Question 1

According to the text, how early can the foetus's heartbeat be heard with a stethoscope?

Accepted Answer

The text states that the foetus's heartbeat can be heard with a stethoscope during the third month of pregnancy.

Question 2

During the embryonic period, the endoderm is formed, which will become the ____.

Accepted Answer

During the embryonic period, the endoderm layer forms the epithelial lining of the digestive and respiratory systems.

Question 3

During the embryonic period, the ectoderm is formed, which will become the ____.

Accepted Answer

During the embryonic period, the ectoderm is formed, which gives rise to the skin, hair, nails, sensory organs, and nervous system. The muscles, bones, reproductive system, circulatory system, digestive system, and respiratory system are formed from different layers of embryonic tissue. The hormonal and endocrine systems develop from various glands throughout the body.

Question 4

Damage to the neural tube would consist of

Accepted Answer

The neural tube develops into the spinal cord and brain, so if there is damage to it, the spinal cord and brain will not develop correctly. This can cause a range of developmental problems, including paralysis, intellectual disability, and even death. Option A is incorrect because the formation of the digestive system occurs separately. Option B is incorrect because it refers to the connection between the placenta and uterus, which is not directly related to the neural tube. Option C is incorrect because the development of pores and hair follicles is also separate from the neural tube's development.

Question 5

During the embryonic period, the mesoderm is formed, which will become the ____.

Accepted Answer

During the embryonic period, the mesoderm develops into the muscles, bones, reproductive system, and circulatory system.

Question 6

Fernando and Rebecca are anxious to know the sex of their baby. It would not be until the end of the ____ month of pregnancy that they can find out, because the genitalia will not have fully formed before then.

Accepted Answer

The genitalia typically do not fully form until the end of the third month of pregnancy, so the best choice is B. The second month is too early to determine the sex, and the fourth and fifth months are too late as the genitalia will have already fully formed.

Question 7

The foetal period ends at birth. When does it begin?

Accepted Answer

The foetal period begins at the end of the embryonic period, which is at 9 weeks after conception. Prior to this, the developing organism is considered an embryo.

Question 8

Nearly all of the major organs are formed during what period?

Accepted Answer

The embryonic period is the time from conception to the end of the eighth week of gestation, during which nearly all major organs are formed.

Question 9

At what rate are neurons produced during the embryonic period?

Accepted Answer

During the embryonic period, neurons are produced at a rate of approximately 250,000 per minute. This rapid production of neurons is crucial for the development of the nervous system.

Question 10

By the end of the third week, the neural tube begins to form. This structure will eventually become ____.

Accepted Answer

The neural tube becomes the spinal cord and brain, not the other structures listed in the answer choices.

Question 11

The end of the third month marks the end of the _______ trimester.

Accepted Answer

The end of the third month marks the end of the first trimester in a typical pregnancy.

Question 12

At 3 months, the average foetus _____.

Accepted Answer

At 3 months, the average foetus weighs 85 grams (just under 3 ounces) and is 7.6 centimetres (3 inches) long. However, brain structures and sensory systems continue to develop throughout the pregnancy, so options C and D may also be true, but they are not specifically related to the 3-month stage.

Question 13

Prenatal development is divided into segments. What are these segments called?

Accepted Answer

Prenatal development is divided into three trimesters, each lasting approximately 12-13 weeks.

Question 14

The outer layer of the embryonic disk will become ____.

Accepted Answer

The outer layer of the embryonic disk is the ectoderm, which gives rise to the skin, hair, nails, and the nervous system.

Question 15

Your friend just had her first pregnancy check-up and is just starting her second month of pregnancy. She is very upset that she was not given the chance to hear her foetus's heartbeat. Remembering what you learned in developmental class, what should you tell her?

Accepted Answer

During the first two months of pregnancy, it is not always possible to hear the foetal heartbeat with a stethoscope. This is because the foetus is still very small and its heart is not fully developed. Typically, a foetal heartbeat can be heard with a Doppler ultrasound device around 10-12 weeks into the pregnancy. It is important to reassure your friend that not being able to hear the heartbeat at this stage does not necessarily mean that there is a problem with the foetus.

Question 16

By the end of the fourth week, the embryo's head is apparent and the eyes, nose, mouth and ears begin to form. How long is the embryo at this point?

Accepted Answer

At the end of the fourth week, the embryo is approximately 6 millimetres long.

Question 17

The ____ period lasts from the ninth week after conception until birth.

Accepted Answer

The foetal period is the third and final period of prenatal development and lasts from the ninth week after conception until birth. It is characterized by the continued growth and development of organs and tissues, the refinement of reflexes and movements, and the maturation of the central nervous system. The germinal period is the first period of prenatal development, which lasts from conception to implantation. The embryonic period is the second period of prenatal development, which lasts from implantation to the end of the eighth week. The zygote is the single cell formed by the fusion of sperm and egg at conception.

Question 18

What embryonic structure will become the brain and spinal cord?

Accepted Answer

The neural tube is the embryonic structure that will become the brain and spinal cord. It forms during the first month of pregnancy from the ectoderm, and eventually gives rise to the entire central nervous system. The other options (A, B, and D) are also related to the nervous system, but do not specifically refer to the embryonic structure that will become the brain and spinal cord.

Question 19

By the end of the eighth week, the embryo ____.

Accepted Answer

The embryo responds to touch and can move by the end of the eighth week.

Question 20

At the end of the eighth week, the embryo is only one inch long and weighs just one gram. According to the text, what can the embryo now do?

Accepted Answer

At eight weeks, the embryo can respond to touch, but is not yet capable of stepping in place, sucking its thumb, or vocalizing.

Quiz 2: Genetics and Prenatal Development