bio 1

The number of mitochondria in a cell would be a general indicator of the extent of

• active transport.

• diffusion.

• facilitated transport.

Which is a correct association of protein types?

• carrier proteins-provide a channel for substances to move across a membrane

• cell recognition proteins-allow a specific molecule to bind to it and may cause a cell response

• enzymatic proteins-carry out metabolic reactions directly

All of the following are true statements regarding the cell membrane except

• it regulates the entrance and exit of molecules to and from the cell.

• it separates the internal environment of the cell from the external environment.

• serves as a site for protein synthesis.

If we inspect most cell membranes in a living human body, we would find a nearly continuous flow of substances back and forth across the plasma membrane. Which of the following explains this continuous flow?

• Cell metabolism constantly produces oxygen in respiration, this increases the cell's affinity for carbon dioxide which diffuses into the cell.

• Cell metabolism is constantly using up oxygen and raw materials; this lowers their concentration, so more will diffuse into the Cell

• Cells produce useful secretions, this increases their concentration, and more will diffuse into the cell.

¡ What property of phospholipids makes them suitable for the formation of the double layer found in membranes?

• They are uncharged.

• They can interact with proteins.

• They have both a hydrophobic and a hydrophilic end.

Which of the following factors could cause the cell membrane to become less permeable?

• the channel proteins were to denature and become inactive

• if the size of the protein channel was to increase

• if the hydrophilic head of the phospholipids were to become hydrophobic while the hydrophobic tails become hydrophilic

Which membrane transport process can continue whether the cell is alive or dead?

• diffusion

• phagocytosis

• exocytosis

When an intestinal cell ingests substances inside very small vesicles that can only be seen with an electron microscope, this is

• diffusion.

• pinocytosis.

• exocytosis.

Of the following conditions, which is absolutely necessary for diffusion to take place?

• low temperatures

• a differentially permeable membrane

• a concentration difference

Oxygen diffuses into the capillaries of the lungs because there is

• a higher concentration of O2 in the alveoli than the capillaries.

• a higher concentration of CO2 in the capillaries than the alveoli.

• a higher concentration of CO2 in the alveoli than the capillaries.