Readings for Test 1 Flashcards
Protist
eukaryotic organism that is not an animal, land plant, or fungus
Photosynthetic protist
have chloroplasts and are capable of photosynthesis
Half-life
time required for half a sample of radioactive isotopes to decay to nonradioactive/stable form
What two events causedoxygen to increase in the atmosphere?
- beginning of photosynthesis, multicellular organisms, and eukaryotes
- the rapid diversification of multicellular animals and photosynthetic protists
In what periods did the O2 increase in the atmosphere?
- Precambrian
- Cambrian
How did a meteorite cause the extinction of dinosaurs and other organisms 65 million yearsago?
Meteorite collided with earth, released a bunch of energy causing tsunamis, massive plume of debris covered sun, atmosphere because very hot, no photosynthesizing, created iridium layer between rocks of Cretaceous and Paleogene periods.
Indigenous rocks
formed when molten material cools
How does 14C dating work?
Paleontologists use the amount of 14C in the fossil and compare it to a reference amount of 14C in a living organism.
How old of fossils can be dated with 14C dating?
60,000 years
What is the difference between pre-zygotic and post-zygotic mechanisms?
Pre-zygotic prevents hybridization, and post-zygotic allows hybrids but reduces the fitness of hybrids
Pre-zygotic Isolating Mechanisms
prevent hybridization
Post-zygotic Isolating Mechanisms
reduces fitness of hybrid offspring, resulting in reinforcement of Pre-zygotic isolating mechanisms
Mechanical Isolation
Organisms of different species have differences in the sizes and shapes of their reproductive organs, meaning it is physically impossible for some species to reproduce with others
Temporal Isolation
Organisms have different mating seasons/times which reduces hybridization in those species
Gametic Isolation
The sperm of one species won’t attach to the eggs of another because they are chemically incompatible
