Unit 4: Cell Cycles

All BUT ONE statement describes an advantage of meiosis.

• Variation is aided by crossing-over which occurs during meiosis.

• Independent assortment provides a huge number of possible genetic combinations in daughter cells.

• Meiosis ensures daughter cells receive one allele for each gene and half the number of chromosomes.

• Meiosis occurs often because it allows growth and repair of body tissues in multicellular organisms.

Answer explanation

Meiosis occurs often because it allows growth and repair of body tissues in multicellular organisms. This is an advantage of mitosis.

In multicellular organisms, life begins as a single cell until ___________ occurs, causing growth.

• fertilization

• conjugation

• mitosis

• mitosis

Answer explanation

Mitosis in the only single cell that develops and grows.

What is the outcome when a cell undergoes meiosis?

• Two haploid cells

• Four haploid cells

• Two diploid cells

• Four diploid cells

Answer explanation

Four haploid cells are created

Which statement correctly lists the order of the stages?

• P, R, Q

• Q, R, P

• R, P, Q

• P, Q, R

Answer explanation

Stage R shows the chromosomes lined up at the equator of the cell. Stage P shows the chromatids being pulled apart to the opposite ends of each new cell. Stage Q shows the nuclear membrane forming again around the chromosomes. Therefore, the correct order of the stages is R → P → Q. So, R, P, Q.

Suppose that the great green galoofus lizard has fifty-two chromosomes in the nucleus of its body or somatic cells. How many chromosomes will be in the unfertilized egg of a great green galoofus lizard?

• 104

• 26

• 52

• 13

Answer explanation

Would be half of it.

An organism with 24 chromosomes in each body cell will produce sex cells with __________ chromosomes.

• 12

• 96

• 24

• 48

Answer explanation

12 chromosomes will be found in each sex cell because sperm and egg contain one-half of the genetic information that is found in body cells.

Both male and female gametes are created during the process of meiosis. The formation of male gametes or sperm is called spermatogenesis. After telophase II of spermatogenesis, there would be __________ male gametes created that are all genetically __________.

• 4; different

• 4; identical

• 2; identical

• 2; different

Answer explanation

Meiosis creates 4 gametes and they are all genetically different from each other. One diploid cell is transformed into four genetically different haploid cells during meiosis.

The process of gamete formation during sexual reproduction is correctly represented by which illustration?

• 
• 
• 
• 

Answer explanation

Process A represents meiosis. This is the process by which gametes are produced. During this process, the chromosome number is reduced: diploid cells become haploid.

Which of these correctly distinguishes mitosis from meiosis?

• Mitosis occurs in germ cells and meiosis occurs in somatic cells.

• Meiosis produces four 2N daughter cells; mitosis produces two 2N daughter cells.

• The number of chromosomes remains the same in mitosis and is reduced by half in meiosis.

• Crossing over takes place in mitosis and not in meiotic cell division.

Answer explanation

The number of chromosomes remains the same in mitosis and is reduced by half in meiosis.