Reproductive isolation. Species refer to the group of organisms which share common morphological features and can interbreed and produce a viable offspring. Thus, the organisms of one species are reproductively isolated from the organisms of other species
<h3><u>Answer;</u></h3>
Compressions
Rarefactions
<h3><u>Explanations;</u></h3>
- A wave is a transmission of a disturbance from one point to another, and involve the transfer of energy from the source to another point.
- Waves may be classified as longitudinal waves or transverse wave depending on the vibration of particles relative to the wave motion or mechanical and electromagnetic waves based on the material medium of transmission.
- <em><u>Sound waves are examples of longitudinal waves that are mechanical waves since they require material medium for transmission. Longitudinal waves involves transmission of waves such that the vibration of particles is parallel to the wave motion , creating compressions and rarefactions.</u></em>
Answer:
The interaction of heredity and the environment works to shape who children are and who they will become. The complex interaction of nature and nurture does not just occur at certain moments or at certain periods of time it is persistent and lifelong.
The most important idea is that the genetic material of any organism must be able to accurately replicate itself at least every generation (or for multicellular organisms at each cell division).
Base pairing (A-T or U and C-G)allows DNA and RNA (eg in polio virus, see Wikipedia page on RNA dependent RNA polymerase) to create a copy of themselves, when the appropriate enzymes are present. Proteins have no way of making a copy of themselves.
Stability is probably the main reason DNA is the most common genetic material. DNA has no enzymatic activity and was probably selected for to maintain the integrity of the genetic material (rather than having to perform a function for the cell/virus, during which it may be destroyed). The double helix structure also protects its integrity, and proofreading enzymes have also evolved which correct most of the mistakes made at DNA replication. RNA viruses don't have this mechanism- which could be said to be an advantage (as they can rapidly change and therefore avoid their hosts' immune systems), however in non-parasitic organisms most mutations in a gene would lead to a loss of an essential function and the extinction of that genome.
I don't think either of these reasons are relevant, but I think the main reasons retroviruses convert their RNA to DNA are so they can use the host cell's replication machinery (this was they do not need to encode as many genes), and secondly they need avoid the antiviral mechanisms of the cell, which would destroy any double stranded RNA molecules found (even if the virus was single stranded, dsRNA would have to be produced at replication).
The accumulation of several mutations in the main gene on the virus's surface may be able to give H7N9 the ability to spread like human flu viruses do, passing from person to person through coughing and sneezing.
