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Year 10 Biology > Movement Of Molecules > Flashcards

Movement Of Molecules Flashcards

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1
Q

Define equilibrium

A

Particles will move to reach equilibrium- both sides of the membrane have an equal concentration or number of particles

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2
Q

What is osmosis

A
  • Osmosis is the movement of water across a semi permeable membrane (a membrane which only allows some particles through)
  • it is a process by which molecules of a solvent tends to pass through a semipermeable membrane from a less concentrated to a more concentrated solution
  • at first, the concentration of solute will be very high on one side of the membrane but, over time, the water will move across the semipermeable membrane and dilute the particles on this side- making both sides of the membrane reach equilibrium.
  • from high concentration (of water) to low concentration (of water)
  • from (an area of) dilute solution to an area of concentrated solution
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3
Q

Draw a diagram of osmosis

A

Include:

  • outside of cell
  • inside of cell
  • semi permeable membrane
  • high/low water concentration
  • direction of movement
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4
Q

What is a turgid cell?

A
  • occurs when a plant cell is in a hypotonic solution
  • water enters by osmosis and the vacuole swells and pushes against the cell wall
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5
Q

What is a flaccid cell?

A
  • occurs when a plant cell is in a hypertonic solution
  • water is lost from the cell and the vacuole shrinks so the cell loses shape
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6
Q

What is a hypertonic solution?

A
  • a solution containing less water than the cells inside
  • If a cell is placed in a hypertonic solution, water will leave the cell, and the cell will shrink
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7
Q

What is an isotonic solution?

A
  • a solution containing the same amount of water as the cells in it
  • there is no net water movement, so there is no change in the size of a cell put into it
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8
Q

What is a hypotonic solution?

A
  • a solution with more water in it than the cells within
  • When a cell is placed in a hypotonic environment, water will enter the cell, and the cell will swell, sometimes burst
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9
Q

Describe the experiment used to investigate the effect of concentration of blackcurrant squash on osmosis in chipped potatoes

A

-label beakers with different concentrations of the squash you will use
-prepare different concentrations of the squash, each 30cm3 (concentrations from 0-100%)
-peel, blot and cut the potatoes, making sure each slice has the same mass
-place the chips into the squashes, wait 10 mins, then record the mass of the final potato chips
-

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10
Q

Why is it a good idea to remove all the potato skin in the potato blackcurrant squash experiment?

A
  • The potato skin may slow the rate of diffusion between the squash and potato chip
  • when you peel the potatoes the water particles don’t need to diffuse through any skin.
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11
Q

Why do we dry the chips on a paper towel before weighing them in the potatoe blackcurrant squash experiment

A

So that any water on the chips is not included in the overall weight of the chip which would give an accurate results

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12
Q

Explain in biological terms what is happening to the potato chips in the different blackcurrant squash solutions

A
  • when the concentration of the squash is between zero and 20% the chip increases in mass
  • this is because the black current squash has a higher concentration of water than the potato cells so the water molecules diffuse into the cells causing the chip to become larger and heavier
  • when the squash has concentrations over 28% the mass of the chip decreases as the chip contains a higher concentration of water particles therefore will diffuse water particles into the squash
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13
Q

What is the equation used to calculate percentage change

A

Percentage change= (change in mass/initial mass) x100

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14
Q

Describe the experiment used to investigate osmosis in Dandelion stems

A
  • Cut Dandelion stems into sections and then strips about 5 cm long and 3 mm wide using a scalpel and ruler
  • prepare five beakers with different concentrations of sodium chloride solution and one with only water using a measuring cylinder
  • place each Dandelion strip into one beaker and after 10 minutes record the results and repeat for accuracy
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15
Q

What are the variables for the experiment investigating osmosis in Dandelion stems

A

Independent: concentration of sodium chloride
Dependant: the way the stems curl
Controls: size of dandelion strips, time for the stems to soak, volume of liquids, volume of water in the stalks (preserve in water)

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16
Q

What were the results for the experiment investigating osmosis and Dandelion stems

A
  • at low concentrations of sodium chloride, the stems curled outwards
  • in the water, the stems strongly curled outwards
  • at high concentrations of sodium chloride, the stems curled inwards
17
Q

Explain the results for the in experiment investigating osmosis in Dandelion stems

A
  • in the lower concentrations of sodium chloride, the stalks curl outwards as there is a higher concentration of water in the solution than in the stalks so the stalks absorb the water and expand. The outer cells in the stalks don’t change because of the waxy layer protecting them from water, causing them to curl outwards
  • In the higher concentrations of sodium chloride, the stalks curl inwards as they contain a higher concentration than the solutions, so they lose water through osmosis causing them to shrivel up and get smaller and curl inwards. the waxy layer is on the outside because the outer cells haven’t lost water, so are bigger than the others
18
Q

What do osmosis and diffusion both have in common

A
  • both equalise the concentrations of two solutions
  • both cause particles to move down a concentration gradient
19
Q

