Notes #34 I can: Understand how life developed on Earth Origins of Life Notes #34 I can: Understand how life developed on Earth

Exit Ticket Review 1. The breakup of Pangaea had which effect on the subsequent history of animal speciation? A. Animals had to become adapted to distinct climates. B. Animal diversity declined due to loss of available territory. C. Separated animal populations evolved independently. D. A single animal kingdom separated into multiple, distinct phyla.

Exit Ticket Review 2. Mosquito fish found on the islands of the Bahamas live in various isolated freshwater ponds that were once a single body of water. When several male and female mosquito fish are taken from two isolated ponds and placed into a single pond, the breeding preference of each mosquito fish is for fish from its own original pond. Which of these most likely resulted in this breeding preference? A. Availability of food influenced the breeding preferences of the fish. B. Competition for a suitable mate influenced the breeding preferences. C. Predators in the pond influence the breeding preferences of the fish. D. Speciation due to reproductive isolation influenced the breeding preferences.

Exit Ticket Review 3. Two species of wood mouse live on opposite sides of a river. Which is a likely reason they have become separate species? A. They mate at different times. B. They have different courtship rituals. C. Their gametes cannot fertilize each other. D. Geography prevents mating from occurring.

Hadean Eon Earth forms no oxygen in atmosphere constant volcanic activity

Archean Eon first anaerobic prokaryotes first photosynthetic prokaryotes oxygenation of atmosphere causes mass extinction of anaerobic bacteria

Proterozoic Eon first eukaryotes first sexually reproducing organisms first multicellular organisms glaciation event

Phanerozoic Eon major diversification of life major mass extinctions eliminate 90% of marine species modern era

The fossil record provides evidence about the history of life on Earth and how different groups of organisms have changed over time. Fossils are remains of dead organisms. Paleontologists are scientists who study fossils. They look for anatomical similarities and differences between the fossil and living organisms.

The age of a fossil is very important and can be determined in two ways: 1. Relative dating – allows paleontologists to estimate a fossil’s age compared with that of other fossils. youngest fossils The oldest fossils are the furthest down. The youngest fossils are nearest to the surface. oldest fossils

The age of a fossil is very important and can be determined in two ways: 2. Absolute dating – scientists determine the exact age of a fossil by using radiometric dating

anaerobic – without oxygen aerobic – with oxygen Vocabulary Review anaerobic – without oxygen aerobic – with oxygen prokaryotes are simple cells with no nucleus or membrane-bound organelles eukaryotes are larger, have a nucleus and membrane-bound organelles

How did life develop on Earth? The Earth formed 4.6 billion years ago. anaerobic atmosphere with simple organic compounds water was present How did life develop on Earth?

The Miller-Urey experiment showed that the mixture of complex organic compounds necessary for life could form from simpler compounds present on primitive Earth. COMPLEX COMPOUNDS!

Important events in the development of life on Earth

3.5 billion years ago – the first anaerobic organism formed. The first organisms were anaerobic prokaryotes who were able to thrive in the harsh conditions of early Earth.

What does photosynthesis produce? Then aerobic prokaryotes developed. 3.4 billion years ago – anaerobic photosynthetic organisms evolve. What does photosynthesis produce? After the evolution of photosynthetic bacteria, the Earth’s atmosphere had much more oxygen in it – it became aerobic. Then aerobic prokaryotes developed.

2 billion years ago – aerobic eukaryotic cells developed. The endosymbiotic theory explains how the first eukaryotic cells developed. a symbiotic relationship formed among several different prokaryotic organisms prokaryotes became permanent organelles

both bacteria and mitochondria and chloroplasts have circular DNA Evidence of endosymbiosis: mitochondria and chloroplasts contain their own DNA the ribosomes of these two organelles are similar to those found in bacteria mitochondria and chloroplasts reproduce by binary fission, just like bacteria both bacteria and mitochondria and chloroplasts have circular DNA both bacteria and mitochondria and chloroplasts reproduce by binary fission

??? years ago – sexual reproduction developed the crossing-over and shuffling of genes that occur during sexual reproduction allowed for tremendous diversity to develop

??? years ago – multicellularity evolves multicellular organisms consist of more than one cell this allows for cells in organisms to have specific jobs