All Free Biology MCQs with Answers
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19844 questions · page 703 of 1985
7021. The deficiency of adrenal cortex hormones can lead to _
- A. Dwarfism
- B. GERD
- C. Addison's Disease
- D. Acromegaly
Explanation: When adrenal glands don't produce enough hormones, this can lead to adrenal insufficiency (Addison's disease). Adrenal glands may develop nodules that can be benign or malignant, which can potentially produce excessive amounts of certain hormones leading to various health issues.
Correct answer: Addison's Disease7022. Which of the following are not steroid hormones but still do not act through second messenger system, are small, nonpolar and can be taken orally
- A. Prostaglandins
- B. Estrogen and progesterone
- C. Insulin and glucagon
- D. Thyroid hormones (T3 and T4)
Explanation: Prostaglandins are regulatory molecules but are not considered hormones. Estrogens and progesterones are nonpolar but are steroids. Insulin and glucagon are polar therefore cannot be taken orally.
Correct answer: Thyroid hormones (T3 and T4)7023. Whether a molecule acts as a neurotransmitter or a hormone, which statement about physiological regulation by these molecules is false?
- A. Target cells must have specific receptor proteins with which these molecules combine
- B. When these molecules bind to target cells, specific sequences of changes must occur
- C. There must be an 'off-switch' that will stop the induced changes
- D. Second messengers will always be involved in the response of the target cell
Explanation: This statement is false because not all hormones and neurotransmitters utilize second messengers. Steroid hormones (like testosterone and estrogen) and thyroid hormones are lipid-soluble, allowing them to pass directly through the cell membrane and bind to intracellular receptors in the cytoplasm or nucleus, directly influencing gene expression without needing a second messenger. Conversely, protein/peptide hormones and most neurotransmitters are water-soluble and must bind to surface receptors, which then typically trigger a second messenger cascade inside the cell to transmit the signal.
Correct answer: Second messengers will always be involved in the response of the target cell7024. Between which of the following hormone pairs is the interaction between hormones not an example of the permissive effect of a first hormone for a second hormone?
- A. Estrogen for prolactin on the mammary glands during pregnancy
- B. Parathyroid hormone for vitamin D3 on blood Ca2+ levels
- C. Estrogen for progesterone on the uterus
- D. Insulin for glucagon on adipose tissue
Explanation: The action of insulin and glucagon on adipose tissue is an example of antagonistic effect. Insulin decreases blood sugar level whereas glucagon increases it.
Correct answer: Insulin for glucagon on adipose tissue7025. Glucocorticoids do not:
- A. Stimulate gluconeogenesis
- B. Cause lipolysis
- C. Cause proteolysis
- D. Stimulate cellular uptake and utilization of amino acids
Explanation: Lucocorticoids are steroids chemically. Cortisol is an example of glucocorticoid. Glucocorticoids stimulate gluconeogenesis, lipolysis and proteolysis and inhibit cellular uptake and utilisation of amino acids.
Correct answer: Stimulate cellular uptake and utilization of amino acids7026. The endocrine system and the nervous system are chemically related. Which of the following substances best illustrates this relationship?
- A. Estrogen
- B. Calcitonin
- C. Norepinephrine
- D. Calcium
Explanation: Norepinephrine is a chemical released from the sympathetic nervous system in response to stress. It is classified as a neurotransmitter, a chemical that is released from neurons. Because the release of norepinephrine affects other organs of the body, it is also referred to as a stress hormone. So, norepinephrine is a chemical regulator, released as a neurotransmitter by sympathetic nerve endings and is also secreted by the adrenal gland as a hormone.
Correct answer: Norepinephrine7027. Which of the following is not true concerning glucocorticoids?
