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BIOLOGY A LEVEL > CHAPTER 2 - BASIC COMPONENTS OF LIVING SYSTEMS > Flashcards

CHAPTER 2 - BASIC COMPONENTS OF LIVING SYSTEMS Flashcards

Microscopy, Magnification and Calibration, More microscopy, Eukaryotic cell structure, Ultrastructure of plant cells, Prokaryotic and Eukaryotic Cells

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1
Q

How many types of microscopes are there?

A

3 - Light, Transmission electron micrscope, Scanning Electron Microscope

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1
Q

What is Cell theory

A

Both plants and animal tissue is composed of cells
Cells are the basic unit of life
Cells only develop from existing cells

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2
Q

Benefits of Light Microscopy

A

Easily Available

Cheap

Can be used out in the field

Can observe both dead and prepared specimens

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3
Q

How many lenses does a (compound) light microscope have?

A

2 - Eyepiece and objective

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4
Q

How many different slides preparation types are there?

A

4 - Wet mount, Dry Mount, Squash slides, Smear Slides

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5
Q

How are Dry Mounts prepared?

A

Solid Specimens are viewed whole or cut into very Thin slices with a sharp blade - this is called sectioning.

The specimen is placed on the centre of the slide and a cover slip is placed on top

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6
Q

What would a dry mount be used to view?

A

eg. Hair, pollen, dust, muscle tissue and plant tissue

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7
Q

How is a wet mount prepared?

A

Specimens are suspended in a liquid such as water or immersion oil

A cover slip is placed on from an angle

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8
Q

What would a wet mount be used to view?

A

Aquatic samples and other living organisms

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9
Q

How is a squash slide prepared?

A

Wet mount is first prepared,

then a lens tissue is used to gently press down on the cover slip

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10
Q

What are squash slides used to view?

A

Root tip squashes, other soft samples

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11
Q

How are Smear slides prepared?

A

the edge of a slide is used to smear the sample, creating a thin, even coating on another slide.

A cover slip is then placed over the top of the sample

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12
Q

What are smear slides used to view?

A

Blood, other thick liquids

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13
Q

Outline the importance of microscopes in the study of living organisms

A

Microscopes allowed scientists to investigate cell structure, observe the tiniest details of plants, animals, and fungi, and learn about the presence of microbes.

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14
Q

Suggest, with reasons, why cell theory was not fully developed before the mid-19th century

A

Prior to the mid-19th century microscopes were of too low a magnification to see and identify cells and cell components

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15
Q

suggest reasons why specimens must be thin during microscopy

A

So light can be seen through
Details can be seen

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16
Q

suggest why when preparing a wet mount the refraction index (ability to bend light) of the medium should be roughly he same as the glass.

A

reduce / prevent, diffraction between liquid and glass

prevent / reduce distortion of
image

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17
Q

A cover slip must be placed onto the wet mount at an angle suggest why

A

reduce / prevent air bubbles being trapped

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18
Q

explain why when using basic light microscopy the sample’s image tend to have low contrast

A

the whole sample is illuminated at once from below

so most cells do not absorb a lot of light

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19
Q

what is resolution in a basic light microscope limited by?

A

resolution is limited by the wavelength of light

and diffraction of light as it passes through the sample

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20
Q

what is diffraction

A

diffraction is the bending of light as it passes close to the edge of an object

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21
Q

what parts of cells are often transparent

A

the cytosol (aqueous interior) and other structures

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22
Q

explain why staining is used in microscopy

A

Staining provides contrast

Different Organelles absorb stain differently allowing identification

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23
Q

explain how to prepare a sample for staining

A

Placed on a slide an allowed to air dry

Passed it through a flame

Specimen will then adhere to the microscope side and will take up stain

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24
Q

Explain how crystal violet or methylene blue dyes perform in staining samples

A

Positively charged dyes

Attracted to negatively charged materials in cytoplasm

Stains of cell components

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25
Q

Explain how the dyes nigrosin or Congo red perform in staining samples

A

Negatively charged

Repelled by negatively charged materials in cytoplasm

This means that they stay out of cells

Leaves the cells unstained

Which then stand out against the stained background

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26
Q

What are the techniques using the dyes nigrosin or Congo red called?

