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15 Cards in this Set
- Front
- Back
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What is cell theory?
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1) All living things are made up of one or more cells
2)cells are the smallest unit of life 3) all cells come from pre-existing cells |
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Discuss the statement 'cells are the smallest unit of life'?
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1)nothing smaller than a cell can survive independently
2)subcellular structures cannot survive independently (nuclei, ER, golgi, chloroplasts, mitochondria) 3)the lower limit on cell size is about 200nm, large enough for DNA, ribosomes, and membranes |
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Discuss the statement 'all cells come from pre-existing cells'?
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1)this seems to imply that life has always existed, which is incompatible with geological evidence about the age of Earth
2)therefore, an exception is made for the origin of life, when cells must have arisen from non-living substances 3)since the conditions of early Earth were anaerobic, they allowed for cells to form from non-living substances 4)the conditions of present Earth are aerobic, precluding the formation of cells from non-living substances |
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Discuss the statement "All living things are made of one or more cells"?
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1)microscopes allow us to observe that all living things are either unicellular or multicellular
exceptions: skeletal muscle, some fungal hyphae, and some algae have multinucleate cytoplasm, lacking normal cell separations connective tissue, such as bone, blood and cartilage, is composed of both cellular and extracellular structures, especially extracellular proteins and fluids; however, these extracellular structures are products of cellular activities |
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Metabolism
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chemical reactions inside the cell, including cell respiration to release energy
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sensitivity
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perceiving and responding to changes in the environment
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homeostasis
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keeping conditions inside the cell at a tolerable level
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growth
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an irreversible change in size
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reproduction
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producing offspring either sexually or asexually
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nutrition
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obtaining food, to provide energy and materials needed for growth
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how big? molecules
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1 nm
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how big? cell membrane thickness
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10nm
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how big? viruses
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100nm
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how big? bactaeria
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1 micrometre
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How many nanometres in a metre?
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1 billion
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