Question

t2. binary fission occurs in eukaryotic cells.
a. true
b. false
t3. dna replication is semiconservative.
a. true
b. false
t4. cell cycle checkpoints prevent damaged cells from dividing.
a. true
b. false
t5. apoptosis is a form of uncontrolled cell division.
a. true
b. false
section 3: sexual reproduction & meiosis
multiple choice questions (1 point each):

1. what is the result of meiosis?

● a. two identical cells
● b. four identical cells
● c. four unique gametes
● d. one diploid cell

1. which process increases genetic variation?

● a. mitosis
● b. binary fission
● c. crossing over
● d. cytokinesis

1. what separates during meiosis i?

● a. sister chromatids
● b. homologous chromosomes
● c. dna strands
● d. centromeres

1. where does meiosis occur?

Explanation:

• T2: Binary fission is a form of asexual reproduction in prokaryotic cells (e.g., bacteria), not eukaryotic cells. Eukaryotic cells have more complex cell - division mechanisms like mitosis and meiosis.
• T3: DNA replication is semiconservative. In this process, each new DNA molecule consists of one old (parental) strand and one new strand. This was proven by the Meselson - Stahl experiment.
• T4: Cell cycle checkpoints (such as the G1, S, and G2 checkpoints) monitor the cell for DNA damage, proper DNA replication, and other factors. If damage is detected, they prevent the cell from progressing to the next stage of the cell cycle (e.g., from G1 to S or from G2 to M), thus preventing damaged cells from dividing.
• T5: Apoptosis is programmed cell death, not a form of cell division. Uncontrolled cell division is more related to processes like cancer (where cells divide without proper regulation).
• Section 3 - 1: Meiosis results in four unique gametes. Mitosis results in two identical cells. Meiosis involves two rounds of division (meiosis I and meiosis II) and processes like crossing - over, which leads to genetic variation among the gametes.
• Section 3 - 2: Crossing over (the exchange of genetic material between homologous chromosomes during prophase I of meiosis) increases genetic variation. Mitosis and binary fission produce genetically identical or nearly identical cells (in the case of binary fission in a clonal population). Cytokinesis is just the physical division of the cell cytoplasm.
• Section 3 - 3: During meiosis I, homologous chromosomes separate. Sister chromatids separate during meiosis II. DNA strands separate during DNA replication. Centromeres play a role in the attachment of spindle fibers but do not separate in the sense of chromosome segregation during meiosis I.
• Section 3 - 4: Meiosis occurs in the gonads (testes in males and ovaries in females) to produce gametes (sperm and eggs).

Answer:

T2. B. False
T3. A. True
T4. A. True
T5. B. False
Section 3 - 1: C. Four unique gametes
Section 3 - 2: C. Crossing over
Section 3 - 3: B. Homologous chromosomes
Section 3 - 4: (Assuming options are not fully shown, but typically in gonads. If no options, conceptually in germ - cell producing tissues like gonads)