Question 1

Which process restores the diploid chromosome number in the sexual life cycle, as shown in the first diagram?

Accepted Answer

Fertilization

Question 2

During which phase of meiosis does crossing over occur, as illustrated in the second diagram?

Accepted Answer

Prophase I

Question 3

What is the result of independent assortment, as shown in the third diagram?

Accepted Answer

Gametes have random combinations of maternal and paternal chromosomes

Question 4

If a diploid organism has $$2n = 34$$ chromosomes, how many chromosomes will each gamete have after meiosis?

Accepted Answer

$$17$$

Question 5

Which event separates homologous chromosomes, as depicted in the fourth diagram?

Accepted Answer

Anaphase I

Question 6

What is the consequence of nondisjunction during Meiosis I, as shown in the fifth diagram?

Accepted Answer

Half the gametes have an extra chromosome, half lack one

Question 7

The sixth diagram shows a karyotype with three copies of chromosome 21. What condition does this represent?

Accepted Answer

Down Syndrome (Trisomy 21)

Question 8

If a gamete with 24 chromosomes (due to nondisjunction) is fertilized by a normal gamete with 23 chromosomes, what is the chromosome number in the zygote?

Accepted Answer

$$47$$

Question 9

Why are siblings genetically unique, even with the same parents?

Accepted Answer

Random fertilization and independent assortment create unique combinations

Question 10

Which mechanism would be eliminated if a population experienced a mutation that prevented crossing over?

Accepted Answer

Genetic diversity from recombination

Question 11

What is the main difference between mitosis and meiosis regarding genetic diversity?

Accepted Answer

Mitosis produces genetically identical cells, meiosis produces genetically diverse cells

Question 12

During which stage of meiosis does independent assortment occur?

Accepted Answer

Metaphase I

Question 13

Why does meiosis have two divisions?

Accepted Answer

To halve the chromosome number and separate sister chromatids

Question 14

What is the final product of mitosis compared to meiosis?

Accepted Answer

Mitosis produces two diploid cells; meiosis produces four haploid cells

Question 15

If each human gamete can produce $$8 	imes 10^6$ combinations due to independent assortment, how does random fertilization affect total possible zygotic combinations?

Accepted Answer

It multiplies combinations between gametes from both parents

Question 16

Why is Down Syndrome (Trisomy 21) more common than other trisomies such as Trisomy 18 or Trisomy 13?

Accepted Answer

Chromosome 21 is smaller and its extra copy is more compatible with life

Question 17

What is the role of germ cells in the sexual life cycle?

Accepted Answer

They undergo meiosis to produce gametes

Question 18

Which chromosomes and chromatids are involved in crossing over?

Accepted Answer

Non-sister chromatids of homologous chromosomes

Question 19

What is the difference between haploid and diploid cells?

Accepted Answer

Haploid cells have one set of chromosomes ($$n$$), diploid cells have two sets ($$2n)$$

Question 20

Why doesn’t crossing over happen in mitosis?

Accepted Answer

Homologous chromosomes do not pair up in mitosis

Comprehensive Study Guide: Meiosis, Genetic Diversity, and Chromosome Disorders

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