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National 5 Biology-Transport Across Cell Membranes
Fichas del conjunto (17)
- 1What is the cell membrane composed of?Phospholipids and proteins.
- 2What is the cell membrane known to be?Selectively permeable-it only allows molecules that are small enough to pass through it.
- 3What is a concentration gradient?A difference in concentration of a substance.
- 4Describe what passive transport of a substance isThe movement of its molecules from a region of high concentration to a region of low concentration, down a concentration gradient. This does not require additional energy.
- 5Give two examples of passive transportDiffusion and osmosis.
- 6What is the difference between diffusion and osmosis?Osmosis is the movement of water through a selectively permeable membrane, whereas diffusion is the movement of a substance.
- 7Give three examples of substances that enter most cells through diffusionOxygen, glucose and amino acids.
- 8Give two examples of substances that leave most cells through diffusionCarbon dioxide and urea.
- 9Why is diffusion important?It helps to provide the cell with raw materials and helps to remove waste products.
- 10Describe what active transport of a substance isThe movement of molecules from a region of low concenration to a region of high concentration against a concentration gradient. This requires additional energy (ATP).
- 11Why does active tranpsort require additional energy?To allow membrane proteins to move molecules against the concentration gradient.
- 12What happens to an animal cell in a hypotonic solution?Water is taken into the cell through osmosis and it bursts.
- 13What happens to an animal cell in a hypertonic solution?Water will be lost by osmosis and the cell shrinks.
- 14What happens to an animal cell in an isotonic solution?No gain or loss in water, and therefore the cell remains unchanged.
- 15What happens to a plant cell if it is placed in a hypotonic solution?It will take up water by osmosis and become turgid-the vacuole swells and cell membrane and cytoplasm are pushed against the cell wall.
- 16What happens to a plant cell placed in a hypertonic solution?It will lose water by osmosis and become plasmolysed-vacuole shrinks, and the cell membrane pulls away from the cell wall, tissue is flaccid.
- 17Describe the role of protein molecules in osmosis and active transportIn osmosis, protein molecules allow the passage of water molecules in pores. In active transport, proteins act as carriers.
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- CfE Higher (Unit 1-Cell Biology) Biology Fichas sobre National 5 Biology-Transport Across Cell Membranes , creado por NinaJasT el 28/12/2014.
- Creado por
- NinaJasT · dic 2014
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- 24 nov 2016
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