Unicellular Organisms 1.13 – pg. 42-46 NAME: 1. Why do you think bacteria are considered to be more primitive than other cells that you have studied? I think bacteria are considered to be more primitive than other cells I’ve studied such as plant cells or animal cells because the bacteria are not as developed as the other cells. For example, both plant and animal cells have nuclei, ribosomes and mitochondria. Bacteria are less advanced (primitive) than plant and animal cells and do not have nuclei, ribosomes or mitochondria. 2. Why are diatoms called plantlike protists? Protists are microorganisms (one-celled organisms) that live in moist places. Unlike bacteria which are also considered microorganisms, protists have a nucleus and organelles (mitochondria, ribosomes, lysosomes). Diatoms and Euglenas are two types of protists that are plantlike. Amoebas and paramecia (plural of paramecium) are two types of protists that are animal-like. Diatoms are called plantlike protists because they have a green chemical called chlorophyll, and they can make their own food just like plants. 3. Compare euglena to a plant cell. Make a list of similarities and differences. Characteristic chloroplasts cell wall Golgi apparatus mitochondria nucleus flagellum (movement) contractile vacuole eyespot Single cell EUGLENA PLANT CELL yes yes yes (pellicle) yes yes yes yes yes yes yes yes no yes no yes no yes no 4. Compare the process of feeding in the paramecium and amoeba. Paramecium feed using a mouth-shaped opening on the cell that is called an oral groove. The oral groove (as well as the rest of the cell) is lined with hairs. These hairs around the oral groove sweep back and forth causing food to be swept into the oral groove. The food travels down a tube known as a gullet and enters a food vacuole. The food is slowly digested inside the food vacuole. The amoeba, on the other hand, feeds by extending a branch of its cytoplasm, called a pseudopod (false foot), until the bloblike amoeba encircles and swallows up the food. Once swallowed, the food is surrounded by a membrane and becomes a food vacuole where the food will slowly be digested. 5. Why do many people associate microorganisms with disease? Often when people get sick, it is because they have been exposed to a microorganism. Hence, most people believe that microorganisms are associated with diseases. 6. Using the information that you have gained about osmosis, indicate why euglena, paramecia, and amoebas need contractile vacuoles. The function of contractile vacuoles is to pump excess water out from their cells. Euglena, paramecia, and amoebas that find themselves in solutions where the concentration of water outside of their cells is greater than the concentration of water inside their cells will have water diffuse across their membranes by osmosis from an area of high water concentration to an area of low water concentration. When this happens the cells will start to swell up with water and burst. In these cases, the euglena, paramecia, and amoebas need the contractile vacuoles to expel excess water to keep them from bursting. 7. Penicillin is an antibiotic that weakens the cell wall of bacteria. The sugars and proteins in the cytoplasm of the bacteria are in higher concentration than they are in their environment. Draw a series of diagrams showing how penicillin kills bacteria. .