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Cell Biology Flashcards

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1
Q

What is cell theory?

A

All living organisms are composed of cells
Cells are the smallest units of life
Cells only come from pre-existing cells by cell division

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2
Q

What do all cells have?

A

Cytoplasm
Cell membrane
DNA
Ribosomes

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3
Q

What are the exceptions of cell theory?(Explain)

A

Striated Skeletal Muscles Fibres= very long cells with many nuclei
Aseptate fungi= each hyphae is undivided and has many nuclei
Giant algae= grow very large but are unicellular

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4
Q

Define magnification

A

Ability to make an object larger

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5
Q

Define resolution

A

Ability to distinguish separate parts of an object/two objects from each other

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6
Q

Compare an EM microscope vs. a Light microscope

A

EM has higher resolution, higher magnification
BUT, expensive, difficult sample preparation, cannot image living organisms

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7
Q

For each of the following state whether they are prokaryotes or eukaryotes and state whether they are unicellular or multicellular:

Bacteria
Protoctista
Fungi
Animals
Plants

A

Bacteria- Prok, uni
Protoctista- Euk , mostly uni
Fungi- Euk, multi except for yeast
Animals- Euk, multi
Plants-Euk, multi

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8
Q

Give two features of a prokaryotic cells

A

Unicellular
No compartmentalisation

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9
Q

What does compartmentalisation mean?

A

No membrane- bound organelles

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10
Q

Draw a prokaryotic cell and label it fully.

A

Must have:
70S ribosomes
cell/plasma membrane
cell wall
DNA/genetic material
pili
cytoplasm
flagellum

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11
Q

What is the genetic material of a prokaryotic cell?

A

1 circular naked chromosome in Nucleoid

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12
Q

What are pili used for?

A

Adhesion and conjugation

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13
Q

Draw an animal cell and label it fully.

A

Rough ER
Mitochondrion
Nucleus
Nuclear envelope
Golgi apparatus
vesicle
cytoplasm
80s ribosomes
cell membrane
nuclear pore

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14
Q

What are the differences between plant and animal cells?

A

Plants have chloroplasts animals do not
Plants have cell walls animals do not
Plants have a large and permanent vacuole animals have small and temporary
Most plants do not have centrioles animal cells do

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15
Q

Draw a mitochondria and a chloroplast

A

Double membrane!

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16
Q

Distinguish between prokaryotic and eukaryotic cells

A
  1. Naked DNA; DNA associated with histone proteins
  2. Circular DNA, linear DNA
  3. DNA in nucleoid; DNA in nucleus
  4. 1 chromosome; 2 or more different
  5. no membrane bound organelles; yes
  6. 70S ribosomes; 80S ribosomes
  7. pili; no pili
  8. plasmids; no plasmids
  9. no mitochondria; mitochondria
  10. cell wall; only in plants and fungi
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17
Q

Lable the following and describe how it carries out the functions of life.

A

Food vacuole- nutrition

Contractile Vacuole- homeostasis(fills up with H20 and expels it throught the membrane)
Nucleus- reproduction

Cytoplasm- metabolism

cilia- Response and movement towards the food

Cell Membrane- Excretion(controls exit of molecules)

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18
Q

What are the levels of organisation?

A

cell- tissue-organ-organ system-organism

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19
Q

Why are there emergent properties at each level?

A

Because there are interactions of component parts

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20
Q

Outline the differention of cells in a multicellular organism.

A

All cells in the body have the same DNA but each cell is differnt in the sense that different genes are expressed. They are expressed by transcription and translation and these carry out different functions. A group of specialised cells is called a tissue.

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21
Q

Describe the division of labour

A

Specialised cells carry out different functions an dhave different structure which is adapted to their function. THis happens because a different set of genes is expressed through transcription and translation

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22
Q

Describe the functions of life in a chlamydomonas cell

A
  1. Flagella- response towards food
  2. Contractile vacuole- homeostasis
  3. cell membrane- excretion
  4. Stigma(eye spot)- response detects light
  5. chloroplast- nutrition site of photosynthesis
  6. vacuole- nutrition
  7. cytoplasm- metabolism
  8. nucleus- reproduction
  9. pyrenoid starch grain- nutrition food storage
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23
Q

How do you go from cm to mm?

A

x10

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24
Q

How do you from mm to micrometer?

A

x1000

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25
Q

How do you go from micrometer to nanometer?

