NEET Biology Biological Classification MCQs Set 23

Biology Objective Questions and Answers: Biological Classification

Explore reliable objective questions for Biological Classification tailored for NEET learners. Utilizing these Biology multiple-choice formats ensures thorough preparation and strengthens problem-solving speed for upcoming school assessments.

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Multiple Choice Questions

Question 1: The main role of bacteria in the carbon cycle involves
(a) photosynthesis
(b) chemosynthesis
(c) digestion or breakdown of organic compounds
(d) assimilation of nitrogenous compounds
Show Answer & Explanation

Answer: (c) digestion or breakdown of organic compounds

Explanation:
1. Bacteria decompose dead organic matter, returning carbon as CO2 to the atmosphere in the carbon cycle.

Teacher's Note:
1. Their role is breakdown, not photosynthesis.
2. Without decomposers, carbon would remain locked in dead bodies.

Question 2: Two bacteria found to be very useful in genetic engineering experiments are
(a) Escherichia and Agrobacterium
(b) Nitrobacter and Azotobacter
(c) Rhizobium and Diplococcus
(d) Nitrosomonas and Klebsiella
Show Answer & Explanation

Answer: (a) Escherichia and Agrobacterium

Explanation:
1. Escherichia coli (host and cloning vector source) and Agrobacterium tumefaciens (Ti plasmid vector) are widely used in genetic engineering.

Teacher's Note:
1. The Ti plasmid transfers genes into dicot plants.
2. Nitrobacter and Rhizobium are agricultural bacteria.

Question 3: Transfer of genetic information from one bacterium to another in the transduction process is through
(a) conjugation
(b) bacteriophages released from the donor bacterial strain
(c) another bacterium
(d) physical contact between donor and recipient strain
Show Answer & Explanation

Answer: (b) bacteriophages released from the donor bacterial strain

Explanation:
1. In transduction a bacteriophage carries a piece of donor DNA to the recipient bacterium.

Teacher's Note:
1. Conjugation needs physical contact.
2. Transformation is the uptake of naked DNA.

Question 4: Due to which of the following organisms, yield of rice has been increased?
(a) Anabaena
(b) Bacillus papilliae
(c) Sesbania
(d) Bacillus polymyxa
Show Answer & Explanation

Answer: (a) Anabaena

Explanation:
1. The cyanobacterium Anabaena, living in rice fields, fixes nitrogen and has raised rice yield.

Teacher's Note:
1. Anabaena also lives in Azolla.
2. It is used as a biofertiliser.

Question 5: Photosynthetic bacteria have pigments in
(a) leucoplasts
(b) chloroplasts
(c) chromoplasts
(d) chromatophores
Show Answer & Explanation

Answer: (d) chromatophores

Explanation:
1. In photosynthetic bacteria the pigments lie in the chromatophores, which are membranous vesicles of the plasma membrane.

Teacher's Note:
1. They lack chloroplasts.
2. Chromatophores are not the same as plant chromoplasts.

Question 6: Plasmid is
(a) fragment of DNA which acts as vector
(b) fragment which joins two genes
(c) mRNA which acts as carrier
(d) autotrophic fragment
Show Answer & Explanation

Answer: (a) fragment of DNA which acts as vector

Explanation:
1. A plasmid is a small piece of extra-chromosomal DNA that can carry a foreign gene, so it acts as a vector.

Teacher's Note:
1. It can replicate independently.
2. pBR322 is a well-known cloning plasmid.

Question 7: The semilog of per minute growing bacteria is plotted against time. What will be the shape of graph?
(a) Sigmoid
(b) Hyperbola
(c) Ascending straight line
(d) Descending straight line
Show Answer & Explanation

Answer: (c) Ascending straight line

Explanation:
1. During the log phase bacteria multiply exponentially, so log of numbers plotted against time gives an ascending straight line.

Teacher's Note:
1. The ordinary growth curve is sigmoid.
2. Plotting on a semilog scale straightens the exponential phase.

Question 8: In bacteria, plasmid is
(a) extra-chromosomal material
(b) main DNA
(c) non-functional DNA
(d) repetitive gene
Show Answer & Explanation

Answer: (a) extra-chromosomal material

Explanation:
1. In bacteria the plasmid is extra-chromosomal DNA.

Teacher's Note:
1. It is self-replicating.
2. It often carries drug-resistance genes.

