Biology Questions and Answers

Biology Questions and Answers

generation, the phenotypical proportion
is three red (75%) to one yellow (25%).

5. Considering hybridization in
   a trait like the color of the
   flowers of a given plant
   species (red/yellow)
   conditioned by a pair of
   different alleles in relation to
   complete dominance (red
   dominant/ yellow recessive),
   why in the F1 generation is
   one of the colors missing?

In this monohybridism one of the colorsdoes not appear in the F1 generation
because pure, i.e., their parental generators arehomozygous, and in F1 all
descendants are heterozygous (each
parental individual forms oof gamete). Since only heterozygousnly one type
genotypes appear and red is dominant
over yellow thgeneration will present only red flowers.e individuals of the F1

6. Considering hybridization in
   a given trait like the color of
   the hair of a mammalian
   species (white/black)
   conditioned by a pair of
   different alleles under
   complete dominance (black
   dominant, B/ white recessive,
   w), how can the phenotypical
   proportion obtained in the F2
   generation be explained?
   What is this proportion?

In the monohybridism conditioned by

two different alleles thpresents only heterozygous individualse F1 generation (^)
(Bw). In F2 there is one individual BB,
two individuals Bw and one individualww. In relation to the phenotype there (^)
are in F2 two black individuals and one
white individual, since dominant color. So the proportion isblack is the (^)
3:1, three black-haired to one white-
haired.

7. What is meant by saying
   that in relation to a given trait
   conditioned by a gene with
   two different alleles the
   gametes are always “pure”?
   To say that gametes are pure means
   that ththe referred trait.ey always carry only one allele Gametes are alwaysof
   “pure” because in them the
   chromosomes arcontain only one chrome not homologous, thosome of eachey
   type.


8. What is the Mendel’s first
   law?
   The Mendel’s first law postulates that a

characteristicalways determined by two (trait) of an individual isfactors, one (^)
inherited from the father and the other
from thof the individual re mother and the direct offspringeceives from it only
one of these factors (aleatory). In other
words, eacfactors that seh trait is determined by twogregate during gamete
formation.
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