1. Samples of a microbial colony obtained from the natural environment are not pure culture. They are mixed cultures because the environment consists of an array of microorganisms and not one specific organism. A sample obtained from the natural environment such as water or soil may contain several species of microbes that need to be further isolated to obtain a pure culture.
2. Isolation streak plate technique involves the dilution of the sample several folds and then streaking a small amount using a sterile inoculation loop on an agar plate in a zig-zag manner. This is done to obtain a pure culture of bacteria from a mixed population by separating the microprocessor. When the sample is diluted into a small concentration and is streaked onto agar placed, widely spaced, discrete colonies of bacteria can be observed. These isolated colonies can be further cultured to obtain pure cultures by picking and re-streaking them on fresh agar plates.
3. A microbial colony is considered a pure culture because it consists of single species. A single species of bacteria cluster and form an isolated colony on an agar plate which can be further plated on fresh medium.
3-1 - If your agar plate shows discrete uncluttered colonies then you have obtained an isolated colony. The following picture might help you to understand.
3-2. If you subculture isolated microbes into a sterile nutrient broth without any contamination, it will still be considered pure culture because it is single isolated species in a sterile aseptic environment of the nutrient broth.
3.3. A pure culture can become a mixed culture due to contamination. This could be caused by airborne bacteria if your conditions are not aseptic. Contamination is possible if the work area is not clean and sterile or if the glassware is not sterile. The contamination can transform your pure culture into a mixed culture and is hence problematic. So, it is very important to maintain a sterile and aseptic environment, glassware, and instruments.
Learn more about subcultured at
brainly.com/question/26525141
#SPJ4
Answer:
Animal skins provided thermal protection and prevented water from penetrating and wetting the interior of the home.
Explanation:
The paleo Indians lived in the paleolithic period, which was a period where the climate was very cold and difficult to survive.
Within this environment, the paleo Indians were a nomadic people, building simple residences, but very well adapted to the climate in which they were subjected. Their houses, generally, were of round shape, being structured by sticks that were covered by bushes and animal skins.
The skins allowed thermal protection, gave the houses a check and prevent rain water, or moisture from entering the interior of the house.
Answer:
D. amphetamines became available from illegal laboratories rather than legitimate pharmacies
Explanation:
Due to the amendments to federal drug laws known as Drug Abuse Control Amendment of 1965, amphetamine became available from illegal laboratories rather than legitimate pharmacies. Prior to the amendment drugs like barbiturate, amphetamine and lysergic acid diethylamide (LSD) could easy be gotten from pharmacies but the amendment restricted the availability of such drugs. The amendment was as a result of increase in drug abuse among the American population.
Answer:
Sometimes geographers do not want to study the world just at a regional level. Instead they want to learn how people interact globally, or around the world. To do so, geographers ask how events and ideas from one region of the world affect people in other regions. In other words, they study the world on a global level.
