Pre AP Biology -CELLS 5.2 Cell Cycle: Cell Division- MCQ Exam Style Questions -New Syllabus 2025-2026
Pre AP Biology -CELLS 5.2 Cell Cycle: Cell Division- MCQ Exam Style Questions – New Syllabus 2025-2026
Pre AP Biology -CELLS 5.2 Cell Cycle: Cell Division- MCQ Exam Style Questions – Pre AP Biology – per latest Pre AP Biology Syllabus.
▶️ Answer/Explanation
Primary growth occurs at apical meristems and increases the length of the plant.
The pith is a central ground tissue formed from the ground meristem during primary growth.
In contrast, cork and periderm are products of the cork cambium during secondary growth.
Heartwood is older, non-functional secondary xylem formed as the plant increases in girth.
Therefore, only the pith is a primary tissue present from the initial development stage.
The correct option is (a).
▶️ Answer/Explanation
The correct answer is d.
Cancer cells arise from the accumulation of multiple mutations in DNA.
The $TP53$ gene codes for the $p53$ protein, which regulates the cell cycle and apoptosis.
Mutations in $TP53$ are found in approximately $50\%$ of all human cancers.
Typical cancer cells convert proto-oncogenes into oncogenes, not the reverse.
They exhibit an imbalance where oncogenes are overactive and tumor suppressors are inactivated.
These genetic changes lead to uncontrolled cell division and survival.
▶️ Answer/Explanation
The correct answer is d. $4$.
The image displays chromosomes in metaphase, meaning DNA replication has already occurred.
A standard somatic cell of a diploid organism like a vole contains $2$ sets of chromosomes ($2n$).
During metaphase, each chromosome consists of two identical sister chromatids.
Each sister chromatid represents one full copy of the genetic information (the genome).
Since there are $2$ homologous chromosomes, each with $2$ chromatids, there are $2 \times 2 = 4$ copies.
Therefore, there are $4$ total copies of the pine vole genome present in the cell at this stage.
▶️ Answer/Explanation
The correct answer is b. avoidance of Hayflick factors.
Cancer cells bypass the Hayflick limit, which normally restricts the number of times a cell can divide.
They often achieve this by activating telomerase to maintain chromosome length indefinitely.
Unlike normal cells, cancer cells lose contact inhibition, allowing them to grow in layers.
They fail to undergo cycle arrest at checkpoints, leading to uncontrolled proliferation.
Metastasis is a hallmark of cancer; therefore, they promote rather than avoid it.
▶️ Answer/Explanation
The correct answer is b.
During metaphase, spindle fibers pull the chromosomes to the metaphase plate.
This ensures each daughter cell receives exactly $1$ copy of every chromosome.
Option a is incorrect because sister chromatids separate during anaphase, not prophase.
Option c is incorrect as the furrow and plate form at the equator (center), not the poles.
Option d is incorrect because cytokinesis is the division of cytoplasm, not a method of chromosome movement.
▶️ Answer/Explanation
• Mitosis is the process that ensures DNA is replicated and organized before the cell divides.
• Cytokinesis is the physical splitting of the cytoplasm into two daughter cells.
• If cytokinesis occurs before mitosis, the genetic material has not been properly segregated.
• This results in daughter cells receiving incomplete or random sets of chromosomes and organelles.
• Lacking essential genetic instructions, these cells cannot function and will trigger apoptosis (cell death).
• Therefore, statement D is the most accurate biological consequence of this error.