Chapter 25, Evolution of Life Flashcards
What are the four groups of eukaryotes we will study?
Protists, Fungi, plants, and animals
When was the earth formed?
4.6 BYO
Describe the bias in the fossil record
Not all species are represented equally, there is bias toward those that existed for a long time, were abundant and widespread, and had hard parts such as shells or skeletons
Describe radiometric dating
A method used to date fossils using the characteristic rate of decay (half-life) of a parent isotope to its daughter
How do we date fossils younger than 75,000 years?
The half-life of C-14
How do we date fossils older than 75,000 years?
Isotopes like U-238 are used to date the volcanic rock layers above and below the fossil
What are the three most recent eras?
Paleozoic, Mesozoic, Cenozoic
What marks the start of the 1st era?
Cambrian explosion-> Paleozoic
What was the name of the first prokaryotes? Describe them. When did they appear?
Stromatolites, bacterial mats that lived during the Archaean
What was the first eukaryotic organism? When was it?
Red algae, Proterozoic
When did the first multicellular eukaryotes appear? What were they?
Proterozoic, sponges and cnidarians
When was the age of the dinosaurs?
Mesozoic
When was the age of the mammals?
Cenozoic
When did atmospheric oxygen first start to rise? Who produced it? What was its effect on the life already present?
Archaean, cyanobacteria, killed many of the prokaryotes but some others used it for cellular respiration
When was land colonized? Who colonized it?
Start of Phanerozoic, arthropods (insects)
When did humans appear?
Cenozoic
What is an endosymbiont?
A cell that lives within a host cell
How did eukaryotes get their mitochondia?
A archaean engulfed an aerobic bacterium
Describe the theory of serial endosymbiosis. What are some pieces of key evidence to support this theory?
Mitochondria evolved before plastids through a sequence of endosymbiotic events
Inner membranes are similar to plasma membranes, DNA and cell division is similar to bacteria, both transcribe and translate their own DNA, ribosomes are more similar to bacteria
How did eukaryotes get their nucleus?
Infolding of the plasma membrane
How did eukaryotes get a plastid?
A heterotrophic ancestral eukaryote engulfed a photosynthetic bacterium
What is the Edicaran biota?
An assemblage of larger and more diverse soft-bodied organisms that lived from 635 to 541 MYA
When were the first real predator-prey interactions?
Cambrian explosion
Why did fungi and plants colonize land together?
Plants work with fungi for increased surface area and nitrogen/carbon fixing
Describe the first plants. What was their major limitation?
Mosses, lichens and liverworts were the first plants, but they had to rely on diffusion to transport water due to their lack of vascular tissue and were very small
Describe the second group of plants. What improvements did they have?
Ferns were the first vascular plants, so they could grow larger but still needed water to reproduce
Define mycorrrhizae
Mutually beneficial relationships between plants and fungi
How many mass extinctions occurred before humans formed?
5
How do foraminifera found in rock layers above the K-T boundary compare to those in rock layers above?
Those above the boundary are smaller and less diverse than those below
Why were scientists slow to accept the asteroid impact hypothesis?
At the time, most geologists thought that the Earth changed slowly and gradually, and not by major catastrophes
What are the four major eons?
Hadean, Archaean, Proterozoic, Phanerozoic
