Biology Class Demonstrations

    We share these for use by Qualified Science Educators Only. Some have inherent safety problems that must be provided for. We have room for the demonstration outline only. You must assume the responsibility for the safety and success of your own demonstration.


Week 1

Life sciences:


Week 2

A Story: Is Sammy Alive?

This is a modification of "Substituted Sammy: An exercise in defining life".
It raises some interesting questions about defining life.

    Sammy was a normal, healthy boy. There was nothing in his life to indicate that he was anything different from anyone else. When he completed high school, he obtained a job in a factory, operating a machine press. On this job he had an accident and lost his hand. It was replaced with an artificial hand that looked and operated almost like a real one.
    Is Sammy Alive?

    Soon afterward, Sammy developed a severe intestinal difficulty, and a large portion of his lower intestine had to be removed. It was replaced with an elastic silicon tube.
    Is Sammy Alive?

    Everything looked good for Sammy until he was involved in a serious car accident. Both of his legs and his good arm were crushed and had to be amputated. He also lost an ear. Artificial legs enabled Sammy to walk again, and an artificial arm replaced the real arm. Plastic surgery enabled doctors to rebuild the ear.
    Is Sammy Alive?

    Over the next several years, Sammy was plagued with internal disorders. First, he had to have an operation to remove his aorta and replace it with a synthetic vessel. Next, he developed a kidney malfunction, and the only way he could survive was to use a kidney dialysis machine (no donor was found for a kidney transplant). Later, his digestive system became cancerous and was removed. He received nourishment intravenously. Finally, his heart failed. Luckily for Sammy, a donor heart was available, and he had a heart transplant.
    Is Sammy Alive?

    It was now obvious that sammy had become a medical phenomenon. He had artificial limbs, nourishment was supplied to him through his veins; therefore he had no solid wastes. All waste material was removed by the kidney dialysis machine. The heart that pumped his blood to carry oxygen and food to his cells was not his original heart. But Sammy's transplanted heart began to fail. He was immediately placed on a heart-lung machine. This supplied oxygen and removed carbon dioxide from his blood, and it circulated blood through his body.
    Is Sammy Alive?

    The doctors consulted bioengineers about Sammy. Because almost all of his life-sustaining functions were being carried on by machine, it might be possible to compress all of these machines into one mobile unit, which would be controlled by electrical impulses from Sammy's brain. This unit would be equipped with mechanical arms to enable him to perform manipulative tasks. A mechanism to create a flow of air over his vocal cords might enable him to speak. To do all this, they would have to amputate at the neck and attach his head to the machine, which would then supply all nutrients to his brain. Sammy consented, and the operation was successfully performed.
    Is Sammy Alive?

    Sammy functioned well for a few years. However, a slow deterioration of his brain cells was observed and was diagnosed as terminal. So the medical team that had developed around Sammy began to program his brain. A miniature computer was developed: it could be housed in a machine that was humanlike in appearance, movement, and mannerisms. As the computer was installed, Sammy's brain cells completely deteriorated. Sammy was once again able to leave the hospital with complete assurance that he would not return with biological illness.
    Is Sammy Alive?

    The End

    If Sammy is not alive at the story's end, exactly when did Sammy stop being alive?


Week 3

caution

Osmosis #1:

  • Remove the shell of two fresh eggs by covering them with 3M hydrochloric acid. When most of the shell has dissolved, rinse them and remove the remaining shell. This leaves the semipermeable chorion membrane.
  • Cover one egg with distilled water in a beaker.
  • Cover one egg with white corn syrup in a beaker.
  • Observe after 24 hours.
  • The results will be obvious, but you could quantify your results with measurements before and after.
Osmosis #2:
  • Have students eat a handful of salted nuts.
  • "What happens after eating salty foods?"
  • The nuts have a high concentration of salt and a low concentration of water. This causes water to leave the cells of the mouth, making you thirsty.
  • "How do you remedy the condition?"
Cell membrane:
  • Cover the surface of a tray of water with ping pong balls.
  • The balls represent the lipid molecules of the cell membrane.
  • Their movement will domonstrate how a particle moves through the membrane.
Surface area and solution:
  • Weigh a sugar cube.
  • Weigh an equal mass of granulated sugar.
  • Place both in different beakers containing the same amount of water.
  • Notice the speed at which the two samples dissolve.
Surface area vs volume:
  • The formula for calculating the surface area of a sphere is 4 pi r2
  • The formula for calculating the volume of a sphere is 4/3 pi r3
  • Use 3.1 for pi
  • Measure the diameter of a large marble, ping pong ball, and a baseball to two significant digits.
  • Calculate the surface area and volume of each to two significant digits.
  • Compare the rate of increase of surface area to the rate of increase of volume.
Product of respiration:
  • Prepare two test tubes of 10% sugar water solution.
  • Add baker's yeast to each test tube.
  • Cover the test tubes with flexible wrap.
  • Observe the tubes through the period and at the beginning of the next class day.
  • "What are the bubbles?"

