Question 91
What is a primary characteristic of cancer cells?
A) Controlled growth
B) Normal apoptosis
C) High levels of differentiation
D) Ability to invade surrounding tissues
Answer: D) Ability to invade surrounding tissues
Explanation: Cancer cells are characterized by their ability to invade surrounding tissues and spread to other parts of the body, unlike normal cells that stay localized.
Question 92
What happens during S phase?
A) Cells grow and perform normal functions.
B) DNA is replicated.
C) Cells prepare for division.
D) Chromosomes condense.
Answer: B) DNA is replicated.
Explanation: The S phase is specifically for DNA replication, ensuring that each daughter cell will have a complete set of chromosomes after cell division.
Question 93
In which phase do chromatids separate and move towards opposite poles?
A) Telophase
B) Anaphase
C) Prophase
D) Metaphase
Answer: B) Anaphase
Explanation: During anaphase, sister chromatids are pulled apart and move toward opposite ends of the cell.
Question 94
What is the role of the spindle fibers?
A) To replicate DNA
B) To condense chromosomes
C) To pull chromosomes apart during cell division
D) To form the nuclear envelope
Answer: C) To pull chromosomes apart during cell division
Explanation: Spindle fibers are crucial for the separation of chromosomes during mitosis and meiosis, ensuring accurate distribution to daughter cells.
Question 95
What is the primary function of the G1 checkpoint?
A) To check for DNA damage
B) To assess cell size and nutrient availability
C) To ensure that DNA has been replicated
D) To monitor spindle fiber attachment
Answer: B) To assess cell size and nutrient availability
Explanation: The G1 checkpoint evaluates whether the cell is ready to enter the S phase by checking its size and available resources.
Question 96
Which of the following describes the process of meiosis?
A) A single division producing identical cells
B) A two-step division reducing chromosome number by half
C) A process that occurs only in prokaryotes
D) A process that produces diploid cells
Answer: B) A two-step division reducing chromosome number by half
Explanation: Meiosis consists of two rounds of division that reduce the chromosome number from diploid to haploid, producing gametes.
Question 97
What event occurs during metaphase I of meiosis?
A) Chromosomes align in pairs along the metaphase plate.
B) Sister chromatids are separated.
C) The nuclear envelope re-forms.
D) Crossing over occurs.
Answer: A) Chromosomes align in pairs along the metaphase plate.
Explanation: During metaphase I, homologous chromosome pairs align at the metaphase plate in preparation for separation.
Question 98
What is the consequence of uncontrolled cell division?
A) Normal tissue function
B) Cancer formation
C) Proper organ development
D) Cell senescence
Answer: B) Cancer formation
Explanation: Uncontrolled cell division can lead to cancer, where cells grow and proliferate inappropriately, forming tumors.
Question 99
How do mutations in proto-oncogenes affect cell behavior?
A) They reduce cell division.
B) They have no effect on cell behavior.
C) They promote uncontrolled cell growth.
D) They induce apoptosis.
Answer: C) They promote uncontrolled cell growth.
Explanation: Mutations in proto-oncogenes can convert them into oncogenes, leading to uncontrolled cell proliferation and potential cancer.
Question 100
What occurs during telophase II of meiosis?
A) Homologous chromosomes separate.
B) Sister chromatids are pulled apart.
C) Nuclear envelopes re-form around four haploid cells.
D) Chromosomes condense into chromatin.
Answer: C) Nuclear envelopes re-form around four haploid cells.
Explanation: During telophase II, the nuclear envelopes reform around the four haploid daughter cells that result from meiosis.
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