Characteristics of Life
What two characteristics of life are defined by maintaining a state of internal balance and organisms creating new organisms?
Homeostasis & Reproduction
What is the Big Bang Theory?
The universe began as a single point with a high density and temperature. It suddenly exploded and created all matter, energy, space, and time. This process continued to expand, eventually leading to the formation of stars, which in turn converted heat into elements that became the building blocks for planets, moons, life, etc.
Was the earliest cell prokaryotic or eukaryotic?
Prokaryotic
What are protocells?
Collections of non-living molecules surrounded by a membrane and maintained a different internal chemical environment than their surroundings
What is one explanation of how diversity happened?
Continental drift, mass extinctions, adaptive radiation, heterochrony, changes in nucleotide sequences, etc.
What two characteristics of life are defined by the requirement of materials and energy to function, and reacting to changes in the environment?
Metabolism & Response to Stimuli
What is the RNA world theory?
Life began as a simple RNA molecule that self-replicated itself to create a complex world of RNA molecules that could carry genetic information
How did the first eukaryotic cell originate?
Endosymbiosis involving prokaryotic ancestors - a prokaryotic cell engulfed a small cell that evolved into a mitochondrion and maintained a symbiotic relationship to eventually form a single organism
Why was the Earth uninhabitable for its first few hundred million years?
Earth was bombarded by rocks and ice from the solar system which generated so much heat that all water was vaporized
Provide an argument as to whether or not life can exist elsewhere.
Life can exist in the habitable zone: the specific distance from a star that allows water to exist on the surface of a planet (as long as it has an atmosphere)
What characteristics of life are defined by the smallest unit of life and material that carries genetic information from generation to generation?
Cells & Genetic Material
What is the Panspermia theory?
Panspermia means “seeds everywhere”, so the theory states that seeds of life existed throughout the Universe. Life did not begin on Earth, rather it took place on another planet or in space and was carried to Earth through mechanisms such as asteroids, meteoroids, comets, interstellar dust, etc.
How did the Cambrian explosion diversify animal groups?
All animals previously existing were soft-bodied whereas these animals developed features for capturing prey and defensive adaptations such as hard shells and sharp spines
What were the conditions of Earth’s first atmosphere (4 billion years after bombardment)?
Little oxygen, thick with water vapor and compounds like nitrogen, carbon dioxide, methane, ammonia, and hydrogen
What is LUCA and its significance?
The LUCA is the last universal common ancestor, meaning all life that exists today has evolved from it.
What characteristic of life is defined by an increase in size and changing over the course of life?
Growth & Development
What is the clay theory?
Life may have evolved on clay, as it concentrated chemical activity and served as a breeding ground for organic compounds. Clay minerals have the ability to catalyze the formation of polymers, so the combination of minerals and molecules in clay favored the development and replication of biological molecules that form life
What is the oldest known multicellular eukaryote and approximately how old is it?
Small red algae & 1.2 billion years old
Aside from volcanoes and vents, what was a source of organic molecules such as amino acids, lipids, simple sugars and nitrogenous bases?
Meteorites contained 80+ amino acids which couldn’t have come from Earth because they were D and L isomers and organisms only make/use L isomers
How did the oxygen revolution harm prokaryotic groups and how did survivors adapt?
The rise in oxygen levels became poisonous and damaged cells. The survivors evolved to use cellular respiration which requires/uses oxygen.
What characteristic of life is defined by changes in a closely related group of organisms over time?
Evolution
What are deep-sea hydrothermal (alkaline) vents and how are they thought to have first produced organic compounds?
Areas on the seafloor where mineral-rich water flows from the Earth’s interior. Some vents released warm water with a high pH (9-11) that is suitable for the origin of life.
What was the first molecule that was formed?
Helium hydride - after the big bang, the universe was very hot and only a few atoms existed. These atoms combined to form the first molecules, and scientists believe helium hydride was the first one.
Describe the sequence of chemical and physical processed that led to production of simple cells.
Abiotic synthesis of small organic molecules → joining of molecules into macromolecules → packaged into protocells → development of self-replicating molecules
What is one adaptation from the period of colonization of land that made it possible for fungi and plants to reproduce on land and prevent dehydration?
A vascular system that transports materials internally
Waterproof coating of wax on the leaves that slows the loss of water