NEET-PG 2015 - Physiology Practice Questions

Q: Miracle fruit is used to change the taste from?

Sour to Sweet. ***Sour to Sweet*** - The **miracle fruit** (Synsepalum dulcificum) contains a glycoprotein called **miraculin**. - Miraculin binds to taste receptors on the tongue and modifies their perception, making **sour foods taste sweet**. *Sour to Bitter* - The primary effect of miracle fruit is to convert **sour tastes into sweet tastes**, not bitter ones. - No known natural compound consistently changes sour perception to bitter. *Bitter to Sweet* - While miraculin makes sour foods sweet, it does not typically convert **bitter tastes into sweet sensations**. - Bitter taste perception involves different receptor pathways that are not significantly altered by miraculin. *Salty to Sweet* - Miracle fruit primarily targets **sour taste receptors**. - It does not have a significant effect on altering the perception of **salty tastes to sweet**.

Q: Hyperpigmentation is seen with which hormone?

ACTH. ***ACTH*** - In conditions like **Addison's disease**, the adrenal glands' inability to produce cortisol leads to increased **ACTH** (adrenocorticotropic hormone) secretion due to a lack of negative feedback [3], [4]. - ACTH is derived from proopiomelanocortin (POMC), which also gives rise to alpha-melanocyte-stimulating hormone (α-MSH). Elevated ACTH levels can thus stimulate melanocytes, causing **hyperpigmentation** in skin folds, buccal mucosa, and pressure points [4]. *FSH* - **FSH** (follicle-stimulating hormone) primarily regulates the development of **follicles in the ovaries** and sperm production in the testes [1]. - There is no known direct association between excessive FSH levels and **hyperpigmentation**. *TSH* - **TSH** (thyroid-stimulating hormone) stimulates the **thyroid gland** to produce thyroid hormones (T3 and T4) [1]. - While thyroid disorders can affect skin texture and moisture, there is no direct link between elevated TSH and **hyperpigmentation**. *LH* - **LH** (luteinizing hormone) plays a key role in **ovulation** in females and testosterone production in males [2]. - High LH levels are not associated with **hyperpigmentation**.

Q: What is the intensity in decibel of normal conversation in humans?

60dB. ***60dB*** - The sound intensity of **normal human conversation** is typically around **60 decibels (dB)**. - This level is considered **moderate** and is comfortably audible without causing discomfort or hearing damage. *30dB* - A sound intensity of **30dB** is characteristic of a **quiet whisper** or a **soft rustle of leaves**. - This level is much **quieter** than a normal conversation and would require closer proximity to be clearly heard. *90dB* - **90dB** represents a significantly **louder sound**, comparable to that of a **lawnmower** or a **heavy truck** passing by. - Prolonged exposure to sounds at this intensity can start to cause **hearing damage**. *150dB* - **150dB** is an **extremely loud** and potentially **painful** sound level, similar to a **jet engine at takeoff** or a **firecracker** exploding nearby. - Exposure to sounds this intense can cause **immediate and permanent hearing loss**.

Q: What is the SI unit of luminous intensity?

Candela. ***Candela*** - The **candela (cd)** is the **SI base unit** used to measure **luminous intensity**. - **Luminous intensity** quantifies the power emitted by a light source in a particular direction per unit solid angle. *Lumen* - The **lumen (lm)** is the **SI derived unit** for **luminous flux**, which measures the total perceived power of light. - It describes the total amount of visible light emitted by a source in all directions, not its intensity in a specific direction. *Lux* - The **lux (lx)** is the **SI derived unit** for **illuminance**, which measures how much luminous flux is spread over a given area. - It indicates the perceived brightness of a surface, rather than the intensity of the light source itself. *Coulomb* - The **coulomb (C)** is the **SI derived unit** for **electric charge**. - It is completely unrelated to light or luminous intensity.

Q: The role of human placental lactogen is :

Supports fetal growth and development.. ***Supports fetal growth and development.*** - Human placental lactogen (hPL) acts as a **growth hormone** for the fetus, primarily by altering maternal metabolism to favor fetal nutrient supply. - It increases **maternal insulin resistance**, leading to higher maternal glucose and free fatty acids, which are then shunted to the fetus, supporting its growth and development. *Stimulate milk production* - **Prolactin**, secreted by the anterior pituitary, is the primary hormone responsible for stimulating milk production (lactogenesis). - While hPL has some structural similarity to growth hormone and prolactin, its primary role is not to directly stimulate milk production during pregnancy; rather, it prepares the breasts. *Promotes growth of breast for lactation.* - hPL, along with **estrogen** and **progesterone**, contributes to the **mammary gland development** during pregnancy, preparing the breasts for lactation. - However, its direct role is more about **mammary gland proliferation and differentiation** rather than initiation of milk production. *Provide fetal nutrition by antagonizing the action of insulin in maternal circulation, breakdown of fats and proteins and transport of fatty acids and amino acids from maternal to fetal circulation.* - This is a highly detailed and largely accurate description of *how* hPL supports fetal growth and development, making it a mechanism rather than the primary, concise role. - It describes the metabolic changes induced by hPL, which ultimately lead to the **support of fetal growth and development**.

