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 171–180 of 273
Topics in NEET Zoology
Q.171 Medium Genetics & Evolution
X-linked recessive inheritance patterns typically show:
A More affected males than females
B More affected females than males
C Equal distribution between sexes
D No sex-linked pattern
Correct Answer:  A. More affected males than females
EXPLANATION

X-linked recessive traits show more affected males (XᵃY) than females because males need only one copy of recessive allele on their single X chromosome.

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Q.172 Medium Genetics & Evolution
A population of 1000 individuals has 640 individuals with dominant phenotype and 360 with recessive phenotype. The frequency of recessive allele (q) is:
A 0.36
B 0.60
C 0.64
D 0.40
Correct Answer:  B. 0.60
EXPLANATION

Recessive phenotype = 360/1000 = 0.36 = q². Therefore q = √0.36 = 0.60. This represents the frequency of recessive allele.

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Q.173 Medium Genetics & Evolution
According to the Hardy-Weinberg equation (p² + 2pq + q² = 1), what do p and q represent?
A Genotype frequencies
B Allele frequencies
C Phenotype ratios
D Mutation rates
Correct Answer:  B. Allele frequencies
EXPLANATION

In Hardy-Weinberg equation, p and q represent frequencies of two alleles in a population. p² and q² are homozygous frequencies; 2pq is heterozygous frequency.

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Q.174 Medium Genetics & Evolution
Which of the following represents the correct order of organization in genetic material?
A Nucleotide → Gene → Chromosome → DNA
B DNA → Nucleotide → Gene → Chromosome
C Nucleotide → DNA → Gene → Chromosome
D Gene → DNA → Nucleotide → Chromosome
Correct Answer:  C. Nucleotide → DNA → Gene → Chromosome
EXPLANATION

The correct hierarchical order is: Nucleotide (basic unit) → DNA (polymer of nucleotides) → Gene (segment of DNA) → Chromosome (condensed DNA with proteins).

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Q.175 Medium Genetics & Evolution
In pea plants, round seeds (R) are dominant over wrinkled seeds (r). If a plant with round seeds is crossed with a wrinkled seed plant and produces 50% round and 50% wrinkled seeds, the genotype of the round seed plant is:
A RR
B Rr
C rr
D Cannot be determined
Correct Answer:  B. Rr
EXPLANATION

The 1:1 ratio indicates a testcross result (Rr × rr). The round seed parent must be heterozygous (Rr) to produce wrinkled (rr) offspring.

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Q.176 Medium Human Physiology
Which of the following statements about the human kidney's counter-current multiplier system is correct?
A It operates in the proximal convoluted tubule to filter glucose
B It functions in the loop of Henle to create osmotic gradients for water reabsorption
C It is responsible for active secretion of urea in the collecting duct
D It prevents the formation of concentrated urine in dehydrated conditions
Correct Answer:  B. It functions in the loop of Henle to create osmotic gradients for water reabsorption
EXPLANATION

The counter-current multiplier system in the loop of Henle (particularly the thick ascending limb) creates an osmotic gradient that enables water reabsorption in the collecting duct, essential for urine concentration.

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Q.177 Medium Human Physiology
A patient exhibits symptoms of excessive thirst, frequent urination, and fatigue. Blood tests reveal elevated glucose levels and reduced insulin secretion. Which pancreatic cells are primarily affected in this condition?
A Alpha cells producing glucagon
B Beta cells producing insulin
C Delta cells producing somatostatin
D Acinar cells producing digestive enzymes
Correct Answer:  B. Beta cells producing insulin
EXPLANATION

The symptoms (polydipsia, polyuria, fatigue) along with elevated blood glucose and reduced insulin indicate Type 1 diabetes mellitus, where autoimmune destruction of pancreatic beta cells occurs, reducing insulin production.

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Q.178 Medium Human Physiology
Which hormone is essential for maintaining calcium homeostasis and is activated by low blood calcium levels?
A Calcitonin
B Parathyroid hormone (PTH)
C Thyroxine
D Cortisol
Correct Answer:  B. Parathyroid hormone (PTH)
EXPLANATION

PTH is secreted by parathyroid glands in response to hypocalcemia, increases calcium reabsorption in kidneys, and promotes calcium mobilization from bones.

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Q.179 Medium Human Physiology
During exercise, what is the primary mechanism by which muscles obtain additional oxygen?
A Increased breathing rate and increased cardiac output
B Decreased oxygen consumption by other organs
C Increased hemoglobin concentration in blood
D Enhanced oxygen storage in myoglobin
Correct Answer:  A. Increased breathing rate and increased cardiac output
EXPLANATION

Exercise triggers increased respiratory and heart rates, enhancing oxygen delivery to muscles through elevated blood flow and ventilation.

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Q.180 Medium Human Physiology
Which of the following best explains how the human body maintains stable internal temperature despite environmental changes?
A Continuous movement and exercise
B Negative feedback loops involving the hypothalamus
C Increased consumption of food
D Wearing appropriate clothing
Correct Answer:  B. Negative feedback loops involving the hypothalamus
EXPLANATION

The hypothalamus acts as the body's thermostat, detecting temperature changes and triggering responses (sweating, vasoconstriction) through negative feedback mechanisms.

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