A research group claims that they have discovered microscopic fossilized embryos, including some at the blastula stage, but other researchers are skeptical. Finally, one student develops a technique for splitting the embryos in half to reveal the substructure. Cutting open the first blastocyst embryo, the student is very excited. “It is a blastula!" she shouts,"Look, you can see the ____________________ inside!”
A. granulosa cells
B. hollow blastocoel
C. archenteron
D. neural tube
Clarify Question
What is the key concept addressed by the question?
What type of thinking is required?
Gather Content
What do you already know about a blastula? What other information is related to the question?
Choose Answer
Given what you now know, what information is most likely to produce the correct answer?
Reflect on Process
Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
B. hollow blastocoel
Clarify Question
What is the key concept addressed by the question?
· The concept addressed here is the recognition of the developmental stage known as the blastula.
What type of thinking is required?
· Apply level:
o You are being asked to take what you already know and use, or apply, it to identify the diagnostic features of a blastula.
Gather Content
What do you already know about a blastula? What other information is related to the question?
· A fertilized egg is known as a zygote.
· As a zygote divides, it does not increase in size. Rather it subdivides, so each generation of cells is smaller than the previous one.
· Eventually the new cells form a hollow ball of cells. These cells surround a central cavity called a blastocoel.
Choose Answer
Given what you now know, what information is most likely to produce the correct answer?
· The archenteron and neural tube form after the blastula. If either of these structures are present the blastula stage has been left behind.
· Granulosa cells are part of an unfertilized egg. If these cells are present it would be too early for a blastula to have formed.
· Seeing a blastocoel would be indicative that a blastula is present, as a blastocoel is a characteristic of a blastula.
Reflect on Process
Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
· Apply level:
o Answering this question correctly depended on your ability to use the nature of a blastula in a new situation. If you got an incorrect answer, did you remember that blastula is a hollow ball of cells, or that in the middle of the hollow ball of cells is a space known as the blastocoel? Did you have trouble recognizing the diagnostic features of a blastula to determine the correct answer?
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