1. What is the primary factor that causes basal cell carcinoma?
A. Wounds with open sores
B. Exposure to artificial radiation
C. Long-term sun exposure Correct
D. Arsenic poisoning
Explanation
Basal cell carcinoma, the most common form of skin cancer, is primarily caused by cumulative, long-term exposure to ultraviolet (UV) radiation from the sun. This damage to the basal cells in the deepest layer of the epidermis leads to uncontrolled cell growth.
2. What is the innermost coating of the eye?
A. Inner synaptic layer
B. Fibrous tunic
C. Outer synaptic layer
D. Neural tunic Correct
Explanation
The eye has three layers or tunics: the fibrous tunic (outer layer, includes sclera and cornea), the vascular tunic (middle layer, includes choroid, ciliary body, iris), and the neural tunic (innermost layer, which is the retina).
3. Which behavior is demonstrated by leakage channels?
A. They reduce the frequency of active transport.
B. They increase the rate of depolarization.
C. They release calcium ions into the cytoplasm.
D. They open and close independently of stimuli. Correct
Explanation
Leakage channels (or passive channels) are nongated, meaning they are always open and allow ions to leak across the membrane according to their electrochemical gradient. Their operation is random and not dependent on a specific stimulus.
4. What cells are responsible for the absorption of colored light?
A. Neuroglia
B. Cones Correct
C. Astrocytes
D. Rods
Explanation
Photoreceptor cells in the retina are responsible for absorbing light. Cones are specialized for color vision and fine detail in bright light, while rods are for vision in dim light and do not perceive color.
5. Which action describes cellular movement against a concentration or an electrochemical gradient?
A. Molecules move with the help of energy. Correct
B. Materials move directly through the lipid bilayer.
C. Molecules move with a concentration gradient.
D. Materials move into the cell using natural kinetic energy.
Explanation
Movement against a concentration gradient requires energy input in the form of ATP. This is the definition of active transport, which uses energy to pump molecules from an area of low concentration to an area of high concentration.