Carbon dioxide and oxygen cannot pass through but move in and out
Colder air masses are temped Polar or Arctic. While warmer air masses are termed Tropical. Continental and Superior air masses are dry while maritime monsoon air masses are moist. Weather fronts separate air ,asses with different density (Temperature and/or Moisture) characteristics.
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The Devonian Period was part of the better known Paleozoic Period. Some scientist think it was 416 million years ago. It was the time of the great fish. It gets its name from when red rocks from Devon, England were also found in North America. It is believed that during this period parts of North America, Europe, Russia and Greenland crashed together making a new land mass. Scientists believe this period ended about 354 million years ago when land plants began to take over and much of what was an ocean disappeared.
Answer:
a. Proteins
Explanation:
Chromosomes are made up of DNA tightly coiled many times around proteins
Answer:
meiosis
Explanation:
Down syndrome is an abnormality that occurs on chromosomes 21, it occurs because chromosomes 21 cannot be separated in meiosis, the pair of chromosomes 21 do not separate and go together to one of the daughter cells. In this way, the oocyte or the resulting sperm will have 24 chromosomes instead of 23. When in conception that oocyte or sperm joins the germ cell of its partner that contributes the 23 chromosomes, the total sum of chromosomes that will have the first cell of the new conceived being will be 47.
