LifeSci (Midterm 2024) Flashcards
What makes something alive?
- Has DNA/RNA
- Evolves over time
- Is able to reproduce
Describe how life is categorized.
Kingdom, phylum, class, order, family, genus, species
What are three key classification tools for organisms?
- Dichotomous keys (yes/no questions, sorting’)
- Cladograms ( evolution map)
- Phylogenetic Trees (shows when species branched off)
What is evolution?
Change in the allele frequency of a population over time.
Describe four mechanisms of evolution
- Natural selection
- Genetic drift (random events)
- Gene flow (movement)
- Mutations
Describe four types of natural selection
- Directional (high frequency of 1 allele)
- Divergent (tends to extremes)
- Sexual (sexual-specific traits)
- Artificial (for human purposes)
Describe Hardy-Weinberg Principle
Null hypothesis to test if evolution is happening to a certain gene. States that when alleles are transmitted, frequencies remain the same. No mechanisms of evolution, random mating.
Describe the two types of species isolation
Prezygotic -prevents fertilization.
Postzygotic - prevents offspring from gaining fitness
What is diversity?
The state of being diverse. Different origins. A tool to understand ecosystems.
What are the measures of diversity?
Alpha (local)
Beta (between)
Gamma (sum)
Define richness vs evenness
Richness - how many species?
Evenness - what are the ratios of each species?
What is a bioindicator species?
A species whose population fluctuates in space and/or time based upon measurable changes in the environment.
Diversity depends on….
How you measure, calculate, and define it.
What is the significance of the wolf/mouse diagram?
Everything in biological systems is scale and perspective dependent (a whole range for the mouse is only one step for the wolf).
Name the advantages and disadvantages of hierarchical organization of biological systems.
Useful to define - simplifies, creates categories, easy comparisons. Contains bias - humans always at top.
What the the components of a scientific study?
- Question. Why?
- Hypothesis (what we think the answer is)
- Methods: variables, procedures, etc.
- Data, analysis, conclusion.
Why are there groupings of similar species?
- similar phylogenetic origin
- roles in environment
-easy comparison/categorization
Why are there groupings of similar species?
- similar phylogenetic origin
- roles in environment
-easy comparison/categorization
What is psychological essentialism?
The belief that members of a group/category have an UNSEEN PROPERTY that causes them to be in the category. Problematic, especially in social environments (leads to stereotyping)
Why are Darwin and Wallace so crucial to our understanding of evolution?
Proposed theories that explained the MECHANISM of evolution (through natural selection/adaptation)
What was Darwin’s original theory of evolution?
Descent with modification.
What are the two major points from the ‘Origin of Species’?
1 - There is evidence that modern organisms are descendant from ancestral species.
2 - Natural selection causes evolution
Are all adaptations positive? Discuss and provide an example.
Adaptations are environment-dependent, suited to specific circumstances.
Example: sickle cell. Reduces ability of the cells to carry oxygen, but makes the sufferer Maria-resistant. Usually negative, becomes a positive in some environments.
What are three key modern postulates of evolution?
1 - populations evolve
2 - traits are heritable
3-natural selection is NOT progressive (animals don’t act for the good of the species, not all traits are adaptive)
