Questions: Remaining Time: 2 hours, 32 minutes, 28 seconds. Question Completion Status: QUESTION 66 The transparent portion of the fibrous layer of the eye is the pupil. conjunctiva. cornea. canthus. iris. QUESTION 67 Which of the following are the most active type of leukocytes, phagocytically, and are usually the first to arrive at an injury site? lymphocytes neutrophils erythrocytes basophils eosinophils QUESTION 68 The endocrine system is regulated mainly by positive feedback. relies on the release of chemicals that bind to target cells. is not involved in homeostasis. releases neurotransmitters into the bloodstream for distribution throughout the body. produces effects that last for seconds or minutes.

QUESTION 66 The answer is the third one (cornea): the transparent portion of the fibrous layer of the eye is the cornea. Explanation:

• Pupil: Incorrect. The pupil is the opening in the center of the iris that allows light to enter the eye.
• Conjunctiva: Incorrect. The conjunctiva is a thin, transparent tissue that covers the outer surface of the eye and the inner surface of the eyelids.
• Cornea: Correct. The cornea is the transparent, dome-shaped surface that covers the front of the eye and is part of the fibrous layer.
• Canthus: Incorrect. The canthus refers to the corners of the eye where the upper and lower eyelids meet.
• Iris: Incorrect. The iris is the colored part of the eye that controls the size of the pupil.

QUESTION 67 The answer is the second one (neutrophils): the most active type of leukocytes, phagocytically, and are usually the first to arrive at an injury site. Explanation:

• Lymphocytes: Incorrect. Lymphocytes are involved in the adaptive immune response and are not primarily phagocytic.
• Neutrophils: Correct. Neutrophils are the most active phagocytic leukocytes and are typically the first to arrive at the site of an injury or infection.
• Erythrocytes: Incorrect. Erythrocytes are red blood cells and are not involved in phagocytosis.
• Basophils: Incorrect. Basophils are involved in inflammatory responses and allergic reactions but are not primarily phagocytic.
• Eosinophils: Incorrect. Eosinophils are involved in combating parasitic infections and allergic reactions but are not the most active phagocytic leukocytes.

QUESTION 68 The answer is the second one (relies on the release of chemicals that bind to target cells): the endocrine system relies on the release of chemicals that bind to target cells. Explanation:

• Is regulated mainly by positive feedback: Incorrect. The endocrine system is primarily regulated by negative feedback mechanisms.
• Relies on the release of chemicals that bind to target cells: Correct. The endocrine system releases hormones that travel through the bloodstream and bind to specific receptors on target cells.
• Is not involved in homeostasis: Incorrect. The endocrine system plays a crucial role in maintaining homeostasis by regulating various physiological processes.
• Releases neurotransmitters into the bloodstream for distribution throughout the body: Incorrect. Neurotransmitters are released by neurons, not the endocrine system. The endocrine system releases hormones.
• Produces effects that last for seconds or minutes: Incorrect. The effects of the endocrine system can last for hours, days, or even longer, depending on the hormone and the target tissue.

Summary:

• QUESTION 66: The transparent portion of the fibrous layer of the eye is the cornea.
• QUESTION 67: The most active type of leukocytes, phagocytically, and usually the first to arrive at an injury site are neutrophils.
• QUESTION 68: The endocrine system relies on the release of chemicals that bind to target cells.