Are SA citizens vaccinated against yellow fever? give two reason for your answer.

1 answer:

4 0

South African people are vaccinated with Yellow fever. First, SA is strict in the implementation proof of vaccination in travelers coming in the country. The vaccination card must show vaccination at least ten days prior to travel. This is to prevent reintroduction of the disease to SA people. Second, In the list of Center for Disease Control, South Africa is not included in the countries with an endemic Yellow fever which means that the disease is wiped out if not controlled through vaccination.

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__________________ dating involves age-dating fossils with known time periods grouped into four eras that represent distinct age

RSB [31]

According to the research, the correct option is Relative dating. It involves age-dating fossils with known time periods grouped into four eras that represent distinct ages in the history of earth.

<h3>What is Relative dating?</h3>

It consists of ordering fossils or events in a proper formation sequence from the oldest to the most modern, it tends to be used as a method for making chronologies, the ordering of events, fossils or rocks.

Since it does not give an exact or approximate date, they can only give us a fairly long period of time, or in their case a temporal ordering of the fossils.

Therefore, we can conclude that according to the research, the correct option is Relative dating. It involves age-dating fossils with known time periods grouped into four eras that represent distinct ages in the history of earth.

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Identify how the addition of acetyl groups to histones leads to a weaker association of DNA in nucleosomes.

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The addition of acetyl groups to histones leads to a weaker association of DNA in nucleosomes because they help to condense it into chromatin.

<h3>What is the relationship between histones and DNA?</h3>

Histones are a family of basic proteins that associate with DNA in the nucleus and help to condense it into chromatin. Nuclear DNA does not appear on free linear strands; it is highly condensed and involves histones to fit inside the nucleus and participate in the formation of chromosomes.

<h3>How does DNA compact with histones?</h3>

Each chromosome is made up of a single molecule of double-stranded DNA wrapped around histones, the nucleosome. This fiber rewinds into a second level of compression, known as the solenoid. Most of the time, cells keep the DNA compacted in the selenoid loops attached to the chromosomal backbone.

Whit this information, we can conclude that the addition of acetyl groups to histones leads to a weaker association of DNA in nucleosomes because they help to condense it into chromatin.

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A seal is a mammal. How can it survive in the cold polar seas when a human can die in a few minutes

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