A

x1000

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26
Q

What are stem cells?

A

Unspecialised cells that dicide continuously by mitosis and can give rise to many differentiated cells

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27
Q

Describe how Stargardt’s disease can be treated by use of stem cells

A
  • It is a progressive loss of vision due to degenaration of retinal cells(genetic disease)
  • Embryonic stem cells are harvested and differentiated in the lab into retinal cells.
  • Retinal cells injected into patient’s eye where they are established
  • Vision restored
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28
Q

Describe how leukemia can be treated by stem cells

A
  • Cancer of bone marrow
  • HSCs (hematopoetic stem cells) are harvested from donor or patient
  • chemotherapy to destroy cancer cells
  • HSCs transplanted back to patient–> divide and differentiate to form WBCs
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29
Q

What are sources of stem cells?

A

Embryonic stem cells

Adult tissues

Umbilical cord

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30
Q

Describe the advantages and disadvantages of the use of adult tissues compared to embryonic stem cells.

A

Advantages:

  • consent
  • less likely to form a tumor
  • If own, less chance of rejection
  • less ethical issues/individual not killed

Disadvantages:

  • Difficult to obtain
  • Less potential
  • Some tissues do not have stem cells
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31
Q

What can surface area to volume ratio do ?

A

Limit cell size

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32
Q

Explain how SA/Volume influences cell sizes

A

As cell increases in size, the ratio of surface area/volume decreases.

Cells divide when they reach a certain size

The rate at which materials are produced is reliant on volume

The rate at which materials enter or leave a cell depends on the surface area

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33
Q

What is spontaneous generation?

A

Fomation of organsims from non living matter

DISPROVED BY PASTEUR

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34
Q

What is genetic code?

A

It is almost entirely a universal common fundamental biochemistry

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35
Q

How did the origin of the first cell happen?

A
  1. Synthesis of simple organic molecules from inorganic- Miller and Urey experiment
  2. Assembly of simple organic molecules into polymers- sea vents
  3. Self replicating molecule that can store genetic information- RNA
  4. Enclosure of the self- replicating molecule in a membrane- spontaneous assembly of lipids into a bilayer when placed in H2O
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36
Q

What does endosymbotic theory ecplain?

A

The origin of mitochondria and chlropolsats which were once free living prokaryote

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37
Q

Describe the endosymbiotic theory

A

An anaerobic prokaryote englufed an aerobic prokaryote. It was engulfed but not digested becasue the relationship was mutually beneficial and so it became the mitochondrion.

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38
Q

What is the evidence that supports the endosymbiotic theory?

A
  1. 70S ribosomes
  2. Circular, Naked DNA
  3. Double membrane- as a result of engulfement
  4. Mitochondria divide by binary fission
  5. Similar size to prokaryotes
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39
Q

What is the function of the membrane?

A

It controls the flow of substances in an dout of a cell and separates the cell from surroundings.

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40
Q

What is the membrane made out of?

A

Lipids(mainly phopholipids; animals also cholestrol)

Proteins

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41
Q

Draw a phospholipid and label it.

A
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42
Q

What does amphipathic mean?

A

It has both hydrophilic and hydrophobic parts

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43
Q

Which parts are hydrophobic and hydrophilic in a phospholipid and what are their other names?

A

Hydrophilic- Phosphate head

Hydrophobic- Hydrocarbon tail

Hydrophilic- polar

Hydrophobic- non-polar

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44
Q

What makes the membrane very stable?

A

Attraction between heads- H20 and between the tails

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45
Q

Draw a phopholipid with a cholestrol

A
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46
Q

What is the role of the cholestrol?

A
  1. Affects membrane fluidity
  2. Reduces permeability to some solutes
  3. Helps membranes to curve
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47
Q

List all the proteins found in the membrane

A

Integral- entirely integral/transmembrane

Peripheral

Channels

Glycoproteins

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48
Q

What can determine the localisation of proteins?

A

The amino acid sequence. Non polar AA casue proteisn to become embedded. Polar AA cause proteins to be peripheral a channel to be formed for hydrophilic substance to diffuse and an integral to protrude.

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49
Q

What are functions of membrane proteins?

A
  1. Receptors (hormones or neurotransmitters)
  2. Immobilized enzymes
  3. Channels
  4. Pumps
  5. Electron transport
  6. Cell to cell adhesion
  7. Cell to cell communication
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50
Q

Draw the Singer Nicolson Fluid Mosaic Model. FULLY LABELLED AND INDICATION OF HYDROPHOBIC AN DHYDROPHILIC PARTS IS NEEDED.

