Wild type E. coli metabolizes the sugar lactose by expressing the enzyme ß-galactosidase. You have isolated a mutant that you call lac1–, which cannot synthesize ß-galactosidase and cannot grow on lactose (Lac–). During an condition isolate a mutation that constitutively expresses abnormally high levels of ßgalactosidase, which you designate lacc. Preliminary P1 transduction experiments indicate that lacc  is linked to the Tn5 insertion.  To map lacc  relative to lac1– you set up two reciprocal crosses. In the first cross you grow P1 on a strain that carries the Tn5 insertion and the lac1– mutation. You then use this lysate to infect a lacc mutant and select for Kanr. From 100 Kanr transductants examined, 20 are Lac–, 76 express ß-galactosidase constitutively and 4 show normal ß-galactosidase expression. In the second cross you grow P1 on a strain that carries the Tn5 insertion and the lacc mutation. You then use this lysate to infect a lac1– mutant, and select for Kanr. From 100 Kanr transductants examined, 81 are Lac– and 19  express ß-galactosidase constitutively. So what will be the correct order of  the Tn5 insertion and the lac1– and lacc  mutations. Express any measured distances as cotransduction frequencies.

#Question id: 7284

#Unit 5. Developmental Biology

Choose the correct match.

#Question id: 7285

#Unit 5. Developmental Biology

During xenopus gastrulation, C3a functions as a short-range chemoattractant to guide the radial intercalation movements of cells. If Knockdown of C3a with antisense morpholinos results:

#Question id: 7286

#Unit 5. Developmental Biology

Which of the floral whorls is affected in apetala 3/pistillata (ap3/pi) mutants?

#Question id: 7287

#Unit 5. Developmental Biology

Following statements are regarding to the the floral quartet model and the underlying ABCDE model of organ identity determination in Arabidopsis thaliana.

A. Five floral organ identities (sepals, petals, stamens, carpels, and ovules) are specified by the formation of floral organ-specific tetrameric complexes of MADS-domain transcription factors that bind to two nearby enhancer elements, forming a DNA loop in between.

B. A complex of two class A proteins (APETALA 1) and two class E proteins  (SEPALLATA) determines petal identity.

C. A complex of one class A protein, one class E protein, and one of each of the class B proteins (APETALA 3 and PISTILLATA) determines sepal identity.

D. A complex of one class E protein, two class B proteins, and one class C protein (AGAMOUS) determines stamen identity, while a complex of two class E proteins and two class C proteins determines carpel identity.D. A complex of one class E protein, two class B proteins, and one class C protein (AGAMOUS) determines stamen identity, while a complex of two class E proteins and two class C proteins determines carpel identity.

E. A complex of one class E protein, one class C protein, and one of each of the class D proteins (SHATTERPROOF and SEEDSTICK) controls ovule identity.

Which of the following combination are correct?

#Question id: 7288

#Unit 5. Developmental Biology

Following statements are regarding to the expression of genes in floral quartate model in Arabidopsis thaliana.

A. Sepals- AP1(heterodimer) + SEP(homodimer)

B. Petals-AP1(monomer)+PI(monomer)+AP3(monomer)+SEP(monomer)

C. Stamens- AP3(monomer)+PI(monomer)+AG(monomer)+SEP(monomer)

D. Carpels- AG(homodimer)+SEP(homodimer)

Which of the following genetic combinations are incorrect?

#Question id: 7289

#Unit 1. Molecules and their Interaction Relevant to Biology

The following scheme shows the flowering status of a plant species and the photoperiodism. Which of the following conclusions is most appropriate?