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Category: My Classroom Material
Introduction to Animals Study Guide
Introduction to Animals Study Guide
How are most animals classified?
What are the main characteristics of chordates?
How are vertebrates classified?
What are heterotrophs & give some examples.
In what ways do animals differ from plants?
What are tissues?
What determines an animal’s body plan?
In what habitat do you find most species of animals?
What is bilateral symmetry?
What does bipedal mean?
Where are the dorsal & ventral surfaces on a bipedal organism?
What is radial symmetry?
Name invertebrates that are asymmetrical, radial symmetry, & bilateral symmetry.
What does cephalization mean?
What invertebrate group was first to show cephalization?
Describe the “surfaces” of animals with radial symmetry.
Why is cephalization an advantage for animals?
What is a postanal tail & give examples of adult chordates with this characteristic?
Describe the “skeletal” support found in roundworms.
What is segmentation, & what animals exhibit this characteristic?
What is the function of kidneys, and what organisms have these organs?
How do closed & open circulatory systems differ?
How are terrestrial animals protected against water loss?
What structures show segmentation in vertebrates?
What is the advantage of having a long intestinal tract?
How are nutrients moved through a cnidarian’s body?
Describe how spiral cleavage occurs.
describe the embryo at the start of gastrulation.
What forms from endoderm in cnidarians.
Floating Leaf Disk Assay
The Floating Leaf Disk Assay for Investigating Photosynthesis
Brad Williamson
Introduction:
Trying to find a good, quantitative procedure that students can use for exploring photosynthesis is a challenge. The standard procedures such as counting oxygen bubbles generated by an elodea stem tend to not be “student” proof or reliable. This is a particular problem if your laboratory instruction emphasizes student-generated questions. Over the years, I’ve found that the floating leaf disk assay technique to be reliable and understandable to students. Once the students are familiar with the technique they can readily design experiments to answer their own questions about photosynthesis. I plan to add to this page as I have time to elaborate on the technique and provide suggestions for modifications.
Materials:
| 1. Sodium bicarbonate (Baking soda)
2. Liquid Soap 3. Plastic syringe (10 cc or larger)—remove any needle! 4. Leaf material 5. Hole punch 6. Plastic cups 7. Timer 8. Light source
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Optional:
Buffer Solutions Colored Cellophane or filters Leaf material of different ages Variegated leaf material Clear Nail polish
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Procedure:
- Prepare 300 ml of bicarbonate solution for each trial.
- The bicarbonate serves as an alternate dissolved source of carbon dioxide for photosynthesis. Prepare a 0.2% solution. (This is not very much—it’s about 1/8 of a teaspoon of baking soda in 300 ml of water.) Too much bicarbonate will cause small bubbles (CO2)to form on the surface of the leaf which will make it difficult to sink the leaf disk.
- Add 1 drop of dilute liquid soap to this solution. The soap wets the hydrophobic surface of the leaf allowing the solution to be drawn into the leaf. It’s difficult to quantify this since liquid soaps vary in concentration. Avoid suds. If your solution generates suds then dilute it with more bicarbonate solution.
- Cut 10 or more uniform leaf disks for each trial
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- Single hole punches work well for this but stout plastic straws will work as well
- Choice of the leaf material is perhaps the most critical aspect of this procedure. The leaf surface should be smooth and not too thick. Avoid plants with hairy leaves. Ivy, fresh spinach, Wisconsin Fast Plant cotyledons—all work well. Ivy seems to provide very consistent results. Any number of plants work. My classes have found that in the spring, Pokeweed may be the best choice.
- Avoid major veins.
- Infiltrate the leaf disks with sodium bicarbonate solution.
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- Remove the piston or plunger and place the leaf disks into the syringe barrel. Replace the plunger being careful not to crush the leaf disks. Push on the plunger until only a small volume of air and leaf disk remain in the barrel (< 10%).
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- Pull a small volume of sodium bicarbonate solution into the syringe. Tap the syringe to suspend the leaf disks in the solution.
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- Holding a finger over the syringe-opening, draw back on the plunger to create a vacuum. Hold this vacuum for about 10 seconds. While holding the vacuum, swirl the leaf disks to suspend them in the solution. Let off the vacuum. The bicarbonate solution will infiltrate the air spaces in the leaf causing the disks to sink. You will probably have to repeat this procedure several times in order to get the disks to sink. You may have difficulty getting the disks to sink even after applying a vacuum three or four times. Generally, this is usually an indication that you need more soap in the bicarbonate solution. Some leaf surfaces are more water repellent than others are. Adding a bit more soap usually solves the problem.
