Question

1. which structure typically plays a role in cell division and is only found in animal cells, never plant cells?

a. cell plate
b. cell wall
c. centrioles
d. cytoskeleton

1. why is the s phase of the cell cycle important?

a. the cell grows.
b. the cell makes more organelles.
c. the cell copies its dna.
d. the cell divides into 2 daughter cells.

1. which stage of the cell cycle is shown below?

a. metaphase
b. telophase
c. prophase
d. interphase

1. the completion of cytokinesis marks the beginning of a new cell cycle. which phase does a cell enter after cytokinesis?

a. s phase
b. m phase
c. g2 phase
d. g1 phase

Explanation:

• Question 15: Centrioles are involved in cell division and are found in animal cells, not plant cells. Cell plate is for plant cell cytokinesis, cell wall is a structure in plant cells (not specific to animal - only cell division), and cytoskeleton has multiple functions beyond just animal - specific cell division.
• Question 16: In the S (synthesis) phase of the cell cycle, DNA replication (copying) occurs. Cell growth mainly in G1, making more organelles can be in G1 or G2, and cell division into two daughter cells is in M phase.
• Question 17: In prophase, chromosomes condense (as shown in the diagram), nuclear envelope starts to break down. In metaphase, chromosomes align at the equator. In telophase, new nuclear envelopes form. In interphase, chromosomes are in a less - condensed chromatin form.
• Question 18: After cytokinesis (completion of cell division), the cell enters G1 phase (first gap phase) where it grows, makes proteins, and prepares for DNA replication in S phase. M phase is mitosis (cell division), G2 is after S phase (pre - mitotic preparation).

Answer:

1. C. centrioles
2. C. The cell copies its DNA.
3. C. Prophase
4. D. G1 phase