Bio 2 Chapter 25

What is macroevolution?

The broad pattern of evolution above the species level.

What does the fossil record show?

Macroevolutionary changes over large time scales, including the emergence of terrestrial vertebrates, mass extinctions, and key adaptations like flight.

What were the four stages that led to simple cells?

Abiotic synthesis of organic molecules, formation of macromolecules, packaging into protocells, and origin of self-replicating molecules.

When did Earth form?

About 4.6 billion years ago.

What gases were present in the early atmosphere?

Water vapor, nitrogen and its oxides, carbon dioxide, methane, ammonia, and hydrogen.

What did Oparin and Haldane propose about early Earth?

That it had a reducing atmosphere that facilitated organic molecule formation.

What did Miller and Urey demonstrate in 1953?

That organic molecules could form in a reducing atmosphere.

Where else could organic compounds have formed?

Near volcanic openings or deep-sea hydrothermal vents.

What are hydrothermal vents?

Areas where hot water and minerals gush from Earth's interior into the ocean.

Why are black smoker vents unlikely sources of life?

Their extreme heat makes organic compounds unstable.

Why are alkaline vents a better candidate for life’s origin?

They release warm, high-pH water, which is more suitable for life formation.

What organic compounds have been found in meteorites?

Amino acids, lipids, simple sugars, and nitrogenous bases.

How have scientists demonstrated RNA synthesis?

RNA monomers can form spontaneously in lab conditions.

What are protocells?

Fluid-filled vesicles with membrane-like structures that could have exhibited simple life functions.

How does montmorillonite clay affect protocells?

It increases vesicle formation and allows organic molecules to be absorbed.

What life-like properties do protocells exhibit?

Growth, reproduction, metabolism, and maintaining an internal environment.

What was likely the first genetic material?

RNA, not DNA.

What are ribozymes?

RNA molecules that can catalyze reactions, including self-replication.

How did self-replicating RNA evolve?

Natural selection favored RNA molecules that replicated efficiently.

Why did life transition from RNA to DNA?

DNA is more chemically stable and allows for more accurate replication.

What is the fossil record?

The accumulation of fossils in sedimentary rock layers called strata.

What are different types of fossils?

Mineralized organic matter, trace fossils, amber-preserved organisms, and frozen remains.

Why is the fossil record incomplete?

Many organisms did not fossilize, some fossils were destroyed, and many remain undiscovered.

Which species are most likely to be found in the fossil record?

Those that were abundant, long-lived, and had hard body parts.

How does rock strata help date fossils?

It shows the sequence in which fossils were formed.

How does radiometric dating work?

It measures the decay of radioactive isotopes to determine fossil age.

What are stromatolites?

Layered rocks formed by prokaryotic films, the earliest evidence of life.

What caused the oxygen revolution?

Photosynthetic bacteria released oxygen, which accumulated over time.

How did oxygen affect early life?

It drove many anaerobic species to extinction, while others adapted to use oxygen for respiration.

What does the endosymbiosis theory propose?

Mitochondria and plastids originated from engulfed prokaryotic cells.

What led to multicellular life?

The appearance of eukaryotic cells allowed for greater morphological diversity.

What were the Ediacaran biota?

Early multicellular eukaryotes, including algae and soft-bodied animals.

What is plate tectonics?

The theory that Earth's crust is composed of floating plates.

What causes continental drift?

Movement of tectonic plates due to mantle activity.

What was Pangaea?

A supercontinent that formed about 250 million years ago.

How did Pangaea impact life?

It altered ocean basins, destroyed habitats, and changed climate conditions.

How does continental drift cause speciation?

It isolates populations, leading to evolutionary divergence.

How did the Hawaiian Islands lead to speciation?

They were colonized by stray organisms, which then evolved into unique species.

What do developmental genes control?

The rate, timing, and spatial arrangement of body development.

What is heterochrony?

A change in the timing or rate of developmental events.

What is paedomorphosis?

When sexually mature organisms retain juvenile ancestral traits.

What do homeotic genes control?

The placement of body structures, such as limbs and organs.

What do Hox genes determine?

The positioning of body parts in developing embryos.

How can Hox gene mutations affect organisms?

They can shift body part locations, altering an organism’s structure.

How do developmental genes influence evolution?

Changes in their sequence or regulation lead to morphological diversity.

What properties do abiotically produced vesicles exhibit?

Simple growth, reproduction, metabolism, and maintenance of an internal environment different from their surroundings.

What is serial endosymbiosis?

The hypothesis that mitochondria evolved before plastids through a sequence of endosymbiotic events.