Erosion is the process of eroding or being eroded by wind, water, or other natural agents. Erosion can dissolve rock, weakening it or turning it into tiny fragments. Deposition is the process by which sediments settles out of the water or wind that is carrying it, and is deposited in a new location. <span>Deposition transports previously eroded sediments, which, at the loss of enough kinetic energy in the fluid, is deposited, building up layers of sediment. </span>
Significant evolution, in Darwin's opinion, moves much too slowly to be seen in a person's lifetime. Recent biological tests have demonstrated that some populations may develop extremely quickly, with significant changes happening over many generations in the lab.
What role does Darwin's theory of evolution play?
- Charles Darwin, a scientist of the 19th century, investigated the idea of natural selection. Natural selection provides an explanation for how a species' genetic features might evolve through time. This might result in speciation, or the creation of a new, separate species.
- The genesis and adaptations of species entered the scientific canon with Darwin's finding of natural selection. The adaptive characteristics of creatures might now be explained by natural processes, much as the occurrences of the inanimate universe, without the need for an Intelligent Designer.
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A researcher is interested in screening for p-elements inserted into a region on chromosome 3. to produce new insertions, she crosses females homozygous for a miniwhite + p-element on the x chromosome with males homozygous for immobilized transposase on chromosome 2. what genotype will the f1 male flies have? (note that a "+" indicates a wild-type chromosome without the transposase locus or the p {miniwhite +} insertion. the x /y chromosomes are listed first, followed by the second
Answer:ionic bond
Explanation: Ionic bonds form when electrons are transferred, covalent bonds form when electrons are shared. polar covalent bonds form when electrons are shared unequally (basically).
<h2>Differential test</h2>
Explanation:
A differential test helps to distinguish that which species lack or have the particular biochemical process,the three differential test media are:
1) Blood agar: Blood Agar is an enriched medium which is used to culture those bacteria or microbes that do not grow easily
- It is also required to detect and differentiate haemolytic bacteria, especially Streptococcus species
- It is also a differential media in allowing the detection of hemolysis (destroying the RBC) by cytolytic toxins secreted by some bacteria, such as certain strains of Bacillus, Streptococcus, Enterococcus and Staphylococcus
2) Eosin methylene blue agar (EMB): It is a selective and differential medium used to isolate fecal coliforms
- Eosin methylene blue are pH indicator dyes which combine to form a dark purple precipitate at low pH; they also serve to inhibit the growth of most Gram positive organisms
- Sucrose and lactose serve as fermentable carbohydrate sources which encourage the growth of fecal coliforms and provide a means of differentiating them
3) Mannitol Salt Agar (MSA): It is a selective and differential medium
- The high concentration of salt (7.5%) selects for members of the genus Staphylococcus, since they can tolerate high saline levels
- Organisms from other genera may grow, but they typically grow very weakly
Three examples of tests which are done on colonies are:
1) Catalase test: Catalase is an enzyme that breaks hydrogen peroxide (H2O2) into H2O and O2
- Hydrogen peroxide is often used as a topical disinfectant in wounds, and the bubbling that is seen is due to the evolution of O2 gas
- A small amount of growth from the culture is placed onto a clean microscope slide
- Few drops of H2O2 onto the smear is added
- A positive result is the rapid evolution of O2 as evidenced by bubbling
- A negative result is no bubbles or only a few scattered bubbles
2) Indole test: The main requirement for a suitable indole test medium is that it contain
s a sufficient amount of tryptophan
- Tryptone broth is commonly used
- The tube of tryptone broth with a small amount of a pure culture is inoculated
- Incubation is done at 35°C (+/- 2°C) for 24 to 48 hours
- To test for indole production, 5 drops of Kovács reagent is directly added to the tube
- A positive indole test is indicated by the formation of a pink to red color in the reagent layer on top of the medium within seconds of adding the reagent
- If a culture is indole negative, the reagent layer will remain yellow or be slightly cloudy
3) Urease test: Urease is a constitutively expressed enzyme that hydrolyzes urea to carbon dioxide and ammonia
- The urease test identifies those organisms that are capable of hydrolyzing urea to produce ammonia and carbon dioxide
- Urease test media contain 2% urea and phenol red as a pH indicator
- An increase in pH due to the production of ammonia results in a color change from yellow (pH 6.8) to bright pink (pH 8.2)
- Urea broth is a highly buffered medium requiring large quantities of ammonia to raise the pH above 8.0 resulting in a color change
