In humans, albinism (unpigmented skin, hair, and eyes) is due to an enzymatic deficiency, and it is an autosomal recessive trait. Suppose that in a small country of one million people (“Generation 1”), there are 500 aa albinos and 9000 Aa heterozygous carriers. What is the probability that a child will be albino if: Both parents are members of Generation 2, and one parent is albino and the other is non-albino.

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#Question id: 7310

#Unit 5. Developmental Biology

Which statement best describes the mechanism for circadian rhythm?

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#Question id: 12483

#Unit 2. Cellular Organization

ATM and ATR are protein kinases that become activated following specific types of DNA damage. 

A. ATM becomes activated in response to double‐strand breaks, which are detected by the MRN protein complex. 

B. ATR becomes activated by protein‐coated ssDNA that forms when replication forks become stalled or the DNA is being repaired after various types of damage.

C. ATR phosphorylates and activates the checkpoint kinase Chk2, which phosphorylates p53. D. ATM phosphorylates and activates the checkpoint kinase Chk1, which phosphorylates and inactivates the phosphatase Cdc25.

Which of the following combination is incorrect?

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#Question id: 16126

#Unit 13. Methods in Biology

2 You are studying regulation of the yeast enzyme glutamine synthetase (GS), which is encoded by the GLN1 gene. You have isolated two mutants, designated gln2– and gln3–, that give decreased GS activity. Mating of either gln2– or gln3– haploids to wild type produces heterozygous diploids that show normal amounts of GS expression. When you cross either a gln2– or gln3– haploid to a gln1– strain the resulting diploids show normal expression of GS, that could explain the effect of the gln2– and gln3– mutations on the regulation of GLN1.

The GLN1 gene shows a rather complex regulation in response to different amino acids. When either glutamate (glu) or glutamine (gln) is added to the medium, the amount of GS expression diminished and when both glutamate and glutamine are added to the medium GS expression is shut off completely. The effects of different mutants on the response to glu and gln are shown below.

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#Question id: 2136

#Unit 2. Cellular Organization

When a bacterium such as E. coli is shifted from a warmer growth temperature to a cooler growth temperature, it compensates by:

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#Question id: 4315

#Unit 3. Fundamental Processes

A researcher introduces double-stranded RNA into a culture of mammalian cells and can identify its location or that of its smaller subsections experimentally, using a fluorescent probe. When she finds that the introduced strand separates into single-stranded RNAs, what other evidence of this single-stranded RNA piece's activity would she find?