NC Bio 1.2.3 #1

Which bacterial behavior demonstrates chemotaxis?

• decomposing dead organisms

• sensing external sources of light

• filtering nutrients out of the environment

• moving toward nutrients in the environment

If a paramecium swims into an unfavorable region, which avoidance reactions helps to ensure survival of the paramecium?

• closing of the oral groove

• beating of the cilia in the opposite direction

• inhibiting the formation of the food vacuole

• contracting the contractile vacuole to expel water

The paramecium contains a contractile vacuole that helps regulate water balance. Its cytoplasm contains a greater solute concentration compared to its freshwater environment, so water moves into the organism. How does the contractile vacuole help regulate excess water?

• The contractile vacuole collects and stores all the excess water.

• The contractile vacuole swells and expels the water outside.

• The contractile vacuole reduces the solute concentration in the cytoplasm.

• The contractile vacuole distributes the water to different organelles for use.

Amoebas move with the help of pseudopodia. Pseudopodia form when the cell tries to extend the sides of its body in one direction, which results in projections of cytoplasm. These extensions help the amoebas move forward. What is another use for pseudopodia in amoebas?

• to create food from sunlight

• to maintain the shape of amoebas

• to engulf food particles

• to defend against predators

Organisms such as amoeba are capable of using the process of chemotaxis to find food. This is most similar to what process in higher organisms?

• ants following a scent trail to a discarded piece of bread several feet away

• bees flying off to a food source after observing the waggle dance of other bees

• bats targeting and catching moths and other insects in mid-air using echolocation

• birds migrating long distances for better food sources using Earth’s magnetic field