Following are the statements regarding to establishment of positive feedback loops for limb bud formation.

A. In the presumptive forelimb field, Tbx5 induces Wnt2b, which then upregulates Fgf10, which in turn positively feeds back to maintain activation of both Wnt2b and Tbx5.

B. Mesodermal Fgf10 tells the surface ectoderm to continue to make Fgf8, and the surface ectoderm continues to tell the underlying mesoderm to make Fgf10.

C. Fgf10 provides the signal to initiate and propagate the limb-forming interactions between ectoderm and mesoderm, and these signaling interactions directly promote limb bud formation and growth.

D. The Wnt protein acts through the canonical β-catenin pathway to induce Fgf8 expression in the ectoderm. This relay of signaling represents a foundational stage in the formation of limb buds, because once Fgf8 is made in the surface ectoderm, the surface ectoderm elongates to physically become the AER.

Which of the following statements correctly explained positive feedback loops during limb development?

#Question id: 4785

#Unit 8. Inheritance Biology

One form of white eye is a recessive X-linked gene in Drosophila. From a mating of a heterozygous wild-type Drosophila female with a white-eyed male, what is the probability of wild type offspring?

#Question id: 4786

#Unit 8. Inheritance Biology

Following biochemical pathway for agouti phenotype in mice is control by gene A and B. when cross between AAbb xaaBB, what will be phenotype ratio in F2 generation? 

#Question id: 4787

#Unit 8. Inheritance Biology

In humans, PKU (phenylketonuria) is a recessive disease caused by enzyme inefficiency at step A in the following simplified reaction sequence, and AKU (alkaptonuria) is a recessive disease due to enzyme inefficiency in one of the steps summarized as step B here:A person with PKU and homozygous for normal of other character was married a person with AKU and homozygous for normal of other character. What is expected phenotypes in their children?

#Question id: 4788

#Unit 8. Inheritance Biology

The wild-type (W) Abraxas moth has large spots on its wings, but the lacticolor (L) form of this species has very small spots. Crosses were made between strains differing in this character, with the following results:

 What are correct conclude from genetic explanation of the results in these two crosses

a. female are heterogametic but male are homogametic for sex chromosome

b. female are homogametic but male are heterogametic for sex chromosome

c.Trait  for spot shape linked with sex chromosome

d. Trait  for spot shape linked with autosome chromosome

e. Gene  for spot shape  present on  mitochondrial genome

#Question id: 4789

#Unit 8. Inheritance Biology

Red flower in plant mediated by three non-allelic genes as a follows Homozygous for mutant allele a ,b,c at any locus give white flower. A plant with Genotype Aabbcc is cross with genotype aaBbCc Plant. What is proportional of white flower among their offspring?

#Question id: 4790

#Unit 8. Inheritance Biology

The F2 genotypes of two independently assorting gene A and B with complete dominance result in a 9 : 3 : 3 : 1 ratio of phenotypes if there is no interaction between the genes. Following modify phenotypic ratio of 9:3:3:1 given as following table (p - phenotype) Which of the following correct matching of gene interaction and their deviated phenotype ratio?