Question

These five concepts provide a modem interpretation of Mendelian postulates.

- Inheritance is governed by information stored in discrete factors called genes.
- Genes are transmitted from generation to generation on vehicles called chromosomes.
- Chromosomes, which exist in pairs in diploid organisms, provide the basis of biparental inheritance.
- During gamete formation, chromosomes are distributed according to postulates first described by Gregor Mendel, based on his nineteenth-century research with the garden pea.
- Mendelian postulates prescribe that homologous chromosomes segregate from one another and assort independently with other segregating homologous during gamete formation.
Based on these concepts, choose statements that correlate Mendel's four postulates with what is now known about genes, alleles, and homologous chromosomes.
Select the five correct statements.
a. Some gene pairs on nonhomologous chromosomes can aggregate after separation and mitosis or meiosis would stop.
b. Some genes have dominant and recessive alleles.
c. Unit factors occur in pairs.
d. Some possible gametic combinations are formed with higher probability if dominant alleles take part in meiosis.
e. During mitosis and meiosis, when chromosomes are visible in their characteristic shapes. members of a homologous pair have different sizes and exhibit opposite centromere locations.
f. Different gene pairs on non-homologous chromosomes will separate independently from each other during meiosis.
g. Alleles segregate from each other during gamete formation at anaphase
h. Dominant alleles can become codominant alleles during mitosis.
e. One gene pair separates independently from other gene pairs.

Answer 1

b. Some genes have dominant and recessive alleles.

C. Unit factors occur in pairs.

e. During mitosis and meiosis, when chromosomes are visible in their characteristic shapes. members of a homologous pair have different sizes and exhibit opposite centromere locations

f. Different gene pairs on non-homologous chromosomes will separate independently from each other during meiosis.

g. Alleles segregate from each other during gamete formation at anaphase

Step-by-step explanation:

Mendel's postulates of inheritance are: (1) Principles of Paired Factors (2) Principle of Dominance(3) Law of Segregation or Law of Purity of Gametes (Mendel’s First Law of Inheritance) and (4) Law of Independent Assortment (Mendel’s Second Law of Inheritance).

Each of these laws provide information on how inheritance of traits by offspring from parents occur.

Principle of paired factors:

A character is represented in an organism (diploid) by at least two factors. The two factors lie on the two homologous chromosomes at the same locus or position.

Principle of Dominance:

Dominant characters are those which always appear in every generatio whereas recessive characters may not appear in some generations e.g. F1 generation.

Law of segregation:

During the formation of gametes (egg or pollen), the paired genes separate or segregate randomly so that each gamete receives one or the other with equal likelihood

Law of Independent assortment:

During gamete formation, segregating pairs of unit factors (genes) assort independently of each other.

From the above consideration,

Option A is wrong because it doesn't correlate with the law of Independent assortment

Option B is correct based on the second postulate

Option C is correct based on the first postulate

Option D is wrong based on the law of segregation which assigns equal likely to gene separation

Option E is correct based on recent studies of genes

Option F is correct based on the law of Independent assortment

Option G is correct based on recent studies on genes

Option H is wrong because dominant genes remain dominant. Co-dominance occurs when allelic pairs are neither dominant nor recessive

Option 'e' is wrong because independent assortment occurs between pairs of genes with contrasting character not a gene pair having the same character where only segregation occurs.