TLS Online TPP Program

#Question id: 4959


If a fossil is encased in a stratum of sedimentary rock without any strata of igneous rock (e.g., lava, volcanic ash) nearby, then it should be

#SCPH06 I Botany
  1. easy to determine the absolute age of the fossil, because the radioisotopes in the sediments will not have been ʺresetʺ by the heat of the igneous rocks.

  2. easy to determine the absolute age of the fossil, because the igneous rocks will not have physically obstructed the deposition of sediment of a single age next to the fossil.

  3. difficult to determine the absolute age of the fossil, because the ʺmarker fossilsʺ common to igneous rock will be absent.

  4. difficult to determine the absolute age of the fossil, because radiometric dating of sedimentary rock is less accurate than that of igneous rock.

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TLS Online TPP Program

#Question id: 16130

#SCPH06 I Botany

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.              
How many units of ß-galactiosidase would you expect to be expressed from deletion 1 in a gln2– mutant? 

TLS Online TPP Program

#Question id: 16131

#SCPH01 Biochemistry

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.              
 How many units of ß-galactiosidase would you expect to be expressed from deletion 4 in a gln2– mutant?

TLS Online TPP Program

#Question id: 16132

#SCPH01 Biochemistry

You are running a human assisted reproduction clinic and providing state-of-the-art genetic diagnostic services. A married couple who already had a child with cystic fibrosis approach you because they wish to have another child, but only if they can be assured that the child will not have cystic fibrosis. You genotype the woman and discover that she is a heterozygote for Del508, the most common mutation causing cystic fibrosis. You suggest that the couple consider first polar body testing, in which several unfertilized oocytes (each with its first polar body) are retrieved from the woman, the first polar bodies are removed, and PCR tests are conducted on DNA from each of the first polar bodies. The couple agrees, and you obtain the following results:
 
the observation that the polar bodies for oocytes #1 and #5 test positive for both Del508 and the wild type sequence, because

TLS Online TPP Program

#Question id: 16132

#SCPH06 I Botany

You are running a human assisted reproduction clinic and providing state-of-the-art genetic diagnostic services. A married couple who already had a child with cystic fibrosis approach you because they wish to have another child, but only if they can be assured that the child will not have cystic fibrosis. You genotype the woman and discover that she is a heterozygote for Del508, the most common mutation causing cystic fibrosis. You suggest that the couple consider first polar body testing, in which several unfertilized oocytes (each with its first polar body) are retrieved from the woman, the first polar bodies are removed, and PCR tests are conducted on DNA from each of the first polar bodies. The couple agrees, and you obtain the following results:
 
the observation that the polar bodies for oocytes #1 and #5 test positive for both Del508 and the wild type sequence, because

TLS Online TPP Program

#Question id: 16133

#SCPH01 Biochemistry

You are running a human assisted reproduction clinic and providing state-of-the-art genetic diagnostic services. A married couple who already had a child with cystic fibrosis approach you because they wish to have another child, but only if they can be assured that the child will not have cystic fibrosis. You genotype the woman and discover that she is a heterozygote for Del508, the most common mutation causing cystic fibrosis. You suggest that the couple consider first polar body testing, in which several unfertilized oocytes (each with its first polar body) are retrieved from the woman, the first polar bodies are removed, and PCR tests are conducted on DNA from each of the first polar bodies. The couple agrees, and you obtain the following results:

 
Given the couple's desire to have a child without cystic fibrosis, which oocytes would you employ in vitro fertilization?

TLS Online TPP Program

#Question id: 16133

#SCPH06 I Botany

You are running a human assisted reproduction clinic and providing state-of-the-art genetic diagnostic services. A married couple who already had a child with cystic fibrosis approach you because they wish to have another child, but only if they can be assured that the child will not have cystic fibrosis. You genotype the woman and discover that she is a heterozygote for Del508, the most common mutation causing cystic fibrosis. You suggest that the couple consider first polar body testing, in which several unfertilized oocytes (each with its first polar body) are retrieved from the woman, the first polar bodies are removed, and PCR tests are conducted on DNA from each of the first polar bodies. The couple agrees, and you obtain the following results:

 
Given the couple's desire to have a child without cystic fibrosis, which oocytes would you employ in vitro fertilization?