Cosmology & Nucleosynthesis
Which elements formed during the Big Bang?
H and He
Which formed first, the gas giants or the rocky planets?
The gas giants.
What are the six elements that make up most of life on Earth?
CHONPS
What is the difference between an autotroph and a heterotroph?
An autotroph gets its energy and carbon from the environment, while a heterotroph gets its carbon and energy from autotrophs.
What type of meteorites are rich in organic molecules?
Carbonaceous chondrites
What is the Central Dogma of biology?
DNA to RNA to Protein
During which eon did the first rocks form and life emerge?
Archean
How are elements heavier than iron formed?
During supernova explosions.
What do you call the flattened cloud of debris from which the solar system formed?
Protoplanetary disc
What type of macromolecule is starch, and what are it's monomers?
Carbohydrate (or polysaccharide), composed of glucose.
What does ATP stand for and why is it important for life.
Adenosine triphosphase is the "energy currency" for life on Earth. Its three phosphate bonds store energy that can be moved around the cell and used for doing work.
What is the oldest undisputed evidence of life on Earth?
Carbon isotopes from graphite inclusions in rocks about 3.7 billion years old.
What is the principle of uniformitarianism?
The present is the key to the past.
Why do stars "burn"?
The mass defect of nuclear fusion is converted into energy (E = mc2).
What is the process called when particles stick together to eventually form planets?
Planetary accretion
What are the three components of nucleotides?
A sugar (ribose or deoxyribose), a phosphate group, and a nitrogenous base.
What do astrobiologists consider the three essential requirements for life?
1. A source of energy
2. Essential elements
3. A solvent
Name one random process that helps drive evolution.
1. Genetic drift
2. Bottlenecks
3. Founder effect
4. Gene flow
What is a codon?
A sequence of three nucleotides in DNA or RNA that codes for a specific amino acid in a polypeptide (protein).
Which of the five big mass extinctions was the largest?
Permian-Triassic (~250 Mya)
What is the Cosmological Principle?
The universe is both isotropic and homogeneous, or on the large scale, the universe looks about the same from any location.
Why does Earth have different layers (core, mantle, and crust)?
During planetary differentiation, as the planet cooled and solidified, the heavier elements sank to the core and the lighter elements remained on the surface.
What are the four components of amino acids?
A central carbon, an amine group, a carboxyl group, and an R group.
What sources of energy and carbon does a photoheterotroph use?
Light energy and organic compounds.
Explain why reproductive isolation is a key part of speciation.
When different populations of the same species are reproductively isolated for a long time, the genetic differences between them accumulate, eventually causing enough divergence that they become different species.
Explain how DNA mutations are the basis for evolution of life on Earth.
A change in the DNA sequence changes the codons, and thus the proteins that are formed, which then changes the traits in that individual.
Why do we consider the fossil record biased?
Only the hard parts of organisms are fossilized, so most of the fossil record consists of shells, bones, and teeth. Also, most of the rocks on Earth are fairly young, so we have many more younger fossils than older ones.
What is the universe made of?
Dark energy: ~73%,
Dark matter: ~25%
Regular matter: ~2%
What are the two leading theories for how Earth got its water?
1. Planetary accretion - the water was already in the materials that made Earth
2. Later delivery by asteroids
What are phospholipids composed of, and why are they important for life?
Phospholipids are made up of two fatty acid "tails" and a phosphate group "head". They make up the cellular membranes of life on Earth.
Name three extreme conditions in the dry valleys of Antarctica and the types of extremophiles that can withstand those conditions.
1. Extreme cold - psychrophiles or cryophiles
2. Extreme desiccation - xerophiles
3. High levels of UV radiation - radioresistant
How did the Miller-Urey experiment work and what were the results?
Miller and Urey attempted to model the atmosphere of earth Earth by combining reducing molecules, such as CH4, H2, and NH3, with water vapor. Then they added a spark as an energy source, which simulated lightning. After a few days they found that many organic molecules had formed, including amino acids.
Why aren't viruses included on the phylogenetic tree of life?
They don't have ribosomes, so they don't have ribosomal DNA.
What geological evidence first led Alvarez and Alvarez to propose the impact hypothesis for the K-T extinction?
The high abundance of iridium in the clay layer at the K-T boundary.
Why is the rate of expansion of our universe important for the development of life?
If the universe had expanded too quickly then it would have thinned out too much for galaxies (and thus planets, and life) to form. If the universe had expanded too slowly, then it would have started to collapse back in on itself.
How do we know how old Earth is? (Give three main pieces of evidence.)
1. The ages of the oldest known rocks (~4.2 Ga) and minerals (~4.4 Ga).
2. The ages of lunar samples (~4.5 Ga)
3. The ages of inclusions in meteorites (carbonaceous chondrites) (~4.68-4.5 Ga).
Explain how dehydration synthesis and hydrolysis reaction are essentially equal and opposite.
Dehydration synthesis reactions are endergonic and produce water as a by-product. Hydrolysis reactions are exergonic and require water as a reactant.
Why does life as we know it need a solvent?
A solvent (such as liquid water) dissolves chemicals in the cell, plays a role in many metabolic reactions, and helps transport things across the cell membrane.
What is the RNA World hypothesis?
The theory that RNA molecules formed first and acted as both catalysts for chemical reactions and carriers of genetic information.
What is the endosymbiotic theory?
The idea that some of the eukaryotic organelles formed from prokaryotic symbiosis, where one cell survived inside another.
What was the Great Oxidation Event and how did it impact life on Earth?
The GOE (~2.4-2.1 Bya) was when Earth's atmosphere became oxygenated due to photosynthetic organisms. This led to the death of many anaerobic organisms and the rise of aerobic ones.