Learning
1. Which two properties are shared by cancer cells?
A) Rapid growth and small size
B) Uncontrolled cell division and the ability to invade other tissues
(metastasis)
C) Large nuclei and multiple nucleoli
D) Apoptosis and differentiation
Correct Answer: Uncontrolled cell division and the ability to invade other
tissues (metastasis)
Rationale: Cancer cells are defined by their ability to divide uncontrollably
(loss of cell cycle regulation) and their invasive potential (metastasis). While
other features like large nuclei may be observed, they are not defining
criteria.
2. True or False: Most cancer gene mutations are inherited.
A) True
B) False
Correct Answer: False
Rationale: The vast majority of cancer-causing mutations are somatic
(acquired during a person's lifetime due to environmental factors or random
errors in DNA replication), not inherited through germline cells. Only about 5–
10% of cancers are hereditary.
3. A tumor confined to a localized region of the body is called a ______ tumor.
If that tumor breaks off and invades other tissues, it is called a ______ tumor.
,A) Malignant; benign
B) Benign; malignant
C) Primary; secondary
D) Local; metastatic
Correct Answer: Benign; malignant
Rationale: Benign tumors are non-cancerous growths that remain localized
and do not spread. Malignant tumors are cancerous, can invade nearby
tissues, and metastasize to distant sites.
4. Which protein is responsible for "checking" DNA damage at the G1/S
checkpoint?
A) p53
B) Cyclin D
C) CDK4
D) Rb
Correct Answer: p53
Rationale: p53 is a tumor suppressor protein that acts as a transcription
factor, activating DNA repair genes and arresting the cell cycle at G1/S when
damage is detected. If damage is irreparable, p53 can initiate apoptosis.
5. The retinoblastoma protein (Rb) functions to:
A) Promote progression from G1 to S phase
B) Inhibit E2F transcription factor, blocking cell cycle progression
C) Activate cyclin-dependent kinases
, D) Repair double-strand DNA breaks
Correct Answer: Inhibit E2F transcription factor, blocking cell cycle
progression
Rationale: In its active (hypophosphorylated) state, Rb binds to E2F
transcription factors, preventing them from activating genes required for S
phase entry. When phosphorylated by cyclin-CDK complexes, Rb releases
E2F, allowing cell cycle progression.
6. Which of the following best describes a proto-oncogene?
A) A gene that normally promotes cell division but can mutate to cause
cancer
B) A gene that normally suppresses tumors
C) A gene that repairs DNA damage
D) A gene that induces apoptosis
Correct Answer: A gene that normally promotes cell division but can mutate
to cause cancer
Rationale: Proto-oncogenes are normal genes involved in cell growth and
division (e.g., growth factors, receptors, signal transducers). When mutated
or overexpressed, they become oncogenes that drive uncontrolled
proliferation.
7. A tumor suppressor gene is best described as:
A) A gene that promotes cell division
B) A gene that normally prevents uncontrolled cell growth
C) A gene that causes metastasis
D) A gene that is always mutated in cancer