A

Negative stain technique

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27
Q

Explain what differential staining is

A

Differential staining distinguishes between two types of organisms that are hard to identify

Can also distinguish between two different organelles of a single organism within a tissue sample

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28
Q

what is gram stain technique used for?

A

Gram stained technique is used to separate bacteria into two groups

Gram-positive
Gram Negative

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29
Q

How are Gram Stains prepared?

A

Crystal violet is applied to bacterial specimen on a slide

Iodine is then applied to fix the dye

The slide is then washed with alcohol

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30
Q

explain how gram positive bacteria are identified using the gram stain technique

A

Gram positive bacteria retain crystal violet stain and will appear blue/purple

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31
Q

How is gram negative bacteria identified

A

Gram negative bacteria have thinner walls and therefore lose the crystal violet stain

Then stained with safranin dye - called a COUNTERSTAIN

Bacteria will then appear red

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32
Q

Describe the effect of the antibiotic penicillin on gram positive and negative bacteria

A

Gram positive are susceptible to the antibiotic penicillin, which inhibits the formation of cell walls

gram-negative have much thinner cell walls and are not susceptible to penicillium

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33
Q

What is acid-fast technique used for

A

Differentiate species of Mycobacterium from other bacteria

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34
Q

explain how acid-fast technique is carried out

A

Lipid solvent is used to carry carbolfuchsin dye into the cells being studied

Cells are then washed with a dilute acid-alcohol solution

Mycobacterium are not affected by the acid-alcohol and retain the carbolfuchsin stain, which is bright red.

Other bacteria lose the stain and are exposed to a methylene blue stain - which is blue

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35
Q

explain the process of ‘fixing’ on slides that have been pre-prepared

A

chemicals like formaldehyde are used to preserve specimens in as near natural state as possible

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36
Q

explain the process of ‘sectioning’ on slides that have been pre-prepared

A

Specimens are dehydrated with alcohols

Then placed in a mould with wax or resin to form a hard block.

this can be then thinly sliced with a knife called a microtome

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37
Q

explain the process of ‘staining’ on slides that have been pre-prepared

A

specimens are often treated with multiple stains to show different structures

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38
Q

explain the process of ‘mounting’ on slides that have been pre-prepared

A

the specimens are then secured to a microscope slide and a coverslip is placed on top

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39
Q

Why must a risk assessment be carried out?

A

many of the stains used in preparations of slides are toxic,

risk assessment is used to identify any procedures involved that may result in harm.

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40
Q

Use your knowledge of gram positive and gram negative bacteria:
Suggest why gram -negative infections are more difficult to treat than gram positive

A

Gram negative have thinner cell wall
Penicillin disrupts cell wall formation
Less cell wall formation (in gram negative)
Prevents entry of penicillin (1)

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41
Q

Rules for the production good scientific drawings

A
  • include title
  • magnification
  • sharp pencil for drawing and labels
  • while unlined paper
  • as much proportion of paper as possible
  • smooth continuous lines
  • no shade
  • clear defined structures
  • ensure proportions are correct
  • no crossing of label lines and no arrow heads
  • labels barrel and drawn with ruler
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42
Q

Magnification formula

A

Magnification = Image size/actual size

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43
Q

What is the difference between magnification and resolution

A

Magnification is the ratio of the image size to the object size

Resolution is the ability to distinguish two separate points

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44
Q

Explain why a light microscope will not usually magnify images to greater than 1500x

A

The resolution of a light microscope is not sufficent

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45
Q

What are the disadvantages of light microscopes

A

Resolution is limited

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46
Q

How can you tell the difference between images created by an electron microscope and one created by a transmission electron microscope