What are the differences of osmosis and diffusion

A
  • osmosis only allows solvent molecules to move freely but diffusion allows both solvent and solute molecules to move freely
  • osmosis uses a semi permeable membrane, diffusion does not
20
Q

Draw a diagram of the experiment investigating osmosis using visking tubing

A

Include:

  • glass tube
  • liquid level at start
  • liquid level after a few hours
  • Elastic band to stop visking tubing falling off glass tube
  • sugar solution inside visking tubing
  • knot to seal end
21
Q

Explain the results of the experiment investigating osmosis using visking tubing

A
  • The concentration of water molecules is greater in the beaker than inside the Visken tubing
  • osmosis results in a net movement of water into the tubing increasing the volume of the solution in the visking tubing
22
Q

Summarise the results from the experiment investigating the effect of temperature on the diffusion of glucose through visking tubing

A
  • as the temperature increases the time taken for a positive test for glucose decreases
  • this is because the particles have more kinetic energy
23
Q

What is diffusion

A
  • Diffusion is the movement of molecules from an area of high concentration to an area of lower concentration
  • we can also say that molecules move down the concentration gradient
24
Q

Give three examples of places where diffusion occurs

A
  • The lungs
  • carbon dioxide entering leaf cells
  • digested food substances from the small intestine entering the blood
25
Q

Draw a diagram for the experiment investigating the effect of temperature on the diffusion of glucose through Visking tubing

A

include:

  • boiling tube
  • visking tubing
  • glucose solution (inside visking tubing)
  • water
26
Q

In the experiment investigating the effect of temperature on the diffusion of glucose through visking tubing, what is used to test for the glucose

A

Benedicts solution

27
Q

Describe the experiment investigating the effect of size on uptake by diffusion

A
  • collect agar cubes of different sizes
  • place the cubes in a beaker and cover with the diffusion solution and leave for five minutes
  • pour off the solution and rinse the cubes in water and then blot the surface of each cube dry with a paper towel
  • add universal indicator and time how long it takes for the acid to change the colour of the indicator in each agar block
28
Q

What are the variables of the practical which investigates the effect of surface area to volume ratio on the rate of diffusion

A

control: time for cubes to sit in acid, volume and concentration of acid
Independent: size of cubes
Dependant: time taken for cube to change colour from red to white

29
Q

Draw a diagram to show active transport for a sugar molecule through a carrier protein

A

Include:

  • concentration gradient
  • carrier protein with specific shape
  • cell membrane
30
Q

What is active transport?

A
  • Osmosis and diffusion depend on a concentration gradient in the right direction to work
  • substances are moved against a gradient by active transport which uses energy produced by respiration
31
Q

Explain how active transport works in a cell

A
  • Carrier proteins in a cells cell membrane have a specific shape to allow substances in/out of the cell, against the concentration graduent.
  • When the conc of a substance is higher on the outside of the cell than the inside, the carrier proteins will hook onto these cells inside , flip round and put it outside the cell.
  • The energy needed to do this comes from respiratiom
32
Q

Give some examples of situations when a substance cannot be moved into a cell by osmosis or diffusion and how active transport solves the problem

A

PLANTS:
- Allows the absorption of dilute minerals from the soil into the plant, against a concentration gradient.
-for example, the uptake of nitrate irons by root cells in clients needs active transport as the concentration of nitrate irons is lower in the soil
ANIMALS
-Allows the absorption of glucose (which is essential for respiration) into the blood from kidney tubules as the concentration of glucose is the same

33
Q

Why does an organism have to produce energy for active transport when diffusion and osmosis do not need energy?

A
  • The energy is needed to move the carrier proteins, transporting particles against the concentration gradient, whereas in osmosis and diffusion the particles will move naturally as they more with the concentration gradient .
  • The energy comes from respiration from mitochondria in cells
34
Q

Why is cyanide such an affective poison

A
  • cyanide stops active transport by stopping mitochondria from respiring
  • with new respiration, there is no active transport
35
Q

What of for factors that affect the rate of movement of substances across a partially permeable membrane

A
  • Concentration gradient
  • distance
  • temperature
  • surface area
36
Q

Why does concentration gradient affect the rate of diffusion

A
  • if there is a greater difference in concentration between two areas, then there will be a greater net movement from the area of high concentration to the area of lower concentration because there will be more particles moving away from the area of higher concentration then towards it
  • so rate of diffusion is faster
37
Q

Why does surface area to volume ratio decrease as size increases

A
  • as size increases, area increases, as the square of the length, but volume increases by the cube of the length
  • this means that volume increases faster than an area so the ratio of surface area to volume must get smaller
38
Q

What is plasmolysis?

A

the process in which cells lose water in a hypertonic solution

39
Q

Why do animal cells sometimes burst in hypotonic solutions?

A

They absorb water and burst as they have no cell wall

Year 10 Biology (6 decks)

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