Home Subjects NEET Zoology

NEET Zoology

Zoology questions for NEET UG — Animal Kingdom, Human Physiology, Genetics, Evolution.

540 Q 6 Topics Take Test
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Difficulty: All Easy Medium Hard 181–190 of 540
Topics in NEET Zoology
Which hormone is primarily responsible for maintaining the corpus luteum during early pregnancy?
A Human chorionic gonadotropin (hCG)
B Follicle-stimulating hormone (FSH)
C Luteinizing hormone (LH)
D Oxytocin
Correct Answer:  A. Human chorionic gonadotropin (hCG)
EXPLANATION

hCG is secreted by the trophoblast cells of the blastocyst and maintains the corpus luteum, preventing its degeneration and ensuring continued progesterone production during early pregnancy.

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Q.182 Medium Reproductive Health
What is the mechanism of action of misoprostol when used for medical abortion in the first trimester?
A Inhibits progesterone receptor, detaches endometrium
B Causes uterine contractions to expel pregnancy tissue
C Induces apoptosis of trophoblastic cells
D Blocks blood supply to developing embryo
Correct Answer:  B. Causes uterine contractions to expel pregnancy tissue
EXPLANATION

Misoprostol, a prostaglandin analog, causes sustained uterine contractions that expel pregnancy tissues. It is typically used after mifepristone (progesterone antagonist) in medical abortion protocols.

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During oogenesis, at which stage does the first meiotic division complete?
A Before puberty in fetal ovaries
B At ovulation
C After fertilization when sperm penetrates egg
D During fetal development but arrested at metaphase II
Correct Answer:  B. At ovulation
EXPLANATION

Oocytes arrest in prophase I during fetal development and remain in this arrested state (dictyotene). First meiotic division completes just before ovulation, producing secondary oocyte and polar body.

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Q.184 Medium Reproductive Health
Which sexually transmitted infection is characterized by painless genital ulcers with indurated edges and a clean base?
A Gonorrhea
B Primary syphilis
C Herpes simplex virus
D Lymphogranuloma venereum
Correct Answer:  B. Primary syphilis
EXPLANATION

Primary syphilis presents with painless, indurated ulcers (chancre) with a clean base and raised borders. HSV causes painful vesicles; LGV causes small painless pustules.

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Q.185 Medium Reproductive Health
A woman using combined oral contraceptive pills reports breakthrough bleeding. Which factor is MOST likely responsible?
A Excessive estrogen dose
B Insufficient progestin for endometrial stability
C Increased endometrial proliferation from high estrogen
D Overdose of progestin causing endometrial atrophy
Correct Answer:  B. Insufficient progestin for endometrial stability
EXPLANATION

Breakthrough bleeding typically results from insufficient progestin to stabilize endometrium. Management includes switching to a pill with higher progestin content.

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Q.186 Medium Reproductive Health
What is the most common chromosomal abnormality in spontaneous miscarriages?
A Trisomy 13
B Trisomy 21
C Trisomy 16
D Monosomy X
Correct Answer:  C. Trisomy 16
EXPLANATION

Trisomy 16 is the most common chromosomal abnormality in first-trimester miscarriages (accounts for ~15% of chromosomal losses) but is incompatible with life beyond early pregnancy.

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Which phase of the ovarian cycle is characterized by rising estrogen levels and endometrial proliferation?
A Follicular phase
B Luteal phase
C Ovulation
D Menstruation
Correct Answer:  A. Follicular phase
EXPLANATION

The follicular phase (days 5-14) is marked by rising estrogen from developing follicles, causing endometrial proliferation and preparation for ovulation.

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A 26-year-old male presents with complaints of erectile dysfunction and reduced sperm count. Testosterone level is 2.5 ng/mL (normal: 3-10 ng/mL). What could be the underlying cause?
A Primary hypogonadism
B Secondary hypogonadism from pituitary dysfunction
C Androgen insensitivity syndrome
D Klinefelter syndrome with normal testosterone
Correct Answer:  B. Secondary hypogonadism from pituitary dysfunction
EXPLANATION

Low testosterone with erectile dysfunction requires assessment of LH and FSH. If LH/FSH are low, it indicates secondary hypogonadism (pituitary/hypothalamic origin).

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What is the recommended interval for cervical cancer screening using Pap smear in women aged 21-65 years with normal previous results?
A Every year
B Every 3 years
C Every 5 years
D Every 10 years
Correct Answer:  B. Every 3 years
EXPLANATION

As per WHO and Indian guidelines, women with normal Pap smear results should be screened every 3 years. Annual screening is reserved for high-risk cases.

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Q.190 Medium Reproductive Health
Which of the following is a characteristic feature of Polycystic Ovary Syndrome (PCOS)?
A High LH to FSH ratio (>2:1 or 3:1)
B Low androgen levels
C Regular ovulatory cycles
D Elevated TSH levels
Correct Answer:  A. High LH to FSH ratio (>2:1 or 3:1)
EXPLANATION

PCOS typically presents with elevated LH:FSH ratio (>2:1 or 3:1), hyperandrogenism, insulin resistance, and anovulation, not regular cycles.

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