What is the frequency of a wave that has a wave speed of 120 m/s and a wavelength of 0.40 m

Hunter-gatherer societies are often _____. permanent semipermanent very dense nomadic

zmey [24]

Hunter-gatherer societies are often nomadic. I believe.

8 0

3 years ago

Effects of pollution might includea. inability to see the top of skyscrapers because of the smog.b. acid rain-induced destructio

poizon [28]

Answer:

e. all of these answers

Explanation:

Air pollution in addition to affecting people, animals, plants and goods, causes other problems related to the changes that occur in its composition, such as: climate change, acid rain and the destruction of the ozone layer phenomena that affect the planet globally and that it is necessary to stop urgently by taking the necessary measures.

Main effects of pollution:

- Effects on human health : It is difficult to determine the exact relationships between exposure to air pollution and diseases developed in humans, especially in the long term, they are not known exactly, but there is evidence that high concentrations of pollutants in the atmosphere are a danger for the human being. it can also act as a vector to spread diseases

- Effects on the environment :

It is in the natural environment where the first signs of the harmful effects of air pollution were seen, plants and vegetation act as an indicator in this regard.

Some of the most common contaminants :

SO2 ; O3 ; Fluorides ; HCL; Cl2; NO2

- Effect on materials :

Contaminants can affect materials by particle deposition or abrasion and also by chemical reactions between the contaminant and the material. For example : stone, iron and paintings

- SMOG:

SMOG is known as fog-type pollution that occurs in some cities when the combination of certain factors occurs, depending on weather conditions and certain pollutants.

Some of them are:

Industrial smog

Photochemical smog

This phenomenon (SMOG) occurs when the mixture of nitrogen oxides and volatile hydrocarbons emitted by cars and industries and atmospheric oxygen react with solar radiation and form ozone.

- Acid deposition.

It is a regional effect. It results from the transformation of atmospheric pollutants such as sulfur dioxide (SO2) and nitrogen oxides (NOx) into secondary pollutants such as sulfuric acid (H2SO4), ammonium nitrate (NH4NO3) and nitric acid (HNO3).

Therefore, air pollution caused by SOx and NOx affects water, soil and ecosystems.

- Water contamination

Pollution of the waters of a sick river and kill fish, but not only these, but all forms of aquatic life .

Pesticides and other toxic chemicals that are used in the domestic environment, farms and industrial production, and that are dumped into the water, cause fish death.

3 0

3 years ago

scientist and all branches of science have developed scientific theories. Which of the following statements is TRUE about all sc

Vikentia [17]

Answer:

Scientific theories are based on large amount of evidence

Explanation:

5 0

2 years ago

How is a mantle plume (hot spot) different from volcanoes in the Ring of Fire? How are they similar? Give one specific example o

riadik2000 [5.3K]

The difference between a hot spot volcano and the volcanoes from Ring of Fire can mainly be seen in the way of formation and functioning. The hot spot volcanoes are far away from any tectonic plate boundary and they manage to penetrate the crust over them and come out on the surface to usually create volcanic islands. The activity of the volcanoes from the Ring of Fire depends directly from the activity between the bordering tectonic plates, and as the borders move over time, the volcanoes stop existing, and new ones rise in the direction where the boundary moves.

The similarity can be seen in the type of eruptions, and that usually both types of volcanoes form volcanic islands.

Example for a hot spot volcano is Mauna Loa on Hawaii.

3 0

3 years ago

Read 2 more answers

Biochemical and differential tests can be incorporated into growth media or performed on isolated colonies after they have been

Cloud [144]

<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

4 0

3 years ago