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NEET Zoology PYQs
Class XI & Class XII
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🧬 Zoology
📘 Class XI & XII
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407 questions in Zoology
The opening between the right atrium and the right ventricle is guarded by ________.
A
Bicuspid valve
B
Tricuspid valve
C
Semilunar valve
D
Sino-atrial node
Show explanation
The tricuspid valve is present between the right atrium and the right ventricle and prevents backflow of blood.
Sponges exchange O2 with CO2 by ________.
A
Simple diffusion over their entire body surfaces
B
Moist cuticle
C
Tracheal tubes
D
Gills
Show explanation
Sponges lack specialised respiratory organs. Exchange of gases occurs by simple diffusion through the body surface.
Muscle contraction is initiated by a signal sent by the central nervous system by the release of _______.
A
Acetyl choline
B
Acetyl coenzyme A
C
Cyclic guanine monophosphate
D
Cyclic adenine monophosphate
Show explanation
Acetylcholine is released at the neuromuscular junction and initiates muscle contraction.
Which of the following statements about the reabsorption process in Henle's loop are correct?+ and water takes place in Henle's loop.
A
(a) and (b) only
B
(b), (c) and (d) only
C
(a), (b) and (c) only
D
(a), (b) and (d) only
Show explanation
The descending limb reabsorbs water, whereas the ascending limb reabsorbs electrolytes and is impermeable to water. The filtrate becomes concentrated in the descending limb.
Which of the following is the correct order of arrangement of vertebral column from head to toe?
A
Cervical vertebra, thoracic vertebra, sacrum, lumbar vertebra
B
Sacrum, lumbar vertebra, thoracic vertebra, cervical vertebra
C
Cervical vertebra, lumbar vertebra, thoracic vertebra, sacrum
D
Cervical vertebra, thoracic vertebra, lumbar vertebra, sacrum
Show explanation
The vertebral column is arranged from top to bottom as cervical, thoracic, lumbar, sacral and coccygeal vertebrae.
Which of the following is not evidence for evolution?
A
Convergent evolution of traits like wings of birds and butterflies
B
Paleontological evidence from fossil records
C
Embryological support for evolution as proposed by Ernst Heckel
D
Divergent evolution of anatomical structures such as forelimbs
Show explanation
Haeckel's biogenetic law has been discredited and is no longer accepted as valid evidence for evolution.
Given below are two statements:Statement I: Modern Homo sapiens arose in Australia and moved across continents.Statement II: Homo sapiens arose around 75000 to 10000 years ago.
A
Both Statement I and Statement II are correct
B
Both Statement I and Statement II are incorrect
C
Statement I is correct but Statement II is incorrect
D
Statement I is incorrect but Statement II is incorrect
Show explanation
Modern Homo sapiens originated in Africa. NCERT states that Homo sapiens arose in Africa about 2 lakh years ago and later spread to other continents.
Consider a population of 10 million cells. Given the per-capita birth rate of 0.002 (per unit time) and the per-capita death rate of 0.002 (per unit time), the expected number of cells after 10 generations is
A
1 million
B
5 million
C
10 million
D
100 million
Show explanation
Since the per-capita birth rate equals the per-capita death rate, the population growth rate is zero. Therefore, the population size remains unchanged.
Adaptive radiation in placental mammals and Australian marsupials leading to similarity between distant species is an example of
A
Divergent evolution
B
Convergent evolution
C
Founder effect
D
Genetic drift
Show explanation
Placental mammals and Australian marsupials evolved similar adaptive features independently in similar habitats, demonstrating convergent evolution.
Which of the following are secondary lymphoid organs?
A
(a) and (b) only
B
(b) and (c) only
C
(b) and (d) only
D
(a) and (d) only
Show explanation
Tonsils and spleen are secondary lymphoid organs. Bone marrow and thymus are primary lymphoid organs.