Question 9: Choose the correct sequence of stages of growth curve for bacteria
(a) lag, log, stationary, decline phase
(b) lag, log, stationary phase
(c) stationary, lag, log, decline phase
(d) decline, lag, log phase
Show Answer & Explanation

Answer: (a) lag, log, stationary, decline phase

Explanation:
1. The growth curve of bacteria has the lag, log (exponential), stationary and decline (death) phases in that order.

Teacher's Note:
1. Cells adapt in the lag phase.
2. Nutrient depletion causes the stationary phase.

Question 10: Chromosomes in a bacterial cell can be 1-3 in number and
(a) can be circular as well as linear within the same cell
(b) are always circular
(c) are always linear
(d) can be either circular or linear, but never both within the same cell
Show Answer & Explanation

Answer: (b) are always circular

Explanation:
1. Bacterial chromosomes are single and always circular.

Teacher's Note:
1. The nucleoid has no nuclear membrane.
2. Plasmids are additional circular DNAs.

Question 11: Which one of the following pairs is not correctly matched?
(a) Streptomyces — Antibiotic
(b) Serratia — Drug addiction
(c) Spirulina — Single cell protein
(d) Rhizobium — Biofertilizer
Show Answer & Explanation

Answer: (b) Serratia — Drug addiction

Explanation:
1. Serratia is a bacterium (S. marcescens) and has nothing to do with drug addiction, so this pair is wrong. The other pairs are right.

Teacher's Note:
1. Streptomyces gives antibiotics such as streptomycin.
2. Spirulina is rich in protein.

Question 12: For retting of jute the fermenting microbe used is
(a) Methophilic bacteria
(b) Butyric acid bacteria
(c) Helicobacter pylori
(d) Streptococcus lactis
Show Answer & Explanation

Answer: (b) Butyric acid bacteria

Explanation:
1. Retting of jute and other fibres is done by pectin-digesting butyric acid bacteria such as Clostridium butyricum.

Teacher's Note:
1. Retting separates the fibres from the stem.
2. Lactic acid bacteria make curd.

Question 13: All of the following statements concerning the Actinomycetes filamentous soil bacterium and Frankia are correct except that Frankia
(a) can induce root nodules on many plant species
(b) cannot fix nitrogen in the free-living - state
(c) forms specialized vesicles in which the nitrogenase is protected from oxygen by a chemical involving triterpene hepanoids
(d) like Rhizobium, it usually infects its host plant through root hair deformation and stimulates cell proliferation in the host’s cortex
Show Answer & Explanation

Answer: (b) cannot fix nitrogen in the free-living - state

Explanation:
1. Frankia can fix nitrogen even in free-living state, so statement (b) is the wrong one.

Teacher's Note:
1. It forms root nodules in non-leguminous plants such as Alnus.
2. It protects its nitrogenase from oxygen in special vesicles.

Question 14: Which one of the following pairs is not correct matched ?
(a) Methanogens — Gobar gas
(b) Yeast — Ethanol
(c) Streptomycetes — Antibiotic
(d) Coliforms — Vinegar
Show Answer & Explanation

Answer: (d) Coliforms — Vinegar

Explanation:
1. Coliform bacteria indicate faecal pollution of water and are not used to make vinegar, which is produced by Acetobacter.

Teacher's Note:
1. Methanogens produce biogas.
2. Yeast produces ethanol.

Question 15: Consider the following four measures (A-D) that could be taken to successfully grow chick pea in an area where bacterial blight disease is common (A) Spray with Bordeaux mixture (B) Control of the “insect vector of the disease pathogen” (C) Use of only disease-free seeds (D) Use of varieties resistant to the disease Which two of the above measures can control the disease?
(a) B and C
(b) A and B
(c) C and D
(d) A and D
Show Answer & Explanation

Answer: (c) C and D

Explanation:
1. Using disease-free seeds and resistant varieties controls bacterial blight, as Bordeaux mixture is a fungicide and bacterial blight is not insect-borne.

Teacher's Note:
1. Bordeaux mixture controls fungi only.
2. Resistant varieties are the best control.

Question 16: Which of the following are used in gene cloning ?
(a) Lomasomes
(b) Mesosmes
(c) Plasmids
(d) Nucleoids
Show Answer & Explanation

Answer: (c) Plasmids

Explanation:
1. Plasmids are used as vectors in gene cloning.

Teacher's Note:
1. Nucleoids are the bacterial genomic regions.
2. Mesosomes and lomasomes are membranous structures.

