|Classification Lab: Kingdom Protista||SUPER VLB|
- Draw and Diagram
- Classify to Class
The paramecium are protozoans with two nuclei. The larger macronucleus controls general cell activites, while the smaller micronucleus is involved in reproduction. The paramecium is surronded by a rigid cell membrane with many hairlike cilia which move in a rhythmic, oarlike movement to allow the paramecium to swim. One side of the paramecium contains a depression called the oral groove, which leads into a tubular gullet. The cilia sweep food particles down the oral groove into the tubular gullet, which collects untill the cell membrane bulges inward and forms a food vacuole. The food vacuole travels through the cytoplasm untill it fuses with a lysosome, who's digestive enzymes digest the food. The usable products of the food diffuse into the cytoplasm while the indgestible material is discharged from the cell through an opening called the anal pore. To excrete wastes, the paramecium must use active transport to maintain homeostasis. Water constantly diffuses into the cell by osmosis, as the paramecium is a freshwater organism. But because water is produced by the paramecium from cellular respiration, water must also be pumped out against the concentration gradient. This is done by the contractile vacuoles, where excess water collects and is ejected from the cell when the vacuole is full. In gas exchange in paramecium, oxygen from the surronding water diffuses through the cell membrane into the cytoplasm, while carbon dioxide diffuses out of the cytoplasm through the cell membrane.
Paramecium reproduce asexually by binary fission. In the paramecium, the micronucleus divides by mitosis while the macronucleus divides by a modified form of mitosis. One of each type of nucleus goes to each daughter cell. Also, the gullet and oral groove replicate and two new contractile vacuoles appear. After all the organs are reproduced, the cytoplasm divides by pinching in.
Back to the Protista Page
Back to the Classification Page
Sidwell Main | Science Home | Biology Home | Super VLB
Questions and comments should be sent to firstname.lastname@example.org.