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BIOLOGY > Movement Of Substances > Flashcards

Movement Of Substances Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Define diffusion

A

Movement of particles from an area of high concentration to an area of low concentration

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2
Q

What does equilibrium mean?

A

Where particles will be equally distributed. Neither concentration is higher / lower than the other

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3
Q

Four factors that affect rate of diffusion

A

Temperature
Distance
Concentration gradient
Surface area: volume

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4
Q

How does temperature affect rate of diffusion?

A

molecules have more KE -> move faster
Diffusion occurs faster

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5
Q

How does concentration gradient affect diffusion?

A

Large concentration gradient -> molecules will diffuse from high to low quicker

If concentration gradient is small -> diffusion will happen slower

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6
Q

How does distance affect diffusion?

A
  • Diffusion takes longer if molecules have to travel further
  • therefore cells are small -> smaller volume reduces distance
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7
Q

How does SA:V affect diffusion?

A
  • Larger SA speeds up rate of diffusion -> there are more opportunities for molecules to move
  • large SA compared to the distance molecules must travel
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8
Q

Definition of osmosis

A

Net diffusion of free water molecules from an area of high water concentration to an area of low water concentration across a partially permeable membrane

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9
Q

When are free water molecules not considered ‘free’

A
  • When other molecules (eg. Sugar) dissolve into the water, the water molecules are attracted to them.
  • this means there are less free water molecules in the substance
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10
Q

What is a partially permeable membrane

A
  • Membrane that only allows certain particles through
  • particles can be selected by size
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11
Q

Define water potential

A
  • Measure of concentration of free water molecules in a solution
  • pure water has a water potential of 0
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12
Q

What happens to water potential in a solution as a solute is added?

A
  • Water potential falls as there is a lower concentration of free water molecules.
  • Solution with a high concentration of (eg. sucrose) have a low water potential.
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13
Q

Why do plant cells and animal cells react differently when being placed in different concentrations?

A

Plant cells have a cell wall which allows the cell to withstand a large amount of pressure

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14
Q

What is an isotonic solution?

A
  • The solution outside the cell has the same water potential as inside the cel
  • no net movement
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15
Q

What is a hypotonic solution?

A
  • The solution outside the cell has a higher water potential than inside the cell
  • net movement of free water molecules into the cell
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16
Q

What is a hypertonic solution?

A
  • The solution outside the cell has a lower water potential than onside the cell
  • net movement of free water molecules outside of the cell
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17
Q

Animal cell in hypotonic solution

A

Lysed

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18
Q

Animal cell in isotonic solution

A

Normal

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19
Q

Animal cell in hypertonic solution

A

Shrivelled

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20
Q

Plant cell in hypotonic solution

A

Turgid (normal)

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21
Q

Plant cell in isotonic solution

A

Flaccid

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22
Q

Plant cell in hypertonic solution

A

Plasmolyzed
- cytoplasm shrinks away from cell wall when there isn’t enough water to fill the cell

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23
Q

Define active transport

A

Movement of molecules form an area of low concentration to an area of high concentration ( against/ up a concentration gradient) using ATP

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24
Q

Does active transport go against / up or down a concentration gradient?

A

Against/ up

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25
Q

Does osmosis go against/ up or down a water potential gradient

A

Down

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26
Q

Does diffusion go against/ up or down concentration gradient

A

Down

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27
Q

What is a active transport used for

A

Transport substances against concentration gradient

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28
Q

What does an organism need in order to use active transport to transport substances?

A

Carrier proteins
- these use ATP to provide energy to move the substances across the membrane against the conc. gradient

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29
Q

What does the transport system in plants allow leaves to receive

A

Water - for photosynthesis
Mineral ions - to convert products of photosynthesis into useful substances

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30
Q

What does the xylem transport?
And where from -> to?

A
  • Water and mineral ions
  • roots -> leaves
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31
Q

What is the xylem made up of?

A

Cells that are:
-Thick walled
-dead
- hollow
- contain no cytoplasm
- arranged end to end to form tubes

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32
Q

What does the cell wall of the xylem contain + what does this do?

