Unit 07 Evolution: Student Note Packet

This set of flashcards covers the entirety of Unit 07: Evolution, including theories on the origin of life, patterns of evolution, speciation, Hardy-Weinberg equilibrium, and the human immune system responses.

How is a scientific theory defined in the context of the Note Packet?

A theory is a broad explanation that connects together many tested observations and hypotheses.

According to scientific evidence, how old is the Earth and how long ago did life begin?

The Earth is approximately $4.5\text{ billion years}$ old, and life began approximately $3.5\text{ billion years}$ ago.

What gases were present in the early Earth's atmosphere, and what was missing?

Early Earth had molten rock, carbon dioxide, water, hydrogen sulfide, ammonia, hydrogen, methane, and mostly nitrogen gas; it did not have free oxygen.

What was the result of the Miller-Urey Experiment?

Combining $CH_4$, $NH_3$, $H_2$, and $H_2O$ with sparks in a glass container for about 2 weeks resulted in the formation of simple amino acids and nucleic acids.

What are coacervates?

Spontaneous membranes formed with phospholipids.

What is the RNA world hypothesis?

The theory that RNA existed before DNA and proteins because it can store genetic code and cause reactions to occur (like proteins), eventually evolving into more efficient DNA and protein systems.

Identify the progression of early life forms from heterotrophs to photosynthesizers.

Life moved from simple anaerobic heterotrophs to anaerobic photosynthesizers using hydrogen sulfide, and then to cyanobacteria which broke down $H_2O$ and released free oxygen into the atmosphere.

What is endosymbiosis and what organelles did it form?

The formation of complex organelles through internal symbiosis, specifically creating mitochondria and chloroplasts.

What are the stages of evolving from unicellular life to true multicellular life?

Unicellular organisms undergo clumping (forming a colony) followed by cell differentiation to become true multicellular organisms.

What was the core concept of Lamarck's Theory of Evolution?

The inheritance of acquired characteristics, where traits an organism develops during its life are passed on to its offspring (e.g., giraffe necks).

List Darwin's Principles of Natural Selection.

Variations exist in gene makeup; organisms overproduce offspring; competition occurs; individuals better suited for the environment survive; survivors reproduce and pass on better traits (speciation).

Define Adaptive Radiation.

A process where a number of new species form from a common ancestor and rapidly change to differ from one another, such as Darwin's Finches.

What is Convergent Evolution?

When species with different ancestors independently acquire similar characteristics due to similar environmental pressures, such as the body shape of a fish and a dolphin.

Differentiate between Parallel Evolution and Coevolution.

Parallel evolution involves two species from the same common ancestor remaining similar, whereas coevolution involve species causing adaptations in each other through close relations (e.g., flowers and pollinators).

What is the difference between Geographic Isolation and Temporal Isolation?

Geographic isolation occurs when populations are blocked by physical features like mountains or rivers, while temporal isolation occurs when populations mate at different times of the day or year.

Contrast Gradualism with Punctuated Equilibrium.

Gradualism suggests species evolve through continuous, slight morphological changes over long periods, whereas Punctuated Equilibrium suggests brief periods of significant change interrupted by long periods of no change.

State the Hardy-Weinberg Equilibrium principle.

If there is no outside influence and no mutations in a population, gene frequencies will stay constant generation after generation ($p + q = 1$).

Name the factors that can disrupt Hardy-Weinberg equilibrium and change gene frequencies.

Genetic drift (Bottleneck, Founder’s effect), Migration (Gene flow), and Mutations.

What are the three lines of defense in the human immune system?

1st line: Non-specific barriers (skin, mucus, stomach acid); 2nd line: General short-term response (inflammation, histamines, cytokines); 3rd line: Specific immune response (T-cells and B-cells).

What is the difference between an antigen and an antibody?

An antigen is a foreign substance (usually a protein) that invades the body, while an antibody is a 'good' protein secreted by B-cells that binds to and 'handcuffs' antigens.

Identify the four types of T-Cells and their functions.

Killer T (fights), Helper T (seeks and activates B/T cells), Suppressor T (stops response after invader is gone), and Memory T (remembers antigens).

What is the role of Plasma B cells versus Memory B cells?

Plasma B cells produce specific antibodies that clump invaders, while Memory B cells live for months or years to provide future recognition and a quick response.

What are MHC Proteins (Major Histocompatibility Complex)?

Proteins located on all vertebrate cells that determine 'self' vs 'non-self' so the immune system can identify and destroy invaders.

How do vaccinations work to provide immunity?

Harmless proteins mimicking an invader are injected to stimulate B cells and produce memory cells, so the immune system is prepared if the active virus is encountered later.

Describe an allergy in terms of the immune system.

An inappropriate response by the immune system to a harmless foreign invader, which includes the release of histamines.

Match the three categories of natural selection to their descriptions.

Directional Selection: curve shifts toward one extreme; Stabilizing Selection: variations at both ends are selected against; Disruptive Selection: individuals at both ends are favored over those in the middle.