A

LOOK INTO NOTES FOR FURTHER DETAIL

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51
Q

What is the width of the membrane?

A

10nm

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52
Q

Draw the Davson- Danielli Model

A
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53
Q

Evidence of the Davson-Danielli Model.

A

Organic solvents penetrate facter than H2O–> non polar regions

Chemical analysis–> proteins and lipids

Amount of phopholipids in RBCs—> phopholipid bilayer

EM–> 2 dark lines separated by a lighter band (they thouhgt dark lines are the proteins light band the bilayer)

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54
Q

What did the singer nicolson model convey?

A

Proteins occupy a varitey of postions

Components move

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55
Q

What was evidence for the singer- nicolson model?

A
  1. Freeze fracture EM: proteins inside the bilayer
  2. Parts of the surface of membrane proteins are hydrophobic
  3. fusion of cells with labelled proteisn(different colour) therefore colours mixed–> proteins move.
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56
Q

What are organelles?

A

Discrete structures within cells that carry a specific function.

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57
Q

How do prokaryortic cells divide?

A

By binary fission

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58
Q

Which structures of double membranes?

A

Nucleus

Mitochondria

Chloroplasts

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59
Q

What do cell walls do?

A

Protects teh cell from bursting, maintains the cell’s shape

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60
Q

What does the cytoplasm do?

A

Site of cehmical reactions

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61
Q

What does the nucleoid do?

A

Region containing the bacterial DNA, which is a single, naked circular chrmosome

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62
Q

What do ribosomes do?

A

Site of protein syntehesis

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63
Q

What are plasmids?

A

Small circcular DNA in the cytoplasm

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64
Q

What does the flagellum do?

A

Rotates to move the cell

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65
Q

What does the rough endoplasmic reticulum do?

A

Synthesises proteins that will go to the cell membrane and will be secreted from the cell.

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66
Q

What does the Golgi apparatus do?

A

Proteins from teh RER arrive to the Golgi body in vesicles and are modified here. The proteins are then packaged into vesicles and are transported to teh membrane.

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67
Q

What do vesicles do?

A

Transport molecules inside the cell

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68
Q

What does the nucleus do?

A

Contains teh DNA and controls cell activitites, transcription takes place in the nucleus.

69
Q

What is the nucleolus?

A

Inside the nucleus- site of robosomal RNA synthesis

70
Q

What does the mitochondria do?

A

The reactions of aerobic respiration taje place in order to produce ATP which is the energy of the cell.

71
Q

What is the smooth endoplasmic reticulum?

A

Synthesises lipids adn steroid hormones

72
Q

What are lysosomes?

A

Contain hydrolytic enzymes for intracellular digestion. Break down engulfed organisms, organelles, macromolecules.

73
Q

What are centrioles?

A

Cylindrical cell structures that form the anchor point o fmicrotubules. An associated pair of centrioles makes up the centrosome.

74
Q

What is the following and how could you identify it?

A

EXOCRINE GLAND CELL OF PANCREAS

nucleus adn membrane bound organelles so cell is eukaryotic

No cell wall so animal cell

Extensive rer and vesicles as the cell syntehsises many proteins and treansports them for secretion

Many mitochondria as teh cell needs a lot of ATP for transport and protein syntesis

75
Q

What is the following and how could you identify it?

A

nucleus and membrane- bound organelles so the cell is eukaryotic

cell wall, chloroplasts so a plant cell

many chloroplasts as it is a photosynthesising cell

76
Q

What are the functions of life?

A

Metabolism

Response

Homeostasis

Growth

Reproduction

Excretion

Nutrition

77
Q

What is metabolism?

A

All the chemical reactions occuring in an organism

78
Q

What is response?

A

Ability to sense internal and external environment and respond

79
Q

What is homeostasis?

A

Maintenance of internal environment within tolerable limits

80
Q

What is growth?

A

A permanent increase in size and dry mass by cell growth and/or cell division

81
Q

What is reproduction?

A

Production of new members of the same kind

82
Q

What is excretion?

A

Gettign rid of waste products of metabolism

83
Q

What is nutrition?

A

obtaining chemicals required for respiration and growth

84
Q

How do you focus a light microscope?

