Chapter 1 - Biology and the Tree of Life Flashcards
0
Q
Define scientific theory.
A
- explains related observations
* general principles for field of study
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
2
Q
Who first observed cells in the late 1660s?
A
- Robert Hooke
* Anton van Leeuwenhoek
3
Q
What are the fundamental building blocks of life?
A
• Cells
4
Q
What two parts make a scientific theory?
A
- pattern: describe a pattern observed in nature
* process: explain what causes the pattern
5
Q
What is a cell?
A
• highly organized compartment bounded by plasma membrane that contains concentrated chemicals in aqueous solution
6
Q
What does the cell theory state?
A
- pattern: all organisms are made of cells
* process: all cells come from preexisting cells
6
Q
Within a multicellular individual, where do all cells descend from?
A
• zygote (fertilized egg)
7
Q
What did Anton van Leeuwenhoek discover?
A
• microorganisms in pond water
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
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
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
11
Q
Which two hypotheses tried to explain where cells come from?
A
- spontaneous generation hypothesis
* all-cells-from-cells hypothesis (cell theory)
12
Q
What was the spontaneous generation hypothesis?
A
• organisms spontaneously appear in non-living materials
13
Q
What did Louis Pasteur do?
A
- conducted an experiment to test where cells come from
- hypothesis: cell theory
- null hypothesis: spontaneous generation
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
15
Q
Explain the results of Louis Pasteur’s experiment.
A
- straight neck: cells appeared
- swan neck: no cells appeared
- spontaneous generation hypothesis rejected
17
Q
Who realized all species are related?
A
- Charles Darwin
* Alfred Russell Wallace
21
Q
What would you conclude if both of Pasteur’s treatments filled with cells?
A
• spontaneous generation hypothesis is valid
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
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
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)
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
26
Q
What is an organism?
A
- contiguous living system
* capable of response to stimuli, reproduction, growth and development, and maintenance of homeostasis
27
Why is a virus, ecosystem, or sperm cell not an organism?
• cannot reproduce on their own
28
What is the theory of evolution by natural selection?
* all species are related by common ancestry
* evolutionary change: traits of species can be modified from generation to generation
* natural selection: mechanism for change
29
What does evolution postulate?
* species are related to each other
| * species can change through time
30
What is natural selection?
• process explaining how evolution occurs
31
What is fitness?
• relative ability of individual to produce offspring that will survive and also reproduce (grandparents)
32
What is adaptation? (noun; verb)
* characteristic/trait that increases fitness of individual in particular environment;
* process of species acquiring adaptive (fitness-improving) traits over time
33
What is needed for natural selection to occur?
* variation
* heritable traits
* trait influences fitness
34
What happens if certain heritable traits lead to higher fitness?
* trait leads to increased success in producing offspring
| * trait becomes more common in population over time
35
What is the difference between natural selection and evolutionary change?
* natural selection: acts on individuals
| * evolutionary change: affects populations
36
When does evolution occur?
• heritable trait leads to differential success in reproduction
37
What is artificial selection?
* 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
How was the theory of evolution by natural selection created?
* 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
Why do peacocks have such vibrant colours?
* sexual selection
| * males with colourful feathers selected for by females
40
Why does thylacine (Tasmanian wolf) look like a dog and have tiger stripes on its back?
* convergent evolution
| * similar environmental pressures (selection) in Australia have caused thylacine to develop similar morphology to dogs
41
How did rock pigeon undergo artificial selection?
* 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
What is biology?
• the study of life
44
What is wild mustard (Brassica oleracea) an example of and why?
* 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
What is phenotype?
• describes how something looks
46
What is genotype?
• genes that underlie an appearance (phenotype)
47
What is wild mustard (Brassica oleracea) an example of and why?
* 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
What unites cell theory and the theory of evolution by natural selection?
* 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
What is a phylogenetic tree?
• representation of evolutionary relationships among species and cells
50
What does speed (number of generations required) of artificial selection depend on?
* 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
What does the magnitude of artificial selection depend on?
* 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
How does unintended artificial selection occur and what are its consequences?
* due to predation by humans (i.e. fishing)
| * evolution of small size, early maturation, behavioural responses
53
Which animals die in an ecosystem without human predation?
• younger, elderly, diseased
54
Which animals die in an ecosystem with human predation?
• biggest, strongest
55
What is a Canadian example of unintended artificial selection due to human predation?
* codfisheries in Nova Scotia
* over 30 years, size of Atlantic cod has drastically decreased
* due to overfishing disrupting size and age distribution
56
What is the difference between artificial selection and genetic modification?
* 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
How can you tell if two organisms are different species?
• cannot interbreed and/or produce viable offspring (sterile)
58
What is speciation?
* process of forming new species
| * divergence through time (branching of phylogentic tree)
59
What is the tree of life?
* 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
What can we use to estimate the tree of life?
• molecular variation in nucleotides of a gene (more similar sequences = more closely related - more able to exchange genetic material through time)
61
What are Linnaeus' Taxonomic Levels
• Kingdom, Phylum, Class, Order, Family, Genus, Species
62
What is the format for a species name?
* two part Latin name
| * Genus species (in italics or underlined)
63
How many kingdoms are there?
* 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
What are the three domains?
```
Prokaryotes:
• bacteria
• archaea
Eukaryotes:
• eukarya
```
65
What does a node represent?
• common ancestor of the following connected branches
66
What is an important caveat of the tree of life?
* 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
Can the tree of life be changed?
• Yes, positions of branches are debated and continuously changed as databases expand
68
Where on the tree of life did the structure called the nucleus originate?
* most parsimonious: on the eukarya branch
| * less parsimonious but possible: on the common ancestor node (was then lost by bacteria and archaea)
