Post-lab The post-laboratory discussion should center on the students' explanations of the changes observed in the Elodea cells. Discuss what happens to the cell wall as the salt concentration increases. Students should have been able to distinguish between the cell walls and the cell membrane more clearly as more water leaves the cell and the cytoplasm shrinks. Ask students the following questions to guide the post-lab discussion.
As students answer the questions, sketch an Elodea plant cell on the board, filling in the cell with the subcellular structures being discussed. See the Elodea Plasmolysis website for pictures of Elodea cells in various salt solutions. You can review these with the class and ask students to compare these with what they saw in their observations.
The following key concepts should be discussed with students:. Have students answer the Conclusions questions of the worksheet in their lab notebook. These questions can be used as an assessment tool to check student understanding. A website with an active description about osmosis and the movement of water in and out of cells is How Substances Get Into and Out of Cells. Students can read the information on this site and view the animations until the section entitled "Demonstration of Osmosis Using Visking Tubing," which is not relevant to high school students.
From this activity, students could proceed to Diffusion, Osmosis and Active Transport , a site that can enhance their understanding of dynamic equilibrium within cells, diffusion, and osmosis.
There is an interactive on this page that allows students to observe diffusion, osmosis, and active transport. In this lesson, students explore how infographics can be used to portray the differences and similarities between and among animal species. This lesson helps students understand that all animals have a life cycle that includes being born, developing into an adult, reproducing, and eventually dying. In this lesson, students use the book Caesar's Last Breath to learn about the substances in the air we breathe and to explore the See the Tool.
See the Collection. See the Lesson. Did you find this resource helpful? Life Science. Have you tried this lesson? Share your tips. Feeling the pinch from the current economy?
Carolina understands. In this lab students observe Elodea leaves under magnification. They will see cell walls and chloroplasts. From the movement of chloroplasts they will infer that cyclosis, or protoplasmic streaming, is occurring. They also will observe that most chloroplasts are pressed tightly against the cell wall and should infer from this that much of the cell is occupied by a vacuole.
Elodea , , or In Elodea , cyclosis is easy to observe because chloroplasts move with the cytoplasm as it flows. Light and heat stimulate cyclosis in Elodea. Tungsten or halogen substage microscope lamps produce both heat and light, so after 2—3 minutes, students should be able to observe the movement of chloroplasts. If your microscopes have fluorescent or LED lamps, these produce very little heat and often will not stimulate cyclosis. To provide the needed heat, use a desk lamp equipped with a halogen bulb.
Position the lamp so that it shines down on the lab bench. After a few minutes, the surface of the lab bench should become noticeably warm to the touch. Students can place their slides on this warm surface for 3 minutes and then look for signs of cyclosis. A somewhat better arrangement is to position the lamp so that it shines directly onto the stage of a microscope, thereby heating the slide while students view it.
Not all slides will show cyclosis, so have students share those that do, so that everyone has the opportunity see the movement. Ensure that students understand and adhere to safe laboratory practices when performing any activity in the classroom or lab. Demonstrate the protocol for correctly using the instruments and materials necessary to complete the activities, and emphasize the importance of proper usage.
Use personal protective equipment such as safety glasses or goggles , gloves , and aprons when appropriate. Model proper laboratory safety practices for your students and require them to adhere to all laboratory safety rules. Although you can receive Elodea and use it the same day, it is much better to condition the plants under lights for 2 days. On the day of the lab set up 2 or more small tanks or large beakers, each containing water and Elodea. Place forceps and droppers alongside each container.
Also, set up stations for pickup of microscope slides, coverslips, and dissecting needles. Optional: If students have studied osmosis, they can observe plasmolysis.
Students are unlikely to observe nuclei in Elodea cells. However, nuclei are easily observed in stained cells of onion skin. Quarter an onion and separate the layers. Use forceps to remove the skin from the inner concave surface of a layer. Cut or tear the onion skin into small pieces that will fit under a coverslip. Place the onion skin on a microscope slide and smooth out as many wrinkles as possible. Add a drop of stain to cover the onion skin. A number of stains can be used, including iodine solutions iodine-potassium iodide , Lugol solution , Gram iodine , crystal violet , toluidine blue , and methylene blue.
After 1 minute, rinse away the stain with tap water, add a coverslip, and observe the cells. Nuclei will be evident. In addition to light and heat, pH also influences cyclosis. Have students conduct a study to determine at what pH cyclosis is most likely to occur. We use cookies to provide you with a great user experience.
By using our site, you accept our use of cookies. You can review our cookie and privacy policy here. Login or Register My Account Login or register now to maximize your savings and access profile information, order history, tracking, shopping lists, and more.
Login Create an Account. Call: International Ordering Information. My Cart Your Shopping Cart is currently empty. New Products New Products View our newest products for your classroom and lab.
New - Life Science Browse the latest tools and resources for life sciences at Carolina. Biotechnology For a quarter century, Carolina Biological Supply has been committed to bringing biotechnology into the classroom. Building Blocks of Science Building Blocks of Science Elementary Curriculum offers kits that are affordable and easy to implement in your classroom.
Top Categories Chemicals Choose from over chemical products in chemical grades, sizes and concentrations to meet your needs. Distance Learning Kits Enhance the science experience with Carolina's lab kits designed specifically for college-level distance education. View all Distance Learning Kits. Middle School eLearning Resources Stale lesson plans? High School eLearning Resources Stimulating digital resorces for the high school classroom.
Dissection Supplies We offer a full range of dissecting equipment to fit all your lab needs. Lab Equipment Carolina is your quality source for a well-equipped lab. No nucleus, no chloroplasts, no mitochondria. Do have a cell wall. Plant cells : eukaryotic.
Relatively large. Have a nucleus, have mitochondria, sometimes have chloroplasts. Have a large central vacuole and a cell wall. Animal cells : eukaryotic. Have a nucleus and mitochondria. Never have chloroplasts. Lack a cell wall, and have no central vacuole. Return to top.
0コメント