Answer:
B. Some countries have many sources of beryllium, and some have no sources of beryllium.
Explanation:
Beryllium is a very important mineral that is present in many countries. All countries did not have beryllium deposits. Some countries have many sources and deposits of beryllium, and some have no sources of beryllium. There are many deposits of beryllium in different parts of United states of America. Those countries which have no beryllium deposits have cell phones because they purchase cell phones from international market by paying money which can be earned through selling of its goods.
Answer:
Plants and animals depend upon each other as mutual interdependence is must for their survival. Plants provide shelter for animals and they make oxygen for the animals to live. When animals die they decompose and become natural fertilizer plants. Plants depend on animals for nutrients, pollination and seed dispersal.
Explanation:
Answer:
False
Explanation:
In DNA double helix molecule, there are four types of nitrogenous bases: adenine, guanine, cytosine and thymine. Purines (i.e., adenine, guanine) and pyrimidines (i.e., cytosine and thymine) hold DNA strands together via hydrogen bonds. In base pairing, guanine always pairs with cytosine through 3 hydrogen bonds, while adenine always pairs with thymine by 2 hydrogen bonds. Hydrogen bonds are a type of dipole–dipole interaction where a hydrogen atom is covalently bonded to a very electronegative atom (e.g., Nitrogen or Oxygen).
<span>Answer: a. overabundance; synaptic connections
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In early childhood, the brain creates overabundance link of the nerve cells called synapses. The link will allow the brain cells have multiple paths to communicate with each other so that if some cells died the path is not blocked. The synaptic connections will be reduced later by a process called pruning.