- Pour the disks and solution into a clear plastic cup. Add bicarbonate solution to a depth of about 3 centimeters. Use the same depth for each trial. Shallower depths work just as well.
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- This experimental setup includes a control. The leaf disks in the cup on the right were infiltrated with a water solution with a drop of soap—no bicarbonate.
- Place under the light source and start the timer. At the end of each minute, record the number of floating disks. Then swirl the disks to dislodge any that are stuck against the sides of the cups. Continue until all of the disks are floating.
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- The control is on the left in each image. In the experimental treatment, on the right, leaf disks are rising and floating on the surface.
- Sample results:
| Time (minutes) | Disk Floating | |
| 1 | 0 | |
| 2 | 0 | |
| 3 | 0 | |
| 4 | 0 | |
| 5 | 0 | |
| 6 | 0 | |
| 7 | 1 | |
| 8 | 1 | |
| 9 | 1 | |
| 10 | 1 | |
| 11 | 4 | |
| 12 | 7 | |
| 13 | 8 | |
| 14 | 10 |
- The point at which 50% of the leaf disks are floating is the point of reference for this procedure. By interpolating from the graph, the 50% floating point is about 11.5 minutes. Using the 50% point provides a greater degree of reliability and repeatability for this procedure.
Only You Can Help Save Sam
Only You Can Help Save Sam!
Sam has been spending his summer boating on the great lakes. However, he’s not too bright (after all, the brains of worms are pretty small). He’s never learned how to swim, and he never wears his life preserver. The worst has happened! His boat has capsized and he’s stuck! Fortunately, his life preserver is in the boat, but unfortunately he does not know how to reach it without falling off and drowning.
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Use the Scientific Method to:
Problem:
How can you and your partner save Fred using only 4 paper clips. You may not touch Fred, the boat, or the life preserver directly with your hands.
Materials:
· Gummy Worm
· Gummy life preserver
· 1 Plastic Cup
· 4 Paper Clips
Procedures:
1. Work with your partner and “Save Fred”.
2. Follow the rules.
§ Fred, the boat, the life preserver can be touched only with the paper clips. NO HANDS.
3. Develop a data section that includes
§ Diagrams of how you saved Fred
§ A detailed protocol describing the diagrams.
4. Homework:
§ Analyze and conclude the experiment.
· This means that you must discuss (tell me what you think) about the difficulty of the task, what other strategies you and your partner worked on before you succeeded, and what you think the critical steps were for solving this problem.
§ Although this is working backwards, and not how scientists normally work, please develop a hypothesis for this lab. (Remember that a hypothesis is an ‘if-then’ statement: if I do this, then this will happen)
Teacher Notes:
Fred sits on the inverted cup. The cup sits covering the life preserver on the tabletop. No real water is involved. If the group size is 3 or 4, each person gets only 1 paper clip. Have a camera ready.
There are not any real answers – since it’s more of a team-building problem solving initiative rather than a yes/no answer. However, what they need to figure out is that if they work together, then one person maneuvers Fred (without hooking him) and the other uses the paper clips to stretch the gummy lifesaver for him to slip on. (The lifesaver will have a smaller inner diameter than Fred’s outer diameter by a fairly obvious amount.)
Ask them typical debriefing-type questions: what worked, what didn’t, did you plan, did you share ideas, did you just mangle poor Fred trying to make it work?, etc.
Groups of 3 and make it more of a challenge by allowing only 1 paperclip per student – that takes more thought and coordination to save Fred without drowning him. (No mouth-to0mouth resuscitation allowed!)
Organism Classification Webquest
Living Thing #1
Cells have chlorophyll  Adults live underground or under logs and rocks They breed and lay eggs in the water Young live in the water, have external gills, budding arms and legs and a fish like tail Adults must keep skin moist Ectothermic (an animal whose body temperature is determined by the temperature of its immediate environment.) Do not have scales Have Slimy skin No external ears Eats insects and small fish
Click on picture to hear its call
Has rough, shaggy hair-like feathers Tiny wings Sharp claws Endothermic (an animal whose body temperature is determined by its own metabolic heat production) Lays eggs Eats insects and worms Has whiskers to find way in the dark
Breathe air Has tough wrinkly skin Bristled hairs cover entire body Eats algae and crustaceans Has teeth Babies are born live and cared for by mother for up to 2 years Have mammary glands Live in warm coastal waters Are Endothermic. |
