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Stage 2 Biology > Topic 4: Evolution > Flashcards

Topic 4: Evolution Flashcards

1
Q

What evidence suggests the first cells were RNA and not DNA?

A
  • RNA can self-replicate
  • RNA can form a double helix
  • RNA can store genetic info
    *RNA enzymes (ribozymes) can catalyse simple chemical reactions
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2
Q

What evidence suggests the first cells were Prokaryotic?

A

Stromatolites (Fossil Records)

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3
Q

What is the Endosymbiotic Theory?

A

Eukaryotic Cells evolved from Prokaryotes that were engulfed via endocytosis.
Aerobic Bacterium - Respiration
Cyanobacterium - Photosynthesis

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4
Q

What evidence supports the Endosymbiotic Theory?

A
  • Have own circular DNA (like prokaryotes)
  • Have their own ribosomes similar to prokaryotes
  • Can Self-replicate
  • Double-membrane - Inner: Prokaryotes, Outer: Eukaryotes
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5
Q

What is Comparative Genomics? What are Examples?

A

Provides evidence for evolution & helps establish evolutionary relationships between different species.
- DNA & RNA Sequences
- Protein (amino-acid) Sequences
- DNA-DNA Hybridisation

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6
Q

How is DNA used to show evolutionary relationships and the most recent common ancestor of species?

A

The more closely related two species are - more DNA in common - More Recent Common Ancestor.
The less closely related two species are - Less DNA in common - More Distant Common Ancestor.

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7
Q

What is DNA-DNA Hybridisation?

A
  • DNA from Different species is separated into single strands using heat
  • If two strands from different species share similar sequences, they will Anneal
  • Amount of Heat required to separate hybrid indicates Similarity
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8
Q

What does high Temperature suggest for DNA-DNA Hybridisation?

A

↑ Temp - ↑ Hydrogen bonding between strands - ↑ DNA in Common
∴ More Recent Common Ancestor

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9
Q

What does Low Temperature suggest for DNA-DNA Hybridisation?

A

↓Temp - ↓ Hydrogen bonding between strands - ↓ DNA in Common
∴ More Distant Common Ancestor

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10
Q

What is the definition of a Species?

A

Group of organisms that can actually or potentially interbreed to produce fertile offspring.

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11
Q

How can species that reproduce asexually be defined?

A

Similarities in:
Morphology - Shape & Anatomy
Biochemistry - Chemical composition of cells & tissues, some metabolic processes
Genetic Composition - DNA nucleotide sequences in genomes

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12
Q

What is Reproductive Isolation?

A

Mechanisms that prevent members of two different species from mating & producing fertile offspring

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13
Q

What are the Pre-Zygotic Isolation Mechanisms?

A
  1. Ecological - Species occupy different habitats/niches
  2. Temporal - Species are sexually mature at different times
  3. Mechanical - Species have different sized shaped genitalia
  4. Behavioural - Different Courtship Patterns
  5. Gametic - Incompatible gametes (unsuccessful fertilisation)
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13
Q

What are the Post-Zygotic Isolation Mechanisms?

A

Hybrid Unviability - Offspring is unhealthy & unlikely to produce its own offspring
Hybrid Sterility - Offspring reaches sexual maturity but is sterile (Meiosis fails to produce gametes due to diff. in chromosomes)

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14
Q

What is a Gene Pool?

A

Set of all genes in a population at a given time

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15
Q

What does a Large Gene Pool Suggest?

A
  • Extensive genetic diversity
  • More likely to survive selection pressures
16
Q

What does a Small Gene Pool Suggest?

A
  • Low genetic diversity
  • Greater risk of Extinction
17
Q

What is Natural Selection?

A

Selection Pressures lead to advantageous alleles increasing in frequency in the population

18
Q

When Does Natural Selection Occur?

A
  1. Population contains genetic variation
  2. Due to selection pressures - not all individuals survive to reproduce
  3. Individuals that survive & reproduce pass on their alleles to the next generation
  4. Frequency of favourable alleles/traits increase in population
19
Q

What are Selection Pressures?

A

Abiotic/Biotic Factors that affect the chances of an individual’s survival & reproduction (Drives evolution of certain traits)
Examples:
- Predation
- Competition for Resources
- Food/water Availability

20
Q

What are sources of Genetic Variation?

A
  • Mutations
  • Independent Assortment & Crossing Over
  • Random Fertilisation
21
Q

What is Genetic Drift?

A

Changes in frequency of alleles in the gene pool of a population due to CHANCE.
*Occurs in all populations
* Can lead to loss of advantageous alleles (↓ genetic diversity)

22
Q

What is Genetic Bottleneck?

A

Size of Population is dramatically reduced by natural disasters

23
Q

What is Allopatric Speciation?

A

Separated by Geographical Barrier
* Prevents interbreeding & gene flow

24
Q

What is Sympatric Speciation?

A

Results of reproductive isolation - Ecological, Behavioural, Temporal
*No Physical Barrier

25
Q

What is Convergent Evolution?

A

Unrelated Species evolve similar structural, biochemical or behavioural characteristics due to similar selection pressures
* Convergent structures = Analogous Structures

26
Q

What is Adaptive Radiation?

A

Organisms diverse rapidly from their ancestral species into a variety of new forms.
* More Frequent
* Homologous structures - look different on the exterior but have the same bones in different forms

27
Q

What is Ecological Succession?

A

Changes that take place in an ecosystem over time

28
Q

What is Primary Succession? What are the steps involved in forming a Climax Community?

A

Occurs in nutrient-poor soil that is incapable of sustaining life.
Pioneer Species — Intermediate Species — Climax Community

29
Q

What is a Climax Community?

A

When all species in an ecosystem possess necessary adaptions to survive

30
Q

What is Secondary Succession?

A

Takes place after natural disasters such as landslides, bushfires, etc..

31
Q

How do Humans Negatively impact species?

A
  • Increased Predation
  • Introduced Species - Compete for resources (↓ pop. of native species)
  • Habitat Destruction
32
Q

How do Humans Contribute to Climate Change?

A
  • Combustion of Fossil Fuels: Releases large quantities of greenhouse gases (CO2) into the atmosphere
  • Deforestation: Fewer Trees available to remove CO2 from atmosphere
  • Agriculture: Releases Methane & CO2, ↑ conc. of both gases in the atmosphere
33
Q

What are the principles of conservation?

A

Protecting Habitats - Maintain Ecosystem Diversity
Minimising Pollution - Prevent Introduction of new selection pressures that lead to extinction
Protecting Species - Different Species are monitored & protected to prevent extinction (↓ species diversity)

Stage 2 Biology (4 decks)

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