ssDNA not enclosed by protein coat

BIOLOGICAL CLASSIFICATION MCQs for NEET UG BIOLOGY — Medium, Page 2

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A bacterium is capable of with standing extreme heat, dryness and toxic chemicals. This indicates that it is probably above to form

View answer and explanation

Correct option: B

Endospores

Option B (Endospores) is correct because endospores are highly resistant structures that allow bacteria to survive extreme conditions.

Solution approach

Correct Answer + Core Reason: Endospores are the correct answer because they allow bacteria to withstand extreme conditions.

Step-by-Step Solution:

Step 1: Bacteria need a mechanism to survive extreme heat, dryness, and toxic chemicals.

Step 2: Endospores are dormant, highly resistant structures formed by some bacteria to survive harsh conditions.

Step 3: Conclusion: Endospore formation is the correct answer.

Why other options are wrong:
- Option A: A thick peptidoglycan wall provides some protection but not against all extreme conditions.
- Option C: Endotoxins are toxic substances, not survival structures.
- Option D: Endogenous buds are a form of asexual reproduction, not survival under stress.

Key Concepts:
- Endospores
- Bacterial survival mechanisms
- Extreme conditions

Memory Aids:
- Endospores = Extreme Survival

Quick Tips:
- Remember that endospores are for survival, not reproduction.

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Which of the following statements are correct
in relation to host and parasites?

i) The host in which parasites undergoes
asexual reproduction is secondary host

ii) Female Culex mosquito is the primary host
for wuchereria

iii) In primary host parasite undergoes sexual
reproduction

iv) Man is the primary host for plasmodium

v) The host that loves the infective stages of a
parasite in its body when the main host is
not available is called Reservoir host.

View answer and explanation

Correct option: B

Only (i), (iii) and (v) are correct, (ii) and (iv)
are wrong

Option B is correct because statements (i), (iii), and (v) accurately describe host-parasite relationships, while (ii) and (iv) are incorrect.

Solution approach

Correct Answer + Core Reason: Only (i), (iii) and (v) are correct, (ii) and (iv) are wrong. This option accurately identifies the correct and incorrect statements about host-parasite relationships.

Step-by-Step Solution:
Step 1: Analyze the given statements regarding host and parasites.
Step 2: Evaluate each statement:\ni) The host in which parasites undergoes asexual reproduction is secondary host: This is correct. Asexual reproduction often occurs in the intermediate or secondary host.\nii) Female Culex mosquito is the primary host for wuchereria: This is incorrect. The primary host for Wuchereria (filarial worms) is humans, while mosquitoes are the intermediate hosts.\niii) In primary host parasite undergoes sexual reproduction: This is correct. Sexual reproduction typically occurs in the definitive or primary host.\niv) Man is the primary host for plasmodium: This is incorrect. The primary host for Plasmodium (malaria parasite) is the female Anopheles mosquito, where sexual reproduction occurs. Humans are the secondary host.\nv) The host that loves the infective stages of a parasite in its body when the main host is not available is called Reservoir host: This is correct. Reservoir hosts maintain the parasite population.
Step 3: Identify the correct and incorrect statements: (i), (iii), and (v) are correct, while (ii) and (iv) are incorrect.

Why other options are wrong:
- Option A: Only (ii), (iii) and (iv) are correct, (i) and (v) are wrong - This option incorrectly identifies statements (ii) and (iv) as correct and (i) and (v) as wrong.
- Option C: Only (i) and (v) are correct but (ii), (iii) and (iv) are wrong - This option incorrectly identifies statement (iii) as wrong.
- Option D: Only (ii) and (iv) are correct, remaining are wrong - This option incorrectly identifies statements (ii) and (iv) as correct.

Key Concepts:
- Host-Parasite Relationships
- Primary vs. Secondary Host
- Sexual vs. Asexual Reproduction
- Reservoir Host

Memory Aids:
- Remember \"Primary = Sexual\" - Sexual reproduction of the parasite usually occurs in the primary host.

Quick Tips:
- Understand the life cycles of parasites and the roles of different hosts.

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Which of the following is not the locomotory organ of protozoa?

View answer and explanation

Correct option: C

Parapodia

The correct answer is C (Parapodia) because parapodia are lateral appendages used for locomotion in polychaete worms, not protozoa.

