Q. How many genes are believed to constitute the human genome?
A. one million
B. ten million
C. 100,000
D. 70,000
Answer- 70,000
Q. During which meiotic division is the number of chromosomes halved?
A. during meiosis I
B. during meiosis II
C. prior to meiosis I, during the S phase
D. after meiosis II
Answer- during meiosis I
Q. Choose the recessive human trait from the list that follows.
A. widow's peak
B. cheek dimples
C. hairless forearms
D. freckles
Answer- hairless forearms
Q. During which phase of meiosis does the phenomenon called crossing-over occur?
A. prophase I
B. metaphase I
C. telophase I
D. prophase II
Answer- prophase I
Q. Homologous chromosomes are separated during _______________.
A. prophase I
B. metaphase I
C. anaphase I
D. telophase I
Answer- anaphase I
Q. Which of these does not contribute to genetic variability?
A. meiosis
B. crossing-over
C. having children with a close relative
D. having children with someone who is not a relative
Answer- having children with a close relative
Q. Several variant forms of a gene for a given trait are called ______________.
A. autosomes
B. alleles
C. sex chromosomes
D. histones
Answer- alleles
Q. A person who can pass either a widow's peak or continuous hairline to the next generation is said to be _______________ for the hairline trait.
A. homozygous
B. heterozygous
C. incompletely dominant
D. recessive
Answer- heterozygous
Q. If a trait, such as hemophilia, occurs more often in males than in females, it is because the gene for the trait is most likely carried on ________________.
A. the X chromosome
B. the Y chromosome
C. a mutant allele
D. an autosome
Answer- the X chromosome
Q. If Chris, who carries the gene for cystic fibrosis but does not have the disease, fathers a child with Rhonda, who also carries the cystic fibrosis gene but does not have the disease, what is the likelihood that their first-born will have cystic fibrosis?
A. 75% chance
B. 50% chance
C. 25% chance
D. 0% chance
Answer- 25% chance
Q. What is an example of a codominant trait in humans?
A. sickle cell disease
B. Huntington disease
C. ABO blood groups
D. Tay-Sachs disease
Answer- ABO blood groups
Q. Traits that are controlled by one or more genes and influenced by the environment are said to be _________________.
A. incompletely dominant
B. multifactorial
C. polygenic
D. incompletely penetrant
Answer- multifactorial
Q. The fact that a woman cannot generally grow a beard is because beard growth is a(n) ________________ trait.
A. completely penetrant
B. pleiotropic
C. sex-limited
D. sex-influenced
Answer- sex-limited
Q. Individuals with Turner syndrome have which genetic abnormality?
A. two X and one Y chromosomes
B. three copies of chromosome 13
C. three copies of chromosome 18
D. one X chromosome; no Y chromosome
Answer- one X chromosome; no Y chromosome
Q. The normal chromosome number is referred to as _____________.
A. euploid
B. aneuploid
C. polyploid
D. tetraploid
Answer- euploid
Q. The last pair of 23 chromosomes is referred to as the _____.
A. karyotype
B. autosomes
C. nondisjunction chromosomes
D. sex chromosomes
Answer- sex chromosomes
Q. In Down's syndrome, there is an extra chromosome number _____.
A. 19
B. 20
C. 21
D. 22
Answer- 21
Q. Which of the following is most common?
A. Patau syndrome
B. Edward syndrome
C. Klinefelter syndrome
D. Turner syndrome
Answer- Klinefelter syndrome
Q. What is the most common chromosomal disorder in this group?
A. Patau's syndrome
B. Edward's syndrome
C. trisomy 13
D. trisomy 21
Answer- trisomy 21
Q. Which chromosomes indicate a normal male fetus?
A. XX
B. XXY
C. XY
D. XYY
Answer- XY
Q. What is the Turner's syndrome chromosome pattern?
A. XXY
B. XYY
C. XO
D. XXO
Answer- XO
Q. Which of the following fetuses will not survive?
A. XXY
B. XYY
C. XXXY
D. YY
Answer- YY
Q. Which chromosome pattern indicates a male with poor sexual development?
A. XYY
B. XXY
C. XY
D. XO
Answer- XXY
Q. What type of inheritance is present in a person who has blue eyes and received a blue-eyed gene from each parent?
A. autosomal dominant
B. sex-linked
C. recessive
D. genetic
Answer- recessive
Q. The disintegration of chromosomes during meiosis is called nondisjunction.
A. TRUE
B. FALSE
C. Nothing can be said
D. None of the mentioned
Answer- FALSE
Q. Older women carry a greater chance of having a child with trisomy 21 than a younger mother.
A. TRUE
B. FALSE
C. Nothing can be said
D. None of the mentioned
Answer- TRUE
Q. Persons with Turner's syndrome have male chromosomes but have a female appearance.
A. TRUE
B. FALSE
C. Nothing can be said
D. None of the mentioned
Answer- FALSE
Q. Syndromes having abnormal numbers of chromosomes are usually related to defective sperm cells.
A. TRUE
B. FALSE
C. Nothing can be said
D. None of the mentioned
Answer- FALSE
Q. Only the sperm have the ability to determine the sex of the offspring.
A. TRUE
B. FALSE
C. Nothing can be said
D. None of the mentioned
Answer- TRUE
Q. All genetic abnormalities have a certain degree of probability to be inherited.
A. TRUE
B. FALSE
C. Nothing can be said
D. None of the mentioned
Answer- FALSE
Q. Sex-linked genes are those associated with chromosomes X or Y.
A. TRUE
B. FALSE
C. Nothing can be said
D. None of the mentioned
Answer- FALSE
Q. Males and females have equal chances of inheriting sex linked disorders.
A. TRUE
B. FALSE
C. Nothing can be said
D. None of the mentioned
Answer- FALSE
Q. All birth defects are genetic and inherited.
A. TRUE
B. FALSE
C. Nothing can be said
D. None of the mentioned
Answer- FALSE