Question

Question 1. M2 a. If A is dominant to a and B is dominant to b what is the expected phenotype ratio of the cross Aobb x MBB А ТА Вь ® 1:2:1 B ye Béb C 3:1 x 1:2 :1 1:2:1 D. 9:1:1:3 E 9:33:1 BEBE AMMA D. Which of the following statements regarding the differences between mitosis and meiosis is false! A In meiosis four daughter cells are produced, whereas in mitosis two daughter cells are produced B Cells produced by mitosis are diploid, whereas cells produced by meiosis are haploid C in mitosis cytokinesis occurs once, whereas in meiosis cytokinesis occurs more than once D. Apart from chromosome number, all the events unique to meiosis occur during meiosis L. Tetrads are formed from homologous chromosomes in mitosis. C. You cross two red griffins with blue eyes and produce offspring that are: red with blue eyes, red with green eyes white with blue eyes, and white with green eyes. Assuming that the genes for body color and eye color are on different chromosomes, what is the ratio of these offspring's phenotype? A 1:1:1:1. ral blue eyes Br RRRR B 9:1:1:1 real green eyes r Rrrr C 9:1:1:3 while blue eyes D. 9:3:3:1 wiele green eyes E 3:1:1:3 M. Four of the five answers listed below are related by a common phase of mitosis Select the exception A chromosomes condense B chromosomes separate - C spindle fibers appear - D nudeolus disappears E nuclear envelope disappears - genes and generally E. Genes located close together on the same chromosome are referred to as genes same chromosome are referred to as A associated...sort independently during meiosis linked...do not sort independently during meiosis C linked...sort independently during meiosis D. homologous...are inherited together E codependent...do not sort independently during meiosis 1. Which of the following best expresses the concept of evolution by natural selection! (A) a process by which the environment generates beneficial mutations B. change in response to need C differential reproductive success based on inherited characteristics D. a process of constant improvement, leading eventually to perfection E inheritance of acquired characteristics 9.A fish breeder wishes to develop a silver goldfish. She starts with a diverse mixture of fish, some more silver than others. Generation after generation, she allows only the most silver fish to breed. After 30 years of work she has a new breed of fish with interesting traits, but on average, the fish are no more silvery than other goldfish Which of the following would be a logical explanation for her failure? A There is no variation for the trait (silver coloration) B. The selection was artificial, not natural, so it did not produce evolutionary change. C. There was no selection (differential reproductive success) related to silver coloration (D) Silver coloration is an environmentally-determined trait E The breeder accidentally picked less silver fish when she meant to pick more silver fish.

Please solve the whole question 1 ( a,b,c,d,e,f,g) or don't solve at all.

Answer 1

As per Chegg Q&A Guidelines, I am answering the first four subparts a, b, c, and d.

a) We have two genes A and B. For gene A we have two alleles A and a where A is dominant over a and for gene B we have two alleles B and b, where B is dominant over b.

A cross is made between the organisms AaBb and AABB and the offsprings are analyzed.

AaBb will give rise to four types of gametes: AB, Ab, aB and ab.

AABB will give rise to a single type of gamete: AB.

We can examine this using a Punnett square as follows:

	AB	Ab	aB	ab
AB	AABB	AABb	AaBB	AaBb

Thus, the offsprings are produced with four genotypes with equal frequency. The phenotypes associated with these genotypes are:

AABB: AB phenotype

AABb: AB phenotype

AaBB: AB phenotype

AaBb: AB phenotype

Thus there is a single phenotype present in the offspring. Hence the phenotypic ratio is 1. The correct option is A.

b) Mitosis begins with a single diploid/haploid cell and two copies of identical cells are produced. Since the chromosomal content in the parental cell and the daughter cell are equal, mitosis is also called an equational division.

Meiosis begins with a single diploid cell and four daughter cells with half the chromosomal content are produced. Hence it is also called as the reductional division.

Let us analyze each of the statements mentioned:

A) As argued above, meiosis does produce four daughter cells while mitosis produces two daughter cells. Hence this statement is correct.

B) Mitosis is observed in both haploid and diploid cells. Hence the daughter cells can be either haploid or diploid based on the parental cell. Meiosis, on the other hand, occurs only with diploid cells and results in production of haploid cells. Hence this statement is incorrect.

C) Cytokinesis refers to division of the cytoplasm. In mitosis, this occurs only once when the two daughter cells are formed. Meiosis takes place in two phases Meiosis I and Meiosis II. Meiosis I results in the production of two daughter cells and Meiosis II produces two daughter cells from each of the daughter cells of Meiosis I. Thus, there are two cytokinesis phases in Meiosis. Hence the statement is correct.

D) Meiosis I is the phase of Meiosis that results in the segregation of chromosomes in pairs. While Meiosis II is similar to mitosis. Hence Meiosis I is a unique phase of Meiosis. This statement is correct.

E) The tetrads are four haploid cells. These are formed in yeast when the parental diploid undergoes meiosis. Hence the statement is incorrect.

Thus there are two false statements here: B and E.

c) We have two genes that code for body color and eyes. Each gene has two alleles and is present on different chromosomes. Hence they are unlinked and can be segregated independently.

Both the parents are red bodied and blue-eyed. And the offsprings produced are red-bodied blue-eyed, red-bodied green-eyed, white-bodied blue-eyed and white-bodied green-eyed. Since there is no recombination event occurring, the new genotypes are a result of the expression of recessive alleles. Hence both the parents must be heterozygous for both the loci. Let R be the allele for body color that is dominant over r and results in the production of red-body as opposed to white-body by the allele r. Let B be the allele for eye color that is dominant over b and results in the production of blue-eyes as opposed to green-eyes by the allele b. Thus since both, the parents are heterozygotes for both the loci. Their genotypes are RrBb and RrBb. This is a dihybrid cross and the offsprings are basically those of the F2 generation in a Mendelian cross. Hence the phenotypic ratio is 9:3:3:1. Hence the correct option is D.

d) Mitosis is divided into several phases that have unique changes attributed to them. These phases are: Interphase, Prophase, Metaphase, Anaphase, and Telophase.

Interphase is the phase there is the onset of mitosis and the nucleolus starts disintegrating and chromosomes start condensing. During prophase, the chromosomes are condensed completely and the nucleolus and nuclear membrane is completely disintegrated. This is accompanied by the formation of spindle fibers that connect the centrioles to the chromosomes and also the homologous chromosome. The cell then enters metaphase, where the are arrange parallelly at a metaphase plate. The spindle fibers from the centrioles then start pulling these chromosomes towards the poles while the inter-chromosomal spindle fibers start pushing them away towards the pole during anaphase. Finally, during telophase, chromosomes start hydrating and undergo decondensation, nucleolus and nuclear starts reappearing a furrow develops that separates the daughter DNA molecules. In the cytokinesis, the cytoplasm divides completely and two daughter cells are formed.

Hence of the given options, the correct option is B. Chromosomes separate during Anaphase, while rest of the processes mentioned occur during Prophase.