A

A SEM Image is in 3D and has surface view

A TEM image allows you to see
inside the organelles

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47
Q

Unit conversions for microscopy

A

1000 nanometres = 1 micrometre
1000 micrometres = 1 millimetre
1000 millimetres = 1 metre

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48
Q

What are the advantages of scanning electron microscope and transmission electron microscope

A

+ high resolution, so image can be magnified more and will still show more detail

+ SEM also give 3D images with depth of field and are good for viewing surfaces

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49
Q

What are the disadvantages of scanning electron microscope and transmission electron microscope

A
  • Large and very expensive
  • Require trained operatives
  • the sample must be dried out and therefore is dead, so they cannot be seen in real time and it may also affect the shape of the features seen
  • need false colour for micrographs
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50
Q

How do you use an eyepiece graticule?

A

Use a x4 objective lens first

Bring both the eye piece graticule and stage micrometer divisions into focus using the course adjustment and fine focusing knobs

Line up the eyepiece graticule and stage micrometer divisions.

Take a reading of how many eyepiece graticule divisions corrospond to the stage micrometer divisions

As every stage micrometer division equates to 0.1 mm you can calculate the equal Lange length of the eyepiece graticule divisions

From there calculate one eye piece graticule division

In both mm and micrometers

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51
Q

State the correct names of the scale used on the stage of the microscope and the scale of the eyepiece

A

Stage Micrometer
Eye Piece Graticule

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52
Q

A blood smear is stained with raisin and harmatoxylin, explain what the observer should expect to see using the light microscope

A

Red blood cells and white blood cells
The nucleus of the white blood cell

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53
Q

State the differing magnification of a light, scanning electron and transmission electron microscope

A
  • Light - 1000- 2000x
  • SEM - 50,000- 500,000x
  • TEM - 300,000 - 1,000,000
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54
Q

State the differing resolution of a light, scanning electron and transmission electron microscope

A

Light - 50- 200 nm

SEM - 0.4-20nm

TEM - 0.05 - 1nm

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55
Q

Uses of light, scanning electron, transmission electron microscopes

A

Light: viewing cells and tissues

Scanning : viewing surface of cells and organelles

Transmission: detailing organelles (ultra structure)

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56
Q

Explain why the resolution of an image can be increased by using beams of electrons

A

Beams of electrons have shorter wave length than light

Electron beams are still diffracted

But the shorter wavelength means the individuals be as can be much more closer together before they overlap

This means objects that are much smaller and closer together can be seen with more detail without diffraction blurring the image

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57
Q

What is an eyepiece graticule

A

used to find out size of specimen

Fit into eyepiece

transparent ruler with numbers
no units

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58
Q

What is a stage micrometer

A

used to work out size of specimen

placed on a stage

microscope slide with accurate scale

it has units

used to work out value of divisions in eyepiece graticule
at a particular magnification

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59
Q

Suggest why it is important to calibrate the lens going to be used to view the specimen

A

Scale on eyepiece graticule is always the same

Magnification of other lenses changes

Need to calibrate eyepiece graticule for each lens to know actual measurements represented by eyepiece graticule at different magnifications

necessary to calculate real size of objects seen.

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60
Q

Suggest why you should put all measurements into the same units before carrying out nay calculations

A

Simplifies calculations

Reduces room for errors

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61
Q

What is contrast?

A

Difference in shade or colour between two objects

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62
Q

Explain how diffraction limits resolution

A

diffraction happens when light passes through structures

light waves spread out

(light waves) overlap

Individual objects do not appear separate

Causes blurring

63
Q

Explain why eyepiece graticules do not have Units

A

Arbitrary units

Calibrated for each lens

Using stage micrometer

64
Q

Improvements to increase VALIDITY in the way slides are produced

A

validity - refers to maintain control variables

sharp blade - thin slices to individual cells are visible /resolution is high

wet mount - prevents dehydration

squash slides - easier to see individual cells and allows light to penetrate tissue

65
Q

What are artefacts?

