Question

chromosomes & meiosis review
part 1 - key concepts
fill in the blanks or circle the correct answer.
1 humans have __ total chromosomes, arranged in __ pairs.
2 sex chromosomes determine ____.
3 chromosomes 1 - 22 are called ____.
4 a cell with two sets of chromosomes (2n) is ____.
5 a cell with one set of chromosomes (n) is ____.
6 gametes are made during ____.
7 fertilization restores the ____ number of chromosomes.
8 the fertilized egg is called a ____.
9 what holds two sister chromatids together? ____
10 chromosomes that have the same genes in the same order are ____
part 2 - processes & errors
match each description to the correct term:
(crossing over - independent assortment - nondisjunction)
which of these increases genetic variation? ____

Explanation:

• Part 1:
• Humans have 46 total chromosomes, arranged in 23 pairs.
• Sex chromosomes determine biological sex (e.g., XX for female, XY for male).
• Chromosomes 1 - 22 are called autosomes.
• A cell with two sets of chromosomes (2n) is diploid.
• A cell with one set of chromosomes (n) is haploid.
• Gametes are made during meiosis.
• Fertilization restores the diploid number of chromosomes.
• The fertilized egg is called a zygote.
• A centromere holds two sister chromatids together.
• Chromosomes that have the same genes in the same order are homologous chromosomes.
• Part 2:
• Exchange of DNA between homologous chromosomes is crossing over.
• Random lineup of chromosomes during Metaphase I is independent assortment.
• Failure of chromosomes to separate properly is nondisjunction.
• Both crossing over and independent assortment increase genetic variation.

Answer:

• Part 1:

1. 46; 23
2. biological sex
3. autosomes
4. diploid
5. haploid
6. meiosis
7. diploid
8. zygote
9. centromere
10. homologous chromosomes

• Part 2:
• Exchange of DNA between homologous chromosomes: Crossing Over
• Random lineup of chromosomes during Metaphase I: Independent Assortment
• Failure of chromosomes to separate properly: Nondisjunction
• Which of these increases genetic variation?: Crossing Over and Independent Assortment