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BIO 1M03 > Chapter 1 - Biology and the Tree of Life > Flashcards

Chapter 1 - Biology and the Tree of Life Flashcards

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Biology 101 flashcards
0
Q

Define scientific theory.

A
  • explains related observations

* general principles for field of study

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1
Q

What characteristics define living things?

A
  • obtain and use energy
  • made of cells
  • store and process information from genes and environment
  • replicate
  • result of evolution and part of evolving population
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2
Q

Who first observed cells in the late 1660s?

A
  • Robert Hooke

* Anton van Leeuwenhoek

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3
Q

What are the fundamental building blocks of life?

A

• Cells

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4
Q

What two parts make a scientific theory?

A
  • pattern: describe a pattern observed in nature

* process: explain what causes the pattern

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5
Q

What is a cell?

A

• highly organized compartment bounded by plasma membrane that contains concentrated chemicals in aqueous solution

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6
Q

What does the cell theory state?

A
  • pattern: all organisms are made of cells

* process: all cells come from preexisting cells

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6
Q

Within a multicellular individual, where do all cells descend from?

A

• zygote (fertilized egg)

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7
Q

What did Anton van Leeuwenhoek discover?

A

• microorganisms in pond water

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8
Q

Why didn’t biologists discover earlier that all life is made of cells?

A

• microscopes powerful enough to see cells were not available

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9
Q

When the microscope was invented, major improvements were also made to what? What era was this all a part of?

A
  • telescope

* the Enlightenment in Europe

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10
Q

What is the difference between a hypothesis and a prediction?

A
  • Hypothesis: proposed explanation for scientific observation or question
  • Prediction: statement describing the expected experimental results if hypothesis is true; can be measured
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11
Q

Which two hypotheses tried to explain where cells come from?

A
  • spontaneous generation hypothesis

* all-cells-from-cells hypothesis (cell theory)

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12
Q

What was the spontaneous generation hypothesis?

A

• organisms spontaneously appear in non-living materials

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13
Q

What did Louis Pasteur do?

A
  • conducted an experiment to test where cells come from
  • hypothesis: cell theory
  • null hypothesis: spontaneous generation
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13
Q

Describe the setup of Louis Pasteur’s experiment.

A
  • placed same nutrient broth in two flasks with different neck shapes
  • boil to sterilize
  • straight neck: exposed to preexisting cells in air
  • swan neck: condensed water prevents exchange with air
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15
Q

Explain the results of Louis Pasteur’s experiment.

A
  • straight neck: cells appeared
  • swan neck: no cells appeared
  • spontaneous generation hypothesis rejected
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17
Q

Who realized all species are related?

A
  • Charles Darwin

* Alfred Russell Wallace

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21
Q

What would you conclude if both of Pasteur’s treatments filled with cells?

A

• spontaneous generation hypothesis is valid

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22
Q

Why was it important for Pasteur to also perform treatment on the straight neck flask?

A

• used as a control to prove that medium is capable of supporting life and that what we’re testing is actually occurring

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23
Q

What caveats should be tested further in Pasteur’s experiment?

A
  • medium used may be capable of supporting life but not capable of generating life
  • condensation in swan neck also closes off oxygen which may be needed to spontaneously generate or support life
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24
Q

How did the original cell form?

A

Theories
• terrestrial (from organic soup - different type of medium, different unique conditions required)
• extraterrestrial (from meteors - panspermia, building blocks of life seeded on earth by meteors or cosmic dust or comets)

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25
Q

What did scientists use to complete a map of every cell division from zygote to adult?

A
  • nematode Caenorhabditis elegans
  • organism is see through
  • only has ~1000 cells in total
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26
Q

What is an organism?

A
  • contiguous living system

* capable of response to stimuli, reproduction, growth and development, and maintenance of homeostasis

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27
Q

Why is a virus, ecosystem, or sperm cell not an organism?

A

• cannot reproduce on their own

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28
Q

What is the theory of evolution by natural selection?

A
  • all species are related by common ancestry
  • evolutionary change: traits of species can be modified from generation to generation
  • natural selection: mechanism for change
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29
Q

What does evolution postulate?

A
  • species are related to each other

* species can change through time

30
Q

What is natural selection?

A

• process explaining how evolution occurs

31
Q

What is fitness?

A

• relative ability of individual to produce offspring that will survive and also reproduce (grandparents)

32
Q

What is adaptation? (noun; verb)

A
  • characteristic/trait that increases fitness of individual in particular environment;
  • process of species acquiring adaptive (fitness-improving) traits over time
33
Q

What is needed for natural selection to occur?

A
  • variation
  • heritable traits
  • trait influences fitness
34
Q

What happens if certain heritable traits lead to higher fitness?

A
  • trait leads to increased success in producing offspring

* trait becomes more common in population over time

35
Q

What is the difference between natural selection and evolutionary change?

A
  • natural selection: acts on individuals

* evolutionary change: affects populations

36
Q

When does evolution occur?

A

• heritable trait leads to differential success in reproduction

37
Q

What is artificial selection?

A
  • individuals of population selected for mating by humans based on certain traits
  • repeating over generations leads to changes in population’s characteristics over time
38
Q

How was the theory of evolution by natural selection created?

