<u>Answer</u>:
Option 1.Eukaryotic cells first seen
Option 5. oxygen builds up in the atmosphere
<u>Explanation</u> :
- The name <em>Proterozoic eon</em> is derived from a Greek word which means earlier life.
- This eon represents the time just before complex life started proliferating on earth.
- One of the most important events that took place during this eon was <em>build up of oxygen in the atmosphere</em>.
The fossil evidence also shows the occurrence of <em>advanced single-celled eukaryotes.</em>
<em>So the events that define the Proterozoic eon are eukaryotic cells first seen and oxygen build up in the atmosphere. </em>
Answer:
Hello, As long as the bird flu virus doesn't change into a human flu virus, it won't spread far in people. But sometimes after close personal contact a person who gets bird flu does infect another person. They can get the virus from tainted surfaces, such as cages and other farming equipment. Most people with the virus have had direct contact with infected poultry or objects contaminated with bird feces or secretions. Until now, very few cases of human-to-human transmission have occurred. Hope That Helps!
Answer:
This question is incomplete as it lacks options. However, it can be answered based on general knowledge of the DNA structure.
Hydrogen bonds in a DNA are located between the nucleotides that holds the double stranded DNA molecules.
Explanation:
Deoxyribonucleic acid (DNA) is the genetic material in living cells. The DNA molecule is made up of nucleotides monomers. However, since the DNA molecule is double-stranded, the nucleotides are of two chains composed of four nucleotide subunits viz: Adenine (A), Thymine (T), Guanine (G) and Cytosine (C).
The two chains of nucleotides in a DNA molecule are called strands. Each strand is bonded to one another by the nucleotides using complementary base pairing i.e. A-T, G-C. The bonds between the nucleotidew of each strand is called HYDROGEN BOND.
Hence, HYDROGEN BONDS in a DNA molecule is located in between two nucleotides of each strand. That is, hydrogen bond holds Adenine to Thymine and Guanine to Cytosine.
Answer:
Autotroph. Autotrophs include plants and some other creatures, vacuoles and chloroplasts are found in plants.
Explanation:
PLANTS! = Autotroph. I don´t even know anymore, it´s been 3 years since I took a basic science class, I am guessing from memory.
