AP BIOLOGY

HEREDITY

NONDISJUNCTION

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
When chromosomes fail to separate correctly during meiosis, what can occur?
A
extra chromosomes are found in the sex cell
B
chromosomes of the sex cell are doubled
C
chromosomes of the sex cell are halved
D
meiosis never completes
Explanation: 

Detailed explanation-1: -Nondisjunction, in which chromosomes fail to separate equally, can occur in meiosis I (first row), meiosis II (second row), and mitosis (third row). These unequal separations can produce daughter cells with unexpected chromosome numbers, called aneuploids.

Detailed explanation-2: -Normally, each egg or sperm cell gets one copy of each chromosome. But if chromosomes separate unevenly, the resulting egg or sperm cell can end up with an extra or a missing chromosome. If this egg or sperm participates in fertilization, then the resulting embryo will have too many or too few chromosomes.

Detailed explanation-3: -A change in the number of chromosomes can cause problems with growth, development, and function of the body’s systems. These changes can occur during the formation of reproductive cells (eggs and sperm), in early fetal development, or in any cell after birth.

Detailed explanation-4: -They are caused by nondisjunction, which occurs when pairs of homologous chromosomes or sister chromatids fail to separate during meiosis. The risk of nondisjunction increases with the age of the parents.

There is 1 question to complete.