Category Archives: labs

Carbon Cycle and a Dead Cat

carbon cycle 1 carbon cycle 2 It was time to learn the carbon cycle in bio class. Two smarty-pants in the back of the class, copied the notes and decided they could now play games. Why not, they got the material. They have good grades. Fortunately I saw this opportunity as a break from my teaching. I handed them the chalk and my notes and said, “Teach.”

They willingly did! They taught about carbon moving from the air, to the trees and plants through photosynthesis, then to the animals that ate the plants, and was eventually breathed out the carbon in the form of carbon dioxide.

“Keep going.” I prodded,
“Do we have to draw the dead rabbit?”
“What do you think?”
“Well we have a picture of a dead dog on our phone we found on our way home from school. Can we use that?”
“Heck yeah.”
dead catThey showed the picture around and explained that the carbon stored in living things is released after death during the process of decomposition.

 

 

 

cat giordon
But there is more to the story. The next day Giordon walks in all geared up carrying a plastic bag. Guess what was in the bag. If you think it was a dead dog, you would be wrong. We examined the carcass through the double plastic bags. It had passed through putrification and was pretty well dessicated. So it smelled sweet as opposed to rancid. We determined by the teeth and claws it was a cat.

 

cat bonesNot to be out done by my students, I brought the carcass home and soaked it in a bucket of water. The fur was stuck hard to the skull so it took all summer for it to finally separate. I fished the bones out with a pair of needle-nosed pliers. Not a bad collection of bones. Some of the spine and ribs are still stuck in the guts, but the skull, leg bones and half the spine can be seen here. Remember some of the body tissue has been released as carbon gas back into the carbon cycle. That is what it is all about.

Pig Dissection

pig drawingThe last week of school the students had the option of doing a fetal pig dissection. They didn’t all participate, but they did the pre-lab, observed and answered questions. For those who did participate, they were fascinated and/or revolted, but they seemed to appreciate the opportunity.

Chelsea and Jovana chronicled Edith’s progress.
dissecting pigFirst: We observed the external anatomy.
Second: Figure out the characteristics that make it a mammal. It has nipples and is warm blooded.
Third: We looked at the ventral side (bottom) and the umbilical chord.
Fourth: We cut the umbilical chord and looked at the different openings.
Fifth: We tied down the pig to the dissecting tray.
Sixth: Edith cut the pig open using the diagram provided in the lab notes.
Seventh: She took out the liver (filters toxins out of the body) and observed the stomach that digests food.
Eighth: We observed, the small intestine that absorbs nutrients, the large intestine that removes waste and compacts the waste. The bladder was long and thin compared to a human. There was a peritoneum around the heart.
Lastly, Edith decided to remove and cut the large and small intestine. And the heart and kidneys.

Blood Typing Forensic Lab–Who done it?

blood testing lab 1A crime has happened and One-Eyed Earl was found murdered in a trash can with a wound on his chest. Next to the trash can was found a small pool of blood and the weapon. There are 3 suspects  for the murder but the CSI has to find out the blood type of the puddle in order to determine the killer. After a scenarios of tests we were able to determine the killer of One-Eyed Earl. In order to figure out who the killer was the CSI had to test the blood with Anti A Anti B and Anti Rh to determine the blood type of the puddle to see who’s blood matches up with the blood found at the sense of the crime.

Written and photographed by Willie & Kyle

blood lab photo 3blood lab photo 2blood lab photo 6blood lab photo 5

Nervous System

At this point in the school year we are studying the Nervous System. Its pretty interesting and the students are having fun with it. Hurray.

neuronThe students drew pictures of neurons, memorized the lobes of the brain and learned what they are for, pretty much everything we think, say, do. They learned about the brain stem and the cerebellum, the little brain.

What they liked most was learning about the eye and how it works. Its pretty amazing. The week before the holiday break they did a lab on special senses. This was their favorite lab because they got to eat. They did taste tests, smell tests, taste minus smell tests. They learned how the ear has three parts, outer, middle and inner. And that the eyes and ears work together to help us balance.

eye test

Cellular Respiration Lab

prepping for experimentSimply put cellular respiration is how organisms take in food (and oxygen) and make energy out of it. Cellular respiration is the process that takes place your cells; it begins in the cytoplasm and ends in the mitochondria.

Your cells go through cellular respiration because they need the energy that is stored in glucose. This glucose comes from sugars in carbohydrates groups of foods you eat.

The energy of one glucose molecule is converted into 38 ATPs.

cellular respirationThe harder your cells work the more ATP they need.

So, they will break down more glucose, use more oxygen and in turn produce more carbon dioxide.

color change 2To test this we did a lab activity.

We took 10 ml of water and added it to a test tube. Then we added 5 drops of bromethymol blue. Bromethymol blue is an indicator chemical that changes from blue to green or yellow in the presence of carbon dioxide. Each group had a student gently blow through a straw into the beaker while another student timed the color change in seconds. This number was recorded. The second part of the experiment one of the students jogged in place for 1 min. then repeated the procedure. The results were recorded.

The students then analyzed the time difference to conclude how much carbon dioxide was given off and in turn how much oxygen was used with and without exercise.

color change

Diffusion Lab

Introduction: In this lab you will observe the diffusion of a substance across a semi-permeable membrane. Iodine is a known indicator for starch. An indicator is a substance that chances color in the presence of the substance it indicates. Iodine turns purplish black in the presents of starch.

diffusion labProcedure:
1.    Fill a plastic baggie with a teaspoon of corn starch and a 60 ml water, spin the baggy shut and tie it tight.
2.    Fill a beaker up to 150ml with water and add ten drops of iodine solution.
3.    Place the baggie in the beaker of water so that the baggy of cornstarch is submerged.
4.    Wait twenty minutes and record your observations in the data table
5.    While you are waiting record your starting data and predict what you think you will see.

Starting Color

Color after 20 minutes

Solution in Beaker

Solution in Bag

1. Define diffusion
2. Define osmosis
3. What is the main difference between osmosis and diffusion?

Conclusion
1. Based on your observations, which substance moved, the iodine or the starch?
2. The plastic baggie was permeable to which substance?
3. Is the plastic baggie selectively permeable?

Blue-Tongued Skink

skinks breathing

Listening to the blood circulate through the skink’s body.

Our class had a visitor from the Berkshire Museum. John from the aquarium brought in the blue-tongued skink.

The blue-tongued skinks are omnivores. In the wild their diet consists of bugs, snails, ants and whatever else they can find. They also eat plants. Blue- tongue skinks are reptiles. They maintain body temperature by using their environment. They sleep with their eyes closed and breaths air in through lungs.

–Written by Talia