A

visible structures

produced due to the preparation process

not a feature of the specimen

66
Q

Define ultrastructure

A

those features that can be seen using an electron microscope

67
Q

explain what is a disadvantage to the process of using an electron microscope

A

specimens can often be damaged by the electron beam

Complex preparation process can create artefacts

68
Q

explain what takes place in a transmission electron microscope (TEM)

A

a beam of electrons is transmitted through a specimen

Focused to produce an image.

69
Q

explain what takes place in a scanning electron microscope (SEM)

A

Beam of electrons is sent across the surface of a specimen

Reflected electrons are collected.

Produces 3D images of surfaces

70
Q

Explain how a specimen is prepared for electron microscopes

A

Fixation using chemicals or freezing
Staining with heavy metals
Dehydration with solvents.

TEM samples will be set in resin and may be stained again

SEM samples may be fractured to expose the inside so will need to be coated in heavy metals

71
Q

why is fixation used in sample prep for electron microscopes

A

Prevents Decomposition

72
Q

why is dehydration used in sample prep of sample for electron microscopes

A

dehydration prevent vaporisation of water

vaporisation would damage sample

73
Q

why is embedding in resin used for prep of sample for electron microscopes

A

Embedding allows thin slices to be obtained

74
Q

why is staining with heavy metals used for prep of sample in electron microscopes

A

staining with heavy metals creates contrast

75
Q

Light Vs Electron

A

Light:
Cheap
Small and portable
Simple prep
No vacuum required
Live specimens can be viewed
- Low mag and resolution

CSPVL

Electron is exact opposite

76
Q

give an example of an artefact in light microscopes

A

air bubbles being trapped undercover slip

77
Q

give an example of an artefact in an electron microscope

A

-loss of continuity of membranes
- distortion of organelles
- empty space in cytoplasm

78
Q

explain how a florescent microscope uses florescence to magnify images

A

Higher light intensity is used to illuminate a specimen

Treated with a florescent chemical

Florescence absorbs and re radiates the light

in a longer and lower energy wave length

Produces a magnified image

79
Q

What is a focal point?

A

the distance that gives the sharpest focus

80
Q

TEM vs SEM microscopes

A

TEM:
+Greater Mag/ resolution (1)
+more detail (1)
- 2D images (1)
- very thin specimen (1)
- more preparation processes and artefacts (1)

SEM
+ 3D images
+ thin specimens not needed
- lower magnification/ resolution
- only surface details seen

81
Q

Define florescence

A

chemical that absorbs and re-radiates light

82
Q

What occurs in laser scanning confocal microscopy

A

A laser moves a single spot of focused light across a specimen

Causes illumination of dyed components

Emitted light from the specimen is filtered through pinhole aperture

83
Q

What is a cell

A

Basic unit of all living things

84
Q

What are the two types of cell?

A

Prokaryotic
Eukaryotic

85
Q

What are Prokaryotes

A

Single celled organisms

Single undivided internal area

86
Q

What type of organisms are made up from Eukaryotic cells?

A

Animals, Plants, Fungi

87
Q

What do Eukaryotic cells contain?

A

Membrane bound organelles

Nucleus and nucleolus

Vesicles

Golgi

Mitochondria

Cytoskeleton

SER

RER

Cytosol

Centriole

Cell surface membrane

Ribosome

Microtubule Network

88
Q

Nucleus information

A

Contains coded genetic information (DNA)

Biggest organelle

Has double membrane (Envelope)

Contains Nuclear pores allowing movement of molecules

Contains histones, which form with DNA to form Chromatin, which further coils into Chromosomes

89
Q

Describe the Nucleolus

A

Responsible for producing ribosomes

Composed of proteins and RNA

90
Q

Describe Mitochondria

A

Site of final stages of cellular respiration (production of ATP)

