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TLS Online TPP Program

#Question id: 4714

After the drought of 1977, researchers hypothesized that on the Galápagos Island Daphne Major, medium ground finches with large, deep beaks survived better than those with smaller beaks because they could more easily crack and eat the tough Tribulus cistoides fruits. A tourist company sets up reliable feeding stations with a variety of bird seeds (different types and sizes) so that tourists can get a better look at the finches. Which of these events is now most likely to occur to finch beaks on this island?

#Unit 11. Evolution and Behavior

  1. evolution of yet larger, deeper beaks over time, until all birds have relatively large, deep beaks

  2. evolution of smaller, pointier beaks over time, until all birds have relatively small, pointy beaks

  3. increased variation in beak size and shape over time

  4. no change in beak size and shape over time

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TLS Online TPP Program

#Question id: 797

#Unit 1. Molecules and their Interaction Relevant to Biology

With respect to microRNAs, which, if any, of the following statements, is FALSE?)

A. MicroRNA genes often occur in gene clusters within introns of protein-coding genes and are usually transcribed by RNA polymerase II.

B. Like an mRNA a miRNA is initially produced as a larger precursor RNA that, like the great majority of mRNAs, usually has a 5’ cap and a poly(A) tail.

C. MicroRNAs are produced by germ-line cells only.

D. A miRNA is initially produced as a duplex RNA but in order to work it needs to be converted into a single-strand RNA.

E. MicroRNAs usually work as transcription factors.
TLS Online TPP Program

#Question id: 798

#Unit 1. Molecules and their Interaction Relevant to Biology

Match the structural properties of DNA with the respective types of DNA in which they are found.

COLUMN – ICOLUMN – II
A. Pitch per turn of helix

1. 45.6 angstrom


2. 24.6 angstrom


3. 33.2 angstrom

B. Helix packing diameter

1. 23.7 angstrom


2. 18.4 angstrom


3. 25.5 angstrom

C. Major-groove proportions

1. Flattened out on helix surface


2. Extremely narrow but very deep


3. Wide and of intermediate depth

D. Minor-groove proportions

1. Very broad but shallow


2. Extremely narrow but very deep


3. Narrow and of intermediate depth
TLS Online TPP Program

#Question id: 799

#Unit 1. Molecules and their Interaction Relevant to Biology

The two cleavage reactions required to generate the miRNA from these primary transcripts are mediated by two distinct RNases. A characteristic of both these enzymes is that they recognize and cleave RNAs on the basis of the structure of their substrates rather than their specific sequence. Which of the following statement is INCORRECT regarding the cleavage reactions that produces a mature RNA?
TLS Online TPP Program

#Question id: 800

#Unit 1. Molecules and their Interaction Relevant to Biology

Following table lists the two major forms of DNA duplexes, conformation of base attached to the sugar and the nature of major and minor grooves.

DNA duplex

Properties

(A)  A form

(i) Syn conformation of the base to sugar

(B)  B form

(ii) Anti conformation of the base to sugar

 

(iii) Wide major groove

 

(iv) Narrow major groove

 

(v) Wide minor groove 

 

(vi) Narrow minor groove 

 

(vii) C-3’ endo sugar puckering

 

(viii) C-2’ endo sugar puckering

TLS Online TPP Program

#Question id: 801

#Unit 1. Molecules and their Interaction Relevant to Biology

Identify the type of DNA from the structures given below and match the correct form with its characteristics described.
TLS Online TPP Program

#Question id: 802

#Unit 1. Molecules and their Interaction Relevant to Biology

A single-stranded DNA molecule contains 40 nucleotides with equal amounts of A, C, G, and T. This DNA strand can combine with a complementary DNA strand to form a double-stranded DNA molecule. Which is a possible sequence and structure for this DNA molecule?