BioPoint


By: Amy
April 27, 1998

Science fair projects are handed in and the invertebrate unit has also come to a close. This unit was exciting for many of students because it was our first opportunity to participate in dissections. Our class was fortunate to dissect a crayfish, earthworm, grasshopper, starfish, and squid. During the crayfish dissection, we first observed many of the external parts of the anatomy. We removed and mounted parts such as the eyes, antennae, walking legs, swimmerets, uropod, and telson. The uropod and telson are parts of the tail. We also removed a chelea, which is one of the crayfish's pincers. We determined the sex of our crayfish by observing the swimmerets, or small swimming appendages. A female has soft and feathery swimmerets, while a man's are rigid and enlarged. We then observed the internal anatomy by cutting down the top of the crayfish. We removed and observed the gills, which were feathery and attached to the legs. The legs pump water through the gill chamber, allowing oxygen to be diffused into the blood. We also observed the stomach. Many were still filled with detritus that crayfish had eaten.

Our next dissection was one of the earthworm. We looked at the mouth, anus, and clitelium of the earthworm. Inside the earthworm we observed the intestine that ran throughout the body. We also found the crop and gizzard, both instrumental in the earthworm's digestion. The grasshopper dissection was only an external investigation. We looked at its hindwings and forewings, tympanic membrane, and ovipositor, which presence determines the grasshopper's sex as female.

The fourth dissection our class participated in was one of a starfish. We first identified the mouth and ambulacral grooves that extended from each ray. We also closely observed the numerous tube feet that are necessary for locomotion and the absorption of oxygen. We then looked at the internal anatomy of the starfish. We cut the top of a ray with scissors and removed the skin. We examined the digestive glands that filled most of the arm. We also located the stomach that is attached to the mouth. After removing the digestive glands, we observed the reproductive organs, called gonads. We also studied the water vascular system, necessary for locomotion.

The fifth and final dissection of the invertebrate unit was of a squid. We first observed the soft shell, or mantle, that enclosed most of the body. We also looked at the ten tentacles at the mollusk foot. We then opened the mantle and observed the gills. We identified the siphon, which serves as an opening for water to be expelled from the body and act a jet propulsion. We also removed the pen, which is the internal shell. With better flexibility. We opened the head and beak to observe the toungelike radula that held many sharp points for chewing. We also observed the large eyes.

After completing the dissections was had a test, or lab practical. In this, Mrs. Mazen set up booths, each containing an invertebrate we had dissected. These invertebrates were already cut open and colored pins were stuck in different places. It was our job to identify the body parts the pins were in. An interesting way to be tested!


By: Amy
January 11, 1998

It's hard to believe that the new year has already begun. We've been very busy during the second marking period working with the cell. After learning the parts if the cell we quickly moved into the topic of plant cells and photosynthesis. During this unit we discussed both the anatomy of the leaf, pigments, and the entire process of photosynthesis.

We did many labs during the course of this unit. First, we looked at the anatomy of the leaf. We observed a spider plant and a begonia and attempted to locate their guard cells and stomata. These areas are where transpiration occurs. We also observed transpiration by placing a leaf on cobalt chloride paper. The paper turns pink when it is wet. We saw it change from the blue to pink can concluded that transpiration had occurred.

In another lab dealing with the structure of living cells, we observed our own cheek cells and compared them to cells of an elodea leaf and an onion. We labeled the parts of all three cells and took special notice of the absence of cell wall and chloroplasts in the cheek cells. We also observed that the onion had no chloroplasts and deduced that this was because the onion was grown underground and received no sun which is required for photosynthesis.

Then we discussed pigments and analyzed the types of photosynthetic pigments through a lab using paper chromatography. Many times, chlorophyll hides all of the pigments that are present. We placed a strip of chromatography paper in a mixture of ether and acetone. The solvent rose almost to the top of the strip and dried in different colors. By calculating the Rf value (Rf = distance moved by substances/distance moved by solvent), we were able to determine if the lines represented chlorophylls, cartenoids, or xanthrophylls. We also took a look at germination. We placed ten RCBr seeds in a petri dish which had a surface embedded with a grid. We then put the petri dish in a water reservoir. We observed the development of radicles, hypocotyls, and cotyledons.