Contain Double membrane

Inner membrane is highly folded, forming Cristae

Fluid interior called matrix

Contains small amount of (mt)DNA

91
Q

Describe vesicles

A

Membranous sacs

Responsible for storage and transport

Single membrane containing fluid

92
Q

Describe Lysosomes

A

Specialised vesicles

Contain Hydrolytic Enzymes

Responsible for breakdown of waste material

Responsible for breakdown of pathogens ingested by phagocytic cells

Play role in Apoptosis

93
Q

Describe the Cytoskeleton

A

Network of fibres

Necessary for shape and stability of a cell

Holds organelles in place

Composed of Microfilaments, Microtubules and intermediate fibres

94
Q

Describe microfilaments

A

Contractile fibres formed from the protein Actin

Responsible for cell contraction during cytokinesis

95
Q

Describe microtubules

A

Globular Tubulin proteins polymerise to form tubes

forms scaffold like structures

Determines shape of cell

acts as tracks for the movement of organelles and vesicles

Spindle fibres are important in cell division

96
Q

Describe intermediate fibres

A

These fibres give mechanical strength to cells

97
Q

Eukaryotic cells

A

DNA is linear
Nucleus present (DNA inside)
No cell wall in animals, cellulose cell wall in plants, or chitin in fungi
Many organelles
Flagella made if microtubule proteins
Larger ribosomes
Example: human liver cell

98
Q

Prokaryotic Cells

A

DNA is circular
No nucleus (DNA is free in the cytoplasm)
Cell wall is made of a polysaccharide but not cellulose or chitin
Few organelles and no membrane bound organelles eg.mitochondria
Flagella made of the protein flagellin, arranged in a helix
Small ribosomes
Example: E. Coli bacteria

99
Q

What do plant cells contain that animals dont?

A

Cell wall with plasmodesmata
Vacuole
Chloroplasts

100
Q

Description of Plasma membrane

A

Membrane found on the surface of animal cells and inside the cell wall of plant cells and prokaryotic cells.

Made mainly of lipids and proteins.

101
Q

Function of Plasma membrane

A

Regulates the movement of substances into and out of the cell.

Also has receptor molecules of which allow it to respond to chemicals like hormones

102
Q

description of Cell wall

A

Rigid structure that surrounds plant cells

Made mainly of the carbohydrate cellulose

103
Q

Function of cell wall

A

Supports plant cells

104
Q

what are cell walls made of?

A

Cellulose

105
Q

description of Ribosome

A

small organelle that either floats free on cytoplasm or attached to the rough endoplasmic reticulum.

106
Q

Function of Ribosome

A

Site of Translation

107
Q

what are ribosomes made of?

A

2 Sub-units (Large and Small)

Comprised of proteins and RNA.

108
Q

Description of Rough endoplasmic reticulum

A

The surface is covered with ribosomes

109
Q

Function of Rough endoplasmic reticulum

A

Folds and processes proteins that have been made at the ribosomes

110
Q

Function of Smooth endoplasmic reticulum

A

Synthesises and processes lipids

111
Q

Description of Mitochondrion

A

Usually oval shaped. Have a double membrane- the inner one is folded to form cristae.

Inside is the matrix which contains enzymes involved in respiration

112
Q

Description of a Chloroplast

A

A small, flattened structure found in plant cells.

double membrane,

Contains membranes inside called thylakoids membranes.

These membranes are stacked up in some parts of the chloroplast to form grana.

Grana are linked together to form lamellae

113
Q

Function of Chloroplasts

A

The site where photosynthesis takes place.

Some parts of photosynthesis happen in the grana and other parts happen in the stroma (a thick fluid found in chloroplasts)

114
Q

Description of a Centriole

A

Small, hollow cylinders made of microtubules (tiny protein cylinders).

Found in animal cells but only some plant cells.

