Biology, 16.03.2020 20:24 dpazmembreno

Some people have freckles, and some people do not have freckles. If a child has freckles, at least one parent has freckles. However, the child may have a sibling that does not have freckles. Which statement best describes the presence of freckles? a) Freckles are not determined by DNA. b) There are two alleles for freckles. c) There is no dominant allele for freckles. d) Freckles are determined by two genes instead of by one.

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Answer from: ykpwincess

The correct answer is: b) There are two alleles for freckles.

Explanation:

According to the question, it is said that, if a child has freckles then it is mandatory that either of his parents must have freckles. This indicates that the freckled character must be transmitted through genes or DNA (deoxyribonucleic acid) from the parents to the offspring and its occurrence is determined by heredity. Hence, option a) is incorrect.Also, it is said that the siblings of the freckled child does not have freckles. This means in a diploid organism having two sets of chromosomes (one from either parent) each character is determined by two variants of the same gene. These variants can be similar (homozygous) or dissimilar (heterozygous) and are called the Alleles. Hence, option b) is correct.Out of the two alleles, one is capable of expressing itself not only in homozygous condition but also in the presence of the allele (heterozygous condition). This is called the Dominant allele. The other allele gets suppressed in presence of the dominant allele and can express itself only in the homozygous condition. This is called the Recessive allele. Option c) is incorrect. This is because if no dominant allele would have existed for freckles then all the people would have developed freckles irrespective of whether they are homozygous or heterozygous for the freckled allele.Option d) is incorrect. This is because if freckles would have been determined by more than one genes it would have been expressed in all the offspring as all of them obtain the genes from either of the parents.

Answer from: Quest

a fossil fuel is a fuel formed by natural processes, such as anaerobic decomposition of buried dead organisms, containing energy originating in ancient photosynthesis.[1] the age of the organisms and their resulting fossil fuels is typically millions of years, and sometimes exceeds 650 million years.[2] fossil fuels contain high percentages of carbon and include petroleum, coal, and natural gas.[3] other commonly used derivatives include kerosene and propane. fossil fuels range from volatile materials with low carbon to hydrogen ratios like methane, to liquids like petroleum, to nonvolatile materials composed of almost pure carbon, like anthracite coal. methane can be found in hydrocarbon fields either alone, associated with oil, or in the form of methane clathrates.

the theory that fossil fuels formed from the fossilized remains of dead plants by exposure to heat and pressure in the earth's crust over millions of years was first introduced by andreas libavius "in his 1597 alchemia [alchymia]" and later by mikhail lomonosov "as early as 1757 and certainly by 1763".[4] the first use of the term "fossil fuel" was by the german chemist caspar neumann, in english translation in 1759.[5]

in 2017 the world's primary energy sources consisted of petroleum (34%), coal (28%), natural gas (23%), amounting to an 85% share for fossil fuels in primary energy consumption in the world.[6] non-fossil sources in 2006 included nuclear (8.5%), hydroelectric (6.3%), and others (geothermal, solar, tidal, wind, wood, waste) amounting to 0.9%.[7] world energy consumption was growing at about 2.3% per year. in 2015 about 18% of worldwide consumption was from renewable sources.[8]

Answer from: Quest

the generally accepted parts of modern cell theory include: all known living things are made up of one or more cells. all living cells arise from pre-existing cells by division. the cell is the fundamental unit of structure and function in all living organisms.

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Some people have freckles, and some people do not have freckles. If a child has freckles, at least o...

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