Human and Fish Embryos Share a Number of Features

question 67

Multiple Choice

Human and fish embryos share a number of features. Why is this?

• A)Humans and fish share a common ancestor.
• B)Embryos of all organisms, plant and animal, look alike.
• C)Mutations in human and fish embryos have caused them to look alike.
• D)Humans and fish have exactly the same genes, but as they develop, different genes are turned on in fish than in humans.

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Definitions:

Knee-Jerk Reflex

Another term for the patellar reflex, indicating the spontaneous kicking movement of the lower leg in response to a sharp tap on the patellar tendon.

Inhibitory Interneurons

Neurons that decrease the likelihood of a target neuron firing, playing a key role in the modulation of neural circuits.

Gamma Motor Neurons

Neurons that control the sensitivity of muscle spindle fibers to stretch, thereby adjusting the tension of muscles.

Muscle Spindles

Sensory receptors within muscles that detect changes in muscle length and participate in regulating muscle contraction.