Q: What is the primary change in fetal circulation that occurs at birth?

Closure of the foramen ovale. ***Closure of the foramen ovale*** - The **foramen ovale** undergoes functional closure within minutes of birth, making it the **primary immediate circulatory change** - At birth, the first breath causes **dramatic decrease in pulmonary vascular resistance** and **increased pulmonary blood flow**, which raises **left atrial pressure** - Simultaneously, umbilical cord clamping **increases systemic vascular resistance** and **decreases right atrial pressure** (loss of placental return) - This **pressure gradient reversal** (left atrial pressure > right atrial pressure) causes the **septum primum** to be pushed against the **septum secundum**, achieving functional closure - This immediately separates the systemic and pulmonary circulations, which is the **most critical primary change** in transitioning from fetal to neonatal circulation *Closure of the patent ductus arteriosus* - The **ductus arteriosus** undergoes **functional closure over 10-15 hours** after birth, followed by **anatomical closure over 2-3 weeks** - Closure occurs due to increased arterial oxygen tension and decreased prostaglandin E2 levels, causing smooth muscle constriction - While important, this is a **secondary change** that occurs more gradually compared to the immediate foramen ovale closure *Closure of the ductus venosus* - The **ductus venosus** closes functionally within 3-7 days as umbilical venous flow ceases - This redirects portal blood through the liver but does not directly impact the critical pulmonary-systemic circulation separation *Increased activity of the right ventricle* - After birth, the **left ventricle** becomes dominant as it pumps against higher systemic vascular resistance - The right ventricle actually experiences **decreased afterload** due to falling pulmonary vascular resistance - This is a consequence of, not the primary change in, the circulatory transition

Q: Antimullerian hormone is secreted by ?

Both Sertoli cells and granulosa cells. ***Both Sertoli cells and granulosa cells*** - **Antimullerian hormone (AMH)** is produced by **Sertoli cells in males** and **granulosa cells in females** - In **males**: Sertoli cells secrete AMH during fetal development to cause **regression of Müllerian ducts** (which would otherwise develop into uterus, fallopian tubes, and upper vagina) - In **females**: Granulosa cells of developing ovarian follicles secrete AMH, which serves as a **marker of ovarian reserve** and inhibits excessive follicle recruitment - This is the only option that correctly identifies both cell types that produce AMH *Theca cells* - Theca cells are found in ovarian follicles and produce **androgens** (androstenedione and testosterone), not AMH - These androgens are converted to estrogens by granulosa cells via aromatase enzyme - Theca cells do not produce antimullerian hormone *Leydig cells* - Leydig cells are located in the **testes** and produce **testosterone** - They do not produce antimullerian hormone - Only Sertoli cells (not Leydig cells) produce AMH in males *None of the above* - This is incorrect because AMH is indeed produced by specific cell types: **Sertoli cells in males** and **granulosa cells in females**

Q: Oxygen consumption increases in pregnancy by

20%. ***20%*** - During **pregnancy**, the maternal **metabolic rate increases** to support fetal growth and the physiological changes occurring in the mother's body. - This increased metabolic demand leads to a **rise in oxygen consumption** by approximately 20% compared to the non-pregnant state. *10%* - A 10% increase is an **underestimation** of the physiological change in oxygen consumption during pregnancy. - The demands of supporting a growing fetus and increased maternal tissue mass require a more substantial metabolic adjustment. *30%* - While oxygen consumption does increase significantly, a 30% rise is generally considered an **overestimation** of the average increase. - The typical physiological adaptation usually falls within the 15-25% range. *40%* - A 40% increase in oxygen consumption would represent an **extreme physiological demand** that is not typically observed during an uncomplicated pregnancy. - Such a drastic increase might indicate underlying pathology rather than normal adaptation.