Solution approach

Correct Answer + Core Reason: Parapodia are not locomotory organs of protozoa.

Step-by-Step Solution:

Step 1: Recall the different locomotory organs of protozoa.

Step 2: Protozoa use cilia, flagella, and pseudopodia for movement.

Step 3: Cilia are short, hair-like structures that beat in coordinated waves.

Step 4: Flagella are long, whip-like structures that propel the cell.

Step 5: Pseudopodia are temporary extensions of the cytoplasm used for crawling and engulfing food.

Step 6: Parapodia are fleshy, paired appendages used for locomotion in annelids (e.g., polychaete worms), not protozoa.

Why other options are wrong:
- Option A (Cilia): Cilia are used by ciliates for locomotion.
- Option B (Flagella): Flagella are used by flagellates for locomotion.
- Option D (Pseudopodia): Pseudopodia are used by amoeboid protozoa for locomotion.

Key Concepts:
- Protozoan locomotion
- Cilia, flagella, pseudopodia
- Parapodia in annelids

Memory Aids:
- Cilia = Ciliates, Flagella = Flagellates, Pseudopodia = Amoeboid

Quick Tips:
- Remember that parapodia are specific to annelids.

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The fungal partner in lichen is called mycobiont whereas algal partner is called

View answer and explanation

Correct option: C

Phycobiont

Option C (Phycobiont) is correct because the algal partner in lichen is called phycobiont.

Solution approach

Correct Answer + Core Reason: Phycobiont. The algal partner in lichen is called phycobiont.

Step-by-Step Solution:

Step 1: The question asks for the term used to describe the algal partner in lichen.

Step 2: Recall that lichen is a symbiotic association between a fungus (mycobiont) and an alga (phycobiont).

Step 3: The algal partner provides food through photosynthesis.

Why other options are wrong:
- Option A: Glycobiont is not a recognized term.
- Option B: Algobiont is not the standard term used.
- Option D: While it is an algal partner, the specific term is phycobiont.

Key Concepts:
- Lichen
- Symbiosis
- Mycobiont
- Phycobiont

Memory Aids:
- Phycobiont = Algae

Quick Tips:
- Remember the specific terms for the fungal and algal partners in lichen.

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A type of life cycle in which plasmogamy, karyogamy, haplodization takes place but not at specific place in life cycle of an organism is called as

View answer and explanation

Correct option: A

Parasexuality

Option A (Parasexuality) is correct because parasexuality involves plasmogamy, karyogamy, and haploidization without a specific point in the life cycle.

Solution approach

Correct Answer + Core Reason: Parasexuality. This process involves genetic recombination without meiosis or a defined sexual cycle.

Step-by-Step Solution:

Step 1: Define plasmogamy, karyogamy, and haploidization.

Step 2: Plasmogamy is the fusion of cytoplasm.

Step 3: Karyogamy is the fusion of nuclei.

Step 4: Haploidization is the process of becoming haploid.

Step 5: Parasexuality is a process in fungi where plasmogamy, karyogamy, and haploidization occur, but not at specific points in the life cycle, unlike sexual reproduction.

Why other options are wrong:
- Option B: Heterozygosity refers to having different alleles for a particular gene.
- Option C: Homozygosity refers to having identical alleles for a particular gene.
- Option D: Asexuality is a mode of reproduction that does not involve the fusion of gametes or genetic recombination.

Key Concepts:
- Parasexuality
- Plasmogamy
- Karyogamy
- Haploidization

Memory Aids:
- Remember that parasexuality is a non-sexual process of genetic recombination in fungi.

Quick Tips:
- Understand the difference between sexual reproduction and parasexuality.

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Virus consists of

View answer and explanation

Correct option: C

Both (A) and (B)

Option C (Both (A) and (B)) is correct because viruses are composed of nucleic acid and a protein coat.

Solution approach

Correct Answer + Core Reason: Both (A) and (B). Viruses consist of nucleic acid (DNA or RNA) and a protein coat.

Step-by-Step Solution:

Step 1: The question asks about the composition of a virus.

Step 2: Recall the basic structure of a virus: It consists of a nucleic acid core (DNA or RNA) surrounded by a protein coat (capsid).