115
Q

Function of Centriole

A

Involved in the separation if chromosomes during cell division

116
Q

Description of Cilia

A

Small, hair like structures found on the surface membrane of sine animal cells.

They have an outer membrane and a ring of nine pairs with protein microtubules inside with two microtubules in the middle.

117
Q

Function of Cilia

A

The microtubules allow the cilia to move.

This movement is used by the cell to move substances along the cell surface.

118
Q

Flagellum Description

A

On eukaryotic cells are like cilia but longer.

They stick out from the cell surface and are surrounded by the plasma membrane

119
Q

Function of Flagellum

A

The microtubules contract to make flagellum move.

Flagella are used like outboard motors to propel cells forward (eg. when a sperm cell swims)

120
Q

Description Cytoskeleton

A

Network of protein threads. In eukaryotic cells the protein threads are arranged as microfilaments (small solid strands) and microtubules (tiny protein cylinders)

121
Q

Function of Cytoskeleton

A

The microfilaments and microtubules support the cells organelles keeping them in position

strengthen the cell and maintain its shape

Responsible for movement of materials within the cell.

Proteins of the cytoskeleton can also cause the cell to move

122
Q

Protein Production

A

-proteins made at ribosomes

-ribosomes on Rough ER make proteins that are excreted or attached to the cell membrane. The free ribosomes in the cytoplasm make proteins that stay in the cytoplasm.
ER=Exctretion

-new proteins produced at the rough ER are folded and processed (eg.sugar chains are added) in the rough ER

-then they’re transported to the Golgi apparatus in vesicles

-at the Golgi apparatus the proteins undergo further processing (eg.sugar chains are trimmed and more are added)

-the proteins enter more vesicles to be transported around the cell eg.glycoproteins (found in mucus) move to the cell surface and are secreted.

123
Q

What is a lysosome and why is the membrane that surrounds it so important?

A

A specialised Vesicle

Contains enzymes which require low pH and would break down other organelles should they escape

124
Q

Explain why cells need to be compartmentalised, and describe 3 examples of compartmentalisation within an animal Cell

A

Reactions require different conditions

Damage would be caused due to hydrolytic enzymes

Eg. Nucleus, vesicles lysosomes, mitochondria, Golgi body, endoplasmic reticulum, chloroplast

125
Q

Compare the structure and function of the rough and smooth Endoplasmic reticulum

A

Rough ER has ribosomes attached AND the smooth ER does not have ribosomes attached

The rough ER is the site of proteins synthesis/modification

Smooth ER is the site of lipid synthesis

126
Q

Describe the structure and function of the cytoskeleton

A

Microfilaments

which are contractile fibres made of actin cause cell contraction during cytokinesis

Microtubules

which are formed from the cylindrical protein Tubulidentata and form scaffold-like structures;
used in movement of organelles and segregation of chromosomes in cell division

Intermediate fibres

give mechanical strength to cells

127
Q

Discuss how the structure of microfilaments and microtubules means these components of the cytoskeleton are involved in the movement of cells but the intermediate fibres are not

A

Microfilaments are composed of actin which is contractile

Microtubules are composed of Tubulidentata which polymerises. Contraction and polymerisation lead to a change in the length of the filaments, this results in the movement of the cell.

Intermediate fibres have a fixed length for stability

128
Q

Features of Cellulose cell wall

A

Freely permeable

Gives the cell shape

Contents of cell press against the cell wall making it rigid

Defence mechanism against invading pathogens

129
Q

Description of Vacuoles

A

Membrane lined sacs in cytoplasm

Contains cell sap

Most are permanent

Membrane in vacuole called Tonoplast

If Vacuoles appear in animal cells, they are small and transient (not permanent)

130
Q

Function of Vacuoles

A

Maintains Turgor so that the contents of cell push against the cell wall and maintain rigid framework

131
Q

When did Prokaryotic cells first appear and what conditions were they present in

A

3.5 billion years ago

Hostile conditions

132
Q

What name are given to organisms that live in extreme conditions

A

Extremophiles

133
Q

Where are Extremophiles found?

