An amoeba is a single-celled organism that feeds on algae, plant cells, and bacteria. When an amoeba feeds, it first makes contact with the food particle. Next, the amoeba starts to surround the particle. Once the particle is completely engulfed, it is surrounded by a layer of the amoeba's membrane, forming a vesicle. The pH in the vesicle is then lowered and the contents are degraded. What type of transport is involved in this process?

A.
endocytosis
B.
diffusion
C.
passive transport
D.
exocytosis

A.  endocytosis

Explanation:

Endocytosis is the type of transport that is involved in this process because it engulf the food material. Amoeba engulfs food particles with the help of its pseudopodia which are the projections of cell membranes. A food vacuole is formed around the food particle. This process of engulfing a matter by the projections of the cell membrane to form a vacuole is called endocytosis.

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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humans are now responsible for causing changes in the environment that hurt animals and plant species. we take up more space on earth for our homes and cities. we pollute habitats. human activity often changes or destroys the habitats that plants and animals need to survive.