A
  • Lignin
  • waterproof
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33
Q

Examples of ions that the xylem transports + why

A

Nitrate ions - make amino acids and proteins
Magnesium ions - make chlorophyll

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34
Q

What does the phloem transport
Where from -> to

A

-sucrose and amino acids
- leaves (where they are made) -> growing points (eg. tips of the shoot and flowers) or storage areas (roots/bulbs)

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35
Q

What is the phloem made of

A
  • Living cells
  • arranged end to end to form tubes
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36
Q

What is the cell walls in phloem made of

A

Cellulose

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37
Q

What is the sugar made photosynthesis converted to in phloem

A

Sucrose

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38
Q

What does moving sucrose and amino acids around require + what is this called

A
  • Requires Energy
  • called translocation
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39
Q

What is the main site of water absorption in plants

A

Root hairs take in water through the soil

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40
Q

How are root hairs adapted for absorbing water

A
  • thin walled ( short diffusion distance)
  • hair like extensions ( increase SA or the root epidermis)
41
Q

Function of a root hair cell

A

Absorb water and minerals from soil

42
Q

How do mineral ions enter root hair cells

A

Active transport
-water conc. is lower than root hair cell’s conc. so ions move in

43
Q

How does water enter root hair cells

A

Osmosis
- soil water has higher conc. of water molecules so water will move in

44
Q

Define transpiration

A

Evaporation of water from the surface of a plant

45
Q

Functions of the transpiration stream

A
  • carry mineral ions to the leaves for synthesis of amino acids and chlorophyll
  • keep turgor pressure high in leaf cells (holding leaves up)
  • evaporation cools in leaves
  • supplies water for photosynthesis
46
Q

How does water pass out of the leaves

A
  • leave cells out the mesophyll
  • evaporates through air spaces between spongy mesophyll
  • diffuse out stomata as water vapour
47
Q

Why does water leave the xylem to replace water lost?

A

Osmosis
- cells have a lower conc. of water molecules
- water moves into them from surronding mesophyll cells
- water leaves xylem to replace water lost from nearby cells

48
Q

What is the loss of water vapour form the leaves called

A

Transpiration

49
Q

What is transpiration stream

A

Water pulled up xylem in the stem and roots in a continuous flow

50
Q

Environmental conditions that affect rate of transpiration

A
  • temperature
  • humidity
  • wind speed
  • light intensity
  • water supply
51
Q

How does temperature affect rate of transpiration

A
  • hotter day, water will evaporate quickly from leaves
  • water molecules have more KE
  • Transpiration increases = temp increases
52
Q

How does humidity affect rate of transpiration

A
  • very humid air contains lots of water vapour
    -> smaller conc. gradient -> transpiration slows
  • dry air - diffusion of water vapour from leaf to atmosphere will be fast
  • transpiration increases = humidity decreases
53
Q

How does wind speed affect rate of transpiration

A
  • moving air, water vapour is blown away from leaf as fast as it diffuses out
    -> speed up transpiration
  • still air = transpiration slows down
  • transpiration increases = wind speed increases
54
Q

How does light intensity affect rate of transpiration

A
  • in daylight - stomata are open to supply CO2 for photosynthesis
  • allows more water to diffuse out of the leaves into the atmosphere
  • Light intensity increases = transpiration increases
55
Q

How does water supply affect rate of transpiration

A
  • lack of water = plant is losing water faster than it is being taken up by roots
  • plant will start to wilt
  • before this, guard cells become flaccid + stomata start to close
    -> reducing transpiration and delaying wilting
  • water supply decreases = transpiration increases
56
Q

What are stomata

A

Holes in ( normally bottom) surface of leaf

57
Q

Where are guard cells ands what do they do

A
  • Either side of the stomata
  • control opening and closing of stomata
  • each guard cell has a thickened, inflexible inner cell wall ( on stomatal side)
58
Q

When the stomata is opened and close what are the guard cells

A

Open - swollen
Closed - shrunken

59
Q

How does the guard cells open the stomata

A
  • in light = photosynthesise
  • conc. of sugars increases + water potential decreases in guard cells.
  • water moves into guard cells (osmosis)
  • become turgid + banana shaped
    = opens stomata
60
Q

How does the guard cells close the stomata

A
  • in dark = no photosynthesis
  • sugar conc. decreases = water potential increases
  • water moves out of guard cells
  • become flaccid
    = stomata close
61
Q

Why are sugars needed in plants

A

Respiration or growth

62
Q

What is the sieve tube

A
  • living
    -thin layer of cytoplasm at edge of cell
  • filled with sap
    Sap = concentrated solution of sucrose + amino acids
  • sap flows through sieve plates and through phloem
63
Q

Does sieve tube have a nucleus

A

No
Controlled and supported by neighbouring companion cells

64
Q

What do companion cells do

A
  • have lots of mitochondria
  • actively transport sucrose into phloem
65
Q

How does water move into the sieve tube

A
  • There is a low water potential in seive tube due to high conc. of sucrose in phloem
  • water moves in ( osmosis )
  • creates high pressure
66
Q

