AP Biology Review: Unit 4

Multiple Choice

Signal transduction pathways sometimes require multiple steps to achieve a certain response. What is the advantage of having many steps in one pathway?

• The enzymes for each step are often located relatively far apart in the cell, so having multiple steps provides time for them to reach each other.

• Having multiple steps allows the response to be amplified, triggering a large response from one signal molecule.

• By breaking the task into multiple steps, the cell can release energy in small increments instead of overheating the cell with one large release of heat.

• The pathway can produce more products by repeating the same steps multiple times.

Multiple Choice

Adrenaline is a neuro transmitter and a hormone that plays a significant role in the human body's flight or fight response. When adrenaline binds to a receptor on smooth muscle, the smooth muscle relaxes. When adrenaline binds to a receptor on skeletal muscle, the skeletal muscle contracts. What causes the different reactions in the two types of muscle when exposed to adrenaline?

• A different signal transduction pathway is triggered by the binding of adrenaline to receptors on smooth muscle, which results in two cell types experiencing different responses.

• The smooth muscle cells are permeable to adrenaline, which activates different genes through transcription factors.

• The smooth muscle cells do not contain any second messengers, such as cGMP or IP3.

• Adrenaline binds to a tyrokinase receptor on one cell type and a G protein-coupled receptor on another cell type.

Multiple Choice

Cancer is an extensive category of diseases caused by unregulated cell growth, where cells grow uncontrollably and for malignant tumors that invade nearby and distant parts of the body. Which of the following identifies a characteristic of cancer cells when compared to healthy cells?

• Cell division is more carefully managed.

• The rate of mitosis is lower.

• Protein translocation occurs at a higher rate

• The cell cycle is shorter.

Multiple Choice

Which of the following correctly pairs the structure and function of part of the chromosome in a eukaryotic cell?

• Centromeres help attach the mitotic spindle

• Nucleosomes hold sister chromatids together

• Chromatids distribute one copy of each chromosome to daughter cells

• Kinetochores help package DNA into a compact structure.

Multiple Choice

Which of the following processes occurs during traditional mitosis?

• Chromosomes pair up with homologous partners

• Chromosomes from paternal gametes line up with maternal gametes

• Chromosomes line up in the middle of the cell before they are replicated.

• Chromosomes line up in the middle of the cell once they're replicated.

Multiple Choice

Which of the following mutations would be most likely to have a discernable change in the phenotype of an individual?

• Deletion of 400 base pairs, resulting in the loss of an enhancer

• Translocation of the last 1,000 base pairs of chromosome 1 onto chromosome 2

• Translocation of the first 1,000 base pairs of chromosome 2 onto chromosome 3

• Substitution of a single base that results in the same amino acid as the original codon.