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OCR A GCSE Biology (B1-B3) > B2.1 - Supplying the cell > Flashcards

B2.1 - Supplying the cell Flashcards

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1
Q

What is diffusion?

A

the (net)/overall movement of particles from a region of high concentration to a low concentration

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2
Q

How do particles move during diffusion?

A

down a concentration gradient

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3
Q

When does diffusion stop?

A

when the concentration gradient reaches zero, and the concentration of the particles is the same everywhere

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4
Q

Is energy required during diffusion? and why?

A
  • No, it is a passive process (passive transport)

- it is the ordinary motion of particles

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5
Q

where does diffusion occur in the body? (3)

A
  • diffusion of oxygen and glucose from alveoli to bloodstream
  • carbon dioxide diffusing away from respiring cells
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6
Q

During most cases of diffusion, where does it pass through?

A

the cell membrane

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7
Q

what 3 factors affect the rate of diffusion?

A
  • surface area
  • concentration gradient
  • distance for diffusion
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8
Q

how do you increase the rate of diffusion? (3)

A
  • increase surface area (more space for diffusion)
  • increase concentration gradient (greater net movement of particles)
  • reduce distance (less time to travel short distance)
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9
Q

Describe one way blood capillaries have adapted to be most efficient at diffusion

A
  • only one cell thick (increases diffusion gases into and out of bloodstream)
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10
Q

describe one way plant cells have adapted to increase its rate of carbon dioxide diffusion (ie. to get in plant)

A
  • carbon dioxide concentration inside cells drops so that there is high concentration gradient from outside plant to inside plant

diffusion from high -> low

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11
Q

describe one way the small intestine has adapted to increase its rate of diffusion

A
  • wall is highly folded (increase surface area in contact with bloodstream)
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12
Q

Define osmosis

A

the net movement of water particles across a partially permeable membrane from a region of high water potential to a region of low water potential

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13
Q

What happens when a solute dissolves in water (ie. sugar)?

A

water molecules cluster around it

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14
Q

define water potential

A

the concentration of free water molecules

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15
Q

if a solution is concentrated, how does it affect the water potential?

A

decreases the water potential (less free water molecules)

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16
Q

describe what would happen to a plant cell when its surroundings are a less concentrated solution (higher water potential) than itself

A
  • The free water molecules would diffuse into the cell (through the semi-permeable membrane)
  • the turgor pressure would increase
  • the cell would become TURGID and firm
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17
Q

describe what would happen to a plant cell when its surroundings are a higher concentrated solution than its cell

A
  • the water molecules would travel out of the cell (through the semi-permeable membrane)
  • lose water
  • the turgor pressure falls
  • the cell becomes flaccid (soft)
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18
Q

Define a semi-permeable membrane

A

a membrane which only allows certain substances to pass through

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19
Q

describe what would happen to an animal cell when its surroundings have a higher concentrated solution (lower water potential) than it

A
  • loses water by osmosis

- becomes CRENATED (crinkled/shrinks)

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20
Q

describe what would happen to an animal cell when its surroundings are a lower concentrated solution than the cell

A
  • water goes into cell
  • swells and may burst (no cell wall)
  • LYSIS
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21
Q

why is glucose unable to enter a partially permeable membrane?

A

because it only allows certain substances to pass through, in this case water

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22
Q

define active transport

A

the movement of molecules against their concentration gradient

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23
Q

in terms of concentration gradients, which way does active transport occur?

A

low -> high concentration gradient

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24
Q

is energy required for active transport? and why?

A
  • yes, in the form of ATP,

- since particles against the concentration gradient

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25
Q

is energy required for osmosis? why?

A

no, moves with ordinary motion of particles

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26
Q

state the three features of active transport;

A
  • carrier proteins
  • ATP is required (from respiration)
  • transported/ pumped against concentration gradient
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27
Q

what process makes ATP?

A

respiration

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28
Q

do cells that carry out a lot of active transport have a lot of mitochondria? why?

A
  • yes

- so that they can respire rapidly to produce large quantities of ATP

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29
Q

what affects the rate of active transport?

A
  • rate of ATP produced during respiration
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30
Q

State where carrier proteins are found in cells

A
  • across the width of the cell membrane
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31
Q

describe the process of of active transport (with carrier proteins etc.)

A

1) energy is transferred from an energy store to the carrier protein
2) carrier protein binds with specific molecule (active site)
3) protein either changed shape or rotates
4) molecule is transported into cell

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32
Q

when is active transport used?

A
  • whenever a substance needs to be transported against the concentration gradient
33
Q

describe 2 examples where active transport is used in animals

A

1) digestion -
carbohydrate broke down to glucose
glucose actively transported through vili

2) nerve cells-
carrier protein pumps sodium ions out of cell
potassium ions are pumped back in (makes nerve impulses)

34
Q

describe an example where active transport is used in plant cells (3)

  • what ions are needed to form proteins?
  • specifically where is it used (ie. what surface)
A
  • take minerals from soil
  • plants need nitrate ions for proteins
  • use active transport to move ions across cell membrane into root cell
35
Q

state two difference between active transport and diffusion

A
  • active transport uses ATP, diffusion does not

- active transport moves against concentration gradient, diffusion moves along concentration gradient

36
Q

State the purpose of mitosis

A
  • to replace worn out cells
  • to repair damaged tissue
  • increases number of cells in a multicellular organism
  • asexual reproduction
37
Q

what is mitosis the process of?

A

by which body cells divide

38
Q

what do cells divide to during mitosis?

A
  • two daughter cells (with identical DNA)

- clones

39
Q

why must mitosis occur constantly?

