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GCSE Biology > Cell Biology > Flashcards

Cell Biology Flashcards

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1
Q

What is a Prokaryote?

A

Prokaryotic cell
(single celled organism)

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2
Q

What is a Eukaryote?

A

Organism made up of Eukaryotic cells

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3
Q

What is a Eukaryotic cell?

A

A Eukaryotic cell - complex
includes animal and plant cells

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4
Q

What is a Prokaryotic cell?

A

A prokaryotic cell- small and simpler
i.e. bacteria

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5
Q

What are the features of a animal cell?
What do these features do?

A

Nucleus- genetic material, controls the cell

Cytoplasm- gel like substance, chemical reactions occur, contains enzymes that control reactions

Cell membrane- holds cell together, controls what enters and leaves cell

Mitochondria- aerobic respiration occurs (respiration- transfers energy for cells to work)

Ribosomes- where protien synthesis is conducted

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6
Q

What are the extra features in a plant cell?

A

Cell wall- rigid, made of cellulose, supports + strengthens cells

Permanent vacuole- cell sap, weak solution of sugars + salts

Chloroplast- photosynthesis occurs, green substance (chlorophyll) absorbs light for photosynthesis.

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7
Q

What are the features of bacteria cells?

A

Cell membrane

Cytoplasm

Cell wall

Plasmids- small rings of DNA

Single circular strand of DNA, floats in cytoplasm

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8
Q

What are light microscopes?

A

Use light and lenses to form an image of a specimen, then magnify it to make it look bigger
Lets us see individual cells + large subcellular structures (nuclei)

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9
Q

What are Electron microscopes?

A

Uses electrons instead of light to form an image
Much higher magnification (than light microscopes)
Higher resolution
Can see smaller things, higher detail (internal structures of mitochondria) (ribosomes, plasmids)

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10
Q

What is the magnification formula?

A

Magnification= image size
————————-
real size

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10
Q

What is resolution?

A

the ability to distinguish between 2 points, higher resolution= sharper image

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11
Q

What is a micrometre? (looks like u mixed with p)

A

10 ^-6

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12
Q

How do you prepare a slide to look at onion cells?

A
  • put it on a microscope slide
  • add a drop of water
  • cut up an onion + seperate the layers. Use tweezers to pull of epidermal layer off of one of the layers.
  • use tweezers + place epidermal tissue onto slide
  • add a drop of iodine solution (stain)
  • place a cover slip on top by carefully lowering it onto the slide by tilting it. (no air bubbles, obstruct view)
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12
Q

What is a nanometre (n)

A

10^ -9

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13
Q

How do you use a light microscope to look at a slide?

A
  • Clip the slide to the stage
  • select lowest-powered objective lens (produces lowest magnification)
  • use adjustment knob to move stage up
  • look down eyepiece, use knob to move stage down until image is in focus
  • adjust focus with fine adjustment knob
    need greater magnification= next higher-powered lens + refocus
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14
Q

What is cell differentiation?

A

the process where a cell changes to become specialised for its job

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15
Q

What happens to cells as they change?

A
  • develop different subcellular structures
  • turn into different types of cells
  • allows them to carry out specific functions
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16
Q

When does most differentiation occur?

A

when an organism develops

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17
Q

differentiation: difference in plant and animal cells

A

animal cells: most lose the ability to differentiate at an early stage (after specialisation)

plant cells: most don’t ever lose the ability to differentiate

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18
Q

Differentiation in animal cells: what is their role?

A
  • used for repairing cells
  • used for replacing cells (skin or blood cells)
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19
Q

What are SPERM cells specialised for? + features

A

specialised for reproduction

  • get male DNA to female DNA
  • long tail + streamlines head to help it swim to egg
  • lots of mitochondria to provide energy
  • carries enzymes (digest through egg cell membrane)
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20
Q

What are NERVE cells specialised for? + features

A

specialised for rapid signalling

  • carry electrical signals from one part of the body to the other
  • long (cover distance)
  • branched connection ends (connect other nerve cells, form a network throughout body)
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21
Q

What are MUSCLE cells specialised for? + features

A

specialised for contraction

  • contracts quickly
  • long (space to contract)
  • lots of energy (for contraction)
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22
Q

What are ROOT HAIR cells specialised for? + features

A

specialised for absorbing water and minerals

  • grow long hairs (into the soil, gives plant big SA, can absorb more water + mineral ions)
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23
Q

What are root hair cells?

A

Cells on the surface of plant roots

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24
Q

What are PHLOEM AND XYLEM specialised for? + features

A

specialised for transporting substances

  • form tubes, transport substances around plants (food + water)
  • cells are long, joined end to end
  • Xylem: hollow (can flow through)
  • Phloem: very few subcellular structures (can flow through)
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25
Q

What are Chromosomes?

A

they are coiled up lengths of DNA molecules

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26
Q

What do genes control?

A

control the development of different characteristics (genetic)
ie hair colour, eye colour

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27
Q

How many copies of chromosomes do body cells usually have?

