Understanding Pregnancy and Development

The fetal stage of development begins at the end of the:

• Second week

• Fourth week

• Eighth week

• Twelfth week

Answer explanation

The fetal stage of development begins at the end of the eighth week, marking the transition from the embryonic stage. Prior to this, the first eight weeks are considered the embryonic period.

Pregnancy can be diagnosed ten days after fertilization by testing the urine of a woman for which of the following substances?

• Estrogen

• Human Chorionic Hormone

• Progesterone

• Amniotic Fluid

Answer explanation

Pregnancy is diagnosed by detecting Human Chorionic Hormone (hCG) in urine, which is produced shortly after fertilization. Estrogen and progesterone levels do not confirm pregnancy as specifically as hCG does.

The ductus venosus shunts blood around the:

• Liver

• Spleen

• Pancreas

• Small intestine

Answer explanation

The ductus venosus is a fetal blood vessel that shunts blood away from the liver, allowing it to bypass this organ and flow directly into the inferior vena cava. Therefore, the correct answer is the liver.

Labor is initiated by a decrease in ________ levels and the secretion of ______ by the posterior pituitary gland.

• LH and Prolactin

• Progesterone and Oxytocin

• Prolactin and Surfactant

• Estrogen and LH

Answer explanation

Labor is initiated by a decrease in progesterone levels, which removes the inhibition on uterine contractions, and the secretion of oxytocin by the posterior pituitary gland, stimulating these contractions.

A premature fetus has an increased chance of survival if it produces enough surfactant to aid the function of its:

• Endocrine system

• Respiratory system

• Digestive system

• Nervous system

Answer explanation

Surfactant is crucial for reducing surface tension in the lungs, aiding the respiratory system's function. A premature fetus needs sufficient surfactant to improve lung function and increase survival chances.

The foramen ovale is an opening that allows fetal blood to pass from the:

• Right atrium to the left atrium

• Left atrium to the right atrium

• Right ventricle to the left ventricle

• Left ventricle to the right ventricle

Answer explanation

The foramen ovale is a fetal structure that allows blood to bypass the non-functioning lungs by flowing from the right atrium directly to the left atrium, thus facilitating efficient circulation in the fetus.

Which of the following fetal structures closes as a result of change in pressure?

• Ductus venosus

• Ductus arteriosus

• Umbilical vessels

• Foramen ovale

Answer explanation

The foramen ovale closes due to increased pressure in the left atrium after birth, which occurs when the lungs expand and blood flow changes. This is a pressure-dependent closure, unlike the other structures listed.

The study of why individuals vary in terms of characteristics is:

• Ichthyology

• Genetics

• Dendrology

• Biology

Answer explanation

The study of why individuals vary in characteristics is known as genetics, which focuses on heredity and variation in organisms. Ichthyology studies fish, dendrology studies trees, and biology is a broader field.

The combining of egg and sperm cell chromosomes is called:

• Fertilization

• Implantation

• Cleavage

• Labor

Answer explanation

Fertilization is the process where the chromosomes from the egg and sperm combine, resulting in the formation of a zygote. This is the correct answer as it directly describes the merging of genetic material.

The condition characterized by the presence of a developing embryo within the uterus is called:

• Emission

• Haploid

• Pregnancy

• Fertilization

Answer explanation

The condition characterized by a developing embryo in the uterus is known as pregnancy. This term specifically refers to the state of carrying a fetus, distinguishing it from other processes like fertilization or emission.