Zoology MCQs for NEET — Practice Questions with Answers

Rod cells contain a pigment called rhodopsin, which is often referred to as visual purple. However, rod cells are not specifically sensitive to purple light; they are more sensitive to low light levels and are responsible for vision in dim light conditions. Hence, the assertion is correct, but the reason is incorrect.

The corpus callosum does join the two cerebral hemispheres, which is true. However, it is composed of myelinated axons (white matter) rather than unipolar neurons. Therefore, the assertion is correct, but the reason is incorrect.

The cranial nerves that supply the muscles of the eye are the oculomotor nerve (cranial nerve III), the trochlear nerve (cranial nerve IV), and the abducens nerve (cranial nerve VI). These nerves control most of the eye's movements, the constriction of the pupil, and maintaining an open eyelid. Hence, the correct answer is option 4: 3, 4, 6.

The glossopharyngeal, trigeminal, and vagus nerves are all mixed cranial nerves, meaning they have both sensory and motor functions. The auditory nerve, however, is purely sensory.

The respiratory centers in the brain are primarily sensitive to high concentrations of CO₂ in the blood. When the levels of carbon dioxide increase, it leads to a decrease in pH (making the blood more acidic), which stimulates the respiratory centers to increase the rate and depth of breathing, thereby expelling CO₂ and returning the blood pH to normal.

The space between the pia mater and the arachnoid mater is called the subarachnoid space. This space is filled with cerebrospinal fluid (CSF) which acts as a cushion for the brain and spinal cord, providing mechanical and immunological protection.

The hypothalamus contains various centers that regulate body temperature. It acts as the body's thermostat, detecting changes in body temperature and initiating appropriate responses to maintain homeostasis. For example, if the body is too hot, the hypothalamus can trigger mechanisms such as sweating to cool down.

The inferior colliculi are part of the midbrain and play a crucial role in auditory processing and reflexes. They help in the localization of sound and the startle response to loud noises.