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Biology - B1 > Cell structure > Flashcards

Cell structure Flashcards

1
Q

What are the two types of cells?

A

Eukaryotic - plant and animal
Prokaryotic - bacteria

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2
Q

What are the differences between eukaryotic and prokaryotic cells?

A

Prokaryotic cells are much smaller then eukaryotic cells
eukarotic cells contain membrane bound-organelles and a nucleus containing gentic material, prokaryotic cells don’t have either

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3
Q

What is the prokaryotic cell wall made of?

A

peptidoglycan

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4
Q

how is genetic information stored in a prokaryotic cell?

A

It’s found free in the cytoplasm as :
- Chromosonal DNA (single large loop of DNA)
- Plasmid DNA (small, circular, double-stranded DNA molecule)

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5
Q

What are plasmids?

A
  • small, circular, double-stranded DNA found free in the cytoplasm and seperate from the main DNA
  • carry genes that provide genetic advantages (e.g. antibiotic resistance)
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6
Q

What is order of magnitude?

A

A power to the base 10, used to quantify and compare size

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7
Q

What is a micrometer?

A

1 x 10^ -6 meters

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8
Q

What is a nanometer?

A

1 x 10 ^ -9 meters

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9
Q

List the componants of both plant and animal cells (5)

A
  • Nucleus
  • Cytoplasm
  • cell membrane
  • mitochondira
  • ribosomes
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10
Q

List the additional componants in plant cells (3)

A
  • chloroplasts
  • permanent vacuole
    -cell wall
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11
Q

Other than storing genetic information, what is the function of the nucleus?

A

controls cellular activities

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12
Q

Describe the structure of the cystoplasm

A
  • fluid componant of the cell
  • contains organelles, enzymes, and dissolved minerals and ions
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13
Q

What is the function of the cytoplasm?

A
  • it’s site of cellular reactions (e.g. first stage of respiration)
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14
Q

What is the funciton of the cell membrane?

A

controls what goes in and out of the cell

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15
Q

What is the function of the mitochondria?

A

the site of later aerobic respiration stages where ATP (adenosine triphosphate) us produced

Whertr aerobic respiration takes place

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16
Q

What is the function of ribosomes?

A

Joins amino acids in a specific order during translation for the synthesis of proteins

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17
Q

What is the plant cell wall made of?

A

cellulose

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18
Q

What is the function of the plant cell wall?

A
  • provides strength
  • prevents the cells from bursting when water enters by osmosis
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19
Q

What does the permenant vacuole contain?

A

Cell sap

Cell sap - a solution of salts, sugars, and organic acids)

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20
Q

What is the function og the permenant vacuole?

A

Supports the cell in maintaining it’s turgidity

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21
Q

What is the function of chloroplasts?

A

Site of photosynthesis

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22
Q

Describe how sperm cells in animals are adapted to their function

A
  • Hapoloid nucleus contains genetic information (a single set of chromosones [23])
  • A tail to enable movement
  • mitochondria providing energy for movement
  • Acrosome that contains enzymes that digest the egg cell membrane to allow the sperm to penetrate the egg
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23
Q

Describe how nerve cells in animals are adapted to their function

A
  • long axons that allow electrical impulses to be transmitted all over the body from the central nervous system
  • Dendrites from the cell body connect to recieve impulses from other nerve cells, muscles and glands
  • myelin sheath insulates the axon and speeds up the transmission of impulses along the nerve cell
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24
Q

