Term
| What is probably the first information storage molecule? Why? |
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Definition
| RNA b/c the molecules can act as catalysts for diverse reactions including RNA replication. |
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Term
| What is the age of the Earth estimated to be? |
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Definition
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Term
| According to the fossil record, when did life begin? (Provide a range of times) |
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Definition
| 3.5 - 3.9 billion years ago |
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Term
| Describe the earliest life form. |
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Definition
| They were prokaryotic, anaerobic bacteria whose genetic material was not in a nucleus. They obtained food by absorbing organic molecules from the environment. |
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Term
| What happened to cause the oxygen levels in the atmosphere to increase? |
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Definition
| Photosynthesis increased oxygen levels. At first, this oxygen was used immediately in other reactions, and it often formed iron oxide w/iron. After the iron had turned to rust, the concentration of oxygen increased. Oxygen was produced by bacteria similar to modern cyanobacteria. |
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Term
| Why did some of the prokaryotic cells become aerobic? |
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Definition
| Oxygen was deadly to many of the organisms. B/c the use of oxygen in metabolism benefitted the organism by increasing the amount of energy to the cell, aerobic cells had an advantage over anaerobic ones. Natural selection probably evolved these cells. |
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Term
| When did the first eukaryotic life forms give rise? |
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Definition
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Term
| What hypothesis explains the origin of organelles such as chloroplast and mitochondria? How did this occur? |
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Definition
| The endosymbiont hypothesis explains the origin of organelles such as chloroplast and mitochondria. It occurred when early eukaryotic cells acquired the precursors of mitochondria/chloroplasts by engulfing certain types of bacteria. When certain types of bacteria were eaten, the cell could not digest it so the bacteria evolved into mitochondria and chloroplasts. |
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Term
| What evidence supports the endosymbiont hypothesis? |
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Definition
| Many distinctive biochemical features are shared by eukaryotic organelles and living bacteria. Mitochondria, chloroplasts, and centrioles also have their own DNA which is interpreted as remnants of the DNA of the bacteria. Living intermediates also show proof b/c they are similar to hypothetical ancestors. Ex: Pelomysea palustrius lacks mitochondria but has a permanent population of aerobic bacteria that carry out the same role. |
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Term
| What was the selective advantage of increased size? |
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Definition
| Larger cells could eat smaller ones, and larger ones were also harder to be ingested. Larger organisms also typically move faster. |
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Term
| Why did increase in size occur by becoming multicellular rather than one enormous cell? |
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Definition
1. Multicellular algae was harder for single-celled predators to engulf.
2. Specialization of cells provide the potential for staying in one place. The larger a cell becomes, the less surface membrane is available per unit of cytoplasm. Oxygen, nutrients, and wastes must diffuse through the membranes. |
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Term
| What were the first multicellular organisms? When do they appear in the fossil record? |
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Definition
| Algae - 1.2 billion years ago |
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Term
| What types of animals are found in the fossils from the Precambrian Era? What feature do they all share in common? |
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Definition
| Animals such as sponges, jellyfish, worms, mollusks, and anthropods are found. They do not have backbones (invertebrates). |
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Term
| What happened during the Cambrian Era? |
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Definition
| Present-day animals emerged. Cambrian fossils reveal an adaptive radiation that had already yielded a diverse array of complex bodyplans. |
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Term
| What became the dominant predators of the sea 530 mya? What adaptive advantage did they have? |
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Definition
| Fish became the dominant predators. They had internal skeletons and proved to be faster than the invertebrates with more accurate senses and bigger brains. |
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Term
| What are the two dating techniques used to date fossils and rock? |
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Definition
| Relative dating and radiometric dating |
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Term
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Definition
| The arrangement of artifacts or events in a sequence relative to one another but w/o ties calendrically measured time; the arrangement of artifacts in a typological sequence or seriation. |
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Term
| What is radiometric dating? |
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Definition
| Any method of determining the age of Earth materials or objects based on measurement of either short-lived radioactive elements or the amount of a long-lived radioactive element plus its decay product. |
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Term
| Which is a more exact dating technique and why? |
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Definition
| Radiometric dating b/c it is actually calculated rather than comparing events or objects to one another. |
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Term
| What obstacles had to be overcame to invade land? |
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Definition
| Animals had to support weight and reproduction had to be modified so eggs/sperm did not dry out. |
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Term
| What were the first organisms to invade land? |
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Definition
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Term
| Why were the first plants restricted to swamps and marshes? |
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Definition
| The first plants had swimming sperm. |
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Term
| How did plants overcome their dependency on water for reproduction? |
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Definition
| Plants evolved to have sperm in drought-resistant pollen grains that could travel on wind from plant to plant to land on eggs that were then directly released into living tissue. Water was no longer needed. |
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Term
| What were the first animals to invade land? Why? |
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Definition
| Arthoropods - this was b/c they had certain structures that, by chance, were suited to live on land. |
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Term
| What were the first vertebrates to move to land? What did they evolve from? |
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Definition
| Amphibians - they evolved from lobefins. |
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Term
| What features did lobefin fish have that would allow their descendents to colonize land? |
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Definition
1. Stout fleshy fins which they crawled about on the bottoms of shallow, quiet waters.
2. An out pouching digestive tract could be filled w/air - primitive lung. |
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Term
| What did reptiles evolve from? |
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Definition
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Term
| What adaptions did reptiles have for life on land that amphibians lacked? |
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Definition
| They had shelled, waterproof eggs that enclosed water for the embryo. They had scaly, water-resistant skin that prevented loss of body water, and they had better lungs. |
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Term
| What did birds and mammals evolve from? |
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Definition
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Term
| What was the initial use of feathers in birds? |
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Definition
| They helped retain body heat. |
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Term
| What unique feature distinguishes mammals from other organisms? |
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Definition
| They evolved live birth and the ability to feed their young with secretions of mammary glands. |
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Term
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Definition
| A relatively sudden extinction of many species belonging to multiple major taxonomic groups, as a result of environmental change. The fossil record reveals five mass extinctions over geologic time. |
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Term
| Climate change has been indicated as a cause of mass extinction. Describe one cause of climate change. |
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Definition
| One cause is plate tectonics which is where Earth's plates shift from one place to another. As the plates shift, the different geological locations on earth undergo different climates, ultimately affecting the organisms living on that specific plate. |
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Term
| What is the order of the eleven organisms based on their appearance in the history of life on earth? |
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Definition
| Anaerobic prokaryotes, photosynthetic anaerobic prokaryotes, aerobic prokaryotes, eukaryotic cells, algae, invertebrates, fish, amphibians, reptiles, birds, and mammals |
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