NEET-PG 2015 - Physiology PYQs Practice Questions

Q: Which of the following characteristics is shared by both active transport and facilitated diffusion?

Requires specific carrier proteins. ***Requires specific carrier proteins*** - Both **active transport** and **facilitated diffusion** rely on specific **transmembrane proteins** to move substances across the cell membrane. - These carrier proteins bind to the specific molecule they transport, undergoing conformational changes that facilitate its movement. *Does not require energy input* - This statement is only true for **facilitated diffusion**, which is a form of passive transport. - **Active transport** requires an input of **metabolic energy**, typically in the form of ATP, to move substances. *Transports solute down concentration gradient* - This is characteristic of **facilitated diffusion**, where molecules move from an area of higher concentration to an area of lower concentration. - **Active transport** moves solutes **against** their concentration gradient, requiring energy. *Transports solute against concentration gradient* - This is a defining feature of **active transport**, which allows cells to accumulate substances even when their external concentration is lower. - **Facilitated diffusion** moves solutes **down** their concentration gradient and cannot transport against a gradient. [Practice more Physiology PYQs on OnCourse]

Q: Through which of the following means of transport is folic acid absorbed in the proximal jejunum?

Both active and passive transport. ***Both active and passive transport*** - **Folic acid** absorption in the **proximal jejunum** occurs through **both active and passive mechanisms**. - At **low physiological concentrations**, an **active carrier-mediated transport** system is primarily responsible, while at **higher concentrations** (e.g., from supplements), **passive diffusion** also plays a significant role. *Facilitated diffusion* - While a type of passive transport, **facilitated diffusion** alone does not fully encompass the entirety of folic acid absorption, especially at low concentrations. - It relies on a **concentration gradient** and **carrier proteins** but does not require metabolic energy. *Active transport* - **Active transport** is crucial for absorbing folic acid when its concentration is low in the gut lumen. - This process requires **energy** and specific **carrier proteins**, like the **reduced folate carrier (RFC)**, to transport folate against a concentration gradient. *Passive transport* - **Passive transport**, specifically **simple diffusion**, contributes to folic acid absorption but primarily at **high lumen concentrations**, such as after taking large doses of supplements. - It occurs down a **concentration gradient** and does not require energy or specific carriers. [Practice more Physiology PYQs on OnCourse]

Q: Labour pain in uterus is carried by

Sympathetic nerves. ***Sympathetic nerves*** - Pain signals from the **uterus** during the first stage of labor (cervical dilation and uterine contractions) are transmitted via **visceral afferent fibers that accompany the sympathetic nerves** through the **hypogastric plexus**. - These fibers synapse in the **thoracolumbar spinal cord** at **T10-L1 segments**, leading to referred pain in these dermatomes. - The pathway is: Uterus → Uterine plexus → Superior hypogastric plexus → Sympathetic chain → T10-L1 dorsal roots. *Splanchnic nerve* - While visceral afferents do travel with splanchnic nerves in the thoracoabdominal region, for **uterine pain** specifically, the standard medical terminology refers to **sympathetic nerves** and the **hypogastric plexus** as the primary pathway. - Splanchnic nerves typically refer to thoracic sympathetic contributions (T5-T12) to upper abdominal viscera. *Pudendal nerve* - The **pudendal nerve (S2-S4)** primarily innervates the perineum, external genitalia, and pelvic floor structures. - It transmits pain during the **second stage of labor**, particularly with stretching of the perineum and vaginal distension, but **not from the uterus itself**. *Parasympathetic nerves* - **Parasympathetic innervation (S2-S4 via pelvic splanchnic nerves)** to the uterus influences motor function but does **not transmit nociceptive (pain) signals** during labor. - These nerves are involved in visceral reflexes and efferent control, not the primary afferent pain pathway. [Practice more Physiology PYQs on OnCourse]

Q: Which of the following is not a recognized stage of prophase I in meiosis?

