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TLS Online TPP Program

#Question id: 5648

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

 What is a broader implication from the observations of the experiment?

#Unit 5. Developmental Biology

  1. In sea urchins, fertilization of eggs by sperm is dependent upon species-specific protein interactions.

  2. Only some species of sea urchins use receptor proteins on their eggs to bind sperm.

  3. Protein-coated plastic beads should not be used to test sperm binding to eggs.

  4. S. franciscanus is probably not a sea urchin, but must be some other type of organism.

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TLS Online TPP Program

#Question id: 12422

#Unit 10. Ecological Principles

What would be the doubling time of a population with an intrinsic rate of increase (r) of 0.024? 
TLS Online TPP Program

#Question id: 27003

#Unit 10. Ecological Principles

In competitive species N1 and N2, four individuals of N2 use the same resource as one individual of N1. According to the conversion factor, what is the value of the per capita competitive effect of N2 on N1(α) and per capita effect of N1 on N2 ( β) respectively?
TLS Online TPP Program

#Question id: 11411

#Unit 10. Ecological Principles

Vulnerability to extinction can be linked to species following characteristics. Which of the following statement are correct?

 A. Rare species are more prone to extinction than common ones.

 B. Species that are capable of migrating between fragments of habitat, such as between mainland areas and islands, may be more resistant to extinction

 C. Organisms that are specialists are more likely to go extinct

 D. Species with naturally long life spans may be more likely to become extinct
TLS Online TPP Program

#Question id: 9210

#Unit 9. Diversity of Life Forms

Overharvesting encourages extinction and is most likely to affect ________.
TLS Online TPP Program

#Question id: 5052

#Unit 5. Developmental Biology

cell populations within each germ layer expand and differentiate, resident stem cells are maintained within these developing tissues and function to generate cell types with restricted specificity for the tissue in which they reside. these stem cells are-