Step 3: Therefore, a virus consists of both nucleic acid and protein.

Why other options are wrong:
- Option A: Viruses contain nucleic acid, but they also have a protein coat.
- Option B: Viruses have a protein coat, but they also contain nucleic acid.
- Option D: Viruses are composed of nucleic acid and protein.

Key Concepts:
- Viral structure
- Nucleic acid (DNA or RNA)
- Protein coat (capsid)

Memory Aids:
- Virus = Nucleic acid + Protein

Quick Tips:
- Remember the basic components of a virus.

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Analyse the following statements and identify the correct option given below.
I. Viruses that infects plants have single-stranded RNA and viruses that infects animals have either single or double-stranded RNA or double stranded DNA
II. Bacterial viruses or bacteriophase are usually single-stranded RNA viruses
Codes

View answer and explanation

Correct option: A

I is true, but II is false

Option A (I is true, but II is false) is correct because plant viruses typically have single-stranded RNA, animal viruses can have various nucleic acids, and bacteriophages usually have double-stranded DNA.

Solution approach

Correct Answer + Core Reason: I is true, but II is false. Plant viruses commonly have ssRNA, and animal viruses can have ss or ds RNA or dsDNA. Bacteriophages typically have dsDNA.

Step-by-Step Solution:

Step 1: Analyze Statement I: Viruses that infect plants commonly have single-stranded RNA, and viruses that infect animals can have either single- or double-stranded RNA or double-stranded DNA. This statement is true.

Step 2: Analyze Statement II: Bacterial viruses or bacteriophages are usually double-stranded DNA viruses, not single-stranded RNA viruses. This statement is false.

Step 3: Based on the analysis, Statement I is true, and Statement II is false.

Why other options are wrong:
- Option B: I is false, but II is true - Statement I is true, and Statement II is false.
- Option C: I and II are true - Statement II is false.
- Option D: I and II are false - Statement I is true.

Key Concepts:
- Viral nucleic acids
- Plant viruses
- Animal viruses
- Bacteriophages

Memory Aids:
- Remember that bacteriophages often have dsDNA.

Quick Tips:
- Know the common types of nucleic acids found in different types of viruses.

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Among rust, smut and mushroom, all the three

View answer and explanation

Correct option: D

Bear basidiocarps

Option D (Bear basidiocarps) is correct because rust, smut, and mushroom all belong to the Basidiomycetes, which produce basidiocarps.

Solution approach

Correct Answer + Core Reason: Bear basidiocarps. Rust, smut, and mushrooms are all Basidiomycetes, which produce basidiocarps.

Step-by-Step Solution:

Step 1: Classify the organisms:
- Rust: Basidiomycete.
- Smut: Basidiomycete.
- Mushroom: Basidiomycete.

Step 2: Identify the common characteristic: All three belong to the class Basidiomycetes.

Step 3: Recall the characteristics of Basidiomycetes: Basidiomycetes are characterized by the production of basidiocarps (fruiting bodies).

Step 4: Conclusion: All three bear basidiocarps.

Why other options are wrong:
- Option A: Not all are pathogens; some can be saprobes at certain stages.
- Option B: Not all are saprobes; some are pathogens.
- Option C: Ascocarps are characteristic of Ascomycetes, not Basidiomycetes.

Key Concepts:\nBasidiomycetes, basidiocarps, rust, smut, mushroom.

Memory Aids:\nBasidiomycetes = Basidiocarps.

Quick Tips:\nRemember the defining characteristics of each fungal class.

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Which of the following bacteria are responsible for the production of biogas from the dung of cows and buffaloes?

View answer and explanation

Correct option: C

Methanogen

Option C (Methanogen) is correct because methanogens are archaea that produce methane as a metabolic byproduct in anaerobic conditions, such as in the gut of cows and buffaloes.

Solution approach

Correct Answer + Core Reason: Methanogen. Methanogens produce methane in anaerobic conditions.

Step-by-Step Solution:

Step 1: Recall the process of biogas production.

Step 2: Biogas is produced by the anaerobic digestion of organic matter.

Step 3: Methanogens are microorganisms that produce methane during this process.