A

2 copies of each chromosome
2 copies from ‘mother’
2 copies from ‘father’

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28
Q

What is mitosis?

A

1- chromosomes in a cell line up at the centre, cell fibres from the edge then pull them apart
2- membranes form around the sets of chromosomes (nucleus has divided)
3- cytoplasm + cell membrane divide
4- cells has not produces 2 identical daughter cells (to each other and the parent cell)

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29
Q

What is ‘growth and DNA replication?’

A

1- DNA spreads out in long strings
2- before dividing, has to grow + increase the amount of subcellular structures (mitochondria + ribosomes)
3- duplicates DNA (1 copy for each cell), forms ‘x’ shaped chromosomes, both ‘arm’ the same as the other

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30
Q

What is the cell cycle?

A

Growth + DNA replication
then
Mitosis

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31
Q

What is Binary fission?

A

1- circular DNA + plasmids replicate
2- cell enlarges, circular DNA moves to opposite poles
3- cytoplasm begins to divide + new cell walls form
4- cytoplasm divides + 2 daughter cells are produces (1 copy of circular DNA + variable number of plasmids)

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32
Q

What type of cell reproduces by Binary fission?

A

Prokaryotic cells

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33
Q

What environment does bacteria division thrive in?

A

a warm environments with lots of nutrients

34
Q

What happens if bacteria division conditions become unfavourable?

A

The cells will stop dividing and begin to die

35
Q

What is a type of culture medium?

A

Nutrient broth solution
OR
Agar jelly (solid)

36
Q

Why can’t labs in schools keep agar plates in conditions over 25 degree C?

A

the conditions are more likely to grow harmful pathogens

37
Q

How do you make an agar plate?

A

1- hot agar jelly poured into a petri dish
2- jelly is cooled, inoculating loops used to transfer microorganisms to culture medium (OR a sterile dropping pipette and spreader to get an even coverage)
3- microorganisms then multiply

38
Q

How do you make sure you have uncontaminated cultures on a petri dish?

A
  • equipment (petri dishes, culture medium) must be sterilised (heat to high temp), kills unwanted microorganisms
  • inoculating loop sterilised by passing it over a hot flame
  • lid of petri dish lightly taped on, stop microorganisms from air getting in
  • petri dish-> stored upside down, stops condensation falling on plate
38
Q

How do you test the effect of antibiotics on bacterial growth?

A

1- place paper discs (soaked in different types/concentrations of antibiotics) on an agar plate evenly covered in bacteria. Leave space between discs

2- antibiotic should diffuse into agar jelly

3- antibiotic resistant bacteria will continue to grow, non resistant strains will die

4- clear area where bacteria have died (inhibition zone)

5-make sure to use a control, compare difference of bacteria growth, make sure its the bacteria growing, not malfunction of paper etc

6- leave plate for 48 hours at 25 degrees

7- more effective the antibiotic, larger the inhibition zone.

39
Q

How do you calculate the size of inhibition zones on an agar plate?

A
  • by eye
  • more accurate results= use diameter, calculate area
40
Q

What are stem cells?

A

undifferentiated cells which can divide lots to produce more undifferentiated cells

41
Q

Where are stem cells found?

A
  • early human embryos
  • bone marrow
42
Q

What is the difference between embryonic stem cells and adult stem cells?

A

Embryo- can turn into any kind of cell

Adult- can only turn to certain types of cells (blood cells)

43
Q

How are stem cells harnessed?

A
  • grown in a lab to produce clones (genetically identical)
  • differentiate to use in medicine OR research
44
Q

How can stem cells be used to cure diseases?

A

Adult: bone marrow-> replace faulty blood cells in new patient

Embryo: replace faulty cells (insulin-producing cell-> diabetes, nerve-cells for paralysis etc)

45
Q

What is therapeutic cloning?

A

Embryo can be made to have same genetic material as the patient

46
Q

What are the benefits to therapeutic cloning?

A

Cells wouldn’t be rejected by patients body if used to repair faulty cells

47
Q

What are the risks of using stem cells?

A

Grown in a lab so can be contaminated with a virus which could pass on to the patient, making them sicker

48
Q

Why are some people against stem cell research?

A
  • human embryos= potential human life, shouldn’t be used for experiments
  • scientists should focus on developing other sources, helping others without the use of embryos
  • some countries its banned
49
Q

Why are some people for stem cell research?

A
  • existing patients suffering= more important than rights of embryos
  • embryos used in research are unused from clinics, would have been destroyed anyways
50
Q

Where are stem cells found in plants?

A

In the meristem tissue

51
Q

What are plant meristems?

A

parts of the plant where growth occurs

52
Q

When does meristem tissue differentiate?

A

throughout the plants life, it can differentiate to any type of cell

53
Q

What are some uses for plant stem cells?

