Answer:
2. A change occurs in the environment.
4. Poorly adapted individuals have decreased survivorship.
1. Well-adapted individuals leave more offspring than do poorly adapted individuals.
3. Genetic frequencies within the population change.
Explanation:
The natural selection theory was developed by Darwin to explain how evolution occur within a population. The environment is in constant state of changes and always select for organisms that are better adapted to it.
Poorly adapted organisms gradually reduce from the population as a result of decreased survival while well-adapted individuals multiply and contribute more to successive generation.
Well-adapted individuals pass on the adaptive alleles to their offspring, eventually leading to a change in gene frequencies within the population.
Hence, the sequence of events is 2, 4, 1 and 3.
The correct answer is - the release of methane from thawed permafrost.
In the past decade it has been noticed that the levels of methane are increasing in the atmosphere, and the biggest ''producer'' of this methane is the melting permafrost. There's huge amounts of methane trapped underground bellow the permafrost. But the permafrost is melting because of the global worming, so the methane is free to come out and go up in the atmosphere.
Answer: Ribose nucleotides and the nitrogenous bases
Explanation: RNA consists of ribose nucleotides (nitrogenous bases appended to a ribose sugar) attached by phosphodiester bonds, forming strands of varying lengths. The nitrogenous bases in RNA are adenine, guanine, cytosine, and uracil, which replaces thymine in DNA.
Answer:
B. The father did not contribute a sex chromosome to his daughter due to nondisjunction of the sex chromosomes. The daughter is XO and her only X chromosome came from her mother, who was a carrier.
A.The mother's X chromosomes failed to separate during meiosis, and the daughter inherited two X chromosomes with the Lesch-Nyhan mutation. The father contributed no sex chromosomes.
Explanation:
As seen in the question above, a little girl was diagnosed with Lesch-Nyhan syndrome, which is an X-linked recessive condition caused by a mutation in the HPRT1 gene responsible for purine metabolism.
The little girl's parents do not have the syndrome, and no one in the little girl's paternal family presented this syndrome, however, we know that the maternal grandfather of the little girl's mother had the syndrome, which means that it was the mother's genetic material that contributed to the development of the syndrome in the little girl. This was because the little girl did not receive any X chromosomes from her father, but she inherited the two X chromosomes from her mother that coded for the Lesch-Nyhan mutation. This happened because the mother's X chromosome disjuction did not occur during meiosis I.
As shown above, the father did not contribute any sex chromosomes to his daughter, which means that the daughter is XO and her only X chromosome came from her mother, who was a carrier.
