Quiz 04-January-2024

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Labmonk quiz, NET Life Science,

#1. The transition to flowering in plants requires

reprogramming of the shoot apical meristem.

growth of plants under short-day conditions.

synthesis of the flowering hormone florigen.

growth of plants under long-day conditions.

#2. cAMP signaling plays a very important role in the development and differentiation of Dictyostelium discoideum. This morphogen is synthesized by different adenyl cyclases expressed at different stages of its life cycle. The following statements (P-S) refer to the effect of mutations in different adenyl cyclase genes: P. aca deficient cells can be allowed to aggregate by exposing them to pulses of cAMP. Q. acb deficient cells would form normal fruiting bodies and the spores can germinate when exposed to favourable conditions. R. acg deficient cells develop normally and the spores germinate in the spore head itself. S. spores formed from the acg deficient cells will germinate irrespective of the osmotic conditions. Which of the above statements are correct?

P only

R and S

P and Q

P and S

#3. When a wrist blastema from a recently cut Axolotl forelimb is placed on a host hind limb cut at the mid-thigh level, it will generate only a wrist. The host (whose own hind limb was removed) will fill the gap and regenerate the limb up to the wrist. However, if the donor blastema is treated with retinoic acid on grafting, the wrist blastema will regenerate a complete limb and will not allow the host to fill the gap. This happens because retinoic acid

helps block the receptors of FGF essential for limb development.

helps in the proximalization of the blastema and activates the Hox genes differentially across the blastema.

helps in the distalization of the blastema and activates the Hox genes differentially across the blastema.

helps vigorous proliferation of the cells at the cut surface.

#4. In case of sea urchin, which of the following is the correct sequence of events taking place during the interaction of sperm and egg?

Chemoattraction of sperm to the egg by soluble molecules secreted by the egg → exocytosis of the sperm acrosomal vesicle to release its enzymes → binding of the sperm to the extracellular matrix of the egg → passage of sperm through this extracellular matrix → fusion of egg and sperm cell membranes

Chemoattraction of sperm to the egg by soluble molecules secreted by the egg → passage of sperm through this extracellular matrix → binding of the sperm to the extracellular matrix of the egg → exocytosis of the sperm acrosomal vesicle to release its enzymes → fusion of egg and sperm cell membranes

Chemoattraction of sperm to the egg by soluble molecules secreted by the egg → binding of the sperm to the extracellular matrix of the egg → exocytosis of the sperm acrosomal vesicle to release its enzymes → passage of sperm through this extracellular matrix → fusion of egg and sperm cell membranes

Chemoattraction of sperm to the egg by soluble molecules secreted by the egg → binding of the sperm to the extracellular matrix of the egg → passage of sperm through this extracellular matrix → exocytosis of the sperm acrosomal vesicle to release its enzymes → fusion of egg and sperm cell membranes

#5. The dwarf pea mutant (le) used by Mendel was defective in which of the following enzyme involved in gibberellin biosynthesis?

GA 3β-hydroxylase

GA 20-oxidase

ent-Kaurene synthase

ent-Kaurenoic acid hydroxylase

#6. During early cleavage of Caenorhabditis elegans embryos, each asymmetrical division produces one founder cell which produces differentiated descendants and one stem cell. The very first cell division produces one anterior founder cell, namely AB and one posterior stem cell, namely P1. When these blastomeres are experimentally separated and allowed to proceed further with development, one could get the following possible outcomes:

P1 cells would show conditional development while AB would show autonomous development.

both would show conditional specification and result in regulative development.

both would show autonomous specification and result in mosaic development.

P1 cell would develop autonomously while the AB would show conditional development.

#7. Which of the following statements with respect to alternate oxidase activity in cyanide-resistant respiration in plants, is not correct?

Alternate oxidase accepts electrons directly from cytochrome C.

When electrons pass to alternate oxidase, two sites of protein pumping are bypassed.

Transcription of alternate oxidase gene is often induced by various abiotic stresses.

Some plants exhibit thermogenesis during inflorescence development.

#8. Injection of noggin mRNA into a 1-cell, UV-irradiated embryos of frog completely rescues dorsal development and allows the formation of a complete embryo. Some of the following statements (P-S) could possibly explain this observation. P. Noggin is a secreted protein which induces dorsal ectoderm to form neural tissue and it dorsalizes the mesoderm cells which would otherwise contribute to ventral mesoderm. Q. Noggin binds directly to BMP4 and BMP2 thus preventing complex formation with their receptors. R. Noggin along with other molecules prevent BMP from binding to and inducing ectoderm and mesoderm cells near the organizer. S. Noggin is a secreted protein which induces the dorsal ectoderm to form the epidermis and it ventralizes the mesoderm cells which would otherwise contribute to dorsal mesoderm. Which of the above statements are correct?

P, Q and R

P and S

Q and R

P and Q

#9. Fill in the blanks (a, b, c and d) in the following statements with a proper combination of m, n o and p. Wherein m represents - longer n represents - shorter o represents - prevents p represents - induces Short day (SD) plants flower when night lengths are a than a critical dark period. Interruption of the dark period by a brief light treatment b flowering in SD plants. Long day (LD) plants flower when night length is c than a critical period. Shortening of the night with a brief light treatment d flowering in LD plants.

a-n, b-o, c-m, d-p

a-m, b-p, c-n, d-o

a-m, b-o, c-n, d-p

a-n, b-p, c-m, d-o

#10. In mature Arabidopsis embryo, root apical meristem consists of cells derived from

hypophysis only

embryo only

suspensor only

embryo and apical suspensor cell

Finish

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Quiz 04-January-2024

#1. The transition to flowering in plants requires

#4. In case of sea urchin, which of the following is the correct sequence of events taking place during the interaction of sperm and egg?

#5. The dwarf pea mutant (le) used by Mendel was defective in which of the following enzyme involved in gibberellin biosynthesis?

#7. Which of the following statements with respect to alternate oxidase activity in cyanide-resistant respiration in plants, is not correct?

#10. In mature Arabidopsis embryo, root apical meristem consists of cells derived from

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