Chapter 1 - diffusion, active transport, osmosis Flashcards

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1
Q

What is the definition of diffusion

A

The net movement of particles from a region of higher concentration to lower concentration down a concentration gradient, as a result of their random movement

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2
Q

Where does the energy for diffusion come from

A

The kinetic energy of the random movement of molecules and ions

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3
Q

What is the importance of the diffusion of gases and solutes

A

Diffusion helps living organisms

  • Obtain many of their requirements
  • Get rid of many of their waste products
  • gas exchange for respiration
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4
Q

How do substances move in and out of cells

A

Via diffusion through the cell membrane

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5
Q

What factors influence diffusion

A
  • tempurature
  • surface area
  • distance
  • concentration gradient
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6
Q

Definition of active transport

A

The movement of particles through a cell membrane from a region of lower concentration to a region of higher concentration using energy from respiration

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7
Q

When is active transport used

A
  • By root hair cells to move ions from soil into root hair cells when the concentration of ions is higher in the hair than the soil
  • By eptihelial cells of the villi in the ileum of humans to move glucose from the intestine into the blood
  • By the cells lining kidney tubules to move glucose from the contents of the tubule back into the blood
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8
Q

How do protein molecules move particles across a membrane during active transport

A
  • Ions move across the membrane through a protein molecule
  • The ion binds to the protein
  • The energy from respiration is used to make the protein change shape
  • The moves the ion across the cell membrane
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9
Q

What diffuses through a partially permeable membrane during osmosis

A

Water molecules

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10
Q

Definition of osmosis

A

The net movement of water molecules from a region of higher water potential (dilute solution) to a region of lower water ptoential (concentrated solution), through a partially permeable membrane

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11
Q

How does water move in and out of cells

A

By osmosis through a cell membrane

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12
Q

What is a turgid cell

A
  • A cell that has taken up water by osmosis
  • The contents of the cell press out on its walls; this is called turgor pressure
  • The cell walls cannot stretch, so the turgidity of the cell helps support the soft parts of the plant, like leaves and flower petals
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13
Q

What is a flaccid cell

A
  • A cell that has lost water by osmosis
  • When this occurs the contents of the cell shrink so much that the cell membrane pulls away from the cell wall; the cell is said to be plasmolysed
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14
Q

What happens when a plant tissue is immersed in a solution with a higher concentration of ions

A
  • Water moves out of cell by osmosis
  • cotnets of the cells shrink back from the cell walll
  • The cell is plasmolysed, the cell s irreversibly damaged and dies often
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15
Q

What happens when a plant tissue is immersed in a solution with a lower concentration of ions

A
  • Water moves into the cell via osmosis
  • Contents of the cell push out on the walls; this is turgor pressure)
  • Cell is turgid
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16
Q

What are plants supported by

A
  • Turgor pressure - contents of cells pushing out on the walls
17
Q

How are plants supported by turgor pressure

A
  • Contents of cells push out on an inelastic wall
  • Therefore pressure from the contents of the cells pushing out increases turgor pressure