A
  • Place the slide on the stage centred below the objective lens
  • Focus by moving the objective lens and specimen apart/ towards each other
  • First use the coarse lens to find the area of interest then use the fine focusing knob
  • First use a low magnification objective lens to find the area of interest. Then use a higher power.
  • Adjust light intensity
85
Q

What was the experiment of Louis Pasteur?

A
  • Broth for palced in swan- necked flasks
  • Curved necks allow the entry of air but prevent the entry of microorganisms
  • Broth boiled to kill microorganisms
  • In flask, no clouding so no bacterial growth
  • After the necks were snapped, teh boiled broth became cloudy meaning bacteria grew
  • This is beacuse bacteria from the air contaminated the broth
86
Q

What is the basis of all membranes?

A

phospholipid bilayer

87
Q

What are integral transmembrane?

A

They span the whole membrane width

88
Q

Which organelle has no membrane?

A

Ribosome

89
Q

What is this?

A

Rough endoplasmic reticulum

90
Q

What is this?

A

Golgi apparatus

91
Q

What is this?

A

Nucleus

92
Q

What is this?

A

Chloroplast

93
Q

What is this?

A

Lysosome

94
Q

What is this?

A

Mitochondria

95
Q

What are the methods of transport?

A

Diffusion

Facilitated Diffusion

Osmosis

Active transport

using vesicles

96
Q

What is the difference between active and passive transport?

A

Active transport requires energy from ATP while passive transport does not need energy

97
Q

What is diffusion?

A

The passive net movement of particles from a region of their higher concentration to a region of their lower concentration, as a result of their random motion

98
Q

How do particles move in simple diffusion?

A

Across membranes, particles move down the concentration gradient and pass between phospholipids. Thus the membrane must be permeable to the particle.

99
Q

What rapidly diffuses across a membrane?

A

The smaller and the more hydrophobic/non polar.

100
Q

Which molecules/atoms CANNOT diffuse across a mebrane?

A

Large proteins

Charged molecules or atoms/ions

(Small uncharged polar molecules diffuse more slowly eg water)

101
Q

What is the difference between facilitated and simple diffusion?

A

The transported molecules do not pass through the phopholipid bilayer but are transported by channel proteins

102
Q

What do channel proteins enable in facilitated diffusion?

A

Enable substances to cross the membrane without interacting with the hydrophobic interior.

103
Q

Which substances diffuse through facilitated diffusion?

A

Polar and charged molecules such as carbohydrates, amino acids and ions

104
Q

What are channel proteins in facilitated diffusion?

A

They are specific for a substance. Voltage- gated sodium and potassium channels of neuronal axons.

105
Q

What is active transport?

A

The movement of particles through the cell membrane against the concentration gradient which requires energy, ATP from hydrolysis which is carried out by protein pumps.

106
Q

How do protein pumps work?

A

The particle enters the pump and binds

The pump changes conformation using energy from ATP

The particle is released at the opposite site of the membrane

The pump returns to its original conformation

107
Q

What is a solvent?

A

Liquid that dissolves a substance

108
Q

What is a solute?

A

Substance that is dissolved in a solvent

109
Q

What is a solution?

A

Solute+ Solvent

110
Q

What is osmosis?

A

The passive net movement of water molecules from a region of lower solute concentration to a region of higher solute concentration through a partially permeable membrane.

111
Q

Where do water molecules pass through?

A

The phospholipid bilayer

112
Q

What is osmolarity?

A

The concentration of osmotically active solutes in the solution (unit =osmole)

113
Q

What is isotonic?

A

If the solution has the same solute concentration as the tissue

114
Q

What is hypertonic?

A

If the solution has a higher solute concentration than the tissue. Net movement is out of the tissue

115
Q

What is hypotonic?

A

If the solution has a lower solute concentration than the tissue. The net movement of water of from the solution into the tissue

116
Q

What is the effect of animal cells in osmosis?

A

An animal cell is placed in a hypotonic solution, water enters by osmosis and it will swell up eventually and burst

If an animal cell is placed in a hypertonic solution water leaves the cell by osmosis and the cytoplasm shrinks and so the cell becomes crenated.

117
Q

What is normal saline used for?

A

To introduce medicine is a patient’s blood, frozen to the consistency of slush for the transport of organs for transplantation, to rinse wounds

118
Q

What is the effect of plant cells in osmosis?

