Answer:
Multiple alleles can modify the classical Mendelian ratio by increasing the number of phenotypes.
For example, in a monohybrid cross, Mendel gets only 2 phenotypes however, in ABO blood groups (a classical example of multiple alleles) there are four phenotypes present in a population.
Lethal alleles are the alleles which when expressed result in the death of an organism. These alleles can be dominant, recessive or conditional (depends on interaction with another gene).
Thus, lethal allele reduces the ratio of the phenotype associated with it by affecting the survival of the organism.
For example, lethal yellow allele in mice results changes the phenotype ratio from 3:1 to 2:1
Answer:
The third diagram shows Refraction of waves.
Explanation:
Refraction is a phenomenon, which occurs in a wave when it travels from one medium to another medium, and during Refraction there is slight or greater change in direction of the wave.
hence, the wave will pass through the surface and displaces from its actual path.
that's why the most appropriate diagram showing Refraction is third one ( c ) .
Answer:
A step that is not part of natural selection is people select which individuals breed and which ones do not.
Explanation:
Natural selection is a process in which favorable or unfavorable environmental conditions determine the evolution of species, producing differences in their genotype over a long period of time.
As its name indicates, it is a natural selection, in which no intervention by people is contemplated, so that <u>people cannot determine which individuals breed</u>.
Natural selection implies that the characteristics on which the environment influences are inheritable, that there is genetic variability in the population and that the variability of these characteristics implies the ease of reproduction and survival capacity.
<em>The other options do form part of natural selection, since they are based on the three premises of this process:
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- <em>Inheritable characteristics.
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- <em>Genetic variability.
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- <em>The variability of characteristics influences reproduction and survival.</em>
