Genes are segments of DNA that determine the phenotype of an individual. Pea colors can be yellow or green. When two plants that
produce yellow peas were crossed, the offspring produced green peas. This is because the parents were _______
a)heterozygous
b)homozygous dominant
c)homozygous recessive
for pea color. Because there are only two options for pea color, the plants’ pea color is a case of____-
a)polygenetic traits
b)semiconservative replication
c)simple Mendelian genetics
a)heterozygous
b)homozygous dominant
c)homozygous recessive
for pea color. Because there are only two options for pea color, the plants’ pea color is a case of____-
a)polygenetic traits
b)semiconservative replication
c)simple Mendelian genetics
2 answers:
Answer: The correct answer for the blanks are-
1) a) heterozygous
2) c) simple Mendelian genetics
Explanation-
1) As per the information given in the question, the two plants with yellow pea are crossed and produced offspring with green peas. This indicates that yellow pea color is a dominant trait and the parent plants have heterozygous dominant genotype ( Yy).
A dominant trait ( represented by capital letter allele such as 'Y' for yellow peas) always masks the expression of recessive trait ( which is represented by small letter allele such as 'y' for green peas).
Yellow pea can have two genotypes, which are 'YY' (homozygous dominant and 'Yy' (heterozygous dominant) whereas green peas will be expressed in single genotype, which is 'yy' ( homozygous recessive).
Two yellow peas can produce green peas only when they possess heterozygous genotype (Yy) that is with two different alleles.
Thus, option a) is right for first question.
Refer punnet square.
2) According to simple Mendelian genetics, a trait is governed by single gene that exist in two different forms ( dominant and recessive allele).
It expresses only two forms for a trait ( such as tall and dwarf height of pea plant) and there is no range/ variation of phenotype in between ( unlike polygenic trait that is depicted by many genes and show range of variations in the phenotype such as skin color).
Thus, option c) is the right answer for the second question.
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