Q: Osteoclasts have all of the following functions except -

Receptor for parathormone. ***Receptor for parathormone*** - **Osteoclasts** do not directly have receptors for **parathormone (PTH)**; instead, **osteoblasts** have PTH receptors. - When PTH binds to osteoblasts, they release factors (like **RANKL**) that stimulate osteoclast activity, thus indirectly regulating bone resorption. *Bone resorption* - **Osteoclasts** are specialized cells primarily responsible for **resorbing bone matrix**, a critical process in bone remodeling. - They secrete **acids and enzymes** to break down the mineral and organic components of bone. *Ruffled border* - The **ruffled border** is a characteristic morphological feature of active osteoclasts, representing a highly folded plasma membrane. - This specialized structure increases the surface area for the secretion of **protons and lysosomal enzymes** into the bone-resorbing compartment. *RANK ligand production* - **Osteoclasts** do not produce **RANK ligand (RANKL)**; rather, they have **RANK receptors** that bind to RANKL produced by **osteoblasts and stromal cells**. - The binding of RANKL to RANK is essential for the **differentiation, activation, and survival** of osteoclasts.

Q: Testes are not palpable in

SRY deletion. ***SRY deletion*** - **SRY (Sex-determining Region Y) gene** is the master regulator of male sex determination on the Y chromosome; its deletion in 46,XY individuals results in **Swyer syndrome** (pure gonadal dysgenesis). - Without functional SRY, **testes fail to develop entirely**, and the gonads remain as non-functional **streak gonads** rather than differentiating into either testes or ovaries. - Result: **No palpable testes** because testicular tissue never forms; individuals develop female external genitalia despite XY karyotype. *DAX1 deletion* - DAX1 (NR0B1) normally **antagonizes testicular development** and supports adrenal/gonadal development. - **Deletion of DAX1** would actually **reduce anti-testis effects**, allowing testicular development to proceed more readily if SRY is present. - DAX1 **duplications** (not deletions) can impair male development; deletions cause **adrenal hypoplasia congenita** but do not prevent testicular formation. *WNT-4 gene mutation* - **WNT4** promotes **ovarian development** and opposes male differentiation pathways in normal female development. - **Loss-of-function mutations** in WNT4 do not prevent testicular development in 46,XY individuals where SRY is present and functional. - WNT4 overexpression (not loss-of-function mutation) could theoretically interfere with male development, but standard WNT4 mutations do not cause absent testes. *RSPO-1 gene mutation* - **RSPO1** (R-spondin 1) enhances **Wnt/β-catenin signaling** and supports ovarian differentiation; primarily relevant in 46,XX sex development. - Loss-of-function mutations in RSPO1 lead to **46,XX testicular/ovotesticular DSD**, where testicular tissue develops inappropriately in XX individuals. - In 46,XY individuals with functional SRY, RSPO1 mutations would **not prevent testicular development**, so testes would be palpable.

Question 1

Miracle fruit is used to change the taste from?

Accepted Answer

Sour to Sweet

Answer

Sour to Bitter

Answer

Bitter to Sweet

Answer

Salty to Sweet

Question 2

Hyperpigmentation is seen with which hormone?

Accepted Answer

ACTH

Answer

TSH

Answer

FSH

Answer

LH

Question 3

What is the intensity in decibel of normal conversation in humans?

Accepted Answer

60dB

Answer

30dB

Answer

90dB

Answer

150dB

Question 4

What is the SI unit of luminous intensity?

Accepted Answer

Candela

Answer

Lumen

Answer

Lux

Answer

Coulomb

Question 5

The role of human placental lactogen is :

Accepted Answer

Supports fetal growth and development.

Answer

Stimulate milk production

Answer

Promotes growth of breast for lactation.

Answer

Provide fetal nutrition by antagonizing the action of insulin in maternal circulation, breakdown of fats and proteins and transport of fatty acids and amino acids from maternal to fetal circulation.

Question 6

What is the primary change in fetal circulation that occurs at birth?

Accepted Answer

Closure of the foramen ovale

Answer

Closure of the ductus venosus

Answer

Increased activity of the right ventricle

Answer

Closure of the patent ductus arteriosus

Question 7

Antimullerian hormone is secreted by ?

Accepted Answer

Both Sertoli cells and granulosa cells

Answer

Theca cells

Answer

Leydig cells

Answer

None of the above

Question 8

Oxygen consumption increases in pregnancy by

Accepted Answer

20%

Answer

10%

Answer

30%

Answer

40%

Question 9

Osteoclasts have all of the following functions except -

Accepted Answer

Receptor for parathormone

Answer

Ruffled border

Answer

Bone resorption

Answer

RANK ligand production

Question 10

Testes are not palpable in

Accepted Answer

SRY deletion

Answer

DAX 1 deletion

Answer

WNT- 4 gene mutation

Answer

RSPO-1 gene mutation

NEET-PG 2015 — Physiology