5. Thinking Critically Paramecium, a single-celled fresh-water organism, takes in water by osmosis. Paramecium uses an organelle called a contractile
vacuole to remove excess water from the cell.

(a) Describe what would happen to Paramecium if it did not have
a contractile vacuole.

(b) Predict the effect of placing Paramecium in salt water.

(A) Protozoa and some low-level multicellular animals There are no organs responsible for excreting liquid waste. Such waste can penetrate the cell surface directly into the water outside of it. If paramecium does not contain vacuoles will cause it to lose the balance of body fluids The contractile vacuole compression rate depends on the osmotic pressure of the water in which the animal lives, i.e. the compression rate decreases. if the osmotic pressure of the water in which it resides increases But it will speed up if the osmotic pressure of water decreases.

(B) The water mixed with salt has a higher concentration than fresh water. So the water diffuses into the paramecium. Therefore, the contractile vacuole is less compressed to remove water from the cell than when in fresh water.

the answer that best describes the relative refractory period in the neuron is the resting membrane potential is restored, but concentrations of sodium and potassium are not restored to their original state.

the refractory period is the time during which another stimulus given to the neuron will not lead to a second potential. thus, because na+ channels are inactivated during this time, additional depolarizing stimuli do not lead to new action potentials.  

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an organism's phenotype is the  form of a trait  that it  displays. for  flowercolor, a pea  plant  can  display  a phenotype of purple or white flowers. an organism's  genotype  is the alleles of a gene it contains. based on his data, mendel concluded that a phenotype can be  determined  by more than one  genotype.