What is a photometer used for

A

Device used to estimate transpiration rates

67
Q

Potential Errors in measuring rate of transpiration experiment

A
  • set up potometer underwater - prevent air bubbles from blocking xylem
  • grease joint with lots of petroleum jelly - prevents water loss and air entry
  • tap needs to be closed and full of water - prevent bubbles
68
Q

How does a Visking tube work

A

Only allows small soluble molecules to pass through ( eg. Glucose and water)
- osmosis can occur

69
Q

examples of experiments to investigate factors affecting rate of diffusion and osmosis

A
  • Agar cubes -> SA:VR and rate of diffusion
  • potato chips in different conc. sucrose/ salt solutions -> osmosis
  • visking tube -> osmosis
70
Q

How does potato chips placed in different conc. of sucrose/ salt solution affect rate of osmosis

A
  • if solution has a higher water potential than potato - water will move into potato chip and mass will increase
  • if solution has lower water potential than potato - water will move out of potato chip and mass will decrease
71
Q

What are amino acids broken down into in the liver

A

Ammonium and carbohydrates

72
Q

How are amino acids filtered into the liver

A

Through the hepatic artery and hepatic portal vein ( along with rest of blood)

73
Q

Why is ammonium converted into urea

A

Ammonia is very toxic
Urea is less toxic

74
Q

How are useful amino acids and urea released back into the body the blood stream (from liver) ?

A

Through the hepatic vein

75
Q

What do nephrons do

A

Filter the blood

76
Q

Why are amino acids broken down in the liver

A

They cant be stored

77
Q

What does the kidney do

A
  • Filters the blood
  • removes any excess materials + passes them to bladder to be excreted
78
Q

What is the cortex on a diagram

A

The outside part of the kidney

79
Q

What is the medulla on a diagram

A

The triangular shaped blotches between the cortex and pelvis

80
Q

What is the pelvis on a diagram

A

The innermost part of the kidney

81
Q

Difference between afferent and efferent arteriole

A

Afferent - entrance to glomuereus
Efferent - exit to glomereus
Efferent diameter is smaller than afferent

82
Q

What does a small exit out of the glomereus (via efferent arteriole) cause

A

Build up of pressure in the capillaries forming glomerules

83
Q

What does the pressure in the golmerulus cause ?
What is the end product called?

A
  • Small molecules eg. Urea, glucose, amino acids, salts out of capillaries and into bowman’s capsule
  • glomerular filtrate
84
Q

Why dont larger molecules move into bowman’s capsule in ultrafiltration?

A

They are to big to fit across capillary walls
Therefore stay in blood

85
Q

What controls whether molecules can pass into bowman’s capsule in ultrafiltration?

A

Basement membrane

86
Q

What are the stages in the kidney?

A

Ultrafiltration
Selective reabsorption
Water reabsorption

87
Q

How are the cells lining the pct specialised for movement of molecules?

A

Folded membrane - increase surface area
Many mitochondria - Provide ATP for active transport

88
Q

Where does the glomerular filtrate travel after the bowman capsule

A

PCT

89
Q

What do the specialised cells in the walls of the PCT do?

A

Move useful materials back into blood stream by diffusion and active transport

90
Q

What is reabsorbed in the PCT (selective reabsorption)

A

All glucose
All amino acids
Some salts
80% of water

91
Q

What is involved in water reabsorption

A

Loop of Henley and collecting duct

92
Q

What does the loop of henle do?

A

Concentrates urine
- by transporting salt back into blood by active transport
- causing the water to diffuse into blood by osmosis

93
Q

What does the collecting duct do

A

Osmoregulation - Responds to hormone called ADH to vary how much water is reabsorbed

94
Q

Where does the blood travel in the kidney

A

Glomerulus
Bowman’s capsule
PCT
Loop of Henle
Distal convoluted tubule
Collecting tubule

95
Q

How is the Upper epidermis specialised for photosynthesis

A

Transparent
Allowing light to penetrate to the mesophyll

96
Q

How are leaves specialised for photosynthesis

A

Large surface area
Thin
To maximise absorption of sunlight by photosynthesising cells.
Increases no. Of stomata - CO2 can diffuses quicker

97
Q

How are the palisade cells specialised for photosynthesis

A

Long, thin, tightly packed
Lots of chloroplasts - maximises absorption of sunlight energy
Main site of photosynthesis

98
Q

How are the stomata specialised for photosynthesis

A

Allow gases to diffuse into air spaces of the leaf - short diffusion distance for CO2

99
Q

How is the xylem specialised for photosynthesis

A

Transports water (absorbed in roots) into leaves -short diffusion distance for water into photosynthesising cells

BIOLOGY (7 decks)

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