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Biology - 3 — MH-CET Full Length Paper MCQs with Solutions
Free MH-CET Full Length Paper Biology - 3 MCQs with step-by-step solutions. Practise online on Prepizo — no login needed.
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Sample questions with solutions
Q1 — easy
In plants like \textit{Commelina} and \textit{Oxalis}, flowers that remain permanently closed and ensure assured seed-set even in the complete absence of pollinators are:
A. Chasmogamous
B. Cleistogamous ✓ Correct
C. Dichogamous
D. Herkogamous
Solution: Cleistogamous flowers never open and are obligately self-pollinating, guaranteeing seed set without pollinators.
Q2 — easy
The microscopic fluid-filled cavity characteristic of a mature tertiary or Graafian follicle is called the:
A. Zona pellucida
B. Antrum ✓ Correct
C. Corona radiata
D. Stroma
Solution: The antrum is the fluid-filled cavity that distinguishes a mature Graafian follicle from earlier stages.
Q3 — easy
The physiological maturation of spermatozoa inside the female reproductive tract that enables them to penetrate the ovum is termed:
A. Spermiation
B. Spermiogenesis
C. Capacitation ✓ Correct
D. Insemination
Solution: Capacitation involves biochemical changes in the sperm membrane in the female tract, enabling zona penetration.
Q4 — easy
In their landmark 1952 experiment proving that DNA is the genetic material, Hershey and Chase used radioactive isotopes to label:
A. $^{35}S$ for DNA and $^{32}P$ for protein
B. $^{32}P$ for DNA and $^{35}S$ for protein ✓ Correct
C. $^{14}C$ for DNA and $^{15}N$ for protein
D. $^{3}H$ for both DNA and protein
Solution: Hershey-Chase used ³²P (labels DNA phosphorus) and ³⁵S (labels protein sulfur) to track which entered bacteria.
Q5 — easy
Placental wolf and Tasmanian marsupial wolf evolved similar morphological features and predatory habits. This evolutionary phenomenon is an example of:
A. Divergent evolution
B. Adaptive convergence ✓ Correct
C. Parallel mutation
D. Saltation
Solution: Convergent evolution: unrelated species evolve similar traits independently due to similar ecological pressures.
Q6 — easy
In plant roots, the apoplastic movement of water and minerals is obstructed when it reaches the endodermis due to the presence of:
A. Plasmodesmata
B. Casparian strips of suberin ✓ Correct
C. Tyloses
D. Pectin layers
Solution: Casparian strips (suberin-impregnated bands in endodermal walls) force water into the symplast at the endodermis.
Q7 — easy
The first heart sound ($LUBB$) occurs at the beginning of ventricular systole and is caused by the closure of:
A. Semilunar valves
B. Atrioventricular (Tricuspid and Bicuspid) valves ✓ Correct
C. Aortic valve only
D. Thebesian valve
Solution: LUBB (S1): closure of AV valves (tricuspid + mitral) at the onset of ventricular systole.
Q8 — easy
The sensory organ of hearing, the Organ of Corti, rests directly upon the:
A. Tectorial membrane
B. Reissner's membrane
C. Basilar membrane ✓ Correct
D. Tympanic membrane
Solution: The Organ of Corti sits on the basilar membrane within the cochlear duct (scala media).
Q9 — easy
Hyposecretion of glucocorticoids and mineralocorticoids from the adrenal cortex due to autoimmune destruction causes:
A. Cushing's syndrome
B. Addison's disease ✓ Correct
C. Graves' disease
D. Conn's syndrome
Solution: Addison's disease: chronic adrenal insufficiency causing fatigue, hyperpigmentation, and electrolyte imbalance.
Q10 — easy
Which of the following is categorized as a secondary lymphoid organ where mature lymphocytes encounter antigens?
A. Bone marrow
B. Thymus
C. Spleen ✓ Correct
D. Bursa of Fabricius
Solution: The spleen is a secondary lymphoid organ; bone marrow and thymus are primary lymphoid organs.
Q11 — easy
The cyanobacterial biofertilizer that fixes atmospheric nitrogen both in free-living state and in symbiotic association with the water fern \textit{Azolla} is:
A. \textit{Rhizobium}
B. \textit{Anabaena azollae} ✓ Correct
C. \textit{Azotobacter}
D. \textit{Frankia}
Solution: Anabaena azollae lives symbiotically in Azolla leaf cavities and fixes nitrogen in rice paddies.
Q12 — easy
The enzyme used in recombinant DNA technology to synthesize complementary DNA (cDNA) from an mRNA template is:
A. DNA polymerase I
B. Reverse transcriptase ✓ Correct
C. RNA polymerase II
D. DNA ligase
Solution: Reverse transcriptase (RNA-dependent DNA polymerase) synthesizes cDNA from mRNA templates.
Q13 — easy
Gause's Competitive Exclusion Principle states that two closely related species competing for the exact same limiting resources cannot co-exist indefinitely if:
A. Resources are unlimited
B. One species has a competitive advantage leading to the elimination of the other ✓ Correct
C. Both species feed at different times
D. Mutualism is established
Solution: Competitive exclusion: the superior competitor eliminates the inferior one when niches overlap completely.
Q14 — easy
According to Lindeman's $10\%$ law of trophic efficiency, if $10{,}000$ J of energy is captured by primary producers, the energy available to tertiary consumers will be:
A. $1000$ J
B. $100$ J
C. $10$ J ✓ Correct
D. $1$ J
Solution: 10000 → 1000 (primary consumers) → 100 (secondary) → 10 J (tertiary consumers).
