3.2.2 All cells arise from other cells

What is the phase of the cell cycle where DNA replication occurs?

• Prophase

• Metaphase

• Interphase

• Anaphase

Answer explanation

DNA replication occurs during Interphase, specifically in the S phase, where the cell prepares for division by duplicating its genetic material.

During which stage of mitosis do chromosomes align at the cell's equator?

• Prophase

• Metaphase

• Anaphase

• Telophase

Answer explanation

During metaphase, chromosomes align at the cell's equator, ensuring they are properly positioned for separation. This stage is crucial for accurate chromosome distribution to daughter cells.

What is the role of spindle fibres during mitosis?

• To replicate DNA

• To attach to centromeres and separate chromatids

• To dissolve the nuclear membrane

• To synthesise proteins

Answer explanation

Spindle fibres play a crucial role in mitosis by attaching to the centromeres of chromosomes and facilitating the separation of sister chromatids, ensuring that each daughter cell receives an identical set of chromosomes.

Which stage of mitosis is characterised by the separation of sister chromatids?

• Prophase

• Metaphase

• Anaphase

• Telophase

Answer explanation

Anaphase is the stage of mitosis where sister chromatids are pulled apart to opposite poles of the cell, marking their separation. This is a key event that ensures each daughter cell receives an identical set of chromosomes.

What happens during cytokinesis?

• DNA is replicated

• Chromosomes condense

• The cytoplasm divides to form two new cells

• Spindle fibres form

Answer explanation

During cytokinesis, the cytoplasm divides, resulting in the formation of two new cells. This process follows mitosis, where the genetic material is separated, and is crucial for cell division.

In which phase of mitosis do the nuclear membranes reform around the separated chromosomes?

• Prophase

• Metaphase

• Anaphase

• Telophase

Answer explanation

During telophase, the nuclear membranes reform around the separated chromosomes, marking the near end of mitosis. This phase follows anaphase, where the chromosomes are pulled apart.

What is the main event that occurs during prophase?

• Chromosomes align at the equator

• Chromosomes condense and become visible

• Sister chromatids are pulled apart

• The cell divides into two

Answer explanation

During prophase, chromosomes condense and become visible under a microscope, marking the beginning of cell division. This is the key event that distinguishes prophase from other stages.

Which of the following is NOT a stage of mitosis?

• Interphase

• Prophase

• Metaphase

• Anaphase

Answer explanation

Interphase is not a stage of mitosis; it is the phase where the cell prepares for division. The stages of mitosis include prophase, metaphase, and anaphase.

What is the function of centromeres during mitosis?

• To replicate DNA

• To hold sister chromatids together

• To dissolve the nuclear membrane

• To synthesise proteins

Answer explanation

Centromeres play a crucial role during mitosis by holding sister chromatids together. This ensures that when the cell divides, each new cell receives an identical set of chromosomes.

Which stage of the cell cycle is the longest?

• Prophase

• Metaphase

• Interphase

• Anaphase

Answer explanation

Interphase is the longest stage of the cell cycle, lasting for the majority of the cycle. It includes G1, S, and G2 phases, where the cell grows, duplicates its DNA, and prepares for mitosis.