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How does natural selection produce adaptations in a species?

For natural selection to occur, several premises must be satisfied. Firstly, there must be variation in a population. If all individuals are the same, there is no variation on which selection can occur. Secondly, these traits must be heritable, meaning they are passed from parent to offspring. Natural selection cannot operate on traits that have no genetic basis. There must also be differential reproduction, which means that some individuals must reproduce more than others. When all of these factors occur, natural selection results in evolution as advantageous traits propagate throughout the p..

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Why can gases be compressed?

Gas particles are in constant motion, bumping into each other and the walls of any container in random fashion. The frequency and force of these impacts constitutes the pressure of the gas. Outside of a container or some other force, such as gravity, keeping them in place, gas particles actually fly apart entirely. In other words, gases expand to fill any container. When restricted by forces, they exert pressure in opposition to those forces. Compressing a gas increases its pressure. So does heating it, even when volume remains constant.\nRegardless of current pressure, compressing a gas is ea..

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What are the properties of air?

Air is a mixture of gases, which is why it has weight. Gases are a composition of several molecules that remain in constant motion. It occupies volume in space, but how much space it takes up depends on its temperature. Normally, gases at a higher temperature take up more space.\n\nAir's density varies in different parts of the atmosphere. At the edge of space, its density is zero. Air density, temperature and pressure can change several times per day and varies from region to region.

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What are uses of artificial satellites?

Satellites vary in size and complexity, and have different features making them suitable for various functions. Space telescopes rank among the largest and most innovative objects in space. These telescopes enjoy a complex internal layout, with capabilities for retrieving and storing information. Space telescopes gather information on objects in outer space, such as the stars and other planets. They include several well-known craft, such as the Hubble Space Telescope. These telescopes provide valuable information to scientists and astronomers. However, they typically rank high on the list of e..

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What are examples of somatic reflexes?

Somatic reflexes are movements of body parts that result nearly instantly when a certain stimulus is delivered. Reflexes are able to occur so quickly because the stimuli that cause them are not processed in the brain. Rather, the nerve impulse generated by the stimulus is relayed only to the spinal cord. A motor nerve impulse, which signals for the muscles to react in a certain way, is then sent back from the spinal cord to the muscle.\nHumans display many different reflexes. The biceps reflex causes the forearm to jerk when the biceps brachii is tapped with a hammer. The corneal reflex causes..

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What is the definition of working distance?

Microscopes use a parfocal lens that stays in focus when the magnification or focal length changes. Working distance refers to the space between the front lens element, or tip of the microscope lens, and the closest cover slip surface. The cover slip is the thin protector cover placed over a specimen. In cases of specimens without cover slips, linear measurement of the front lens to the specimen surface is used to calculate working distance.\nCertain substances, such as toxic or metallurgical specimens, require thick cover slips. In such cases, working distance is described as extra long (ELWD..

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What are some sequoia tree facts?

While the coastal redwood tree has the record for the tallest tree of Earth, sequoias have been measured at over 300 feet in height. While they have the potential to grow even taller, sequoias rarely exceed 275 feet because they typically lose their tops to lightning strikes once they exceed the height of the surrounding trees. It is impossible to accurately determine the age of a living tree, but the ring count on a stump in Sequoia National Forest placed the age of the tree at about 3,200 years at the time of its demise. The Muir snag in the Converse Basin Grove is estimated to have been abo..

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How many days are in November?

November is one of the four months in the year that has 30 days in it. Here is a helpful rhyming poem to remember how many days are in each month:30 days has September,April, June, and November.All the rest have 31Except February alone,Which has 28 days clearAnd 29 in each leap year.

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What are some soil stabilization methods?

Compacting soil is accomplished by steamrollers, special compactors, grading machines and heavy equipment driven over the area. Compacting certain soils is necessary after desiccation to ensure that soil stabilization is more permanent. Making soil more dense reshapes whatever land is needed for projects.\nDesiccating, or removing the water from soil, is done with chemicals such as lime. Coal fly ash and slag cement are added to clay to remove water before soil is compacted. Chemical reactions within the soil change the pH of dirt to allow faster drying times.\nAdding material to the ground re..

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How do you use a color blending chart?

The 12 colors on the color blending chart are classified in into three categories. The first category is the primary colors: red, yellow and blue. All of the other colors on the blending chart originate from a mixture of these three colors.\nThe next category is the secondary colors: violet, green and orange. Secondary colors are produced from an equal blend of two primary colors and are arranged on the chart in between the two primary colors that create them. Violet is made from a mixture of blue and red; orange is made from a mixture of red and yellow; green is made from a mixture of yellow ..

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