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Biology

Onion root mitosis

Mitosis is when a cell replicates itself and makes another genetically identical cell. Mitosis occurs whenever new cells are needed. The stages of mitosis include interphase, prophase, metaphase, anaphase, telophase, and cytokinesis. Mitosis, excluding interphase, takes approximately two hours. Interphase takes the longest time at around 80% of mitosis because in interphase the cell must duplicate its DNA and prepare everything for division. During interphase chromosomes are hard to see because all the chromosomes are chromatids at this point. Under a microscope, the nucleus looks like a black dot within the cell wall. Microtubules come out of centrosomes during interphase as well. Prophase takes the next most amount of time because the sister chromatids must condense around a centromere, creating a chromosome. The next stage is metaphase. In metaphase, the nuclear membrane dissolves and the microtubules attach to the chromosomes and pull them to the center of the cell. Anaphase is the shortest phase, anaphase only takes 0.8 percent of the cell cycle.  Next is Anaphase. In anaphase, the microtubules pull the chromosomes apart and toward opposite sides of the cell. Then telophase forms a nucleus around the chromatids and the microtubules detach from the chromatids and retract to the centrosomes. Finally, cytokinesis pinches the two nuclei apart, creating two new, genetically identical cells.

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Understanding mitosis is important to learning how planarians regenerate and produce genetically identical tissues. Scientists study planarians and other regenerating organisms in order to apply their knowledge to humans to eventually be able to help humans regenerate lost limbs and tissues.

Fertilizer vs. Compost

I decided to test fertilizer vs. compost because the plants that I grew in fertilizer would always dry up and die. What I found was that compost is much better at water retention. I made my compost out of banana peel, coffee grounds, peat moss, and dry leaves. My fertilizer was a store bought all purpose soil.

Compost
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Fertilizer
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If I were to do this experiment again I would add more ingredients to my compost to improve the nutrient composition and density and I would give the compost more time to develop its microorganisms to make it more effective. I would also regulate the temperature of the growing environment because I believe the low temperatures that the plants experienced at night stunted their growth. I would also have measured the plants more in order to have more data and I would have taken more photos.

Photosynthesis lab

In this experiment we attempted to expedite and document the process of photosynthesis (the chemical reaction that plants use to survive whereby H20, carbon dioxide, and light are converted to glucose and oxygen) by making leaves absorb carbon (sodium Bicarbonate a.k.a. baking soda/water solution) which will make the leaf bits sink, then giving it light from a black light and watching the leaf photosynthesize and as a result rise to the top of the water. See the diagram below for more information on photosynthesis.

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Our experiment was semi-successful. Our leaf disks absorbed the carbon and went to the bottom of the syringe fairly quickly. Then we transferred the bicarbonate solution and the disks to the open cup added water and placed it underneath a black light. We swirled the cup every minute for 24 minutes and not a single disk rose. The objective of the experiment was to have the disks convert the carbon to oxygen; you could tell that the leaves had photosynthesized when they were less dense, and floated to the top of the cup. We actually started out with one leaf disk floating, but it sank at minute 4. There could be a number of reasons why that is, one is that we did not add enough dish liquid. we thought there would be enough from the bicarbonate solution, but maybe not. another reason could be that the leaf disks were already too dead from being cut off from their original branch and their leaf. It could also be because we added too much water and not enough solution. The temperature of the water could have also been an effective variable. Another reason would be that it just wasn't under the light long enough for the reaction to occur, or that the light was not strong enough.

directly below is Riley and my data, under that is the class' data, and below are some photos and videos of the expirament.

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monocot or dicot?

In this experiment, we were exploring the differences between a plant that is classified as a monocot and a plant that is classified as a Dicot. We learned about the anatomy of these types of plants, for example, a monocot's leaves are parallel while dicots have a net vein system. The main difference is that dicots have two cotyledons while monocots have only one. You can see this in the diagram below.

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We planted a mung bean and a kernel of corn. Summer told us to inspect the inside of them. I was able to easily smash the bean in two very clean pieces, but I had to use a pencil to find the cotyledon in the corn. So with this information, I predicted that the bean would be the dicot and the corn would be the monocot because the bean was so easily split in two.

 The following photos are of the bean in corn seeds while they grew over the past two weeks.

My bean seed sprouted pretty early on and was doing well. My corn seed sprouted but never grew roots.  I watered them twice one week and once on the other. Since Monday I have watered them every day. I kept the cup by the window, so the seeds received diffused sunlight.

 

When I thought it had enough roots, I transferred the bean to soil and while I was at it I also transferred the rest of the seeds: one sprouted corn seed, one unsprouted corn seed, one sprouted and rooted bean seed, and two unsprouted bean seeds. Once I transferred these sprouts and seeds to soil I watered them and went home for the weekend. When I came back on Monday my most developed bean sprout had shriveled and died. The other seeds have not broken the surface of the soil yet.

 

Findings:

The mung bean was the Dicot. You can tell because once it sprouted the stalk had two small bulbs on either side, these were the cotyledons. Because the corn never sprouted I must go off of what other people's corn looked like. Other student's corn sprouts had parallel veins, which is a sign that a plant is a monocot. This aligns with my predictions. You can see the cotyledons on my sprout in the photo below.

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I think the sprout dried out because of the soil it was planted in. This soil does not absorb water well at all and I wasn't there to water them so they dried and died. :( 

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