A
  • produce clones of plants, cheap + quick
  • grow more plants of rare species (prevent them being wiped out)
  • grow crops of identical plants w desired features for farmers (disease resistance)
54
Q

What is diffusion?

A

the movement of particles from an area of high concentration to an area of low concentration

55
Q

Where does diffusion occur?

A

solutions + gases

56
Q

What effect does the concentration gradient have on the diffusion rate?

A

The larger the concentration gradient, the faster the diffusion rate

57
Q

How will temperature effect the diffusion rate?

A

A higher temperature will give a faster diffusion rate. Particles have more energy, more around faster

58
Q

How do dissolved substances move in and out of cells?

A

through the partially permeable cell membrane (only small molecules, oxygen, glucose, amino acids, water)

59
Q

If the surface area of the membrane is large, how does it affect the diffusion rate?

A

The larger the SA, the faster the diffusion rate

60
Q

What is Osmosis?

A

The movement of water particles from an area of high concentration of water to an area of low concentration of water through a partially permeable membrane

61
Q

What is active transport?

A

the movement of particles against a concentration gradient, from a area of low concentration to an area of high concentration. This process requires energy from respiration

62
Q

How do root hair cells use active transport?

A
  • plants need mineral ions to grow, which can be obtained by root hair cells on the roots from the soil
  • concentration of minerals is usually higher in the root hair cells than in the soil
  • uses active transport, absorbs the minerals against the concentration gradient, using energy from respiration
63
Q

Where is active transport used in humans?

A
  • taking glucose from the gut
  • taking glucose from kidney tubules
64
Q

What is the process of absorbing nutrients from the gut into the blood by active transport?

A
  • there is a higher concentration of glucose and amino acid in gut usually
  • sometimes this differs, means concentration gradient is the wrong way
  • active transport allow nutrients to be taken into the blood
  • glucose can be taken into the blood, when conc in blood is higher than in gut.
  • then transported to cells, used for respiration
65
Q

How do cells exchange substances?

A

Use diffusion to take in substances they need + rid of waste products
- oxygen and carbon dioxide are transferred between cells and environment during gas exchange
- urea (waste product) diffuses from cells into blood plasma to remove by the kidneys

66
Q

What does the easiness of exchanging substances for an organism depend on?

A

The organisms SA to V ratio (SA:V)

67
Q

How does the size of the organism and its surface area relate?

A

The larger an organism, the smaller the surface area (compared to volume)

68
Q

Why do multicellular organisms need exchange surfaces?

A

They have a small SA compared to volume (not enough substances can diffuse to supply entire volume)

69
Q

What is an example of a multicellular organism?

A

plants, animals, fungi

70
Q

What is an example of a single celled organism?

A

bacteria, protists, yeast

71
Q

How have exchange surfaces adapted to maximise effectiveness?

A
  • thin membrane (short diffusion distance)
  • Large SA, lots of substances can diffuse at once
  • (animals) lots of blood vessels
  • (animal gas exchange, eg Alveoli) Often ventilated (air moves in and out)
72
Q

How does gas exchange occur in the lungs?

A
  • lungs transfers oxygen to blood, remove waste CO2
  • alveoli-> gas exchange
  • specialised to maintain diffusion of O2 and CO2
72
Q

How are alveoli specialised for diffusion of gases in the lungs?

A
  • very large SA
  • moist lining (dissolving gases)
  • very thin walls
  • good blood supply
73
Q

What are villi?

A

tiny projections that cover the inside of small intestines

74
Q

What are alveoli?

A

air sacs in the lungs

75
Q

How are villi specialised for diffusion in the small intestine?

A
  • increase surface area, digested food is absorbed much more quickly by the blood
  • single layer of surface cell (1 cell thick)
  • good blood supply, quick absorption
76
Q

What are stomata?

A

Located at exchange surface underneath leaves, little holes where carbon dioxide diffuses through

77
Q

What are the functions of stomata?

A
  • oxygen and water vapour diffuse out the stomata (most water vapour lost, not all (rest of the leaf))
  • size controlled by guard cells
  • guard cells close and open stomata
78
Q

Why do guard cells close the stomata?

A

if the plant is loosing water faster than it is being replaces, other wise plants will wilt

79
Q

How are leaves specialised to increase rates of diffusion?

A
  • stomata (close + open)
  • flattened shape, increase exchange surface area
  • Walls of cells inside leaf, air spaces between cells increase SA
79
Q

How are fish specialised to increase rates of diffusion?

A
  • Gill= gas exchange surface in fish
  • gill filaments-> big surface area
  • lamellae, increase gill SA more
  • lots of blood capillaries-> speed up diffusion
  • thin layer of cells (minimise diffusion distance)
  • ## lamellae, large concentration gradient
80
Q

What are gills and how do they work?

A

Gills are gas exchange surface in fish
Water (oxygen) enters fish through mouth, passes out through gills. -> Oxygen diffuses from water into blood in gills, CO2 from blood into water

81
Q

2

A

GCSE Biology (20 decks)

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