TLS Online TPP Program

#Question id: 7250


Following statements are regarding to signals that regulate axis extension in chick embryos.

A. In the stage 10 chick embryo, Fgf8 inhibits expression of the retinoic acid (RA) synthesizing enzyme Raldh2 in the presomitic mesoderm and the expression of the RA receptor RARβ in the neural ectoderm, thus preventing RA from triggering differentiation in the caudal-lateral epiblast cells and the caudal-most paraxial mesoderm.

B. Fgf8 inhibits Sonic hedgehog (Shh) expression in the neural tube floorplate, controlling the onset of ventral patterning genes.

C. FGF signaling is also required for expression of Delta1 in the medial portion of the caudal-lateral epiblast cells and promotes expression of Wnt8c.

D. Fgf8 decays in the caudal paraxial mesoderm, Wnt signaling, most likely provided by Wnt8c, now acts to promote Raldh2 in the adjacent paraxial mesoderm. RA produced by Raldh2 activity expresses Fgf8 and Wnt8c.

Which of the following statements are correct?

#Unit 5. Developmental Biology
  1. A and B
  2. B, C and D
  3. A, B and C
  4. C and D
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TLS Online TPP Program

#Question id: 24511

#Unit 10. Ecological Principles

During a case, the parasitic worm Plagiorhynchus cylindraceus, that lives in the intestines of songbirds such as starling. They produce eggs that exit with the host feces, the feces are eaten by foraging pillbugs. The eggs hatch into a juvenile infective stage. Eventually, the infected pillbugs are eaten by birds and the life cycle continues. What will predict about these case given above?

TLS Online TPP Program

#Question id: 24512

#Unit 10. Ecological Principles

which parasites are involve to changes in the behaviour of host and making that host more susceptible to being eaten by a second host ?

TLS Online TPP Program

#Question id: 24513

#Unit 10. Ecological Principles

during a life cycle of adult lancet fluke live in cows. They spread their eggs in cow manure, snails eat the eggs and the immature parasites hatch and infect their intestine. The snail coughs up these offspring in balls of slime and ants eat these slime balls loaded with flukes. The flukes migrate to the ant’s head and make them climb to the tops of grass blades where they are eaten by cows and the cycle starts over again
a. Only ant act as inntermediate host 
b. both snail and Ant act as intermediate host
c. cow act as definitive host due to sexual reproduction
d. only snail act as intermediate host due to asexual reproduction

TLS Online TPP Program

#Question id: 24514

#Unit 10. Ecological Principles

Dicrocoelium dendritium  are adult lancet flukes produces egg, which act as definitive host that is,

TLS Online TPP Program

#Question id: 24515

#Unit 10. Ecological Principles

which of the following a definitive host of parasite toxoplasma gondii, where  it complete their sexual reproduction?

TLS Online TPP Program

#Question id: 24516

#Unit 10. Ecological Principles

which of the following parasitism is a form of feeding where one animal takes food that another has caught?