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TLS Online TPP Program

#Question id: 762

Regarding the sugar residues in nucleic acids, which, if any, of the following statements is incorrect?

#Unit 1. Molecules and their Interaction Relevant to Biology

  1. The sugar is always based on a heterocyclic ring that consists of one oxygen atom and four carbon atoms, one of which is connected to a fifth carbon atom, the 5’ carbon atom.

  2. The internal sugar residues in a DNA strand normally have free hydroxyl groups, unlike those in an RNA strand.

  3. Bases are covalently linked to the carbon 1’ atoms of the sugars.

  4. Neighboring sugar residues are linked to each other by a phosphodiester bond that connects the 3’ carbon atom on one sugar to the 5’ carbon atom of its neighbour.

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TLS Online TPP Program

#Question id: 15835

#Unit 8. Inheritance Biology

You are interested in a new type of autosomal dominant mutation that gives purple eyes in Drosophila. You have a true-breeding purple-eyed line carrying a mutation that you call pr-1. You have isolated a second purple-eyed mutation that you call pr-2, which you have established in a true-breeding line that also carries a recessive marker st, which gives stubby legs. You cross a fly from the pr-1 line to a fly from the st, pr-2 line producing F1 females which you then cross to males from a true breeding st line (normal eyes). From this cross, 1000 progeny flies can be categorized into four different phenotypic classes:
                       
What is the distance between pr-1 and pr-2 in cM?
TLS Online TPP Program

#Question id: 28933

#Unit 7. System Physiology – Animal

Posterior pituitary releasing hormones is__
TLS Online TPP Program

#Question id: 23833

#Unit 2. Cellular Organization

Which of the following is NOT a key determinant of Myosin II?
TLS Online TPP Program

#Question id: 1374

#Unit 4. Cell Communication and Cell Signaling

Following statements are regarding to gap junctions.

i. Vertebrate gap junctions are composed of connexins, a family of structurally related transmembrane proteins with molecular weights between 26,000 and 60,000.

ii. Each vertebrate hexagonal particle consists of six noncovalently associated connexin molecules. Each individual connexin molecule has two membrane-spanning α helices with a topology similar to that of claudin.

iii. The permeability of gap junctions is regulated by posttranslational modification of connexins (e.g., phosphorylation) and is sensitive to changes in environmental conditions

such as intracellular pH and Ca2+ concentration, membrane potential, and the intercellular potential between adjacent interconnected cells (“voltage gating”).

iv. The assembly of connexins, their trafficking within cells, and the formation of functional gap junctions apparently depend on N-cadherin and its associated adapter proteins as well as desmosomal proteins.

Which of the following statements are correct?
TLS Online TPP Program

#Question id: 3324

#Unit 11. Evolution and Behavior

If only 20 males and 20 female grizzlies exist today, but only 10 of the males and 6 female breed, what are effective population size?