Week 4

Chromosomes:

  • Give students a drawing of the chromosomes in a human cell.
  • Ask them to describe what they see.
  • Put all answers on the board and discuss.
Inherited traits:
  • Put two different flowering plants on a table.
  • "What traits of these plants are inherited?"
  • List all answers on the board and discuss.
  • The list should be extensive.
Human traits #1:
  • In humans, the ability to taste phenylthiourea (PTU) is dominant. "Tasters" (TT) or (Tt) perceive an extremely bitter taste of PTU, while "non tasters" (tt) experience no taste.
  • Give each student a test strip and compare their responses.
Human traits #2:
  • Have students compare the lengths of their first and third fingers.
  • Which is longest?
  • Record the class data.
  • Which is dominant, long first finger or short first finger?

Week 5

Mutations:

  • Show a video about cancer

Week 6

Evolution:

  • Show students several pictures of domestic dogs and a wolf.
  • "Why are there so many different kinds of dogs today?"
  • "What genetic process could be involved?"
  • "How did the differences in dogs become so pronounced?"
  • Discuss the fact that all dogs are the same species.
  • Discuss the fact that dog breeders "select" for certain characteristics.
Convergent evolution:
  • Show students pictures of a shark and a dolphin.
  • "Why do these animals look so similar even though one is a fish and one a mammal?"
  • List responses on the board.
  • Discuss
The opposable thumb:
  • Use masking tape to tape the thumb to the forefinger on the dominant hand.
  • Ask students to leave the tape on as long as they can during school today.
  • At the beginning of the next class period, ask each student how long they left the tape on.
  • "What caused you to take the tape off?"
  • "Would you say that the opposable thumb is a major advantage for humans over animals that do not have it?"
Stone tools:
  • Show several stone tools and projectile points.
  • Use identification guides to identify and date projectile points.
  • Discuss the use of stone tools by Native Americans in the 1800s.

Week 7

Plant leaves give off water - Transpiration:

  • Pour melted paraffin over the soil of a well-watered potted plant to that no water will evaporate.
  • Place a plastic bag over the plant and seal the bag around the container with tape or a rubber band.
  • After 24 hours, condensation should be evident inside the bag.

Week 8

Classification:

  • Show students several objects.
  • Discuss the characteristics that could be used to put them into groups.

Spontaneous generation:

  • Show students some rotten fruit.
  • "Why did the fruit rot?"
  • "In the 1600s, people were unaward of microorganisms. How do you think they explained the rotting of food?"
  • If someone was bold enough to suggest that some unseen living thing was the cause, how could they test this hypothesis?"

Week 9

Virus replication:

  • A virulent virus may complete its lifecycle in 30 minutes producing 200 new viruses.
  • "How many new viruses can come from one virus in a day?"
  • Make a graph showing this growth in numbers of viruses each hour for the 24 hour period.

Week 10

Where do protozoa live?

  • Add a handful each of soil and dead grass to a jar.
  • Fill the jar with distilled water, cover it, and place it in indirect sunlight.
  • A couple of days later, examine samples of the water under the microscope.
  • "Where did the protozoa come from?"

Week 11

Fungi:

  • Show a large mushroom.
  • Is this a plant?
  • Why?
  • Hold the mushroom over a piece of white paper.
  • Tap the mushroom cap.
  • What is the black power on the paper?
  • Examine under a microscope.

Week 12

Importance of plants:

  • Show the following items to the class:
    1. aspirin
    2. cotton cloth
    3. paper
    4. lipstick
    5. a chocolate bar
  • "What was used to make each of these?"
    1. salicylic acid in willow bark and leaves
    2. cotton plant
    3. wood pulp
    4. castor oil from castor bean and carnauba wax from carnauba palm leaves
    5. cocoa beans

Week 13

Vascular tissues:

  • Split the stem of a white flower (carnation) part way up. A fresh celery stalk (with leaves) can be used.
  • Place each stem half in a different color of water.
  • Observe what happens to the color of the flower.

Plant hormones:

  • Place a green banana in a plastic bag.
  • Place another green banana in a plastic bag with a ripe apple.
  • Observe at the beginning of the next class period.
  • The banana with the apple should already be yellow. The banana in the bag by itself will take a couple of days to ripen.
  • Ask students to form a hypothesis to explain the observation.
  • The apple must give off some substance that affects ripening.

Week 14

Germinating seeds:

  • Line the inside of a glass jar with paper towel.
  • Keep about an inch of water in the bottom of the jar for the length of the demostration.
  • Slip seeds between the paper towel and glass around the sides of the jar.

    Option:

  • Make two jars.
  • Place one jar in a warm place and the other in a cool place.
  • Observe which seeds germinate first?

Gravity on roots and stems:

  • Begin by sprouting seeds as in the demonstration above.
  • After the seeds sprout, turn them in different ways to observe how the roots and stems begin to grow.