A

Hydrothermal vents

Salt lakes

(more recently) Digestive systems

134
Q

Are prokaryotes always unicellular?

A

YES

135
Q

Are Eukaryotes Always Multicellular?

A

NO

136
Q

Describe the DNA in a Prokaryotic Cell

A

Only contain one molecule of DNA - a chromosome- which is supercoiled to make it more compact

Genes on the chromosome are often grouped into operons, meaning a number of genes are all switched on or off at the same time

137
Q

Describe Prokaryotic Ribosomes

A

70S (as opposed to 80S found in Eukaryotes)

Relative size is determined by the rate at which the form sediment in solution

Less Complicated than Eukaryotic Ribosomes

138
Q

Describe the Prokaryotic Cell Wall

A

Made from peptidoglycan

Complex polymer formed from amino acids and sugars

139
Q

Describe Prokaryotic Flagella

A

Doesn’t have 9+2 Arrangement (seen in eukaryotes)

Thinner than Eukaryotic flagella

Energy required to make the filament rotate comes from chemiosmosis, not ATP (in Eukaryotic cells)

Attached to cell membrane of bacterium by a basal body and rotated by molecular motor

140
Q

What is the Endosymbiosis theory?

A

Mitochondria and chloroplasts (and possibly other eukaryotic organelles) were formerly free-living bacteria/ Prokaryotes

These prokaryotes were taken inside another cell as an endosymbiont

Lead to the evolution of eukaryotic cells

140
Q

Prokaryotes vs Eukaryotes Nucleus

A

P: Not present

E: Present

141
Q

Prokaryotes vs Eukaryotes DNA

A

P: Circular

E: Linear

142
Q

Prokaryotes vs Eukaryotes DNA Organisation

A

P: Proteins fold and condense DNA

E: Associated with Proteins called histones

143
Q

Prokaryotes vs Eukaryotes Extra chromosomal DNA

A

P: Circular DNA called Plasmids

E: Only present in certain organelles such as chloroplasts and mitochondria

144
Q

Prokaryotes vs Eukaryotes Ribosomes

A

P: 70S

E: 80S

145
Q

Prokaryotes vs Eukaryotes Organelles

A

P: Non membrane bound

E: Both Membrane and non membrane bound

146
Q

Prokaryotes vs Eukaryotes Cell walls

A

P: Peptidoglycan

E: Chitin in Fungi
Cellulose in Plants
Not present in animals

147
Q

Prokaryotes vs Eukaryotes Cytoskeleton

A

P: Present

E: Present, more complex

148
Q

Prokaryotes vs Eukaryotes Reproduction

A

P: Binary Fission

E: Asexual or Sexual

149
Q

Prokaryotes vs Eukaryotes Cell type

A

P: Unicellular

E: Unicellular or Multicellular

150
Q

Prokaryotes vs Eukaryotes Cell surface membrane

A

P: present

E: Present

151
Q

List three structural differences between prokaryotic cells and eukaryotic cells

A

Nucleus in Euk, none in Pro

DNA is circular in Pro, Linear in Euk

Cell wall Is made of peptidoglycan in Pro, Chitin/cellulose in Euk

152
Q

Suggest why the lack of membrane-bound organelles doesn’t stop prokaryotic cells making proteins

A

Contain Ribosomes

Capable of replicating proteins

153
Q

Some Antibiotics kill bacteria by disrupting the formation of peptidoglycan molecules. Explain why these antibiotics kill bacteria and why they do not have any effects on eukaryotic cells

A

Bacteria Cell walls made from peptidoglycan

Prevents growth and replication of bacteria, unable to form cell wall

Eukaryotes either have no cell walls, or they are made from chitin/cellulose

Hence no cell wall would be disrupted

BIOLOGY A LEVEL (24 decks)

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