Question

adult animal organisms have cell division and mitosis to grow, maintain, and repair cells and tissues. you cells in your body die for various reasons: normal death( called (brinks )apoptosis), stress from (bad) effects. (foreign - called) infections may also call (death) as (part) (method) of (imperfection). (disruptions) of the (checkpoints) for mitosis, (the) (cell) (cycle) (may) (result) (in) (uncontrolled) (cell) (growth). consider this model of the cell cycle.
which statement does not correctly explain the purpose of the various labeled checkpoint in the cycle?
a g1 (the) checkpoint (where) (an) (animal) cell (becomes) (committed) (to) (the) cell (cycle), (which) (is) (determined) (by) (external) (factors) (and) (signals).
b the (spindle) checkpoint (prevents) (separation) (of) (the) (duplicated) (chromosomes) (until) (each) (chromosome) (is) (properly) (attached) (to) (the) (spindle) (fibers).
c the g2 checkpoint (ensures) (all) (of) (the) (chromosomes) (have) (been) (replicated) (and) (that) (the) (replicated) (dna) (is) (not) (damaged) (before) (cell) (enters) (mitosis).
d cell (size), (protein) (reserves), (and) (damage) (to) (dna) (is) (evaluated) (at) (the) g1 (checkpoint); (the) cell (will) (not) (be) (allowed) (to) (continue) (if) (any) (problems) (are) (detected).

Explanation:

The question asks which statement incorrectly describes a cell cycle checkpoint. The G1 checkpoint checks for cell size, nutrients, growth factors, and DNA damage before entering S phase (not just "external factors and signals" as option A implies, but it is still a valid function). The S checkpoint evaluates DNA replication and damage (option D is correct). The G2 checkpoint verifies DNA replication completeness and damage (option C is correct). The spindle checkpoint (metaphase checkpoint) ensures chromosomes are attached to spindle fibers before anaphase (option B is correct). Option A is the only incorrect statement because it oversimplifies the G1 checkpoint's role (it also checks internal factors like DNA damage, not just external signals).

Answer:

A. G1 the check point allows an animal cell becomes commited to the cell cycle, which is determined by external factors and signals.