This table shows the abundance of iridium in and near the K–T boundary layer. Depths are given as meters above or below the boundary layer. The iridium content of an average Earth rock is 0.4 parts per billion (ppb) of iridium. An average meteorite contains about 550 parts per billion of iridium. Which conclusion do these data best support?
1.the earth was struck by a large asteroid 65.5 million years ago
2.an asteriod collision caused a mass extinction that wiped out the dinosaurs
3.the K-T boundary indicates the beginning of an ice age
4.rates of evolution increased dramatically after the K-T boundary
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A) birth defects B) type 2 diabetes C) teratogenic D) gastrulation
Significant mass extinctions occurred during which of the following epochs?
A. Pleistocene, Ordovician, and Triassic B. Ordovician, Triassic, and Jurassic C. Triassic, Permian, and Cretaceous D. Triassic, Permian, Cretaceous, Pleistocene, Ordovician, and Devonian E. Ordovician, Triassic, Jurassic, Silurian, Eocene, and Oligocene
Which organelle breaks down organelles that are no longer useful?
A. Golgi apparatus B. lysosome C. endoplasmic reticulum D. mitochondria
Natural killer (NK) cells recognize and identify their targets in an immunologically nonspecific way, but then kill their targets in a manner very similar to that of TC cells.
Answer the following statement true (T) or false (F)