Portals of entry are the sites where micro-organisms can enter a host and reproduce, causing diseases or infections. There are various portals of entry in the human body. This can include the skin, our mucous membranes, and even our respiratory and gastrointestinal tracts. Portals of exit are where these micro-organisms leave and spread to other individuals. Portals of exit include coughing, sneezing, and some of our bodily fluids.
The correct answer is - 1) inverted pyramid, with a narrow base representing a small number of young individuals.
The populations that are decreasing are usually population in countries that are highly developed. The conditions for living are excellent, the medical care on high level, life expectancy very high, but the birth rates very low.
In this type of conditions, there's smaller and smaller number of young individuals, with the middle aged population being much bigger, and the older population being constantly on the rise. This will give the age-structure histogram a reverse shape than what it is supposed to have, it will be similar in appearance like a inverted pyramid, meaning that the population is aging and that it will be constantly on a decline in the future.
Answer and Explanation
Due to technical problems, I was not able to fill the answer and explanations in the corresponding boxes. You will find them in the attached files.
The immense amount of information stored in DNA is coded with just four base nucleotides. These four nucleotides are paired by twos to form <u>complementary </u>DNA chains.
The makeup of DNA is limited to two <u>pairs </u>of nucleotides bases. One of these pairs is a pyrimidine base whilst the other forms a purine base. The four nucleotides that will make up the entire DNA code are:
- Adenine (A)
- Guanine (G)
- Cytosine (C)
- Thymine (T).
A and G will pair to form the purine base, meanwhile, Cytosine pairs with Thymine to form the <em>pyrimidine base</em>. As per the entire DNA code, A will always pair with G.
Whilst C always pairs with T. This is due to the very nature of the nucleotides themselves and will not change throughout the synthesis or duplication of DNA. Therefore, to complete the complementary strand described in the assignment we must match the letter given with its corresponding base pair, using this rule of DNA.
To learn more visit:
brainly.com/question/967810?referrer=searchResults
The answer is a simple radial nervous system.
Echinoderms do not have brains. Around their mouth, they have central rings from which nerves radially run into arms and along the body. Movement is controlled by the branches of those radial nerves.