Types of fruit:

  • Show the class the following:
    • Apple
    • Orange
    • Cucumber
    • Tomato
    • Potato
    • Carrot
  • What are these?
  • Why?
  • What plant part forms each of them?

Week 15

What is an animal:

  • Show a large bath sponge to the class.
  • Ask them to describe the biology of a sponge.
  • Some students will not already know that a sponge is an animal.
  • Discuss why the sponge is an animal.

Week 16


Week 17


Week 19


Week 20


Week 21


Week 22

Did dinosaurs become birds?

  • Show a video about dinosaurs.

Week 23


Week 24

caution

Muscle contraction:

  • Use a mousetrap to show the idea of the all-or-none principle of muscle contraction.
  • It takes a certain amount of force to trip the trap just as it takes a certain stimulus to trigger the muscle.
  • The trap will snap completely, not partially or excessively as does a muscle contraction.

Week 25

Concentration in parts per million, ppm:

  • Have each of 20 students count out 249 brown beans. (4980 beans)
  • You count out 15 brown beans.
  • Add all beans to a gallon jar. There are now 4995 beans in the jar.
  • Place 5 white beans in the jar and shake.
  • You now have a white bean concentration of 1 part per thousand.
  • This concentration is 1000 times greater than 1 part per million.
  • Students should get the idea.

Week 26

Human digestive system length:

  • An 8.5 meter long piece of rope can be used to illustrate the length of the alimentary canal.
  • Different areas of the digestive tract can be indicated on the rope by painting it different colors.
  • Approximate lengths for each part of the alimentary canal are as follows:
    • mouth, 15cm
    • pharynx, 15cm
    • esophagus, 35cm
    • stomach, 30cm
    • duodenum, 25cm
    • jejunum, 2.5m
    • ileum, 3m
    • colon, 1.5m
    • rectum, 15cm
    • If the rope has a diameter of 2.5cm, the size of the small intesting, the part of the rope representing the small intestine can be coiled to show how the intestine fits into the abdominal cavity.
Food calories:

caution

  • Place 25 ml of water (25 g) in a small beaker and measure the temperature.
  • Measure the mass of a high fat nut (Brazil nuts and cashews work well).
  • Stick a long pin through a cork and place the nut on the point of the pin.
  • Support the beaker of water on a ring stand above the nut.
  • Ignite the nut and let the flame heat the water.
  • Measure the temperature of the water.
  • Use the data to calculate the number of food calories in the nut.
  • Find the accepted value for the calories of your type of nut and compare the experimental value to the theoretical value.

Week 27

How fast do nerve impulses travel in the body?

  • Have one student hold a 6-inch ruler at the top.
  • Have another student place their fingers on either side of the ruler at the bottom, but not touching.
  • When the first student drops the ruler, the second student is to catch it.
  • If the second student does not "cheat", the ruler will fall through their fingers before they can close them.

Week 28


Week 29

Size of Earth's biosphere:

  • Show a large apple to represent the Earth.
  • The apple peel represents the biosphere, that portion of the Earth where life is found.
  • Remove two-thirds of the peel from the apple. The remaining portion represents the biosphere available for human habitation.
  • Cut the apple with the peel to show the thickness of the peel. The thickness of the peel is a good comparison to the thickness of the biosphere.

Week 31


Week 32


Week 33


Week 34


Week 35

Making charcoal by destructive distillation:

Charcoal is the carbon that is left when wood is destroyed by heating in the absence of oxygen. When wood burns normally, flammable gases are released, causing the flame. Charcoal is made in a "cooker" that keeps these flammable gases away from the solid wood.

  • Build a charcoal cooker:
    • Clean a soup can and a tuna-fish can. Make a pencil-sized vent hole in the bottom of the tuna-fish can. The hole should be off-center, closer to the edge of the can than the center.
    • When the cooker is in use, the tuna can is inverted over the open top of the soup can. The vent hole must be over the soup can.

  • Make the charcoal:
    • Cover the bottom of the soup can with wood shavings. Shavings are used for this demonstration instead of larger pieces of wood to allow the process to be completed quickly.
    • Cover the soup can with the inverted tuna can. Be sure the vent hole is over the soup can.
    • Place the cooker over a lab burner.
    • In a few minutes, smoke will come from the vent hole. Carefull bring a lit match to the smoke. At first, the smoke will have too much water vapor to burn. But after a while, the smoke will burn with a steady flame. The flame is produced by the flammable gases being forced out of the wood.
    • Continue heating for at least thirty minutes. Turn off the burner and allow the arrangement to cool thoroughly.

  • Examine the cans and contents.
    • The inside of the tuna can is black with tars given off by the wood.
    • The bottom can has the charcoal in it.
    • Try to ignite the charcoal. If the distillation process is complete, the charcoal will burn with a steady red glow, but not flame.

Other Demonstrations:
Nebraska Earth Science Education Network
Mr Biology' High School Bio Website

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