A

If a plant cell is placed in a hypotonic solution, water enters the cell by osmosis and the cell becomes turgid. The vacuole fills with water and exerts pressure against the cell wall.

If a plant cell is placed in a slightly hypertonic solution, it loses some water by osmosis and becomes flaccid

If a plant cell is placed in a hypertonic solution it loses water and becomes plasmolysed

119
Q

What is bulk transport?

A

The movement of macromolecules and large particles in and out of the cell using vesicles. Two types: Endocytosis, exocytosis

120
Q

What allows materials to be taken into the cells by endocytosis and exocytosis?

A

The fluidity of the membrane;the cholesterol that it has

121
Q

Describe the process of endocytosis.

A

The cells take up macromolecules.

Plasma membrane invaginates and encloses the material to be ingested

The membrane pinches off to form a vesicle

The inside of the plasma membrane becomes the outside of the vesicle membrane.

The membrane seals back on itself

122
Q

What are the two main types of endocytosis?

A
  • phagocytosis(ingestion of large particles)
  • pinocytosis( ingestion of fluid and solutes)
123
Q

Describe the action of exocytosis

A

Material is carried to the plasma membrane by vesicles and is secreted

Vesicles fuse with the membrane to release their contents

when the vesicle contents are expelled, the membrane flattens out again.

124
Q

What are examples of exocytosis?

A

Secretion of hormones by endocrine gland cells, the release of neurotransmitters by neurones, secretion of digestive enzymes by pancreatic exocrine gland cell

125
Q

Describe the process of vesicle transport within cells

A

Proteins and other non-protein material are transported within the cell in vesicles

Secreted proteins and integral membrane proteins are synthesised in the ribosomes of the rER and packed into vesicles

The vesicles bud off the rER and move to the Golgi apparatus

Vesicles fuse with the membrane of the Golgi apparatus

Proteins are being processed as they move through the Golgi apparatus

They are packaged again into vesicles which bud off the Golgi apparatus and are carried to the cell membrane

The vesicles fuse with the membrane and release their contents outside the cell

126
Q

What are two examples of transport in axons?

A

Voltage-gated potassium channels used for facilitated diffusion

Na+/K+ ATPase is a pump performing active transport

127
Q

What are the detailed steps of the Na+/K+ ATPase?

A

The pump is open to the inside of the axon, three Na+ ions enter and bind

ATP transfers one phosphate group to the pump which causes a conformational change to the pump

The pump opens to the outside and the three Na+ ions are released

Two K+ ions enter the pump and bind

Binding of the K+ ions causes the release of the phosphate group and thus a conformational change in the pump

Two pumps open to the inside and the two K+ ions are released. Cycle starts again.

128
Q

What happens at the potassium K+ channels?

A

At resting potential, potassium channels are closed. They open for a short time in response to depolarisation. When potassium channels open they allow K+ ions to diffuse out of the cell, thus repolarising the axon. The channel rapidly closes. This happens by a globular subunit that blocks the channel pore. The globular subunit is attached by a flexible chain, fits inside the pore and remains there until the channel returns to its original closed state.

129
Q

What are the three types of cell division?

A

Binary fission

Mitosis

Meiosis

130
Q

What happens in binary fission?

A

DNA replication cell growth and elongation

DNA pulled to opposite poles and new membrane forms

Cell splits.

131
Q

What is the cell cycle?

A

The sequence of events between two cell divisions

132
Q

What are the two main phases of the cell cycle?

A

Interphase - divided into G1, S, G2

Cell division- Mitosis and cytokinesis.

133
Q

Describe interphase

A
  1. A very active phase in which the cell grows
  2. DNA replication takes place
  3. Transcription and translation takes place
  4. Cell increases number of organelles (if plant increases also chloroplasts; if animal also centrioles)
  5. It is the longest phase of cell cycle
  6. Subdivided into G1, S and G2
134
Q

What happens at the G1 phase?

A

Most of the growth and metabolic activities mentioned in interphase happen during this phase EXCEPT for DNA replication

135
Q

What happens at the S phase?

A

DNA replication takes place. The chromosomes are copies and for the sister chromatids which are identical, which remain attached at the centromere until they separate for mitosis.

136
Q

What happens at G2 phase?

A

More cell growth and preparation for mitosis

137
Q

What is visible during interphase?

A

the genetic material is visible as chromatin NOT individual chromosomes.

138
Q

What is mitosis?

A

The division of the nucleus that forms two genetically identical nuclei.

