Cell Membrane Transport

A person with swollen gums rinses his mouth with warm salt water, and the swelling decreases. Which of the following has occurred?

• The swollen gums have absorbed the saltwater solution.
• The saltwater solution lowers the temperature of the water in the gums.
• The salt in the solution has moved against the concentration gradient.
• The water in the gums has moved out due to the high concentration of salt in the solution. 

The diagram below represents a cell and some molecules in its environment. Which molecule would require the use of energy in order to be brought into the cell?

• 1
• 2
• 3
• 4

A freshwater plant is placed in a container of saltwater. What will most likely happen to the cells of the plant?

• They will swell because water will move into them.
• They will swell because salt will move into them
• They will shrink because water will move out of them.
• They will shrink because salt will move out of them.

The picture shows a contractile vacuole of a unicellular freshwater organism. The contractile vacuole regulates the flow of water into and out of the cell in an aquatic environment.

What conditions cause the contractile vacuole to fill with water?

• The concentration of water is greater outside the cell than inside the cell.

• The temperature of water in the vacuole is higher than the temperature of its environment.

• The concentration of water inside the cell is the same as the concentration outside the cell.

• The temperature of water in the vacuole is lower than the temperature of its environment.

Some students used vinegar to dissolve away the shells of three eggs and used these eggs as models of human red blood cells. The students observed the changes in the eggs when they were placed in different solutions.

• The cell membrane is an impermeable barrier that prevents water from entering the cell.

• The cell membrane allows solutes to enter the cell, which causes the cell to shrink.

• The cell membrane allows water to enter and leave the cell.

• The cell membrane removes solutes from the environment.

Joy took the notes shown below while learning about cells.

• Forms boundary between a cell and the outside environment

• Controls the movement of materials into and out of the cell

• Consists of double layer of phospholipids.

She forgot to write the name of the cell structure that her class was studying that day. What structure is described in her notes?

• Cell Membrane

• Cell Wall

• Lysosome

• Endoplasmic Reticulum

An osmosis investigation was conducted using chicken eggs to represent cells with semi permeable membranes. The mass of each egg was measured to determine how much water diffused into or out of the eggs. The eggs were first soaked in vinegar to dissolve the shell. Each egg was then placed in one of three different solutions for 24 hours. The table below shows the results of the investigation.

• Substances other than water may also cross the cell membrane.

• Substances other than water may block pores in the cell membrane

• Water enters the cell when placed in environments of high water concentration

• Water leaves the cell when placed in environments with a low concentration of solutes

This diagram shows a red blood cell in a beaker that contains a solution with a higher salt concentration than that inside the red blood cell.

What will happen to the red blood cell in this environment?

• The size of the red blood cell will remain constant.

• The red blood cell will swell at first and then shrink.

• The red blood cell will swell from absorbing salt molecules.

• The red blood cell will shrink from losing water molecules

The cellular process known as the sodium-potassium pump was discovered in the 1950s by Jens Christian Skou, a Danish scientist. This process is a form of active transport that moves three sodium ions to the outside of a cell for every two potassium ions that it moves into the cell. Which of these best explains why energy is needed for active transport?

• Ions are negatively charged.

• Ions are attached to large proteins.

• Ions are trapped inside the plasma membrane.

• Ions are moved against the concentration gradient.

The picture shows a contractile vacuole of a unicellular freshwater organism. The contractile vacuole regulates the flow of water into and out of the cell in an aquatic environment. What conditions cause the contractile vacuole to fill with water?

• The concentration of water is greater outside the cell than inside the cell.

• The temperature of water in the vacuole is higher than the temperature of its environment.

• The concentration of water inside the cell is the same as the concentration outside the cell.

• The temperature of water in the vacuole is lower than the temperature of its environment.