J
James A
Guest
Background information - Paramecia are unicellular protists. They have a number of characteristics also found in animals, such needing to ingest food in order to obtain energy and being surrounded by a cell membrane but not by a rigid cell wall. Paramecia have organelles found in animal cells, including a nucleus, mitochondria, ribosomes, and cilia. In addition, they have star-shaped organelles, called contractile vacuoles, that expel excess water. The illustration below depicts a paramecium.
Refer to the illustration above. The data presented in the table below were obtained in an experiment in which paramecia were placed in salt water with different concentrations of salt and the rate at which their contractile vacuoles contracted to pump out excess water was recorded.
Salt ConcentrationNumber of contractile vacuole contractions/minute
Very high2
High8
Medium15
Low22
Very low30
a.How can you explain the observed relationship between salt concentration and rate of contractile vacuole contraction?
b.If something happened to a paramecium that caused its contractile vacuoles to stop contracting, what would you expect to happen? Would this result occur more quickly if the paramecium was in water with a high salt concentration or in water with a low salt concentration? Why?
10 points does not have to be a essay
Refer to the illustration above. The data presented in the table below were obtained in an experiment in which paramecia were placed in salt water with different concentrations of salt and the rate at which their contractile vacuoles contracted to pump out excess water was recorded.
Salt ConcentrationNumber of contractile vacuole contractions/minute
Very high2
High8
Medium15
Low22
Very low30
a.How can you explain the observed relationship between salt concentration and rate of contractile vacuole contraction?
b.If something happened to a paramecium that caused its contractile vacuoles to stop contracting, what would you expect to happen? Would this result occur more quickly if the paramecium was in water with a high salt concentration or in water with a low salt concentration? Why?
10 points does not have to be a essay