium. The endospores were located primarily at the terminal end of the bacillus, and were seen as bright ovals with the darker bacterium surrounding them. This confirmed that the bacillus containing endospores survived pasteurization and was able to continue growing on the nutrient agar. Not all of the bacilli contained endospores, suggesting that the nutrients on the agar were substantial enough to inhibit sporulation. These bacilli grew in diplobacillus and streptobacillus arrangements. A Gram stain of the same colony used for microscopy showed that the endospore forming bacilli were gram positive based on the dark purple color of the bacterium. The endospores were not stained and appeared as clear ovals at the terminal ends of the bacterium. This Gram stain confirmed that the bacterium that formed the endospores were Gram positive. Also, the Gram stain showed that the thick layer of proteins and peptidoglycan surrounding the endospore had not been damaged and was able to keep the stain and water out of the endospore.

I took a statistics class in my sophomore year, and remember it being a very different learning experience compared to the biology classes I was taking. I remember using Excel frequently, and learning lots of formulas to use on the data we entered into the spreadsheet. I remember we focused on simple random sampling, which was the probability that an item is selected for a sample is the same for all population items. We made lots of graphs, including histograms and bar charts to visualize the data we had collected. I remember we learned about the two different types of data, qualitative and quantitative data. We also learned the difference between a discrete and a continuous variable.