Practice Questions

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#Question id: 1514

Following statements are regarding to multiple signaling pathways in vertebrate cells that regulate outer mitochondrial membrane permeability and apoptosis.

A. In healthy cells, the anti-apoptotic protein Bcl-2, or its homolog Bcl-xL, binds to Bak or Bax pro-apoptotic proteins, blocking the ability of Bak or Bax to oligomerize and form pores in the outer mitochondrial membrane.

B. The presence of specific trophic factors (e.g., NGF) leads to activation of their cognate receptor tyrosine kinases (e.g., TrkA) and inactivation of the PI-3 kinase–PKB (protein kinase B) pathway.

C. PKB phosphorylates Bad, and phosphorylated Bad forms a complex with a cytosolic 14-3-3 protein. This sequestered Bad is unable to bind to Bcl-2.

D. In the absence of trophic factors, nonphosphorylated Bad binds to Bcl-2, releasing Bax and Bak and allowing them to form oligomeric membrane pores and holes.

E. DNA damage or ultraviolet irradiation leads to induction of synthesis of the BH3-only Puma protein. Puma binds to Bak and Bax as well as to Bcl-2, allowing Bak and Bax to form oligomeric pores.

F. Removal of a cell from its substratum disrupts integrin signaling, leading to release of the BH3-only Bim protein from the cytoskeleton. Bim also binds to Bak and Bax to promote pore formation.

Which of the following is incorrect?

#Unit 4. Cell Communication and Cell Signaling

A and C
A, B, C and D
C, E and F
B only

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TLS Online TPP Program

#Question id: 12638

#Unit 6. System Physiology – Plant

strigolactone biosynthesis takes place , find the correct sequence of these signal transduction pathways;

a) D14* hydrolyses strigolactone and releases the products of hydrolysis.

b) D14 disengages from the SCFMAX2 complex and returns to its original conformation, allowing it to respond to fresh strigolactone signal.

c) D14* interacts with the F-box protein MAX2 and the other partners of the SCFMAX2 ubiquitin ligase complex.

d) The α-/β-fold hydrolase D14 binds and reacts with strigolactone, changing its conformation to the active form, D14*

e) Target protein(s) are recognized by the D14*–SCFMAX2 complex and are ubiquitinated

TLS Online TPP Program

#Question id: 12639

#Unit 6. System Physiology – Plant

Strigolactones are transported out of sites of synthesis via plasma membrane and have been shown to move in the xylem from root to shoot by which transporter?

TLS Online TPP Program

#Question id: 12640

#Unit 6. System Physiology – Plant

Plant species produce a which type of defensive proteins that bind to carbohydrates or carbohydrate-containing proteins. After being ingested by an herbivore, that bind to the epithelial cells lining the digestive tract and interfere with nutrient absorption

TLS Online TPP Program

#Question id: 12640

#Unit 10. Ecological Principles

Plant species produce a which type of defensive proteins that bind to carbohydrates or carbohydrate-containing proteins. After being ingested by an herbivore, that bind to the epithelial cells lining the digestive tract and interfere with nutrient absorption

TLS Online TPP Program

#Question id: 12641

#Unit 6. System Physiology – Plant

Among the diverse components of plant defense arsenals are proteins that interfere with herbivore digestion, Given some defense compound of plants in column I with its given action in column II

Column I	column II
I) α-amylase inhibitors	a) Antidigestive proteins, block the action of herbivore proteolytic enzymes. After entering the herbivore’s digestive tract, they hinder protein digestion by binding tightly and specifically to the active site of protein-hydrolyzing enzymes such as trypsin and chymotrypsin
II) Lectins	b) block the action of the starch-digesting enzyme
III) proteinase inhibitors	c) A defensive proteins that bind to carbohydrates or carbohydrate-containing proteins. After being ingested by an herbivore, bind to the epithelial cells lining the digestive tract and interfere with nutrient absorption

Correctly match the defence compound withits action on herbivore;

TLS Online TPP Program

#Question id: 12642

#Unit 6. System Physiology – Plant

The systemic production of proteinase inhibitors in young tomato plants is triggered by a complex sequence of events such as;

1) Prosystemin is proteolytically processed to produce the short polypeptide called systemin

2) Systemin is then transported out of the wounded leaf via the phloem.

3) systemin is believed to bind to a site on the plasma membrane and initiate the biosynthesis of jasmonic acid

4) Wounded tomato leaves synthesize prosystemin, a large recursor protein

5) Systemin is released from damaged cells into the apoplast

6) Jasmonic acid eventually activates the expression of genes that encode proteinase inhibitors

Arrange the correct sequence of given above following statements ;