Home Subjects NEET Zoology

NEET Zoology

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

273 Q 6 Topics Take Test
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Difficulty: All Easy Medium Hard 71–80 of 273
Topics in NEET Zoology
Which of the following represents a density-dependent factor affecting population growth?
A Earthquake
B Flood
C Disease
D Volcanic eruption
Correct Answer:  C. Disease
EXPLANATION

Disease transmission increases with population density, making it a density-dependent factor. Natural disasters are density-independent.

Test
What is the carrying capacity of an environment?
A The maximum population size that an environment can sustain indefinitely
B The minimum population needed for survival
C The rate of population growth
D The number of births per year
Correct Answer:  A. The maximum population size that an environment can sustain indefinitely
EXPLANATION

Carrying capacity (K) is the maximum population size an environment can support with available resources without degradation.

Test
In a food chain, what percentage of energy is typically transferred from one trophic level to the next?
A 50%
B 10%
C 25%
D 75%
Correct Answer:  B. 10%
EXPLANATION

The 10% law states that only about 10% of energy is transferred to the next trophic level; the remaining 90% is lost as heat and used in metabolism.

Test
A 35-year-old woman with polycystic ovary syndrome (PCOS) seeks contraception with metabolic benefits. Which method would be most appropriate?
A Combined oral contraceptives with anti-androgenic progestin
B Progestin-only pills
C Copper IUD
D Barrier methods only
Correct Answer:  A. Combined oral contraceptives with anti-androgenic progestin
EXPLANATION

Combined OCPs with anti-androgenic progestins (like cyproterone acetate or spironolactone) provide contraception while treating PCOS-related hyperandrogenism and improving metabolic parameters.

Test
A 31-year-old woman presents with secondary amenorrhea and infertility. Blood tests show elevated prolactin levels. What is the next appropriate investigation?
A Thyroid function tests
B MRI of the pituitary gland
C Progesterone challenge test
D Laparoscopy
Correct Answer:  B. MRI of the pituitary gland
EXPLANATION

Elevated prolactin requires MRI of pituitary to rule out prolactinoma, which is the most common pathological cause of hyperprolactinemia. Thyroid tests should be done to exclude hypothyroidism as a cause.

Test
Which of the following best describes the mechanism of action of levonorgestrel IUD in preventing pregnancy?
A Primarily prevents fertilization by thickening cervical mucus
B Primarily prevents implantation by altering endometrium
C Completely inhibits ovulation
D Creates mechanical barrier against sperm ascent
Correct Answer:  B. Primarily prevents implantation by altering endometrium
EXPLANATION

Levonorgestrel IUD works primarily by altering the endometrium to prevent implantation and secondarily by thickening cervical mucus. Complete ovulation inhibition occurs in only 20-30% of cycles.

Test
What is the window period during which emergency contraception is most effective?
A Within 24 hours of unprotected intercourse
B Within 72 hours of unprotected intercourse
C Within 120 hours of unprotected intercourse
D Only if taken before ovulation
Correct Answer:  C. Within 120 hours of unprotected intercourse
EXPLANATION

Levonorgestrel (Plan B) is effective within 120 hours (5 days) if taken within 72 hours for maximum efficacy. Ulipristal acetate (a selective progesterone receptor modulator) can be used up to 120 hours.

Test
A 34-year-old man has oligozoospermia with motility of 20%. Which of the following is the most likely etiology?
A Varicocele
B Recent fever from acute illness
C Smoking
D All of the above
Correct Answer:  D. All of the above
EXPLANATION

Varicocele is the most common correctable cause of male infertility. Fever temporarily affects spermatogenesis for 2-3 months. Smoking reduces sperm count and motility. All are valid etiologies of oligozoospermia.

Test
Which contraceptive method is absolutely contraindicated in women with current or history of breast cancer?
A Copper IUD
B Combined oral contraceptive pills
C Progestin-only injectable
D Barrier methods
Correct Answer:  B. Combined oral contraceptive pills
EXPLANATION

Combined oral contraceptives containing estrogen are contraindicated in breast cancer patients due to estrogen's proliferative effects. Copper IUD, progestin-only methods, and barrier methods are safe alternatives.

Test
A woman using combined oral contraceptive pills (COCs) presents with breakthrough bleeding. Which action should be taken?
A Discontinue COCs immediately
B Continue the same pills; breakthrough bleeding usually resolves
C Switch to a higher-dose estrogen formulation
D Switch to progestin-only pills
Correct Answer:  B. Continue the same pills; breakthrough bleeding usually resolves
EXPLANATION

Breakthrough bleeding is common in the first 3 months of COC use and usually resolves spontaneously. Continuation of the same regimen is recommended unless bleeding persists beyond 3 months.

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