Subdivided into 4 phases: Prophase, Metaphase, Anaphase and telophase

139
Q

What happens in cytokinesis?

A

The division of the cytoplasm so that two cells are formed. It begins before mitosis has been completed.

140
Q

How does the DNA fit in the nucleus?

A

It condenses- DNA is successively coiled into shorter higher order structures. Super coiling,

141
Q

What happens in eukaryotic chromosomes?

A

The DNA is associated with histone proteins which helps with condensation to form nucleosomes

142
Q

What is the most condensed state?

A

Chromosome

143
Q

When does mitosis occur?

A

Embryonic development

Tissue repair

Growth

Asexual reproduction

144
Q

What are the stages of mitosis?

A

Prophase

Metaphase

Anaphase

Telophase

145
Q

What happens in prophase?

A

Chromosomes become shorter adn fatter by supercoiling. Microtubules grow in cytoplasm to form a spindle shaped array that extends from the cell poles to the equator. Nucleolus breaks down. End of prophase, nuclear membrane breaks down.

146
Q

What happens in metaphase?

A

Microtubules continue to grow and attach to the centromeres on each chromosome. The chromosomes align at the equator of the cell.

147
Q

What happens in the anaphase?

A

The centromere divides and the spindle microtubule pull the sister chromatids, now chromosomes, to opposite poles. Mitosis produces genetically identica nuclei because identical chromosomes are pulled to opposite poles.

148
Q

What happens in telophase?

A

Chromosomes have reached the poles. Nuclear membrane reforms. Spindle microtubules break down. Chromosomes decondense and nucleolus forms.

149
Q

How does cytokinesis take place in animals?

A

A contractile ring forms under the membrane which pulls the membrane to the equator inwards forming a cleavage furrow. When the membrane meets in the centre of the cell, the cell pinches apart

150
Q

How does cytokinesis take place in plants?

A

Vesicles derived from the Golgi apparatus fuse at the cell equator and form the cell plate. The cell plate grows until it merges with the cell walls at the periphery. New membrane and cell wall form, splitting the cell in two.

151
Q

What are the differences between plant and animal cell mitosis?

A
  1. In interphase, animal cells increase centrioles- plants do not have. plant cells increase chloroplasts- animals do not have.
    1. In cytokinesis, plant cells have cell plates while animal cells have cleavage furrow
152
Q

What is the mitotic index?

A

Mitotic index= Number of cells in nitosis/total number of cells

153
Q

What do tumour tissues have?

A

High mitotic index because cancer cells divide more than normal cells.

154
Q

What is a cyclin?

A

Proteins that control cell cycle progression

155
Q

How do cyclins work?

A

Cyclins bind to enzymes called cyclin-dependent kinases(cdk) and activate them. Cdks activate other proteins by phosphorylating them. The phosphorylated proteins carry out specific functions. Levels of cyclins rise and fall.

156
Q

What does cyclin d do?

A

Triggers cells to move from G0 to G1 and and from G1 to S

157
Q

What does cycline E do?

A

Prepares the cell for DNA replication in S phase

158
Q

What does cyclin A do?

A

Activated DNA replication during the S phase

159
Q

What does cyclin B do?

A

Promotes the assembly of the mitotic spindle and other tasks in the cytoplasm to prepare for mitosis

160
Q

What is the order of the cyclins?

A

D is throughout

E-A-B

161
Q

What is a tumour?

A

A cell mass formed by uncontrolled cell division

162
Q

What can primary tumours be?

A

Benign- tumour cells cannot invade nearby tissues or move to other parts

Malignant- Tumour cells can move to other parts of the body and form secondary tumours

163
Q

What is metastasis?

A

Spreading of tumour cells

164
Q

How do tumours occur?

A

Mutations in genes. DNA mutations are random changes in the base of the sequence of the genes. DNA mutations can occur because of errors during DNA replication or because of mutagens.

165
Q

What are oncogenes?

A

Genes that might lead to cancer when mutated. They are usually involved in the control of cell cycle so their mutation can cause uncontrolled cell division.

166
Q

What are mutagens?

A

Agents that increase the rate of mutations and therefore the risk of tumour formation.

167
Q

Which correlation is there between cigarette smoking and death rate due to cancer?

A

Positive

168
Q

What does it mean if you find a correlation?

A

IT DOES NOT PROVE A CAUSAL LINK.

IB HL BIOLOGY (25 decks)

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