Practice Questions

TLS Online TPP Program

#Question id: 2918

Some DNA sequences in our cells have high frequencies of methylated cytosines (hypermethylation); some others have a low frequency of methylated cytosines (hypomethylation). Which of the two methylation states best describes the kind of sequences listed below?

I. Satellite DNA in pericentromeric heterochromatin

II. Promoters

III. Dispersed transposon repeats

IV. CpG islands

V. Enhancers

#Unit 2. Cellular Organization

I – hypermethylated ; III – hypomethylated ; V – hypomethylated
IV – hypermethylated ; II – hypomethylated ; III – hypermethylated
I – hypermethylated ; II – hypomethylated ; III – hypermethylated
V – hypermethylated ; II – hypomethylated ; III – hypermethylated

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TLS Online TPP Program

#Question id: 13190

#Unit 10. Ecological Principles

During the evolution of life on Earth, the photosynthetic organisms initially responsible for raising atmospheric oxygen concentrations from less than 1 percent to about 20 percent were

TLS Online TPP Program

#Question id: 13191

#Unit 10. Ecological Principles

Which of the following statements about circadian rhythms is correct?

TLS Online TPP Program

#Question id: 13192

#Unit 10. Ecological Principles

In the schematic below, the left panel represents climatic zones occupied by two different biomes, X and Y, along gradients of temperature and precipitation. The right panel depicts the expected species-area relationships of these two biomes. From the figures below, which of the following are most likely to be true?

TLS Online TPP Program

#Question id: 13193

#Unit 1. Molecules and their Interaction Relevant to Biology

Data, collected from DNAs of a great many different species, led Chargaff to the following conclusions:

A. The base composition of DNA generally varies from one species to another.

B. DNA specimens isolated from different tissues of the same species have the different base composition.

C. The base composition of DNA in a given species changes with an organism’s age, nutritional state, or changing environment.

D. In all cellular DNAs, the sum of the purine residues equals the sum of the pyrimidine residues.

Which of the above statements are INCORRECT regarding Chargaff’s rule?

TLS Online TPP Program

#Question id: 13194

#Unit 1. Molecules and their Interaction Relevant to Biology