A

since we constantly lose cells from the surface of your skin

40
Q

what are the three stages of cell division?

A

1) interphase
2) mitosis
3) Cytokinesis

41
Q

Describe DNA replication: (3)

A

DNA is replicated :

  • The DNA double helix unwinds with the help of enzymes
  • Enzymes called DNA polymerases then pair new complementary nucleotides to the original strands (separately)
  • until the whole strands have complementary pairings, forming two identical DNA molecules
42
Q

Describe the second stage of the cell cycle;

A

Movement of chromosomes:

  • chromosomes line up across center of cell
  • chromosome separates and moves to opposite ends of cell
  • each end has full set of chromosomes
  • nuclei form (nuclear membrane forms)
43
Q

Describe the third stage of the cell cycle:

A

Cytokinesis

the cytoplasm of the cell divides to form two separate daughter cells

44
Q

what happens when cells differentiate?

A
  • they become specialised to perform a particular job
45
Q

what happens when a cell becomes specialised?

A
  • structure changes so that it’s adapted to perform its function
  • entire organism becomes efficient
46
Q

how is a sperm cell specialised?

A
  • flagella
    (whips side to side to propel cell through liquids)
  • lots of mitochondria
    (high rate of respiration from chemical stores for it to move fast)
47
Q

knock knock

who’s there?

i didap

A

i didap who? (i did a poo)

u fucking retard why would you tell me that?

48
Q

how are red blood cells specialised to their role?

A

TRANSPORT OXYGEN

- biconcave discs (goes in at middle) 
increase surface area : volume ratio 
- haemoglobin 
(protein which allows oxygen to bind to red blood cell) 
- no nucleus
(lots of space to pack in haemoglobin)
49
Q

Define cell differentiation

A

conversion of an unspecialised cell to become specialised to perform a particular task efficiently

50
Q

what can fat cells be used for? (3)

A
  • store of energy
  • insulation
  • protection around vital organs (shock absorber)
51
Q

what are the function of ciliated cells?

A

The function of ciliated cells is to move mucus and particles along the respiratory tract, helping to clear the airways of debris and pathogens.

52
Q

how are palisade cells specialised to their role (plant)? (3)

A
  • chloroplast found near surface of cell
  • packed with chloroplast
  • regular shape (loads of cells can fit in a given area so maximise absorption of sunlight)
53
Q

state the function of a palisade cell

A
  • to carry out photosynthesis (same as plant cell)
54
Q

what are stem cells?

A

undifferentiated cells

55
Q

what is a key feature of stem cells?

A
  • they can divide to form any kind of specialised cell

- can form all types of tissues and organs

56
Q

what are stem cells used by the body for? (2)

A
  • can differentiate into specialised cells to perform important functions
  • can replace specialised cells
57
Q

What are the two main types of stem cells?

A
  • embryonic

- adult

58
Q

describe features of an embryonic stem cell (3)
- where is it found
-how does it divide
- the obvious one

A
  • found in embryos
  • divide by mitosis
  • ability to differentiate into all cell types
59
Q

describe features of an adult stem cell (3)
- where are they found
-how do they divide
- the obvious one

A
  • found in various body tissues (brain, bone marrow, skin, liver)
  • divide by mitosis
  • able to differentiate into some types of cells but not as many as embryonic
60
Q

What kind of cells does a stem cell in your blood differentiate to?

A
  • white blood cell
  • red blood cell
  • platelets
61
Q

which part of plants grow? and what are they?

A

meristems - include shoot tips

62
Q

where are stem cells found in plant cells (and what are they called)

A 
at tips of shoots and roots (meristems)
- but can be found on stem for example as well to make stem thicker (by dividing)
63
Q

describe features of meristem cells (4)

A
  • small compared to plant cells
  • very thin walls
  • small vacuoles
  • no chloroplast
64
Q

can differentiated plant cells divide?

A

no, cell walls are thick and rigid

65
Q

does oxygen move from lungs into the blood through diffusion or active transport?

A

diffusion

66
Q

do carbon dioxide enter leaves of plants through diffusion or active transport?

A

diffusion

67
Q

is glucose absorbed during digestion an example of diffusion or active transport?

A

active transport

68
Q

why would a potato slice become longer in pure water?

A
  • water enters by osmosis

- cells swell/bloat/become larger

69
Q

Suggest why cells need to differentiate.

A

• to do different jobs

70
Q

State three uses for mitosis in organisms.

A
  • growth/making more cells
  • repairing tissue/organs
  • asexual reproduction
71
Q

Describe the difference between embryonic and adult stem cells in humans.

A
  • embryonic cells can turn into any type of cells

- adult cell can only turn into certain types

72
Q

what is urea?

- and what does the body do with it?

A

the waste product of protein synthesis, diffuses from the cells and into the blood to be removed by kidneys

73
Q

can water molecules move both ways during osmosis?

A

yes, but the net movement is from high w.p to low w.p

74
Q

what is the equation for percentage change in mass?

A

((final mass - initial mass) ÷ initial mass) x 100

75
Q

what is an important role of active transport in plants?

A

allow root hair cells to absorb mineral ions even through concentration of minerals is lower in soil than roots

76
Q

why is sugar important in the body?

A

for cellular respiration

77
Q

what is the small intestine adapted for?

A

exchanging nutrients between digested food in the small intestine and the blood

78
Q

what is the independent variable?

A

the variable that is changed throughout the experiment

ie when investigating rate of photosynthesis with different temperatures, temperature is the i.v

OCR A GCSE Biology (B1-B3) (12 decks)

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