A Researcher Working with the Embryo of the Sea Snail

question 228

Multiple Choice

A researcher working with the embryo of the sea snail Ilyanassa allows the embryo to go through two cleavages and then removes one of the four cells.The embryo continues to develop into a swimming larva, but the larva is missing a number of structures, such as the intestine, heart, retractor muscles, and eyes.From this, the researcher is most likely to conclude that

• A) the cell that was removed from this sea snail embryo could develop into an intact larva.
• B) the early embryo of this sea snail is similar to a human embryo in an early stage of development in not being able to regulate after loss of a cell.
• C) there are informational molecules in the early embryo of this sea snail that restrict the fate of early blastomeres.
• D) the sea snail embryo will form conjoined twins if it is divided in half at the four-cell stage.
• E) each cell of the early sea snail embryo is autonomous and able to form a complete larva.

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Definitions:

Biological Drives

Fundamental physiological needs that drive behavior, such as hunger, thirst, sleep, and reproduction.

Attachment Relationships

Emotional bonds formed between individuals, particularly between a child and a caregiver, which are critical for the child's development.

Mirror Neurons

Neurons that fire both when an individual acts and when the individual observes the same action performed by another, thought to be involved in empathy, learning, and understanding others' actions.

Brain Cells

The cells that make up the brain, including neurons, which are responsible for transmitting information, and glia, which support neuron function.