Topic 1- Transport across cell membranes Flashcards
What is the effect of placing an animal cell into a pure water solution?
Animal cells placed in pure water-
The animal cells gain water by osmosis until the membrane swells and bursts.
What effect does placing a plant cell in pure water have?
Placing a plant cell in pure water-
Water moves from a high concentration outside the cell to a low concentration inside the cell by osmosis. The cell swells up and is described as turgid.
What effect does placing an animal cell in a weak solution have?
Animal cells placed in a weak solution are unchanged as there is the same concentration inside and outside the cell.
What is the effect of placing a plant cell into a strong solution?
Placing a plant cell into a strong solution-
The water moves from a higher concentration inside the cell to a lower concentration outside the cell down the concentration gradient. The membrane pulls away from the edge of the cell and the vacuole shrinks, the cell is described as plasmolysed.
What effect does placing an animal cell in a strong solution have?
Animal cells placed in a strong solution lose water by osmosis through the membrane until they shrink.
What is passive transport?
The movement of a substance with the concentration gradient that requires no energy.
Describe osmosis.
Osmosis is the movement of water from an area of high concentration to an area of low concentration across a selectively permeable membrane.
Name two examples of passive transport.
Diffusion
Osmosis
What does selectively permeable mean?
Cell membranes are described as selectively permeable as they have tiny pores which allow small substances (e.g. Water) to move through but not large ones (e.g. Proteins)
What is active transport?
Active transport is the movement of substances from a region of low concentration to high concentration. It requires energy to be used to move one substance against the concentration gradient.
What does against the concentration gradient mean?
Going for a low concentration to a high concentration.
What is the function of the cell membrane?
The cell membrane controls the passage of substances in and out of the cell
What substances enter or leave the cell by diffusion?
Diffusion only occurs in liquids and gases
Food and oxygen enter the cell by diffusion
Waste and carbon dioxide leave the cell by diffusion
What does active transport need?
Membrane proteins.
What effect does placing a plant cell in a dilute solution have?
Placing a plant cell in a dilute solution-
There is no effect as the concentration outside and inside are the same
