Practice Questions

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

In sea urchins, fertilization of eggs by sperm is dependent upon species-specific protein interactions.
Only some species of sea urchins use receptor proteins on their eggs to bind sperm.
Protein-coated plastic beads should not be used to test sperm binding to eggs.
S. franciscanus is probably not a sea urchin, but must be some other type of organism.

More Questions

#Question id: 1406

#Unit 4. Cell Communication and Cell Signaling

Which of the following is a consequence of p53 stabilization?

a. stabilization of Cdc25A b. activation of ATM c. blocked apoptosis

d. transcription of p21 e. DNA repair

#Question id: 16121

#Unit 7. System Physiology – Animal

Match the following mechanisms (Column I) with their correct example (Column II).

Column I	Column II
A. Heat-generating and heat-retaining mechanisms	i. increased metabolic rate (thyroid hormones, sympathetic nervous system)
B. Heat-dissipating mechanisms	ii. vasodilation of blood vessels of the skin (decreased sympathetic tone)
	iii. increased activity of sympathetic cholinergic fibers to sweat glands.
	iv. shivering
	v. vasoconstriction of blood vessels of the skin (increased sympathetic tone)