Q15 — easy
The Ramsar Convention, an intergovernmental treaty adopted in 1971, is dedicated to the international conservation and wise use of:
A. Tropical rainforests
B. Wetlands ✓ Correct
C. Coral reefs
D. Biosphere reserves
Solution: The Ramsar Convention specifically protects wetlands of international importance.
Q16 — easy
Persistent non-functional remnants of nucellar tissue found in seeds of black pepper and beet are designated as:
A. Endosperm
B. Perisperm ✓ Correct
C. Scutellum
D. Aleurone layer
Solution: Perisperm is persistent nucellus tissue that serves as a nutritive reserve in some seeds.
Q17 — easy
The structural cap-like covering of the head of a human sperm containing hydrolytic enzymes is derived from the:
A. Endoplasmic reticulum
B. Golgi apparatus ✓ Correct
C. Centriole
D. Mitochondria
Solution: The acrosome is derived from the Golgi apparatus during spermiogenesis.
Q18 — easy
A man with blood group A marries a woman with blood group B. If both are heterozygous, what fraction of their children will have blood group AB?
A. $100\%$
B. $50\%$
C. $25\%$ ✓ Correct
D. $0\%$
Solution: $I^Ai \times I^Bi$: $I^AI^B$ (AB) : $I^Ai$ (A) : $I^Bi$ (B) : $ii$ (O) = 1:1:1:1, so 25% AB.
Q19 — easy
The transcriptionally silent, highly condensed, and darkly staining fraction of eukaryotic chromatin is called:
A. Euchromatin
B. Heterochromatin ✓ Correct
C. Kinetochore
D. Centromere
Solution: Heterochromatin is tightly packed, gene-poor, and transcriptionally inactive.
Q20 — easy
The theory that life originated from non-living organic molecules via chemical evolution was experimentally verified by Urey and Miller using a mixture of:
A. $CH_4, NH_3, H_2O$ (steam), $H_2$ ✓ Correct
B. $CO_2, NH_3, H_2O, O_2$
C. $CH_4, O_2, H_2O, H_2$
D. $CH_4, H_2S, CO_2, H_2$
Solution: Miller-Urey used CH₄ + NH₃ + H₂O (steam) + H₂ to simulate the primitive reducing atmosphere.
Q21 — easy
The water absorption mechanism wherein water travels through the living protoplasmic continuum via plasmodesmata is the:
A. Apoplastic pathway
B. Symplastic pathway ✓ Correct
C. Transpiration pull
D. Capillarity
Solution: The symplastic pathway moves water through cytoplasm and plasmodesmata between living cells.
Q22 — easy
The plant growth inhibitor hormone that promotes bud dormancy and seed dormancy is:
A. Gibberellic acid
B. Indole-3-acetic acid
C. Abscisic acid ✓ Correct
D. Cytokinin
Solution: ABA is the primary dormancy-promoting hormone, inhibiting growth and inducing bud/seed dormancy.
Q23 — easy
The normal cardiac cycle in an adult human has a duration of approximately:
A. $0.8$ seconds ✓ Correct
B. $0.3$ seconds
C. $0.1$ seconds
D. $1.2$ seconds
Solution: At 72 beats/min, each cardiac cycle ≈ 60/72 = 0.8 seconds.
Q24 — easy
The portion of the human eye that regulates the amount of light entering through the pupil is the:
A. Cornea
B. Iris ✓ Correct
C. Ciliary body
D. Choroid
Solution: The iris contains circular and radial muscles that adjust pupil diameter to regulate light entry.
Q25 — easy
The hormone that triggers vigorous contractions of the uterine myometrium during human parturition is:
A. Progesterone
B. Oxytocin ✓ Correct
C. Prolactin
D. Human chorionic gonadotropin
Solution: Oxytocin from the posterior pituitary stimulates strong uterine contractions during labour.
Q26 — easy
Morphine, an effective analgesic and sedative extracted from the latex of \textit{Papaver somniferum}, binds to specific receptors in the:
A. Central nervous system and gastrointestinal tract ✓ Correct
B. Cardiovascular system
C. Peripheral motor end plates
D. Respiratory alveoli only
Solution: Morphine binds opioid receptors (μ, κ, δ) in the CNS and GI tract.
Q27 — easy
The microbial inoculant commonly used to biologically produce citric acid via aerobic submerged fermentation is:
A. \textit{Acetobacter aceti}
B. \textit{Aspergillus niger} ✓ Correct
C. \textit{Clostridium butylicum}
D. \textit{Lactobacillus bulgaricus}
Solution: Aspergillus niger is the principal industrial organism for citric acid production by submerged fermentation.
Q28 — easy
The interaction where an orchid grows epiphytically on the branch of a mango tree without harming or nourishing the tree is:
A. Parasitism
B. Mutualism
C. Commensalism ✓ Correct
D. Predation
Solution: Commensalism (+/0): orchid benefits from support/light; mango tree is unaffected.
Q29 — easy
In an aquatic ecosystem, the pyramid of biomass is generally:
A. Always upright
B. Inverted ✓ Correct
C. Spindle-shaped
D. Dumbbell-shaped
Solution: In open-water aquatic ecosystems, phytoplankton biomass < zooplankton < fish → inverted biomass pyramid.
Q30 — easy
Which of the following is NOT an in-situ biodiversity conservation method?
A. National park
B. Biosphere reserve
C. Wildlife sanctuary
D. Zoological park ✓ Correct
Solution: Zoological parks are ex-situ conservation. National parks, biosphere reserves, and sanctuaries are in-situ.