Biology_review-Genetics

    28. Sex-linked means that the inherited trait goes wherever the X chromosome goes. Sex-influenced means that this trait may exist in both males and females, but it only affects a certain gender. For instance, males may only be influenced because of certain male hormones.
     29. The Drosophila fly is a suitable organism for experiments because they are easy to care for, easy to breed, have a relatively short lifespan and can show a certain trait easily.
     30. The XX chromosomes in a zygote means that the resulting organism will be female. If the chromosomes are XY, then the organism will be a male. A chromosome is made up of genes, which are certain traits. There are different variations of genes, which are called alleles. Certain alleles are dominant over other ones of the same gene, which are recessive. Depending on which allele(s) is (are) dominant and which allele(s) is (are) recessive will affect how much the gene is expressed.
     31. The rules of genetics that Mendel established are: 1. Law of Dominance. He determined that some traits are expressed over others and hides the recessive trait, which may emerge in the next generation if the inherited chromosomes include both recessive alleles for that particular trait.   2. Law of Segregation. When that recessive trait is hidden by the dominant trait in the 1st generation, then emerges in the second generation, it showed that although it had �disappeared� before, it could segregate itself from the dominant traits and appear in the next generation. 3. Law of Independent Assortment. This law concerned traits that often appeared connected with another trait. Then, these two traits appeared in separate organisms, showing that they are on separate chromosomes.
     32. Crossing over is when several genes are switched with genes on another chromosomes during meiosis. Non-disjunction is when the two gametes fail to separate correctly and the chromosomes don�t separate.
     33. Inbreeding is breeding with a mate with similar characteristics/genetics, which increases the chances of inheriting genetic diseases and deformities.
     34. A source of diversity in gene pools are other species or organisms from different areas. Diversity is important because this allows a wide variety of traits to be inherited.
     35. Species is a group of organisms which can interbreed and produce fertile offspring. Isolation of a gene pool can cause mutations, which can lead to changes in the organism. Vestigal organs are organs which do not have any use to the organism. Adaptations are the ways that an organism changes to survive better.
    36. Survival of the fittest is the natural way of determining who survives and who doesn�t, that the physically most powerful always survives. This theory is part of the theory of natural selection, in which nature selects which animal is best fit to survive and breed. Genetic drift is a random change in which an allele can become common in a population by chance.