Question

Having freckles is a dominant trait. A person is heterozygous for having freckles. Their genotype is _________ and their phenotype is _________. [ Choose the choice with the answers in the correct order. ] *

Freckles, Ff

ff, freckles

freckles, no freckles

Ff, Freckles

A fertilized egg created through sexual reproduction ______________. *

is genetically identical to the parents

contains genetic material from only one parent

is genetically identical to other eggs of the same parents

has a combination of genetic material that is unique

In the diagram , genetic information is exchanged between homologous chromosomes during prophase I of meiosis. What is this process called? *

telophase II

crossing-over

mutation of DNA

segregation

A special type of cell division, called meiosis, is used to form sex cells or gametes. Which statement is true about this type of cell division? *

The new cells inherit a single set of chromosomes from the parent cell.

The products of meiosis are two identical cells.

DNA is not copied at all during meiosis.

Meiosis is complete after only one round of cell division.

Hemophilia (h) is a sex-linked (X-linked) recessive condition in which the blood of affected individuals is unable to clot normally (H). This can lead to hemorrhaging, excessive blood loss, and even death. Nicholas, who is normal, marries Alexandria, a carrier of hemophilia. What are the odds that their son will be a hemophiliac? *

0%

50%

75%

100%

In snapdragon flowers, the red color allele (R) and white color allele (W) are incompletely dominant such that heterozygous (RW) flowers display a pink phenotype. What is the expected result of a cross between a red snapdragon and a white snapdragon? *

25% red, 50% pink, 25% white

0% red, 50% pink, 50% white

50% red, 50% pink, 0% white

0% red, 100% pink, 0% white

Gregor Mendel stated: "the inheritance of one trait is not dependent on the inheritance of another". Today, this is known as his: *

law of probability

law of independent assortment

law of dominance

law of segregation

This is a diagram of meiosis. The gametes can be described as: *

four haploid cells with the exact same chromosomes

two diploid cells with different chromosomes

Two diploid cells with the exact same chromosomes

four haploid cells with different chromosomes

A cross of a black chicken (BB) with a white chicken (WW) produces all speckled, black and white offspring (BW). This type of inheritance is known as *

multiple alleles

incomplete dominance.

codominance.

polygenic inheritance.

Answer 1

1. Dominant traits are traits that can express themselves even if one copy of the dominant allele (here F) is present in their genome. A heterozygous individual is one which has an allele of both types i.e have both a dominant allele (F) and recessive allele (f). Hence here the individual's genotype is Ff and because one dominant allele is enough to express a dominant trait, the person has freckles.

Answer: (d) Ff,Freckles

2.During sexual reproduction, the gametes of both parents fuse to form the zygote. Hence, the offspring has genetic content derived from both parents. In the diploid zygote, half of the chromosomes are of paternal origin and other half of maternal origin. However, if we recall the process of gametogenesis , we know that variation is introduced in acute levels through genetic recombination and synapsis, random assortment of alleles into gamete and random fusion of sperms and eggs. Hence, the egg retains a lot of similarities from mother and father while also having a unique combination of their genetic material.

Answer: (d) has a combination of genetic material that is unique.

3. During prophase 1 of meiosis 1, the homologous chromosomes pair up , a synaptonemal complex develops between them and synapsis occurs. After this the non sister chromatids exchange fragments and recombination occurs. This exchange of chromatid bits occurs by crossing over of chromatic arms.

Answer : (b) Crossing-over

4. While formation of gametes, meiosis occurs. It has two stages Meiosis 1 (reductional division) and Meiosis 2 (equational division) . In this process the diploid (2n)germ cell,passes half a set of chromosomes to daughter cells to produce 4 haploid (n) gametes. Before entering the cell division , during Interphase, the DNA replicates and DNA content doubles up. In meiosis 1 , the homologous chromosomes pair up and synapsis occurs leading to crossing over and recombination during Prophase 1 and in metaphase 1, the bivalents arrange in random manner, in the equatorial plane of cell and in Anaphase 1 and Telophase 1 half a set of the chromosomes move to respective poles and form 2 daughter cells. Meiosis 2 is equational division in the 2 daughter cells , the sister chromatids of each chromosome, separate and move to opposite poles, now forming 4 haploid gametes.Each gamete having a unique combination of genetic material.

Answer: (a) the new cells inherit a single set of chromosomes from the parent cell.

5.Answer: (b) 50%

6. Answer: (d) 0% red, 100% pink, 0% white

7. Law of segregation states that alleles of a trait will separate randomly, without affecting each other and can enter any one of the gamete. Law of independent assortment states that alleles of one gene separate from alleles of another gene independently and their movement doesn't influence the other. Where as law of dominance states that one of the alleles is dominant over the other and can express itself in heterozygous condition. The law of probability isn't a mendelian law.

Answer: (b) law of independent assortment

8. In meiosis the four gametes obtained have haploid set of chromosomes which are not exactly same . They have only one set of chromosomes which are different from each other due to recombination, independent segregation and assortment .

Answer: (d) four haploid cells with different chromosomes.

9. From the condition given in the question it is evident that both the alleles contribute equally to the phenotype of the chicken. None of the allele is dominant over the other and equally expresses itself in heterozygous condition. Hence, the alleles co-dominate over the phenotype of the chicken.
Answer: (c) codominance