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TLS Online TPP Program

#Question id: 12708

800 meiocytes with the genotype AaBb undergoes meiosis with 60% chance of crossing over with A and B. How many recombinant gamete form?

#Unit 8. Inheritance Biology
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TLS Online TPP Program

#Question id: 5647

#Unit 5. Developmental Biology

Use the following information to answer the question. In order to test how sea urchin sperm bind to eggs, scientists isolated the egg receptor protein

that binds to the sperm acrosomal protein called bindin. Plastic beads were coated with egg receptor for bindin (ERB1) from eggs of the sea urchin Strongylocentrotus purpuratus, and then the beads mixed with sperm from S. purpuratus or from the related species, S. franciscanus. The researchers counted how many sperm were bound to each bead. The results are shown in the graph below. Treatments:

A: S. purpuratus sperm mixed with S. purpuratus ERB1 beads

B: S. purpuratus sperm mixed with beads containing no ERB1 protein

C: S. franciscanus sperm mixed with S. purpuratus ERB1 beads

D: S. franciscanus sperm mixed with beads containing no ERB1 protein

Based on the data in the graph, which of the following conclusions is supported?
TLS Online TPP Program

#Question id: 4576

#Unit 11. Evolution and Behavior

Which of the following pairs of structures is least likely to represent homology?
TLS Online TPP Program

#Question id: 909

#Unit 1. Molecules and their Interaction Relevant to Biology

Most proteins denature at both high and low pH. At high pH, the ionization of internal tyrosines is thought to be the main destabilizing influence, whereas at low pH, the protonation of buried histidines. A titration curve for the unfolding of the enzyme ribonuclease is shown in Figure. Given the relation between the titration curves for protein unfolding and histidine protonation, which of the following conclusion can be drawn correctly?

A. The sharp transition in graph indicates a highly cooperative process; when the protein starts to unfold, it completes the process rapidly

B. The sharp transition in graph indicates a highly noncooperative process

C. Several buried histidines can ionize when the chain starts to unfold, so that when one goes, they all go together due to cooperative behaviour of protein folding

D. Buried histidine (pK of 4 in this example) becomes accessible to solvent, its pK will shift toward its normal value of 6, significantly steepening its titration curve.
TLS Online TPP Program

#Question id: 2089

#Unit 2. Cellular Organization

What type of single-pass membrane protein would contain a hydrophobic membrane spanning alpha-helix?
TLS Online TPP Program

#Question id: 15193

#Unit 8. Inheritance Biology

Genes that control coat color in mammals represent some of the best early examples of genes with multiple alleles exhibiting different phenotypes. A classic example is the C gene in hamsters. Three of the known alleles of this gene are C, ca and ck. Each supplies a different amount of black pigment to the coat hair. The phenotypes of three different homozygous strains are as follows.
would mate the true-breeding  ca ca  hamsters to the true-breeding ck ck  hamsters to produce heterozygous  ca and ck  F1 progeny. Crosses and their interpretation that would have allowed geneticists to come to the conclusion that ca and ck were likely to be alleles of the same using the concept that alleles of the same gene will be tightly linked. What will be the ratio of F2 hamster;