STAAR Biology - 5A-5D

A photomicrograph of onion root tip cells during mitosis is shown below.

Which phase of mitosis is occurring in the cell indicated by the arrow?

• Prophase
• Metaphase
• Anaphase
• Telophase

Which of these must occur during S phase of the cell cycle so that two daughter cells can be produced during M phase?

• The DNA must be replicated
• The chromosomes must be joined
• The cytoplasm must be seperated
• The cell membrane must be expanded

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?

• The nuclear membrane disintegrates
• DNA replicates
• Centrioles form
• The nucleolus divides

Telophase is a stage of cellular process that begins after chromosomes have moved to opposite poles of the cell.  During which cellular process does telophase occur?

• Translation
• Interphase
• Transcription
• Mitosis

The model represents the change in the DNA content of a cell during the cell cycle.
Which part of the model represents the S phase?

• I
• II
• III
• IV

Most plants have hair-like cells called trichomes that project from the surface and help the plants in many ways. In some plants trichomes secrete toxic substances that most likely perform which function?

• Absorb carbon dioxide
• Protect against herbivorous insects
• Reflect light off leaves 
• Reduce water loss from evaporation

The table below lists the types of white blood cells found in humans, indicates how abundant they are, and describes their functions.
The two most abundant types of white blood cells may both be involved in a response to which of these?

• Injury
• Heat
• Allergens
• Bacterial infection

Cell differentiation is critical during embryonic development. The process of cell differentiation results in the production of many types of cells, including germ, somatic, and stem cells. Cell differentiation is most directly regulated by —

• ATP
• DNA
• lipids
• sugars

Researchers Robert Briggs and Thomas King used ultraviolet radiation to destroy the nuclear DNA of frog eggs. Nuclei from adult skin cells and from tadpole-gut epithelial cells were cultured and then injected into eggs that had their nuclei destroyed. The results were tadpoles.
Which conclusion is supported by the data from this investigation?

• The DNA information for development was silenced in differentiated cells
• The transplanted DNA functioned as the original nuclear DNA of the egg cell would have
• The DNA from skin cells and epithelial cells was not transcribed
• The transplanted DNA mutated during culturing 

The diagram below represents the cell cycle.

When cells leave the cell cycle, they exit during G₁ phase and then enter G₀ phase, a resting period. Most normal cells can leave G₀ phase and reenter the cell cycle at G₁ phase before entering S phase. Cancer cells are different because they cannot enter G₀ phase and are likely to do which of the following?

• Fail to complete S phase
• Mutate during G₁ phase
• Repeat the cell cycle continuously
• Die after completing mitosis