Question

science 9 | unit 1 | lesson 1
stage 1: _________
the chromosomes, which were duplicated during interphase, condense and shorten. they can be seen through a microscope. the membrane around the nucleus (the nuclear envelope) begins to dissolve and disappear. the spindle forms.
stage 2: _________
the doubled chromosomes line up in the middle of the cell on the spindle. the membrane around the nucleus is completely dissolved.
stage 3: _________
the chromosomes strands separate and move to opposite ends of the cell, drawn along the spindle fibres. the two sets of chromosomes are identical and have the same genetic information.
stage 4: _________
the separated chromosomes arrive at opposite sides of the cell. the spindle disappears. a new nuclear envelope begins to form around each set of chromosomes, forming two new nuclei. the chromosomes begin to lengthen and become less condensed and are no longer visible under microscope.
summarize what happens during cytokinesis.

Explanation:

Filling the Stages (Mitosis Stages)

Stage 1:

The description matches the events of Prophase (chromosomes condense, nuclear envelope dissolves, spindle forms).

Stage 2:

The description matches the events of Metaphase (chromosomes line up at the cell’s equator on the spindle).

Stage 3:

The description matches the events of Anaphase (sister chromatids separate and move to opposite poles).

Stage 4:

The description matches the events of Telophase (nuclear envelopes reform, chromosomes decondense, spindle disappears).

Summarizing Cytokinesis

Cytokinesis is the final stage of cell division (after mitosis). In animal cells, the cell membrane pinches inward (cleavage furrow) until the cell splits into two daughter cells. In plant cells, a cell plate forms between the two new nuclei, developing into a new cell wall and cell membrane, separating the cell into two daughter cells. Both result in two genetically identical daughter cells, each with its own nucleus and cytoplasm.

Answer:

• Stage 1: Prophase
• Stage 2: Metaphase
• Stage 3: Anaphase
• Stage 4: Telophase

Cytokinesis: The cytoplasm divides, forming two separate daughter cells (each with a nucleus). In animals, the cell membrane pinches; in plants, a cell plate forms to split the cell.