Pre AP Biology -CELLS 5.2 Cell Cycle: Cell Division- MCQ Exam Style Questions -New Syllabus
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.