Writing in Biology - Section 1

Seed coat, also called a testa, is an outer covering of seed made from integuments that surround the ovule. Seed coats provide protection to the seed, allowing for the seed to survive conditions that they would otherwise not survive. Seed coat also has a role in controlling the growth, development of the embryo and create a compound that helps with the defense of the cell, with a large number of genes that are specifically expressed only in the seed coat, indicating that seed coat serves as more than that of a physical barrier. While the Seed coat serves an important protective role for seeds, there is evidence suggesting that the seed coat may also inhibit germination in some plants. The aim of this study is to see if the removal of the seed coat, which in turn removes all of the compound and protection offered by the seed coat result in faster germination compared to seeds that do not have their seed coat removed in the specific seeds studied.

To study how the removal of the seed coat affects germination, the seed coat was removed from 6 species of seeds. To do this, 20 seeds of each species were soaked in water for 1 hour. Then the seeds were divided into two groups ten, one group being the control, the other being the seeds with the seed coat removed. The seed coat was removed using an Exacto knife and slicing the seed coat and then peeling it away. The groups of seed were then each placed onto a petri dish individually labeled with their type and experiment group that contains a wet paper towel. The petri dish was then closed and placed in a dark corner, with the Petri dish covered by the lid. The seeds were checked every 12 hours and the state of the seeds was recorded. The state was defined to be initial germination when there was a sign of germination.

If the Earth changed the direction of its spin the sun would rise in the west and set in the east. The westerlies and easterlies would be blowing in the opposite direction than they are now. Because of this I would expect that the latitudinal distributions of biomes would be similar, but the variation of biomes across continents (east-west) would reverse to some extent. I would expect the mountains to have wetter eastern sides rather than western sides.Perhaps California/Oregon/Washington would be more like temperate deciduous New England and New England would be more temperate rainforest like the redwoods, or mediteranean climate like Yosemite.

Over one week, the germination rate in a variety of seed species was tested between seeds with and without testa. Particular species of seeds provided evidence of fast germination while others did not. Visual analysis sees no significant difference between the germination rates of seeds with or without testa. The germination rate of seeds with testa is equal to the germination rate of seeds without a testa. Uncertainties in our experiment include meeting optimal germination environments, as well as the uneven distribution of water to the seeds.
Furthermore, a small sample size experiment increases the likelihood of falsely accepting the null hypothesis. Future questions that can be asked to follow up on our experiment include whether pH or external factors such as soil conditions, temperature, and fertilizers affect the germination rate. These questions would lead the experiment towards figuring out how optimal germination rates vary by seed species.

In terms of data collection, they obtained basal levels of serum cortisol (adrenocortical), dehydroepiandrosterone (DHEA – an earlier form for androgenic and estrogenic steroid formation in tissues), androstenedione, estradiol (estrogen), sex hormone binding globulin, after an overnight fast at 8 in the morning. They did radioimmunoassay using radioactive labels to find the hormones. The main findings were that there was an increased morning cortisol level, higher DHEA and androstenedione in AD patients. Women with AD had a high level of androstenedione and DHEA after BMI and age was considered. There was a strong correlation between androstenedione and DHEA, and cortisol levels, unlike the control group. The most interesting fact is that the levels are this high in the early phase of AD, but it drops in the advanced stage. 

In the brain there are multiple different neural pathways that can affect hunger. But there are rare neurons, that when damaged, cause obesity. One such neuron is the MC4R neuron. This neuron signals for satiety. The POMC neuron excits it and tells the brain that it has enough energy, it doesn't have to eat anything else. The AGRP neuron inhibits the MC4R neuron which then signals for hunger. When the MC4R neuron is silences, the body weight phenotype of the mice tested was doubled. There are numerous experimental methods that can be used to silence the neurons such as rAAV virus to insert diolox sites into the genome of the mouse. This would allow you to insert receptors to specific toxins that not all of the cells have, such as diptherioa toxin or tetnis toxin receptors. By doing this, inserting the toxin into that area of the brain would kill only the cells that succesfully recieved the receptor, causing a loss of function. Loss of function experiments are extrelely useful in determining the function of a specific neuron or neural pathway. 

Continued research on other nocturnal organisms allows more insight into the effects of light pollution on animal behavior, of which continues to invade the lives of night creatures. Scientists could investigate behavioral responses to the effects of artificial light by rearing house crickets from eggs in a controlled environment, and tamper with the way the circadian cycle normally operates. This is a plausible avenue to test if cricket behavior changes when exposed to artificial light, in comparison with our study. This experiment may be better suited for nocturnal organisms, but it could also be conducted with diurnal animals like humans as a measure to gather more and variant data. Better understanding the negatives of artificial light through several contrasting experiments prevents limitation and can help society better understand the effects on a widespread scale. This experiment used a 5 watt lamp, but the results could also connect with bright city lights, technology usage, or even different parts of the world (consequences of jet lag via airplane travel). Studying just one field of animal behavior can answer many questions about the evolutionary mechanisms organisms have developed, and allows an opportunity for scientists to deduct a plethora of new and rich information from behavioral research.

For this project, we focused on leaf miner damage to different species of Elm trees. We collected 25 leaves from two American Elm, two Japanese Elm, and two Smooth Elm trees. We determined the average number of leaf mines and the percent of aborted leaf mines on each species sampled. We found that the American Elm had the highest average number of leaf mines, with the fewest percent aborted. This could mean that the American Elm is more susceptible to leaf miner damage than the other Elm species sampled.

Over a one week period, the germination rate in a variety of seed species was tested between seeds with and without testa. Particular species of seeds provided evidence of fast germination while others did not. A t-test concludes that there is no significant difference between the germination rates of seeds with or without testa. The germination rate of seeds with testa is equal to the germination rate of seeds without a testa. Uncertainties in our experiment include meeting the optimal environment for each species of seed, as well as the uneven distribution of water to the seeds. Furthermore, a small sample size experiment increases the likelihood of falsely accepting the null hypothesis. Another question our experiment brings up is whether the difference in germination rate between seeds with and without testa is practically significant. Even if the mean germination rate is truly significantly different from seeds without testa, what would industries have to invest to make this happen, and if so, would it be worth it?

Our project was based off of group 2's proposal. We loved their idea and thought it would be really interesting to observe lichen around campus, especially for me, because lichen is not something you pay close mind to every day. The idea that the quantity of lichen could be an indicator of the air pollution was a nice comparison. Counting lichen is fairly straightforward to do, and therefore, we set out to search for lichen at the campus pond and Sylvan woods and compare their differences!

We set up one 4 x 4 plot with flags around those two areas and used a metal grid to count each individual lichen on north facing trees that appeared in the grid - one meter up each tree; depending on how many trees were inside of the plot. We were able to get this equipment from Peter Alpert. So we looked for crustose, fruticose, and foliose, though mostly found foliose and crustose because we did not find any fruticose on the trees we looked at. Our results from T testing showed no significant differences between the campus pond and Sylvan, so this told us that there was no difference between the air pollution in those areas.

Although we all expected Sylvan to have much more lichen, and therefore less air pollution because of how rural it is in comparison to the frequented campus pond, we assume the reason for there not being a significant difference is because we did not go deep enough into Sylvan woods. We took data from the outside, and expect that if we ventured deeper, we might have seen more of a difference that we could have drawn evidence from.