Question 1

At birth,the size of an infant's brain is ____% of an adult's brain,and by age 2 it is ____% of an adult's brain.

Accepted Answer

At birth, the size of an infant's brain is approximately 25% of an adult's brain, and by age 2 it is about 70% of an adult's brain.

Question 2

Compared to other animals,the human brain is very large at birth,but it is also ____.

Accepted Answer

The human brain is relatively immature at birth despite its large size. This is why human infants are dependent on their parents for a longer period of time compared to other animals.

Question 3

Neurons communicate between each other chemically across small gaps.What are these gaps called?

Accepted Answer

These gaps are called synapses.

Question 4

Lorenzo first develops the ability to control his chest,then his arms,then his hands,and finally his fingers.This progression of motor development is called the ____.

Accepted Answer

The proximodistal principle of motor development states that children's abilities to control their muscles and movements develop from the center of their bodies (proximal) outward to their extremities (distal). This means that children first gain control of large muscle groups close to their trunk before gaining control of smaller muscle groups in their hands and fingers. This process is evidenced by Lorenzo's progression of motor development from controlling his chest, then arms, then hands, and finally fingers. Therefore, the best choice is D) proximodistal principle.

Question 5

Height during the first year of life increases ____.

Accepted Answer

During the first year of life, height increases in spurts or unevenly. There are rapid periods of growth, followed by periods of slower growth. This is due to the fact that different parts of the body grow at different rates during infancy. For example, the head grows more rapidly in the first few months, while the limbs and trunk catch up later on.

Question 6

In the first year of life,infants accumulate fat.This helps the infant ____.

Accepted Answer

Infants are born with very little body fat and therefore are vulnerable to temperature changes. Accumulating fat in the first year of life helps them maintain a constant body temperature.

Question 7

What part of a neuron receives the neurotransmitters?

Accepted Answer

Neurotransmitters are chemical messengers that are released from the axon terminals of one neuron to the dendrites of another neuron. Therefore, the dendrites are the part of the neuron that receives the neurotransmitters.

Question 8

Helena first develops the ability to control her head.She then could sit up unassisted,and eventually could walk.This progression of motor development is called the ____.

Accepted Answer

The cephalocaudal principle describes the pattern of growth and development that occurs from the head down. This means that infants first gain control of their head and neck, then their upper body and arms, followed by their lower body and legs. Helena's progression from controlling her head, to sitting up unassisted, and finally walking, aligns with this principle.

Question 9

Approximately how many neurons are there in the average infant's brain?

Accepted Answer

The average infant's brain contains around 100 billion to 200 billion neurons.

Question 10

Growth and development in infancy proceeds from the head downward,which is known as the ____.

Accepted Answer

The growth and development in infancy that proceeds from the head downward is known as the cephalocaudal principle. This means that the head, neck, and upper body develop before the lower body and extremities.

Question 11

Chemicals that are used to communicate between neurons are ____.

Accepted Answer

Chemicals that are used to communicate between neurons are called neurotransmitters. Neurotoxins are harmful chemicals that can damage or kill neurons. Neurocommunicators and neurochems are not commonly used terms in the field of neuroscience.

Question 12

Neurotransmitters are ____.

Accepted Answer

Neurotransmitters are chemicals that are released by neurons to transmit signals across a synapse to a target cell, which can be another neuron or an effector cell such as a muscle or gland.

Question 13

Growth and development proceed from the middle of the body outward,which is known as the ____.

Accepted Answer

The proximodistal principle describes how growth and development proceed from the center of the body outward. This means that children gain control over their torso before their extremities.

Question 14

By the end of his or her first year,the typical infant ____.

Accepted Answer

By the end of the first year, a typical infant triples his or her birth weight, reflecting rapid growth and development during this period.

Question 15

What part of a neuron releases the neurotransmitters?

Accepted Answer

Neurotransmitters are released from the axon terminals of a neuron, which are located at the end of the axon.

Question 16

In animals,quite a bit of brain development occurs prenatally.When does this same brain development occur in human infants?

Accepted Answer

The answer of In animals,quite a bit of brain development...

Question 17

If an infant is born weighing 7 pounds,one can expect he or she to weigh about ____ by 12 months.

Accepted Answer

On average, infants triple their birth weight by one year of age. Therefore, a 7-pound infant can be expected to weigh around 21 pounds by their first birthday. However, since growth rates can vary, it is reasonable to expect a range of weights. The closest option is B) 22 pounds.

Question 18

By age 2,the number of neurons in the brain ____.

Accepted Answer

By age 2, the number of neurons decreases to about half as many as were present at birth due to synaptic pruning, where excess neurons and synapses are eliminated to improve the efficiency of neuronal transmissions.

Question 19

____ is a tiny gap between neurons.

Accepted Answer

The synapse is the tiny gap between two neurons where the neurotransmitters are released and received. A neurotransmitter (A) is a chemical that transmits signals across the synapse. A dendrite (C) is a branch-like extension of a neuron that receives signals from other neurons. Myelin (D) is a fatty substance that covers the axon of some neurons and helps to speed up conduction of electrical signals.

Question 20

Which of the following describes a head to tail progression of growth?

Accepted Answer

The cephalocaudal principle describes a head to tail progression of growth, where development in early infancy starts at the head (brain and sensory organs) and gradually progresses downward towards the feet.

Quiz 4: Infancy

At birth,the size of an infant's brain is % of an adult's brain,and by age 2 it is % of an adult's brain.