Contrast typical embryonic development in protostomes and deuterostomes
What will be an ideal response?
Protostome embryos typically have determinate, spiral cleavage as cells divide, while deuterostome
embryos have indeterminate, radial cleavage. Also, protostome mesoderm differentiates near the
blastopore and forms a coelom (schizocoelom) within the mesoderm. Deuterostome mesoderm instead
forms as outpocketings of the archenteron, forming the coelom (enterocoelom) from the space in the
outpocketings. Finally, in protostomes the blastopore becomes the mouth and a second, later opening
becomes the anus, while in deuterostomes the blastopore becomes the anus and the mouth instead
forms from a later opening.
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How do protists assist termites in digesting wood?
a. They protect the termites’ gut from damage from the cellulose fibers. b. Enzymes produced by the protists break down carbon. c. Protists absorb nutrients from the wood in the termites’ guts. d. Enzymes produced by protists in the termites’ guts break down cellulose.
A couple has 5 children, all sons. If the women gives birth to a sixth child, what is the probability that the sixth child will be a son?
A. 5/6 B. 1/2 C. 1/5 D. 1/6 E. 1/64
Water in a pond contaminated with the weed killer atrazine is suspected of inhibiting metamorphosis in northern leopard frogs. A team of scientists collected fertilized northern leopard frog eggs from a different pond that is not contaminated. Which of the following is the best experimental design to determine whether atrazine is responsible for inhibiting metamorphosis in northern leopard frogs?
(A) Place half of the fertilized eggs in a pool of water with the same concentration of atrazine as the contaminated pond and place the other half of the fertilized eggs in a pool of water that has no atrazine. Monitor the development of the embryos through metamorphosis into adulthood. (B) Place all of the fertilized eggs in a pool of pond water with the same concentration of atrazine as the contaminated pond and compare the number of frogs that reach metamorphosis to those that reach adulthood in the contaminated pond. (C) Allow all fertilized eggs to develop into adults. Expose one-third of the frogs to one-half of the concentration of atrazine in the contaminated pond and expose another one-third of the frogs to the same concentration of atrazine as the contaminated pond. Leave the last one-third of the frogs in water with no atrazine and note any adverse changes in the physical condition of the atrazine-treated frogs in three months. (D) Divide the fertilized eggs into three groups and expose each group to a different concentration of atrazine. Release the eggs back into the contaminated pond and check for metamorphosis after three months.
Which compound would be the most useful to treat candidiasis?
A) uracil B) thymine C) flucytosine D) guanine E) penicillin