Every day new products are created and sold. They claim to make you look better, smell better, or be healthier, but how do you know if the product is safe? Personal care products go on your body, in your eyes, in your mouth. Do these products affect everyone in the same way? Might some people be more sensitive to an ingredient in a product than others?
Products are tested and approved before they can be sold in stores. But how are these products tested for safety? Scientists often test products on other living organisms to see whether they cause problems for those organisms.
Might some of them be seen as cruel or morally objectionable? How would you feel about testing products on human subjects, chimpanzees, rabbits, or rats? Might using these groups as possible testing subjects also become expensive? Human subjects need to be paid and laboratory animals can also be expensive. Is there a model organism that could be used to test personal care products that is not so expensive? Is there a model organism that does not cause the moral conflict that testing on humans and animals involves?
Yes, there is, and you will get to test a variety of personal care products on this model organism: Tetrahymena. Tetrahymena is a tiny, single-celled organism that lives in quiet freshwater ponds. It swims in water using small hairs on its body called cilia. It eats bacteria in the water.
Module Protocols
Relevant Concepts
Structural similarity between Single cell and Multicellular Organisms; Relationship of Structure to Function.
Next Generation Science Standards Relationships
Elementary School:
1-LS1-1 Use materials to design a solution to a human problem by mimicking how plants and/or animals use their external parts to help them survive, grow, and meet their needs.
4-LS1-1 Construct an argument that plants and animals have internal and external structures that function to support survival, growth, behavior, and reproduction.
4-LS1-2 Use a model to describe that animals receive different types of information through their senses, process the information in their brains, and respond to the information in different ways.
3-LS4-2 Use evidence to construct an explanation for how the variations in characteristics among individuals of the same species may provide advantages in surviving, finding mates, and reproducing.
See our glossary for the terms used in the modules.