Question 17: Besides paddy fields, cyanobacteria are also found inside vegetative part of
(a) Pinus
(b) Cycas
(c) Equisetum
(d) Psilotum
Show Answer & Explanation

Answer: (b) Cycas

Explanation:
1. Cyanobacteria (Anabaena) live in the coralloid roots of Cycas, where they fix nitrogen.

Teacher's Note:
1. The association is symbiotic.
2. Pinus, Equisetum and Psilotum do not have such roots.

Question 18: Which of the following are likely to be present in deep sea water ?
(a) Archaebacteria
(b) Eubacteria
(c) Blue-green algae
(d) Saprophytic fungi
Show Answer & Explanation

Answer: (a) Archaebacteria

Explanation:
1. Archaebacteria live in extreme conditions such as deep-sea hot vents, salty lakes and hot springs.

Teacher's Note:
1. Eubacteria and blue-green algae need light or milder conditions.
2. Their cell wall lacks peptidoglycan.

Question 19: True nucleus is absent in :
(a) Mucor
(b) Vaucheria
(c) Volvox
(d) Anabaena
Show Answer & Explanation

Answer: (d) Anabaena

Explanation:
1. Anabaena is a cyanobacterium, a prokaryote without a true nucleus. Mucor, Vaucheria and Volvox are eukaryotes.

Teacher's Note:
1. Prokaryotes have a nucleoid.
2. Cyanobacteria are also called blue-green algae.

Question 20: Cell wall is absent in :
(a) Nostoc
(b) Aspergillus
(c) Funaria
(d) Mycoplasma
Show Answer & Explanation

Answer: (d) Mycoplasma

Explanation:
1. Mycoplasma is the smallest known cell-living organism and has no cell wall.

Teacher's Note:
1. Nostoc, Aspergillus and Funaria have cell walls.
2. Mycoplasma causes pleuropneumonia in cattle.

Question 21: Absorptive heterotrophic nutrition is exhibited by
(a) algae
(b) fungi
(c) bryophytes
(d) pteridophytes
Show Answer & Explanation

Answer: (b) fungi

Explanation:
1. Fungi are heterotrophs that absorb dissolved food from their surroundings (absorptive nutrition).

Teacher's Note:
1. Fungi secrete enzymes outside and absorb the digested food.
2. Algae are autotrophic.

Question 22: Ustilago caused plant diseases are called smuts because
(a) they parasitise cereals
(b) mycelium is black
(c) they develop sooty masses of spores
(d) affected parts become completely black
Show Answer & Explanation

Answer: (c) they develop sooty masses of spores

Explanation:
1. Ustilago is a smut fungus; the infected cereals develop black sooty masses of spores, hence the name smut.

Teacher's Note:
1. The disease affects the grain or inflorescence.
2. Smuts are caused by Basidiomycetes.

Question 23: Decomposers are organisms that
(a) elaborate chemical substances, causing death of tissues
(b) operate in living body and simplifying organic substances of cells step by step
(c) attack and kill plants as well as animals
(d) operate in relay terms, simplifying step by step the organic constituents of dead body
Show Answer & Explanation

Answer: (d) operate in relay terms, simplifying step by step the organic constituents of dead body

Explanation:
1. Decomposers act step by step, breaking the organic constituents of dead organisms into simple substances.

Teacher's Note:
1. Decomposers do not kill the living.
2. Most decomposers are fungi and bacteria.

Question 24: Claviceps purpurea is causal organism of
(a) smut of barley
(b) rust of wheat
(c) ergot of rye
(d) powdery mildew of pea
Show Answer & Explanation

Answer: (c) ergot of rye

Explanation:
1. Claviceps purpurea causes ergot of rye and other cereals.

Teacher's Note:
1. Ustilago causes smut and Puccinia rust.
2. Ergot is a source of ergometrine.

Question 25: The chemical compounds produced by the host plants to protect themselves against fungal infection is
(a) phytotoxin
(b) pathogen
(c) phytoalexins
(d) hormone
Show Answer & Explanation

Answer: (c) phytoalexins

Explanation:
1. Phytoalexins are chemicals made by host plants to defend against fungal infection.

Teacher's Note:
1. Phytotoxins are poisons made by the pathogens.
2. A pathogen is the disease-causing organism.

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Biological Classification Objective Questions & Solutions for NEET Biology

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