Nondisjunction Lesson

Multiple Choice

Which letter(s) in the diagram correspond to cells that are haploid? 

• A
• B
• C
• A and B

• GAMETES (sex cells) - sperm or egg are haploid

• The products of meiosis are haploid (sperm or egg), so they have HALF the number of chromosomes as the parent cell.

• Chromosome numbers are restored during fertilization

Haploid (n)

• SOMATIC (body) cells - skin, blood, hair cells are diploid, meaning they have TWO copies of each chromosome

Diploid (2n)

​Vocab Reminder/Check: Diploid v. Haploid

Multiple Choice

How does the process of meiosis contribute to genetic uniqueness in offspring?

• Meiosis only occurs in somatic cells, not in gametes.
• Meiosis contributes to genetic uniqueness through crossing over and independent assortment.
• Meiosis eliminates genetic variation by producing clones.
• Meiosis results in identical offspring due to DNA replication.

Multiple Choice

Why is it important for meiosis to reduce the chromosome number in cells?

• To ensure genetic diversity in offspring

• To produce identical cells

• To increase the number of chromosomes in gametes

• To prevent cell division

Multiple Choice

The process in which homologous chromosomes exchange pieces of DNA during meiosis is called ___.

• crossing over
• DNA replication
• chromosome duplication
• gene mutation

Multiple Choice

What is the main result of crossing over during meiosis?

• It produces recombinant chromosomes with a mix of genes from both parents.

• It causes chromosomes to duplicate.

• It results in identical gametes.

• It leads to cell death.

Multiple Choice

Explain how crossing over during meiosis increases genetic diversity in offspring.

• Crossing over during meiosis increases genetic diversity by creating new allele combinations on chromosomes.
• Crossing over has no effect on the genetic makeup of offspring.
• Crossing over occurs only in mitosis, not meiosis.
• Crossing over reduces genetic diversity by keeping allele combinations the same.

Multiple Select

Which of the following statements about nondisjunction during meiosis are correct?

• It can result in gametes with too many or too few chromosomes.

• It can lead to genetic disorders such as Down syndrome.

• It only occurs during mitosis.

• It always results in normal gametes.

• It occurs when chromosomes do not separate properly during meiosis I or II.

Multiple Choice

Which chromosome is affected in Down syndrome due to nondisjunction?

• Chromosome 21

• Chromosome 13

• Chromosome 23

• Chromosome 18

Multiple Choice

3 copies of the 21st chromosome is known as...

• Monosomy

• Disomy

• Trisomy

Multiple Choice

Nondisjunction occurs when homologous chromosomes are supposed to separate evenly during which phase of meiosis?

• Metaphase I

• Interphase

• Anaphase I

• Prophase I

Multiple Choice

A karyotype showing XXY on chromosome 23 is associated with which genetic disorder?

• Klinefelter syndrome

• Down syndrome

• Patau syndrome

• Turner syndrome

Multiple Choice

Which of the following is a symptom of Turner Syndrome as shown in the image?

• Webbed neck

• Increased height

• Excessive hair growth

• High-pitched voice

Multiple Choice

Fill in the blank: In mitosis, the number of daughter cells produced is ___ and they are ___________ to the parent cell.

• two; genetically identical

• four; genetically unique

• two; genetically unique

• four; genetically identical

Multiple Choice

Explain how errors in meiosis can lead to genetic disorders such as Turner Syndrome. Use information from the diagrams and summaries provided.

• Turner Syndrome occurs due to environmental factors during pregnancy.
• Turner Syndrome results from a mutation in mitochondrial DNA.
• Turner Syndrome is caused by nondisjunction during meiosis, leading to a missing X chromosome in females.
• Turner Syndrome is caused by an extra Y chromosome in males.

Multiple Choice

How does meiosis contribute to genetic diversity in organisms?

• Meiosis eliminates genetic variation through gene duplication.
• Meiosis increases genetic diversity through independent assortment and crossing over.
• Meiosis only occurs in asexual reproduction, limiting genetic variation.
• Meiosis reduces genetic diversity by creating identical gametes.

Multiple Choice

What is the main difference between Meiosis I and Meiosis II?

• Meiosis I separates homologous chromosomes, while Meiosis II separates sister chromatids.

• Meiosis I produces diploid cells, while Meiosis II produces haploid cells.

• Meiosis I occurs in plants, while Meiosis II occurs in animals.

• Meiosis I results in genetically identical cells, while Meiosis II results in genetically unique cells.