Unit 1 Cells - Movement of substances into and out of cells Flashcards

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1
Q

What do cells need to be able to enter through the cell membrane?

A

Oxygen, water, dissolved food molecules and mineral ions.

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2
Q

What does ‘selectively permeable’ mean?

A

Cell membrane will allow some substances through but will prevent movement of others.

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3
Q

What is ‘diffusion’ ?

A

The random movement of a substance from where it is a high concentration to where the concentration is lower.

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4
Q

Is diffusion slower in liquids or gases?

A

Slower in liquids

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5
Q

Plant and animal cells are adapted to allow diffusion to happen at a rapid rate. What are these adaptations?

A

Large surface area, thin barriers.

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6
Q

How does the concentration gradient affect the rate of diffusion?

A

Concentration gradient is the difference in concentation betwen the high and low areas. The larger the difference the FASTER the diffusion.

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7
Q

How does temperature affect the rate of diffusion?

A

Higher temperatures increase the kinetic energy of the molecules making them move faster and increase the rate of diffusion.

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8
Q

How does the surface area affect the rate of diffusion?

A

The larger the surface area over which diffusion takes place th faster diffusion occurs.

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9
Q

Where does diffusion occur in living organisms?

A
  1. Diffusion of oxygen from the air spaces on the lungs into the blood.
  2. The diffusion of carbon dioxide from the bllodstream into the lungs.
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10
Q

How do microvilli in cells in the gut help adsorb food?

A

Microvilli increase surface area. This speeds up the rate at which food molecules diffuse from the gut into the cells.

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11
Q

In the selective permeability experiment using dialysis tubing and starch solution, explain the colour change of iodine.Iodine changes

A

The starch inside the bag turns a blue/black colour whilst the iodine outside the bag remains unchanged.

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12
Q

What 2 factors effect the rate of diffusion?

A

surface area and volume

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13
Q

If cells get too big, can they still rely on diffusion?

A

No … surface area to volume ratio decreases. Diffusion only works well over short distances so the cell would die.

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