A
  • Darwin thought about evolutionary change through time for 20 years while sailing around South America
  • wrote “On the Origin of Species” but nervous due to religious views of society
  • Darwin received letter from Wallace who was travelling South America and Papua New Guinea and collecting specimens to sell to Europeans
  • Darwin decided to publish his theory in a short form next to Wallace’s in a journal
  • Darwin published “On the Origin of Species” a year later
39
Q

Why do peacocks have such vibrant colours?

A
  • sexual selection

* males with colourful feathers selected for by females

40
Q

Why does thylacine (Tasmanian wolf) look like a dog and have tiger stripes on its back?

A
  • convergent evolution

* similar environmental pressures (selection) in Australia have caused thylacine to develop similar morphology to dogs

41
Q

How did rock pigeon undergo artificial selection?

A
  • people were breeding pigeons (popular) and selecting for extreme morphologies to use them as items for display for the wealthy
  • selection for fancy traits like powder, large breasts, fantail
43
Q

What is biology?

A

• the study of life

44
Q

What is wild mustard (Brassica oleracea) an example of and why?

A
  • domestication, artificial selection
  • artificially selected to be cauliflower (flower sterility), broccoli (no flowers), cabbage (short internode), Brussel sprouts, kale (large leaves), kohlrabi (lateral meristems)
  • all one species that can interbreed but have different extreme morphologies (taste, texture, etc.)
  • only select for extreme morphologies during each generation (i.e. widest stalks)
  • average stalk width gradually shifts (i.e. becomes broccoli)
45
Q

What is phenotype?

A

• describes how something looks

46
Q

What is genotype?

A

• genes that underlie an appearance (phenotype)

47
Q

What is wild mustard (Brassica oleracea) an example of and why?

A
  • domestication, artificial selection
  • artificially selected to be cauliflower (flower sterility), broccoli (no flowers), cabbage (short internode), Brussel sprouts, kale (large leaves), kohlrabi (lateral meristems)
  • all one species that can interbreed but have different extreme morphologies (taste, texture, etc.)
  • only select for extreme morphologies during each generation (i.e. widest stalks)
  • average stalk width gradually shifts (i.e. becomes broccoli)
48
Q

What unites cell theory and the theory of evolution by natural selection?

A
  • ancestry and descent
  • all cells come from preexisting cells; therefore all cells descend from preexisting cells and all organisms are related by common ancestry
49
Q

What is a phylogenetic tree?

A

• representation of evolutionary relationships among species and cells

50
Q

What does speed (number of generations required) of artificial selection depend on?

A
  • how many genes influence phenotype (i.e. single or complex multi-genetic traits)
  • how much (natural) genetic variation exists at these genes
  • how much phenotype is controlled by environmental factors (natural selection)
51
Q

What does the magnitude of artificial selection depend on?

A
  • tradeoffs: if there are deleterious consequences of selection (i.e. stalk that is too wide may affect ability to transport water, reproduce, etc.)
  • limits of available genetic variation
52
Q

How does unintended artificial selection occur and what are its consequences?

A
  • due to predation by humans (i.e. fishing)

* evolution of small size, early maturation, behavioural responses

53
Q

Which animals die in an ecosystem without human predation?

A

• younger, elderly, diseased

54
Q

Which animals die in an ecosystem with human predation?

A

• biggest, strongest

55
Q

What is a Canadian example of unintended artificial selection due to human predation?

A
  • codfisheries in Nova Scotia
  • over 30 years, size of Atlantic cod has drastically decreased
  • due to overfishing disrupting size and age distribution
56
Q

What is the difference between artificial selection and genetic modification?

A
  • artificial selection: type of genetic modification on traits of organism which usually modifies the genes underlying desired trait (i.e. domestication of crops and livestock)
  • genetically modified organism: targeted introduction of a new gene from another organism (transgene)
57
Q

How can you tell if two organisms are different species?

A

• cannot interbreed and/or produce viable offspring (sterile)

58
Q

What is speciation?

A
  • process of forming new species

* divergence through time (branching of phylogentic tree)

59
Q

What is the tree of life?

A
  • a diagram that depicts relationships among species from ancestor to descendent
  • cannot be directly observed so must be inferred from data (i.e. genetic, morphological, behavioural)
60
Q

What can we use to estimate the tree of life?

A

• molecular variation in nucleotides of a gene (more similar sequences = more closely related - more able to exchange genetic material through time)

61
Q

What are Linnaeus’ Taxonomic Levels

A

• Kingdom, Phylum, Class, Order, Family, Genus, Species

62
Q

What is the format for a species name?

A
  • two part Latin name

* Genus species (in italics or underlined)

63
Q

How many kingdoms are there?

A
  • Linnaeus proposed two: plants and animals
  • alternative five-kingdom system proposed: Monera, Protista, Plantae, Fungi, Animalia
  • currently there is a higher classification than kingdom: domains (contain many kingdoms)
64
Q

What are the three domains?

A 
Prokaryotes:
• bacteria
• archaea
Eukaryotes:
• eukarya
65
Q

What does a node represent?

A

• common ancestor of the following connected branches

66
Q

What is an important caveat of the tree of life?

A
  • first node represents common ancestor of organisms alive today
  • other branches may have existed but have gone extinct without leaving a record (i.e. no fossils)
67
Q

Can the tree of life be changed?

A

• Yes, positions of branches are debated and continuously changed as databases expand

68
Q

Where on the tree of life did the structure called the nucleus originate?

A
  • most parsimonious: on the eukarya branch

* less parsimonious but possible: on the common ancestor node (was then lost by bacteria and archaea)

BIO 1M03 (5 decks)

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