While talking with a colleague about the structure of the plant cell and the function of the central vacuole, this simple model occurred to me. Materials needed are easily accessible and students will be able to better understand the concepts with related activities.
cell membrane – a thin layer that surrounds and holds a cell together
cytoplasm – a gel-like substance containing chemicals needed by the cell
vacuole – stores substances such as food, water and waste products
cell wall – the outer part of a plant cell that provides structure to the cell
central vacuole – a single large vacuole in plant cells
2 small boxes made of thin cardboard – rectangular solid – same size – I used boxes from butter.
2- medium sized white balloons
green construction paper
Prepare materials as listed above:
Buy 2 plants – same variety – I like to use ivys, but any plant that has fairly large leaves should work. Allow one of the two plants to wilt over several weeks prior to this activity, but water the second plant.
Fill one medium sized balloon with water so that it will fit snugly in the box. Fill the 2nd one with much less water so that it will NOT fit snugly in the box.
Cover the boxes with green construction paper or white paper and color it green. (See pictures.)
This model should be presented during instruction on plant cell structure, focusing on the structural function of the central vacuole.
The boxes represent the cell wall, while the balloons full of water represent the central vacuoles.
Students will compare how the plant cell wall (box) feels when the central vauole is full (large balloon in the box) vs. how the plant cell wall (box) feels when the central vacuole is only partially full – small balloon in the box.
See picture of the full vacuole.
After students feel the full central vacuole model, allow them to feel the leaves of the ivy which didn’t wilt for comparison.
Then after the students have felt the partially full central vacuole model, allow them to feel the wilted leaves of the second plant for comparison.
Ask: Why did the leaves of the plant wilt when it wasn’t watered? Answer: The central vacuoles are not full of water and aren’t holding the cell wall firm so that the leaves are full.
Ask: Which central vacuole – full or not – holds the plant cell wall firm? Answer: The full central vacuole.
When this model is presented to the students, present a fully watered plant with leaves. Have students observe the leaves and ask if they believe the central vacuoles are full in the cells of the leaves.
Students may allow the plant to wilt over several weeks rather than the plant being presented already wilted. In this case, students should be asked to hypothesize what will happen to the plant which is not watered.
If time allows, students may write the answer to the final question in paragraph form after discussing it as a class.
Middle School – Structure and Function and Information Processing
LS1.A: Structure and Function
All living things are made up of cells, which is the smallest unit that can be said to be alive. An organism may consist of one single cell (unicellular) or many different numbers and types of cells (multicellular). (MS-LS1-1)
Within cells, special structures are responsible for particular functions, and the cell membrane forms the boundary that controls what enters and leaves the cell. (MS-LS1-2)
High School – Structure and Function
LS1.A: Structure and Function
Systems of specialized cells within organisms help them perform the essential functions of life. (HS-LS1-1)
All cells contain genetic information in the form of DNA molecules. Genes are regions in the DNA that contain the instructions that code for the formation of proteins, which carry out most of the work of cells. (HS-LS1-1)