Step 4: Therefore, methanogens are responsible for biogas production from the dung of cows and buffaloes.

Why other options are wrong:
- Option A: Thermoacidophiles thrive in hot, acidic environments, not typically involved in biogas production.
- Option B: Halophiles thrive in high salt concentrations, not typically involved in biogas production.
- Option D: Cyanobacteria are photosynthetic bacteria and are not primarily responsible for biogas production from dung.

Key Concepts:
- Biogas production
- Methanogenesis
- Methanogens

Memory Aids:
- Methane = Methanogen

Quick Tips:
- Remember that methanogens are key players in biogas production.

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Assertion (A) : The six kingdom classification
proposed by Carl Woese included Bacteria,
Archaebacteria, Protista, Fungi, Plantae and
Animalia.

Reason (R) : Carl Woese divided six kingdoms
into 2 domains using 16s rRNA.

The correct answer is

View answer and explanation

Correct option: C

(A) is true but (R) is false

Option C ((A) is true but (R) is false) is correct because Carl Woese proposed a three-domain system, not a six-kingdom classification, and he used 16S rRNA to divide organisms into domains, not kingdoms.

Solution approach

Correct Answer + Core Reason: (A) is true but (R) is false. Carl Woese proposed a three-domain system, not a six-kingdom classification, and he used 16S rRNA to divide organisms into domains.

Step-by-Step Solution:

Step 1: Analyze Assertion (A): The six kingdom classification proposed by Carl Woese included Bacteria, Archaebacteria, Protista, Fungi, Plantae and Animalia. This is a generally accepted classification, and Carl Woese contributed to understanding the relationships between these groups. So, Assertion (A) can be considered true in the context of general biological understanding, although Woese is more known for the domain system.

Step 2: Analyze Reason (R): Carl Woese divided organisms into 3 domains (Archaea, Bacteria, and Eukarya) using 16s rRNA. The reason states that he divided six kingdoms into 2 domains, which is incorrect. He divided life into 3 domains. Thus, Reason (R) is false.

Step 3: Since Assertion (A) is true and Reason (R) is false, the correct answer is C.

Why other options are wrong:
- Option A: Both (A) and (R) are true, (R) is the correct explanation of (A) - Reason (R) is false.
- Option B: Both (A) and (R) are true but (R) is not the correct explanation of (A) - Reason (R) is false.
- Option D: (A) is false but (R) is true - Assertion (A) is true.

Key Concepts:
- Carl Woese
- Three-domain system
- Six-kingdom classification
- 16S rRNA

Memory Aids:
- Remember that Carl Woese is known for the three-domain system.

Quick Tips:
- Know the difference between the kingdom and domain classifications.

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Read the following statement about bacteria and select the correct option

View answer and explanation

Correct option: A

Bacteria are simple in structure but complex in behavior

Option A (Bacteria are simple in structure but complex in behavior) is correct because their cellular structure is relatively simple, but they exhibit diverse metabolic and adaptive behaviors.

Solution approach

Correct Answer + Core Reason: Bacteria are simple in structure but complex in behavior because they lack complex organelles but exhibit diverse metabolic activities.

Step-by-Step Solution:

Step 1: Bacteria are prokaryotic cells, which are simpler in structure compared to eukaryotic cells.

Step 2: Despite their simple structure, bacteria exhibit a wide range of behaviors, including diverse metabolic pathways, adaptation to various environments, and complex communication mechanisms.

Step 3: Conclusion: Bacteria are simple in structure but complex in behavior.

Why other options are wrong:
- Option B: Incorrect because bacteria are simple in structure.
- Option C: Incorrect because bacteria exhibit complex behaviors.
- Option D: Incorrect because bacteria are simple in structure.

Key Concepts:
- Bacterial structure
- Prokaryotic cells
- Bacterial behavior
- Metabolic diversity

Memory Aids:
- Simple Structure, Complex Behavior

Quick Tips:
- Remember the difference between prokaryotic and eukaryotic cell structures.

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Insectivorous plants are principally

View answer and explanation

Correct option: A

Autotrophic

Option A (Autotrophic) is correct because insectivorous plants are primarily autotrophic, supplementing their nutrient intake with insects.

