This was a question on a study guide I got in Biology class about evolution. I think I have a good answer, but since this wasn't discussed in my book, I just wanted to make sure that I'm on the right track with my answer. Any ideas?
2006-11-16 10:23:43 · 10 answers · asked by Anonymous in Science & Mathematics ➔ Biology
If you spray a plague of locusts, comprising millions of them, with insecticide, most of them will die. Some of them won't - lets say 1%. Of that 1% some didn't die because they may not have had exposure to the insecticide. They will most likely die with the next spraying. Some of that 1%, however, will happen to have an inate resistance to the insecticide, and they will pass it onto some of their offspring. So next year, the farmer will spray, and perhaps 10% of the locusts will survive, so the following year the farmer increases the strength of the insecticide, and only 1% survive, and so on, over many years, gradually the resistance grows, to a level that the insecticide needs to be at a level where it is toxic not only to locusts but to humans, and so has become useless.
As for bacteria, much antibiotic resistance is plasmid mediated. The plasmid is a small ring of genetic material within many bacteria, it is used to transfer genetic material between bacteria, not just of the same species, but different species of bacteria. The resistance mechanism to antibiotics is similar to the locust example, but it can be transferred to other bacterial species as well, via the plasmid.
The good news with antibiotic resistance is that it requires energy to maintain genetic code within the plasmid. If we stop using a particular antibiotic, then having that genetic code within the plasmid will not be an advantage to survival, in fact it may be a hindrance. Eventually it will be lost, and the antibiotic will become potent again. This is of course a simplistic example, but the basics are there.
2006-11-16 11:15:27 · answer #1 · answered by Labsci 7 · 10⤊ 1⤋
Exposure to insecticides and antibiotics creates a major survival advantage for any resistant creature. Once the resistance is acquired the population will become dominated by the resistant strain.
2006-11-16 20:00:36 · answer #2 · answered by novangelis 7 · 1⤊ 0⤋
Some insects and bacteria build resistance to insecticides and antibiotics due to either mutation or certain genes. Hence, these surviving insects and bacteria will passs on their resistance genes. This is part of evolution since survival of the fittest comes into effect. Hope that helps.
2006-11-16 18:31:23 · answer #3 · answered by Anonymous · 3⤊ 0⤋
I would call this "natural ecological selection". I copied the following excerpt from Wikopedia, and can be applied to your scenario too:
"A well-known example of natural selection in action is the development of antibiotic resistance in microorganisms. Antibiotics have been used to fight bacterial diseases since the discovery of penicillin in 1928 by Alexander Fleming. However, the widespread use and especially misuse of antibiotics has led to increased microbial resistance against antibiotics, to the point that the methicillin-resistant Staphylococcus aureus (MRSA) has been described as a 'superbug' because of the threat it poses to health and its relative invulnerability to existing drugs."
It was thinking about your question. Pass on the good Karma!
2006-11-16 18:34:44 · answer #4 · answered by dumbdumb 4 · 3⤊ 0⤋
In every generation of insects there will be some varieties who are resistant to insecticides. Same with bacteria. So, these will leave more progeny who have the resistant traits. Then soon all have them, more than less.
2006-11-16 18:27:23 · answer #5 · answered by Anonymous · 3⤊ 0⤋
i never went to any university , But it goes like this ,you kill the bugs with insecticide except a very small amount are naturally resistant.they will multiply and pass on their resistance to their offspring in the end you get a whole new population of bugs with resistance to that insecticide.
2006-11-16 19:05:52 · answer #6 · answered by Shark 7 · 3⤊ 0⤋
Bacteria need D-alanine as a building block for their cell walls. Without it, the cell walls fall into disrepair and burst, and the bacteria die. There are proteins that carry D-alanine to construction sites. Penicillins, cephalosporins, and other *beta*-lactam antiobiotics hijack these proteins, bind covalently to them, and prevent them from picking up and carrying D-alanine. Bacteria have many copies of the gene to make D-alanine carrier proteins. When exposed to penicillins, almost all bacteria die. But a few accidentally get mutations in one copy of one gene for the D-alanine carrier protein. This mutation codes for a protein that soaks up penicillin preferentially before the penicillin can hijack carrier proteins. The one in a kajillion bacteria that get this mutation survives the next penicillin attack. That bacterium founds a whole new strain of resistant bacteria.
2006-11-16 18:37:38 · answer #7 · answered by steve_geo1 7 · 2⤊ 1⤋
The insects will become immune to a chemical and we would need to change it. The bacteria that makes us sick will become immune to our antibiotics and we will need to change it.
2006-11-16 18:29:50 · answer #8 · answered by spir_i_tual 6 · 0⤊ 0⤋
Since these compounds generally kill of the various bugs...But they don't kill off all of them...So the ones that are left are resistant to the stuff...They reproduce and come to dominate and those chemicals don't work anymore.
2006-11-16 18:25:47 · answer #9 · answered by feanor 7 · 2⤊ 1⤋
DDT a powerful insecticide, was very efficient and then... bugs just got used to it.
2006-11-16 18:24:59 · answer #10 · answered by Anonymous · 1⤊ 4⤋