- A. They help to control electrolyte balance
- B. They help promote normal metabolism
- C. They help provide resistance to stress
- D. They provide the body with energy through gluconeogenesis
Explanation: Glucocorticoids stimulate, gluconeogenesis, lipolysis, and proteolysis; and inhibit cellular uptake and utilization of amino acids. Cortisol is involved in maintaining the cardiovascular system as well as the kidney functions. Glucocorticoids, particularly cortisol, produces anti-inflammatory reactions and suppress the immune response. Cortisol stimulates the RBC production.
Correct answer: They help to control electrolyte balance7028. A patient who is unable to modulate his own ventilation and heart rate may be suffering damage to which part of his brain?
- A. Midbrain
- B. Temporal lobes
- C. Corpus callosum
- D. Medulla oblongata
Explanation: The medulla oblongata, a part of the hindbrain, is primarily responsible for the control of ventilation and heart rate. The cerebellum is responsible for balance and coordination. Therefore, the patient is most likely suffering from damage to the medulla oblongata.
Correct answer: Medulla oblongata7029. The brain is a very delicate structure with little room to move around. Surrounding the brain and the spinal cord are three protective layers in addition to the skull and the vertebral column. Directly surrounding the brain and spinal cord is the pia mater. Following the pia mater is the arachnoid mater. Between the pia mater and the arachnoid mater is the subarachnoid space where the cerebrospinal fluid circulates. Finally, the protective layer is the dura mater is loosely attached to the arachnoid mater but is strongly associated with the skull bone.Depending on the type of injury, a certain type of vein and/or artery are more susceptible to injury. For example, the meningeal artery and vein run through the foramen spinosum and travel between the two layers making up the dura mater. As the artery and the vein are traveling in between the dura mater, there is a vulnerable region at the temple. A strike to the temple region could rupture these vessels and result in a epidural hematoma. Traveling from the cerebral cortex to the venous dural sinus (located at certain regions between the two layers of the dura mater) is the cerebral vein. When an injury results in the dura mater shifting away from the arachnoid mater, the cerebral vein could rupture and lead to a subdural hematoma. When a physician performs a lumbar puncture, he/she is extracting cerebrospinal fluid. Through which of the follow structure(s) must the needle pass?I. Dura materII. Arachnoid materIII. Pia mater
- A. I
- B. I and II
- C. III and I
- D. III
Explanation: As described in the passage, the innermost layer is the pia mater, then the arachnoid space, arachnoid mater and finally the dura mater. The dura mater is the outermost layer prior to the skull/vertebral column. Therefore, during a lumbar puncture, the needle will have to pass through the dura mater first then through the arachnoid mater to get to the subarachnoid space.
Correct answer: I and II7030. The central nervous system consists of the brain and the spinal cord. In general, tracts allow for the brain to communicate up and down with the spinal cord. The commissures allow for the two hemispheres of the brain to communicate with each other. One of the most important commissures is the corpus callosum. The association fibers allow for the anterior regions of the brain to communicate with the posterior regions. One of the evolved routes from the spinal cord to the brain is via the dorsal column pathway. This route allows for fine touch, vibration, proprioception and 2 points discrimination. This pathway is much faster than the pain route. From the lower limbs, the signal ascends to the brain via a region called the gracile fasciculus. From the upper limbs, the signal ascends via the cuneate fasciculus region in the spinal cord.Patient A has a tumor in his spinal cord. He is able to feel fine touch below the waist. Above the waist, he is unable to feel fine touch on either side. Where is the tumor most likely located?I. All levels of the spinal cordII. In the gracile fasciculus regionIII. In the cuneate fasciculus region
- A. I only
- B. I and II
- C. III only
- D. None of the above
Explanation: The text explains that the dorsal column pathway carries fine touch information. Signals from the lower limbs (below the waist) ascend via the gracile fasciculus, and signals from the upper limbs (above the waist) ascend via the cuneate fasciculus . Patient A can feel fine touch below the waist, meaning the signal from the lower limbs (gracile fasciculus) is intact. However, the patient cannot feel fine touch above the waist, indicating that the tumor is blocking the pathway carrying upper limb sensation, which is the cuneate fasciculus region.
Correct answer: III only