<em>A </em><em>virus </em><em>is an agent that causes infections and diseases.
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<h2>Further Explanation
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Viruses are microscopic parasites that infect cells of biological organisms. Viruses are obligate parasites, this is because viruses can only reproduce in living material by invading and utilizing the cells of living things because viruses do not have cellular equipment to reproduce themselves.
The term virus usually refers to particles that infect eukaryote cells (multicellular organisms and many types of single-cell organisms), while the term bacteriophage or phage is used for types that attack types of prokaryotic cells (bacteria and other organisms that do not cell nucleated).
The virus has been infecting since the days before Christ, this is evidenced by the existence of several discoveries, namely reports of virus infections in hieroglyphics in Memphis, the capital of ancient Egypt (1400 BC) which shows the existence of poliomyelitis. In addition, King Pharaoh Ramses V died in 1196 BC and is believed to have died of the smallpox virus.
In 1880, Louis Pasteur and Robert Koch put forward a "germ theory" namely that microorganisms are the cause of disease. At that time also the famous Koch Postulate which is very well known today, namely:
- A disease agent must be present in every case of the disease
- The agent must be isolated from the host and can be grown in vitro
- When the muri agent culture is inoculated into susceptible healthy host cells, it can cause disease
- The same agent can be taken and re-isolated from the infected host
<h3>Various kinds of viral infections
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- Acute infections are infections that last for a short time but can also be fatal.
- Chronic infection is a prolonged viral infection so there is a risk of symptoms of the disease coming back.
Learn More
Viruses brainly.com/question/11690598
The infection by virus brainly.com/question/8633233
Details
Class: Middle School
Subject: Biology
Keywords: viruses, disease, infection
Answer:
by the nitrocellulose membrane filter method. (more info below)
Explanation:
Genetic relationship between mycoplasma as determined by nucleic acid homology. DNA from each of the mycoplasma isolates tested was reacted separately by complementary RNA synthesized with homologous or heterologous DNA as a primer. The amount of DNA-RNA hybrids formed was tested using the method of the nitrocellulose membrane filter.
hope this helped!
There are four principles at work in evolution—variation, inheritance, selection and time. The theory of evolution by natural selection, first formulated in Darwin's book "On the Origin of Species" in 1859, is the process by which organisms change over time as a result of changes in heritable physical or behavioral traits.
1. outer covering - none of the other answers can occur due to the absorbed solutions inability to reach the centre of the organism, smaller cells in greater numbers are more efficient as they can group together yet all absorb the right amounts of nutrients for its need. multi cellular organisms, such as humans can have the other answers in them as cells group together to make skin, muscles and organs. it also gives the organism to grow larger.
2. bacteria are single celled. bacteria reproduce through mitosis (cell division). bacteria break down decaying matter to obtain energy. every organism requires energy to live. Bacteria can move in order to reach their nutrient source.
