mocking bird
Passive Transport (Section 5-1)
Answer Sheet
VOCABULARY REVIEW Explain the relationship between the terms in each of the following pairs of terms. 1. concentration gradient, diffusion: A difference in the concentration of molecules in two areas, called a concentration gradient, can result in diffusion, the movement of molecules from the area of higher concentration to the area of lower concentration. 2. osmosis, turgor pressure: Osmosis is the diffusion of water molecules across a cell membrane. When osmosis results in water molecules entering a plant cell, the molecules exert a pressure against the cell wall, called turgor pressure. 3. hypertonic, plasmolysis : hypertonic solution has a higher solute concentration than the cytosol of a cell. In a hypertonic solution a plant cell will lose water and shrink away from the cell wall, a process called plasmolysis.
MULTIPLE CHOICE
1. d 2. b 3. a 4. c 5. b
SHORT ANSWER Answer the questions in the space provided.
1. What happens to the movement of molecules at equilibrium? At equilibrium, the movement of molecules continues, but because there is no concentration gradient, there is no net movement in any particular direction. 2. How do carrier proteins transport substances across cell membranes? Carrier proteins bind to a molecule of the substance on one side of the membrane, change shape, transport the molecule across the membrane, and release the molecule on the other side. 3. What types of stimuli can cause the gates on ion channels to open or close?
The stimuli are stretching of the cell membrane, electrical signals, and chemicals in the cytosol or external environment.
4. Critical Thinking How does the interaction between a carrier protein and the substance it transports resemble the interaction between an enzyme and its substrate? Both involve the binding of a specific substance to a particular kind of protein and a change in shape of the protein as the process (transport or
Answer Sheet
VOCABULARY REVIEW Explain the relationship between the terms in each of the following pairs of terms. 1. concentration gradient, diffusion: A difference in the concentration of molecules in two areas, called a concentration gradient, can result in diffusion, the movement of molecules from the area of higher concentration to the area of lower concentration. 2. osmosis, turgor pressure: Osmosis is the diffusion of water molecules across a cell membrane. When osmosis results in water molecules entering a plant cell, the molecules exert a pressure against the cell wall, called turgor pressure. 3. hypertonic, plasmolysis : hypertonic solution has a higher solute concentration than the cytosol of a cell. In a hypertonic solution a plant cell will lose water and shrink away from the cell wall, a process called plasmolysis.
MULTIPLE CHOICE
1. d 2. b 3. a 4. c 5. b
SHORT ANSWER Answer the questions in the space provided.
1. What happens to the movement of molecules at equilibrium? At equilibrium, the movement of molecules continues, but because there is no concentration gradient, there is no net movement in any particular direction. 2. How do carrier proteins transport substances across cell membranes? Carrier proteins bind to a molecule of the substance on one side of the membrane, change shape, transport the molecule across the membrane, and release the molecule on the other side. 3. What types of stimuli can cause the gates on ion channels to open or close?
The stimuli are stretching of the cell membrane, electrical signals, and chemicals in the cytosol or external environment.
4. Critical Thinking How does the interaction between a carrier protein and the substance it transports resemble the interaction between an enzyme and its substrate? Both involve the binding of a specific substance to a particular kind of protein and a change in shape of the protein as the process (transport or