All the options are correct.
1. New ways to preserve and transport blood for blood transfusions were discovered.
2. Blood transfusion safety was improved.
3. Scientists discovered that elements of blood could be separated by centrifuge.
4. Scientists discovered that plasma could be preserved by freezing.
Karl Landsteiner
Karl Landsteiner was the man who discovered some of the human blood types in 1900 and 1901 at the University of Vienna.
<h3><u>Answer;</u></h3>
A) Some protists evolved into other eukaryotic groups.
<h3><u>Explanation</u>;</h3>
- Protists are eukaryotes , making them much more complex than the prokaryotes, such as bacteria.
- Protists may be classified as a paraphyletic group, since they are difficult to group under a single ancestor because of their diversity and dissimilarity from each other.
- Protists evolved from prokaryotes, eventually giving rise to the entire line of eukaryotes that exists today.
Answer: What are the numbers of valence electrons for each atom?
Explanation:
For formation of a neutral ionic compound, the charges on cation and anion must be balanced. The cation is formed by loss of electrons by metals and anions are formed by gain of electrons by non metals.
The cations and anions combine and their oxidation states are exchanged and written in simplest whole number ratios to give neutral ionic compound.
The oxidation states are known by their ability to gain or lose electrons which is decided by the number of valence electrons.
Answer: b. littoral
Insects are most likely found in the littoral aquatic zone. Littoral zone are rich in oxygen and has abundant and diverse food resources. Therefore, this zone supports high diversity of insects. Large taxa of insects like aquatic beetles and bugs, caddisflies, dragonflies and damsflies are important littoral zone communities.