Color Textbook of Histology 3rd Edition by Leslie P. Gartner - Test Bank - Updated 2025

1. A 2-month old infant is brought to the physician’s office to be examined, and the physician notices that he has flaccid muscles, a smaller head than usual, a large tongue, and a short nose and broad face. The parents say that the baby is very quiet and hardly ever cries. The pediatrician suspects aneuploidy. The baby probably has which of the following chromosomal configurations?

a. monosomy

b. trisomy 

c. normal diploid complement

d. haploid complement

e. tetraploid complement

Explanation:

The answer is b. The baby most probably  has trisomy 21 (Down syndrome), in which chromosome 21 is present instead of two chromosomes, one from the mother and the other from the father. During meiosis, nondisjunction occurs, so that one cell has the extra chromosome 21 and the other cell is monosomic—that is, it is missing chromosome 21.

2. A patient with a chromosomal complement of XXY has

a. trisomy of the autosomes

b. Turner’s syndrome

c. monosomy of the sex chromosomes

d. Klinefelter syndrome 

e. a female phenotype

Explanation:

The answer is d. The patient has Klinefelter syndrome and exhibits a male phenotype. Since there are three sex chromosomes, this is not a monosomy nor is it trisomy of the autosomes. Turner’s syndrome is exhibited by females who lack the second X chromosome.

3. A patient with a chromosomal complement of XO has

a. trisomy of the sex chromosomes

b. Turner’s syndrome 

c. monosomy of the autosomes

d. Klinefelter syndrome 

e. a male phenotype

Explanation:

The answer is b. Patients with Turner’s syndrome are females who lack the second X chromosomes; therefore, they are monosomal for the sex chromosomes but not for the autosomes. Turner’s syndrome is a male phenotype with an extra X chromosome. 

4. A patient with a chromosomal complement of XXX has

a. a male phenotype

b. a female phenotype 

c. a very short life span 

d. a higher IQ than his/her siblings

e. trisomy of autosomes

Explanation:

The answer is b. The patient is a female who has the triple X syndrome; thus she has an extra sex chromosome rather than trisomy of the autosomes. These patients usually have a lower IQ than their siblings but have a normal life span and can give birth to children with a normal chromosomal complement. 

5. During a routine examination of a 3-year-old child, the pediatrician notes that the color of the pupil is white and that the child is cross-eyed. She asks the child’s father if there are any cases of retinoblastoma in the family, and when the answer is in the affirmative she calls in a pediatric ophthalmologist. The ophthalmologist knows that retinoblastoma is due to the mutation of the Rb gene (retinoblastoma gene) and that it is a recessive trait. Retinoblastoma can metastasize to the brain via the

a. optic nerve 

b. superior division of the oculomotor nerve

c. trochlear nerve

d. abducent nerve

e. inferior division of the oculomotor nerve

Explanation:

The answer is a. The retina is attached to the brain via the optic nerve, and malignant cells can use the optic nerve as a passageway to the brain. The superior and inferior divisions of the oculomotor nerve, the trochlear nerve, and the abducent nerve all innervate the external muscles of the eye and do not contact the retina.

6. During a routine examination of a 3-year-old child, the pediatrician notes that the color of the pupil is white and that the child is cross-eyed. She asks the child’s father if there are any cases of retinoblastoma in the family, and when the answer is in the affirmative she calls in a pediatric ophthalmologist. The ophthalmologist knows that retinoblastoma is due to the mutation of the Rb gene (retinoblastoma gene) and that it is a recessive trait. Not all cases of retinoblastoma have a familial component. In the sporadic form of retinoblastoma, the child’s normal genetic complement does not predispose the child to have retinoblastoma. If this child had the sporadic form of retinoblastoma, then