After learning about the process by which plants make energy, we began our unit on cellular respiration, how our body makes energy. During this time, we did one of the most challenging labs of the year, Life in a Single Cell. We observed paramecium, euglena, amoeba, and stentor. We observed the inner structure of the paramecium, its locomotion, and the ways it digests food and disposes of waste. We observed the structure and eating methods of euglena, amoeba, and stentor. We placed paramecium and amoeba in the same environment and observed how the amoeba extends an arm around the paramecium to create a food vacuole. The food vacuole allows lysosomes from the amoeba to break down the paramecium which adds nutrients to its own cytoplasm. The lab was very challenging because even with the addition of ProtoSlo, the living organisms moved very quickly and often left the field of view.

The last unit of the semester was on protein synthesis and DNA replication. After learning about the structure of DNA, we created the Incredible Edible DNA Model. Using licorice, gumdrops, cheerios, and marshmallows, we all constructed our own DNA model. We got to eat them of course!

We also extracted DNA from bacterial cells and separated the DNA using gel electrophoresis. We used EcoRI and HindIII as restriction enzymes that allowed us to observe the DNA like many genetic engineers do.


By: Amy
November 7, 1997

How quickly the year in Mrs. Mazen's room is going! After finishing our unit on the origin of life, we began to study the chemistry of biology. By the way, how did you like our essays? Chemistry started out with a basic review of atoms, elements, and bonding. As the unit expanded, we discussed specific ions in our body, the importance of water in our body, and pH. Along with this unit, we did some cool labs. We investigated polar and nonpolar molecules in the first lab. We learned that polar bonds form when there is an unequal sharing of electrons between atoms in a covalent bond between atoms. We also learned that water is a polar molecule. During the lab, we determined if certain substances were polar or nonpolar depending on their ability to dissolve in water and each other. We concluded that the polar substances dissolved in water and each other, while the nonpolar substances did not dissolve in water but did dissolve in each other. The second lab we completed was about pH. We determined the acidity and alkalinity of different substances using indicators such as litmus paper, bromthymol blue, phenolphthalein, and phenol red.

After completing this basic chemistry, we moved into organic chemistry. We discussed macromolecules like carbohydrates, lipids, and proteins. We also discussed amino acids and enzymes and their job in the human body of speeding up chemical reactions. We investigated enzymes and the denaturing of enzymes in a lab. We observed catalase and its effect on the breakdown of hydrogen peroxide. Are materials included apples, liver, and potatoes, and boiled apples, liver and potatoes. We looked for bubbles when we placed each substance into hydrogen peroxide. The bubbles would be present during the breakdown of hydrogen peroxide because during the breakdown there is a release of oxygen. We concluded that the boiled materials contained protein that had been denatured in the temperatures of boiling. No bubbles appeared because the catalase in the boiled materials had denatured and become ineffective in breaking down hydrogen peroxide.

We are just starting our unit on cells. We were each assigned a part of the cell and came up with a presentation for the class describing its structure and function. The projects were creative and interesting so don't miss them! They are coming soon!


By: Amy
September 28, 1997

Amy in the
lab

The year has hardly begun and strange smells are already coming out of our biology classroom. These first weeks of school, before beginning the "origin of life" unit, have been spent discussing and investigating the study of science. We've discussed the scientific method, graphing, and the tools used by biologists.

One of the most important tools we, and other biologists, use is the microscope. The first lab of the year was also focused on this topic. Our classroom is equipped with a compound light microscope for each student and other specialized microscopes. During the lab, we investigated the differences between objects viewed under the microscope and those viewed with the naked eye. (Did you know that a letter appears backwards and upside down under a microscope?) We also got practice preparing wet mounts, using oil immersion, and measuring with the microscope.

Amy in the
lab

The second lab we did involved investigating unknown substances. We placed six different materials, each in one of six test tubes filled with five drops of phenol red. The materials were a piece of paper towel moistened with yeast-sugar solution, a piece of paper towel moistened with boiled yeast-sugar solution, small dry radish seeds, spouted radish seeds, a live cricket, and a dead cricket. In another set of test tubes, we added dilute acid to a test tube of phenol red and a test tube of limewater, carbonated water to a test tube of phenol red and a test tube of limewater, and breath blown through a straw to a test tube of phenol red and a test tube of limewater. In looking at the color changes in the phenol red and the limewater, we were able to deduce that phenol red is an acid indicator and limewater is a carbon dioxide indicator. From these deductions, we could answer many questions about the identity of the substances being given off by the materials.