Plant cells

Biology study - cellular biology

This second activity will focus on imaging and studying microorganisms and plant components under the foldscope to observe and photograph the cellular features and functions in plant and animal cells. The foldscope can produce magnification down to 140x magnification which may not be enough to view certain cellular structures, so samples will need to be selected that have larger cellular structures. Digital enhancements will benefit the students in the viewing of these smaller features and the optics of a modern mobile smartphone will assist in these studies. The students will view the different types of structures in both animal and plant cells to learn about the internal and external components of these subjects. Larger single cell organisms like paramecium and amoeba will work best in the portable microscope as the internal structures will be easily studied and observed. Plan cells offer a different challenge in subject preparation, thin slices of plant material need to be viewed to best observe plant cell features. Several aquatic plants offer very good observation of the internal cell structure and purchasing samples at an aquarium store or collecting samples in freshwater ponds or lakes can produce useful subjects.

Process: Collect and observe aquatic plants and microorganisms to view and photograph under magnifications with the foldscope and a smartphone. The suggested samples can initially be purchased at an aquarium supply store or similar pet store or these can be collected in freshwater bodies of water in the area surrounding the classroom or student’s home. Students can prepare the samples and place them in the paper microscope slides

Concept: Studies of animal and plant cells will demonstrate the structures and organelles that are similar and different in the animal and plant cells including cell walls and chloroplast / chlorophyll. Students will learn to recognize the types of the cells by these obvious differences in the cell structures.

Standards: from NYS standard http://www.nysed.gov/curriculum-instruction/science-learning-standards

MS-LS1-1. Plan and conduct an investigation to provide evidence that living things are made of cells; either one cell or many different numbers and types of cells.

Below is an example of an aquatic plant that is common in freshwater aquariums. The structure of the leaf shows the veins, the individual cells are the small dots huddled together between the veins.

If we zoom into the veins, we can get a view of the individual cells and identify the cell walls. The cell structures are commonly rectangular or square in these types of plant cells

Process: Observe a prepared and stained slide from the foldscope teacher’s kit or similar prepared slides to observe differences in the cellular structure of plants and animals. Several types of prepared slides are available to educators, and some of the common slides use stains to mark the cellular organelles to make these components more visually obvious to the viewer. One example would be a root segment from an onion or similar bulb plant. These cells at the end of the roots are often stained to highlight the nucleus or chromosomes and the process of cellular division, before they are affixed to a glass slide. Animal or fungus cells are also available in prepared slide form to demonstrate cellular division. Students can use these prepared glass slides under instructor supervision, to collect and enhance digital photographs of these subjects.

Concept: Students can use these prepared slides to observe cellular division and use the knowledge they developed in the last activity to observe the changes to both plant and animal cells during cellular division. Student may be able to capture this division in action with live samples from the previous activity, but if the cellular division is not observed in the live cells then a prepared slide can demonstrate this process accurately.

Standards: from NYS standard http://www.nysed.gov/curriculum-instruction/science-learning-standards

MS-LS1-1. Plan and conduct an investigation to provide evidence that living things are made of cells; either one cell or many different numbers and types of cells.

Below are some example images from a prepared slide made from an onion plant root. At the tip of the root, there is growth and the plant cells are stained to display the nucleus and the separation of the chromosomes during mitosis.

The chromosomes are stained dark purple and the nucleus is a lighter pink before it splits into 2 cells.