The net movement of particles from a higher to a lower concentration, down a gradient
The movement of water only across a membrane
The movement of particles against a concentration gradient using energy
The bulk flow of liquid through a tube
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WhyDiffusion is the net movement of particles from a region of higher concentration to a region of lower concentration, down a concentration gradient.
2Multiple choice · Easy
Which process describes the net movement of water molecules across a partially permeable membrane?
Osmosis
Diffusion of solutes
Active transport
Respiration
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WhyOsmosis is the net movement of water molecules from a region of higher water potential to a region of lower water potential through a partially permeable membrane.
3Multiple choice · Easy
Active transport requires which of the following?
Energy from respiration
A partially permeable membrane only
A high temperature only
Sunlight
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WhyActive transport moves substances against a concentration gradient and requires energy from respiration (ATP).
4Multiple choice · Easy
In which direction do particles move during active transport?
From a lower to a higher concentration, against the gradient
From a higher to a lower concentration, down the gradient
Only from outside to inside the cell
In no particular direction
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WhyActive transport moves particles against the concentration gradient, from a lower to a higher concentration.
5Multiple choice · Easy
Which of these substances moves into cells by diffusion during gas exchange?
Oxygen
Glucose against its gradient
Mineral ions against their gradient
Large protein molecules
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WhyOxygen diffuses from a region of higher concentration outside the cell to a lower concentration inside, down a concentration gradient.
6Multiple choice · Easy
Osmosis is best described as the movement of water from a region of:
Higher water potential to lower water potential
Lower water potential to higher water potential
High solute concentration to low solute concentration
Low temperature to high temperature
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WhyOsmosis moves water from higher water potential (dilute solution) to lower water potential (concentrated solution) through a partially permeable membrane.
7Multiple choice · Easy
Which type of membrane is required for osmosis to occur?
A partially permeable membrane
A fully impermeable membrane
A membrane permeable to all molecules
A waterproof membrane
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WhyOsmosis requires a partially permeable membrane that allows water molecules through but not larger solute molecules.
8Multiple choice · Easy
An example of active transport in plants is the uptake of:
Mineral ions by root hair cells
Carbon dioxide by leaves
Oxygen by stomata
Water by osmosis
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WhyRoot hair cells absorb mineral ions from the soil by active transport, often against a concentration gradient.
9Multiple choice · Medium
A cell is placed in a solution with a higher water potential than the cell. What happens to the cell?
Water enters the cell by osmosis and it gains mass
Water leaves the cell by osmosis and it loses mass
There is no net movement of water
Solute moves out of the cell by diffusion
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WhyWater moves into the cell by osmosis from the higher water potential outside to the lower water potential inside, so the cell gains water.
10Multiple choice · Medium
Which factor would increase the rate of diffusion of a gas into a cell?
A steeper concentration gradient
A thicker exchange surface
A smaller surface area
A lower temperature
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WhyA steeper concentration gradient increases the rate of diffusion because there is a greater difference in concentration driving net movement.
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Diffusion: The net movement of particles from a region of higher concentration to a region of lower concentration, down a concentration gradient, as a result of their random movement.
Net movement: The overall movement of particles in one direction once movement in both directions is taken into account.
Concentration gradient: The difference in concentration of a substance between two regions; particles diffuse down it from high to low concentration.
Down a concentration gradient: Movement from a higher concentration to a lower concentration, the natural direction of diffusion and osmosis.
Against a concentration gradient: Movement from a lower concentration to a higher concentration, which requires energy as in active transport.
Passive process: A process that does not require energy from respiration, such as diffusion and osmosis.
Random movement: The continuous, unpredictable motion of particles in liquids and gases that drives diffusion.
Kinetic energy: The energy of moving particles; greater kinetic energy at higher temperatures causes faster diffusion.