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Multiple Choice
Which of the following is true of an infant's brain at birth?
A
It contains nearly all the neurons it will ever have.
B
It has fewer synapses than an adult brain.
C
It is fully myelinated and functions like an adult brain.
D
It is larger than the adult brain relative to body size.
Verified step by step guidance
1
Understand the question: The problem is asking about the characteristics of an infant's brain at birth. Each option provided describes a specific feature of the infant brain, and we need to determine which one is true.
Step 1: Recall the biological development of the brain. At birth, an infant's brain contains nearly all the neurons it will ever have. This is a key fact in developmental biology, as the number of neurons does not significantly increase after birth, but their connections (synapses) and organization change dramatically.
Step 2: Evaluate the second option. An infant's brain has fewer synapses than an adult brain because synaptogenesis (the formation of synapses) occurs rapidly after birth, especially during the first few years of life. This makes the second statement true as well.
Step 3: Analyze the third option. The infant brain is not fully myelinated at birth. Myelination, the process of forming the protective sheath around neurons, continues into adolescence. Therefore, the third statement is false.
Step 4: Consider the fourth option. Relative to body size, an infant's brain is larger than an adult brain. This is true because the brain grows rapidly during early development, and its size is proportionally larger compared to the rest of the body at birth.