Solution approach

Correct Answer + Core Reason: Autotrophic. Insectivorous plants perform photosynthesis and are therefore autotrophic.

Step-by-Step Solution:

Step 1: Define autotrophic and heterotrophic nutrition.

Step 2: Autotrophic organisms produce their own food through photosynthesis or chemosynthesis.

Step 3: Heterotrophic organisms obtain their food from other organisms.

Step 4: Insectivorous plants contain chlorophyll and perform photosynthesis, making them autotrophic.

Step 5: They trap insects to supplement their nutrient intake, especially nitrogen, but this doesn't make them primarily heterotrophic.

Why other options are wrong:
- Option B: Insectivorous plants are not primarily heterotrophic, as they perform photosynthesis.
- Option C: Parasitic plants obtain nutrients from a host plant, which is not the case for insectivorous plants.
- Option D: Pathogenic organisms cause disease, which is not the primary function of insectivorous plants.

Key Concepts:
- Autotrophic nutrition
- Heterotrophic nutrition
- Photosynthesis
- Insectivorous plants

Memory Aids:
- Remember that plants with chlorophyll are generally autotrophic.

Quick Tips:
- Consider the primary mode of nutrition when classifying organisms.

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Who proposed five kingdom classification and named kingdoms as Monera, Protista, Fungi, Plantae and Animalia?

View answer and explanation

Correct option: B

R H Whittaker

Option B (R H Whittaker) is correct because he proposed the five-kingdom classification system.

Solution approach

Correct Answer + Core Reason: R H Whittaker. R.H. Whittaker proposed the five-kingdom classification system.

Step-by-Step Solution:

Step 1: Recall the scientists associated with biological classification.

Step 2: R.H. Whittaker is known for proposing the five-kingdom classification system: Monera, Protista, Fungi, Plantae, and Animalia.

Why other options are wrong:
- Option A: Herbert Copeland proposed a four-kingdom classification.
- Option C: Carl Woese proposed the three-domain system of classification.
- Option D: Carolus Linnaeus developed the binomial nomenclature system and an early classification system.

Key Concepts:
- Five kingdom classification
- Scientists and their contributions to classification

Memory Aids:
- Remember Whittaker's name with \"five kingdoms.\"\"

Quick Tips:
- Know the major contributions of key scientists in biology.

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Which one is the free-living, anaerobic nitrogen-fixer?

View answer and explanation

Correct option: B

Rhodospirillum

Option B (Rhodospirillum) is correct because Rhodospirillum is a free-living, anaerobic nitrogen-fixing bacterium.

Solution approach

Correct Answer + Core Reason: Rhodospirillum. It is a free-living, anaerobic nitrogen-fixer.

Step-by-Step Solution:

Step 1: Recall the different types of nitrogen-fixing bacteria.

Step 2: Identify which of the given options is a free-living, anaerobic nitrogen-fixer.

Step 3: Rhodospirillum is a free-living, anaerobic nitrogen-fixing bacterium.

Why other options are wrong:
- Option A: Beijernickia is a free-living, aerobic nitrogen-fixer.
- Option C: Rhizobium is a symbiotic nitrogen-fixer that lives in the root nodules of leguminous plants.
- Option D: Azotobacter is a free-living, aerobic nitrogen-fixer.

Key Concepts:
- Nitrogen fixation
- Free-living vs. Symbiotic bacteria
- Aerobic vs. Anaerobic bacteria

Memory Aids:
- Rhodospirillum = Anaerobic

Quick Tips:
- Remember the difference between free-living and symbiotic nitrogen fixers.

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A bacterial cell divides once every minute and it takes 1 hour to fill a cup. How much time will it take to fill half the cup.

View answer and explanation

Correct option: D

59 minutes

Option D (59 minutes) is correct because if the cup is full at 60 minutes, it was half full one division (one minute) prior.

Solution approach

Correct Answer + Core Reason: 59 minutes. Since the bacteria doubles every minute, it was half full one minute before being completely full.

Step-by-Step Solution:

Step 1: Understand the exponential growth pattern.

Step 2: If the cup is full at 60 minutes, it means that at 59 minutes, the cup was half full because the bacteria doubles every minute.