Describe how muscle cells in animals are adapted to their function

A
  • arrangement of protein filaments allows them to slide over each other to provide muscle contraction
  • mitochondria to provide energy for contraction
  • Merged cells in skeletal muscle allow muscle fibre to contract in unison
25
Describe how root hair cells in plants are adapted to their function
- Large surface area to absorb nutrients and water from surrounding soil - thin walls that do not restrict water absorbtion
26
Describe how Xylem cells in plants are adapted to their function
- there are no upper or lower margins between cells to provide a continuous route for water to flow - thick, woody, side walls strengthen their structure and prevent collapse
27
describe how phloem cells in plants are adapted to their function
- sieve plates let dissolved amino acids and sugars be transported up and down the stem - companion cells provide energy needed for active transport of substances along the phloem
28
What is cell differentiation
the process that a cell becomes specialised through
29
Why is cell differentiation important?
it allows production of different tissues and organs that perform various vital functions in the human body
30
at what point in their life cycle do animal cells most differentiate?
early in their life cycle
31
How long do plant cells retain the ability to differentiate?
throughout their entire life cycle
32
what is the purpose of cell division in mature animals
repair and replacement of cells
33
What changes does a cell go through as it differentiates?
becomes specialised through acquisition of different sub-cellular structures to enable a specific function to be preformed by the cell
34
define magnification
the number of times bigger an image appears to be to the size of the real object
35
define resolution
the smallest distance between two objects that can be distinguished
36
How do light microscopes work?
it passes a beam of light through the specimen which travels through the eyepiece lens, allowing the specimen to be observed
37
What are the advantages of light microscopes? (4)
- less expensive - easy to use - portable - can observe both living and dead specimens
38
what is the disadvantage of light microscopes?
- limited resolution
39
how does an electron microscope work?
it uses a beam of electrons which are focused using magnets, the electrons will hit a fluorescent screen which emits visible light, producing an image
40
Name the two types of electron microscope
- transmission electron microscope (TEM) - scanning electron microscope (SEM)
41
what is the advantage of electron microscopes?
Greater magnifictaion and resolution
42
why do electron microscopes have a greater magnification and resolution?
they use a beam of electrons which has a shorter wavelength than phontons of light
43
how have electron microscopes enabled scientists to develop their understanding of cells?
- allow small sub-cellular structures (e.g. mitochondria, ribsomes) to be observed in detail - enable scientists to develop more accurate explanations about how cell structure relates to function
44
What are the disadvantages of electron microscopes (4)
- expensive - large, therefore less portable - need to be trained to use - only dead specimens can be observed
45
how can magnification be calculated?
size of image/ size of real object
46
what is standard form?
a figure between 1-10, multiplied by a power of 10
47
how do bacteria multiply?
binary fission (simple cell division)
48
how often to bacteria multiply
once every 20 minutes if enough nutrients are available and the temperature is suitable
49
state 2 ways bacteria can be grown
- nutrient broth solution - colonies on agar gel plate
50
what nutrients make up a nutrient broth solution?
all nutrients required for bacteria to grow, including nitrogen for protein synthesis, carbohydrates for energy, and other minerals
51
what are uncontaminated cultures of microorganisms needed for?
investigating disinfectant and antibiotic action
52
describe the preperation of an uncontaminated culture using aseptic technique
1) Use pre-sterilised plastic Petri dishes or sterilise glass Petri dishes and aga gel before using with an autoclave. 2) Pour the sterile agar gel into the Petri dish and allow time to set. 3) Sterilise the inoculating loop by passing it through a Bunsen burner flame. 4) Dip the inoculating loop into the solution of microorganisms and make streaks with the loop on the surface of the agar. 5) Put the lid on the Petri dish and secure it with tape. Label accordingly then turn and store upside down. 6) Incubate the culture at 25°C in school laboratories.
53
why must petri dishes and culture media be steralised before use?
to kill any bacteria already present
54
why must inoculating loops be steralised by passing them through a bunsen burner flame?
to kill any bacteria present on the inoculating loop
55
why must the petri dish lid be secured with tape and the whole dish stored upside down?
- stops bacteria contaminating the culture - the lid is not fully sealed to prevent the growth of anaerobic bacteria in a lack of oxygen - upside down to prevent condensation from forming and dripping down onto colonies
56
why are cultures incubated at 25°C in school laboratories?
harmful pathogens are less likely to grown at this temperature
57
what is the formula to calculate cross-sectional area of bacterial colony or clear area around a bacterial colony?
π r²
58
how is the number of bacteria in a population after a certain time calculated from the mean division of time?
1) calculate the number of times the bacteria will divide in the given time period from the mean division time 2) use the following equation to work out the number of bacteria : number of bacteria in population at end of time period = number of bacteria at the beginning of the time period x 2^the number of divisions in the time period express in standard form if possible

Biology - B1 (4 decks)

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