TLS Online TPP Program

#Question id: 7297


How is the ABC model for floral identity in Arabidopsis similar to the models for homeotic gene function derived from studies in Drosophila?

#Unit 5. Developmental Biology
  1. The key resposnsibility of homeotic genes in both is patterning of dorsal-ventral asymmetry.
  2. In both organisms, one homeotic gene is expressed at the two ends, a second expressed in to domains more central to that of the first and a third expressed more centrally, thus contributing unambiguous identities to all regions of the organism.
  3. In both organisms, homeotic genes interact, so that it is often the combination of genes present that is critical in specifying structure in adult.
  4. The ABC model of Arabidopsis is essentially identical to the Drosophila model for homeotic gene function, in that the Drosophila version of the A gene is abdominal-A, the Drosophila version of the B gene is Abdominal-B, and the Drosophila version of the C gene is Ultrabithorax.

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TLS Online TPP Program

#Question id: 13203

#Unit 6. System Physiology – Plant

Intermediary cells are specialized companion cells that are involved in phloem loading in the plant. Which of the following pathway that have included the intermediary-type companion cells?

TLS Online TPP Program

#Question id: 13201

#Unit 6. System Physiology – Plant

Phloem loading in the apoplastic pathway thought to mediate the transport of sucrose from the apoplast into the sieve element– companion cell complex. Which of the following  are involved in such sucrose transporting by apoplast?
a) Sucrose is at a higher concentration in the sieve element–companion cell complex indicates that sucrose is actively transported against its chemical-potential gradient
b) Sugars transport from the apoplast into the sieve elements and companion cells energy driven process
c) Phloem loading in the apoplastic pathway involves a sucrose–H+ symporter
d) the route of phloem loading is−mesophyll cells→ bundle sheath cells→ phloem parenchyma cell→ ordinary companion cell→ sieve elements
Which of the following is incorrect?

TLS Online TPP Program

#Question id: 11743

#Unit 6. System Physiology – Plant

The wall between the two mature sieve tube elements contain a sieve plates, these sieve plate pores are open —that is, unobstructed by

TLS Online TPP Program

#Question id: 11742

#Unit 6. System Physiology – Plant

Mature sieve elements external view, showing sieve plates. The pores in the sieve plates between the sieve tube elements are open channels, what is the relevance of this open pores in the sieve plates?

TLS Online TPP Program

#Question id: 11741

#Unit 6. System Physiology – Plant

phloem transport indicating the importance of long distance transport in plants, the experiments demonstrated that removal of a ring of bark around the trunk of a tree, which removes the phloem. What will be its effect?

TLS Online TPP Program

#Question id: 11740

#Unit 6. System Physiology – Plant

Some given characteristics of the two types of sieve elements in seed plants such as Sieve tube elements and Sieve cells. Find out the  true characteristics of sieve tube elements from the given statements;

i) Found in angiosperms

ii) Sieve plate pores are open channels

iii) Albuminous cells sometimes function as companion cells

iv) P-protein is present in all eudicots and many monocots

v) There are no sieve plates; all sieve areas are similar