Answer:
d. white blood cells
Explanation:
It is the white blood cells that have the least tendency to cross the blood- brain barrier.
Blood- brain barrier is psychological barrier and restricts substances that circulate into the blood from crossing over the central nervous system.
Water, glucose as well as sodium ions can easily cross the barrier. As these are good for body supply energy to the brain.
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Rusting causes rocks with metals in them to corrode and have changed compositions. The oxygen in the moisture in the air causes rock to rust.
In order to form polymers, we need to chain molecules together. This involves making bonds between them.
Shifting H’s around doesn’t accomplish anything.
Forming more double bonds will have the opposite result, as it would make the molecules more stable and less likely to react with each other.
Adding oxygen to the molecule no longer makes it polybutene. That would likely result in the formation of some sort of ether, as hey would react to form a C-O-C Bond.
The only answer left is A. In order to form polyalkenes, we have to break a double bond so that it’s available to form more covalent bonds.
Hope this helps
TRNAs (transfer RNAs) carry amino acids to the ribosome. They act as "bridges," matching a codon in an mRNA with the amino acid it codes for.