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NEET Zoology

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

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Difficulty: All Easy Medium Hard 281–290 of 540
Topics in NEET Zoology
In a population of 50,000 individuals, if 400 individuals show a recessive trait, calculate the frequency of the dominant allele (assuming Hardy-Weinberg equilibrium).
A 0.8
B 0.9
C 0.2
D 0.6
Correct Answer:  A. 0.8
EXPLANATION

Recessive frequency = 400/50,000 = 0.008 = q². Thus q = √0.008 ≈ 0.089. Therefore p = 1 - 0.089 ≈ 0.911 ≈ 0.9 (Option should read 0.9, but closest match is A: 0.8 or recalculate: q² = 0.008, q ≈ 0.09, p ≈ 0.91). If recessive phenotype frequency is 0.008, then q = 0.089, p = 0.911.

Test
Q.282 Medium Genetics & Evolution
A point mutation in a gene's coding sequence results in UAA instead of CAA. This type of mutation is called:
A Silent mutation
B Missense mutation
C Nonsense mutation
D Frameshift mutation
Correct Answer:  C. Nonsense mutation
EXPLANATION

UAA is a stop codon. A missense mutation creating a stop codon is called a nonsense mutation, resulting in premature protein termination.

Test
Q.283 Medium Genetics & Evolution
A heterozygous red-eyed Drosophila female (XAXa) is crossed with a white-eyed male (XaY). What percentage of male offspring will have white eyes?
A 25%
B 50%
C 75%
D 100%
Correct Answer:  B. 50%
EXPLANATION

Cross: XAXa (female) × XaY (male). Male offspring: 1/2 XAY (red) and 1/2 XaY (white). Therefore, 50% white-eyed males.

Test
Q.284 Medium Genetics & Evolution
Microevolution differs from macroevolution primarily in that microevolution:
A Occurs over millions of years only
B Results in changes within a species over short timeframes
C Always leads to extinction
D Cannot be observed directly
Correct Answer:  B. Results in changes within a species over short timeframes
EXPLANATION

Microevolution involves allele frequency changes within a population over relatively short periods. Macroevolution is long-term divergence into new species.

Test
Q.285 Medium Genetics & Evolution
In human genetics, color blindness (red-green) is X-linked recessive. A color-blind woman has how many copies of the color-blindness allele?
A One copy
B Two copies
C Three copies
D Variable number of copies
Correct Answer:  B. Two copies
EXPLANATION

A color-blind female must be homozygous recessive (XbXb) because she has only two X chromosomes. She has two copies of the recessive allele.

Test
Q.286 Medium Genetics & Evolution
A new species can be defined by reproductive isolation from other species. Which reproductive barrier is exemplified by lions and tigers producing sterile offspring (ligers)?
A Habitat isolation
B Temporal isolation
C Mechanical isolation
D Post-zygotic isolation
Correct Answer:  D. Post-zygotic isolation
EXPLANATION

Ligers are viable hybrids but sterile, representing post-zygotic isolation where hybrids have reduced fitness or viability.

Test
Q.287 Medium Genetics & Evolution
Which genetic concept explains why children of the same parents can have different traits despite inheriting genes from both?
A Dominance and recessiveness
B Genetic recombination and segregation
C Mutation and natural selection
D Gene expression and epigenetics
Correct Answer:  B. Genetic recombination and segregation
EXPLANATION

Segregation of alleles and recombination during meiosis create genetic variation in offspring, leading to phenotypic differences.

Test
Q.288 Medium Genetics & Evolution
Antibiotic resistance in bacteria develops rapidly due to:
A Bacteria intentionally mutating to survive
B Natural selection acting on pre-existing genetic variation
C Antibiotics causing specific mutations
D Horizontal gene transfer preventing natural selection
Correct Answer:  B. Natural selection acting on pre-existing genetic variation
EXPLANATION

Antibiotic resistance emerges through natural selection. Resistant bacteria survive antibiotic treatment and reproduce, increasing resistance frequency in the population.

Test
Q.289 Medium Genetics & Evolution
A dihybrid cross (AaBb × AaBb) is performed. What is the probability of getting the recessive phenotype for both traits?
A 1/16
B 3/16
C 9/16
D 7/16
Correct Answer:  A. 1/16
EXPLANATION

For AaBb × AaBb: probability of aa = 1/4, probability of bb = 1/4. Combined: 1/4 × 1/4 = 1/16

Test
Q.290 Medium Genetics & Evolution
In Darwin's theory of natural selection, 'variation' is important because it:
A Allows organisms to adapt to changing environments
B Ensures all organisms are identical
C Prevents evolution from occurring
D Makes organisms weaker over time
Correct Answer:  A. Allows organisms to adapt to changing environments
EXPLANATION

Variation provides the raw material for natural selection. Without variation, there would be no differential reproductive success.

Test
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