Arachytene. ***Arachytene*** - **Arachytene** is not a recognized stage of prophase I in meiosis. - The correct stages are leptotene, zygotene, pachytene, diplotene, and diakinesis. *Diakinesis* - **Diakinesis** is the final stage of prophase I, where homologous chromosomes condense further, and the nuclear envelope begins to break down. - Chiasmata terminalize, and the bivalents are ready for metaphase I. *Leptotene* - **Leptotene** is the first stage of prophase I, characterized by the condensation of chromatin into visible chromosomes. - Chromosomes appear as long, thin threads. *Zygotene* - **Zygotene** is the second stage of prophase I, where homologous chromosomes pair up in a process called **synapsis**, forming bivalents. - The synaptonemal complex begins to form between homologous chromosomes. [Practice more Physiology PYQs on OnCourse]

Q: In a patient experiencing a stress response, which structure acts as the major central coordinator of the sympathetic nervous system?

Hypothalamus. ***Hypothalamus*** - The **hypothalamus** is the primary subcortical region that integrates stress responses by coordinating the **autonomic nervous system** and the **endocrine system**. - It directly regulates the **sympathetic nervous system** activation during stress through its projections to lower brainstem and spinal cord centers. *Nucleus ambiguus* - This nucleus is primarily involved in the motor control of the **pharynx, larynx, and esophagus**, as well as controlling the **parasympathetic innervation of the heart**. - While part of the autonomic system, it is not the major central coordinator of the sympathetic stress response. *Nucleus tractus solitarius* - The **nucleus tractus solitarius (NTS)** receives visceral sensory input from cranial nerves (e.g., vagus nerve) and plays a role in cardiovascular and respiratory reflexes. - It influences the autonomic nervous system but acts as a relay and integration center for specific reflexes rather than the overall central coordinator of the stress response. *Edinger-Westphal nucleus* - The **Edinger-Westphal nucleus** is a preganglionic parasympathetic nucleus that controls the **pupillary light reflex** and **accommodation (lens focusing)**. - Its function is related to the parasympathetic division but not as the central coordinator of the systemic sympathetic stress response. [Practice more Physiology PYQs on OnCourse]

Question 1

Which of the following characteristics is shared by both active transport and facilitated diffusion?

Accepted Answer

Requires specific carrier proteins

Answer

Does not require energy input

Answer

Transports solute down concentration gradient

Answer

Transports solute against concentration gradient

Question 2

Through which of the following means of transport is folic acid absorbed in the proximal jejunum?

Accepted Answer

Both active and passive transport

Answer

Facilitated diffusion

Answer

Active transport

Answer

Passive transport

Question 3

Labour pain in uterus is carried by

Accepted Answer

Sympathetic nerves

Answer

Pudendal nerve

Answer

Parasympathetic nerves

Answer

Splanchnic nerve

Question 4

Which of the following is not a recognized stage of prophase I in meiosis?

Accepted Answer

Arachytene

Answer

Diakinesis

Answer

Leptotene

Answer

Zygotene

Question 5

In a patient experiencing a stress response, which structure acts as the major central coordinator of the sympathetic nervous system?

Accepted Answer

Hypothalamus

Answer

Nucleus ambiguus

Answer

Nucleus tractus solitarius

Answer

Edinger-Westphal nucleus

Question 6

Spermatogenesis begins at -

Accepted Answer

Puberty

Answer

Birth

Answer

5 years

Answer

18 years

Question 7

Stapedius pulls stapes in which direction?

Accepted Answer

Posterior

Answer

Answer

Superior

Answer

Inferior

Question 8

Which of the following statements about ENaC is incorrect?

Accepted Answer

Composed of 2 homologous subunits

Answer

Present in kidney and GIT

Answer

Epithelial channel

Answer

Inhibited by amiloride

Question 9

What is the composition of epithelial sodium channels?

Accepted Answer

1α, 1β, 1γ

Answer

2α, 1β, 1γ

Answer

2α, 1β

Answer

2α, 1β, 2γ

Question 10

What is the process of passive transport of molecules through protein pores/channels in the cell membrane?

Accepted Answer

Diffusion

Answer

Transcytosis

Answer

Endocytosis

Answer

Active transport

NEET-PG 2015 — Physiology