5A: Part of the cell cycle is shown in this simplified model. This part of the cell cycle is best described as the process that:

5A: Checkpoints occur between the stages of the cell cycle. If a cell does not meet certain criteria at the end of a stage, it will not move to the next stage. Which of these occurs just before the cell enters the G₂ stage of the cell cycle?

5A: The diagram shows cells in different phases of mitosis. A student is trying to find a cell in a particular phase of mitosis. The student is looking for evidence that spindle fibers are separating the chromosomes to ensure that each new nucleus has one copy of each chromosome. Which cell is in the phase of mitosis that the student is searching for?

Cancer is caused by

5C: Oncogenes are mutated forms of genes. Oncogenes can transform a cell into a tumor cell. Some tumor cells are benign, while others are malignant. How does the presences of an oncogene lead to the transformation of a tumor?

When cells lose their ability to regulate the cell cycle, they can divide at an accelerated rate and form a mass of cells. This mass of cells is referred to as -

Cells typically respond to DNA damage in three ways: by ceasing to grow and divide until the damage is repaired, by permanently ceasing to grow and divide, or by dying. In 2010 a group of scientists reported that a certain kind of immune reaction can cause DNA damage that leads to a fourth response. DNA damage can turn off genes involved in cell-signaling pathways. Turning off these genes can cause less-mature cells to divide too rapidly, often leading to the development of -

6D From a single fertilized ovum undergoing a series of rapid cell divisions, a human infant develops. The embryonic cells become specialized for a variety of functions. Which of these statements best describes how different cell types develop?

What is the name for undifferentiated cells?

Gene expression is regulated by:

Which are internal factors that influence gene expression?

Select two answers

Which are external factors that influence gene expression?

Select two answers

6D: The arctic fox inhabits northern areas of North America. The same arctic fox is shown in the drawing at different times of the year. What causes this change in fur color?