History of life Flashcards
What are the 3 essential components of life?
- Reproduction
- Maintaining homeostasis
- Transforming energy
What molecule provides the energy for work?
ATP
What does “cellular work” consist of in organisms?
Chemical reactions
What are the 3 major sources of energy for life?
- Light
- Inorganic compounds
- Organic compounds
How do plants make their energy? What is the specific term for the way they feed?
They use light and/or chemical energy to break down CO2 to make glucose for themselves -> they are AUTOtrophs.
How do animals make their energy? What is the specific term for the way they feed?
They use organic compounds from outside sources to get their carbon, they are HETEROtrophs.
What is responsible for the diversity of life on the planet?
EVOLUTION.
How do we know that life on earth started by chemical evolution?
Experiments by Miller & Urey (50’s). Created an artificial atmosphere to mimic early Earth’s (with monomers), and zapped it with electricity. They analyzed the products and found all the building block polymers of life.
Why do some scientists believe RNA was the earliest form or life?
- it occurs before DNA (simpler)
- Can act as a catalyst
- Lipids easily form a bilayer around the RNA -> cell walls.
- It is then protected and can self-replicate.
What are the 5 ways that scientists figure out evolutionary relationships?
- Fossils
- Morphology
- Development
- Molecular analysis
- Behavior
What is a CLADE?
A group on a phylogenetic tree that includes the ancestor and ALL its descendents.
What type of group is a clade?
A monophyletic group.
What is the phenomenon of polytomy?
Groups splitting very rapidly from each other, making it hard to determine which split earlier or later.
What is a phylogenetic group that includes a root and SOME of its descendents called?
Paraphyletic group.
What is a polyphyletic group?
A phylogenetic group that includes populations that don’t come from the same direct ancestor.
When talking about traits that organisms have, what is the term to describe when they have a trait in common that definitely came from a common ancestor?
Homology
What is the phenomenon of “homoplasy”?
When organisms have similar traits due to evolutionary PRESSURES to develop a similar function, but the traits don’t come from a common ancestor.
The first life forms on earth appeared: A: 3.8 million yrs ago B: 4.5 billion yrs ago C: 3.8 billion yrs ago D: 1.5 billion yrs ago
C: 3.8 billion yrs ago
What caused the changes that gave rise to early life?
Majorly due to physical changes because of continental drift. Physical change like volcanic activity, meteorite collisions. Temperature changes and ocean changes. Increase in environmental O2.
Which came first, H2O or O2? Explain how that happened.
First there was H2O. As light split the H2O, organisms used the H to fix carbon, leaving behind lots of O2 in the environment as a waste product.
What organism was instrumental in producing massive amounts of O2 which led to complex life forms?
Cyanobacteria
What class of organism does cyanobacteria fit into; prokaryotes, archaea, or eukaryotes?
Prokaryotes
Did animals first evolve before or after the Cambrian Explosion?
Before.
What was special about the Cambrian explosion?
- More O2 –> bigger, mobile animals
- Evolution of predation –> selection for protective external structures and rapid movement
- New habitats developed because of animals being able to move to new habitats
- Hox genes
