Pre-AP Cell Membrane & Transport Exam

A type of cellular transport is shown. Which description best identifies this type of cellular transport?

• Active transport, because energy is being used to move molecules against the concentration gradient

• Facilitated diffusion, because energy is being used to move molecules with the concentration gradient

• Osmosis, because energy is not being used to move molecules with the concentration gradient

• Endocytosis, because energy is not being used to move molecules against the concentration gradient

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TEK 4B

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.

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TEK 4B

This diagram shows cellular activity across a cell membrane. Which two processes does this diagram most directly model?

• Energy conversions and synthesis of new molecules

• Synthesis of new molecules and homeostasis

• Transport of molecules and energy conversions

• Homeostasis and transport of molecules

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TEK 4B

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. Which statement best describes the role of the cell membrane in this model?

• 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.

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TEK 4B

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.

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TEK 4B

The diagram below shows how a paramecium maintains homeostasis. A paramecium normally lives in a hypotonic environment in which water continually diffuses into the cell. To maintain homeostasis, the paramecium must pump out large amounts of water using its contractile vacuole. If the paramecium is then placed in a hypertonic environment, which of the following will occur?

• Water will diffuse into the paramecium.

• Water will diffuse out of the paramecium.

• Salt will be pumped out of the paramecium by the vacuole.

• Salt will be pumped into the paramecium by the vacuole.

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TEK 4B

Which would most likely cause the liquid in Tube A to rise?

• Starch concentration being equal on each side of the membrane.

• Water passing from a region of lower starch concentration to one of higher starch concentration.

• Water and starch volumes being the same.

• Solute in the tubes changing from a higher temperature to a lower temperature.

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TEK 4B

In the nerve cells of humans, sodium ions are "pumped" from a region of lower concentration to a region of higher concentration. This process is an example of -

• passive transport.

• active transport.

• diffusion.

• osmosis.

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TEK 4B

Cell membranes perform all the following functions except -

• making nutrients for cells

• holding cytoplasm within cells

• regulating substances exiting cells

• recognizing other cells

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TEK 4B

A scientist is investigating cell transport. She observes molecules being transported into a cell through proteins present in the cell membrane. These proteins do not use energy to transport the molecules. Which of the following best explains the type of cell transport observed by the scientist?

• Active transport because membrane proteins were used

• Diffusion because the molecules were entering the cell

• Facilitated diffusion because the proteins were not using energy

• Osmosis because the molecules were moving against the concentration gradient

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TEK 4B