Why other options are wrong:
- Option A: 30 minutes - This is incorrect because the growth is exponential, not linear.
- Option B: 60 minutes - This is when the cup is completely full, not half full.
- Option C: 29 minutes - This is incorrect; it would be half full one minute before being completely full.

Key Concepts:
- Exponential growth
- Bacterial division

Memory Aids:
- Work backwards from the full cup to find the half-full time.

Quick Tips:
- Remember that bacterial growth is exponential, not linear.

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Which one is mismatched?

View answer and explanation

Correct option: D

Formation of non-motile gametes - Alternaria

Option D is mismatched. Alternaria reproduces asexually via conidia, not non-motile gametes.

Solution approach

Correct Answer + Core Reason: Formation of non-motile gametes - Alternaria. Alternaria reproduces asexually via conidia, not sexually with non-motile gametes.

Step-by-Step Solution:

Step 1: Recall the reproductive methods of each fungus.

Step 2: Alternaria is a deuteromycete (fungi imperfecti) that reproduces asexually through conidia.

Step 3: Morels are edible ascocarps (fruiting bodies of ascomycetes).

Step 4: Neurospora is used in experimental genetics.

Step 5: Puffballs form basidiocarps (fruiting bodies of basidiomycetes).

Why other options are wrong:
- Option A: Edible ascocarp - Morels is a correct match.
- Option B: Used for experimental genetics - Neurospora is a correct match.
- Option C: Formation of basidiocarp - Puffballs is a correct match.

Key Concepts:
- Reproduction in fungi
- Ascocarps, basidiocarps
- Deuteromycetes

Memory Aids:
- Conidia are asexual spores.

Quick Tips:
- Know the different types of spores and fruiting bodies in fungi.

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Which of these best describes the sporophytic generation in plant’s life cycle?

View answer and explanation

Correct option: C

Generation that produces spores

Option C (Generation that produces spores) is correct because the sporophyte generation is diploid and produces haploid spores through meiosis.

Solution approach

Correct Answer + Core Reason: Generation that produces spores. The sporophyte generation is diploid and produces spores.

Step-by-Step Solution:

Step 1: Define sporophyte: The sporophyte is the diploid (2n) generation in plants that produces spores through meiosis.

Step 2: Define gametophyte: The gametophyte is the haploid (n) generation that produces gametes through mitosis.

Step 3: Relate sporophyte to spore production: The sporophyte generation undergoes meiosis to produce haploid spores.

Why other options are wrong:
- Option A: The haploid generation is the gametophyte, not the sporophyte.
- Option B: The generation that produces gametes is the gametophyte.
- Option D: Both sporophyte and gametophyte generations can have xylem and phloem, depending on the plant group.

Key Concepts:
- Alternation of generations
- Sporophyte and gametophyte generations
- Meiosis and mitosis

Memory Aids:
- Sporo-phyte = Spore-producer
- Gameto-phyte = Gamete-producer

Quick Tips:
- Understand the life cycle of plants and the roles of sporophyte and gametophyte.

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Assertion:Archaea and Eukarya are more closely related to each other than to bacteria (woese)

Reason: Archaea, Eukarya and Bacteria are believed to be originated from different ancestral group.

View answer and explanation

Correct option: C

If Assertion is true but Reason is false.

Option C (If Assertion is true but Reason is false) is correct because Archaea and Eukarya are indeed more closely related, but they are believed to have originated from a common ancestor, not different ancestral groups.

Solution approach

Correct Answer + Core Reason: If Assertion is true but Reason is false. Archaea and Eukarya are more closely related, but they are believed to have originated from a common ancestor.

Step-by-Step Solution:

Step 1: Evaluate Assertion: Archaea and Eukarya are more closely related to each other than to bacteria (Woese). This is true based on evolutionary relationships.

Step 2: Evaluate Reason: Archaea, Eukarya, and Bacteria are believed to have originated from different ancestral groups. This is false; they are believed to have originated from a common ancestor.

Why other options are wrong:
- Option A: Reason is false.
- Option B: Reason is false.
- Option D: Assertion is true.

Key Concepts:
- Evolutionary relationships
- Three-domain system
- Common ancestry

Memory Aids:
- Remember that all life is believed to have a common ancestor.

Quick Tips:
- Consider the evidence for common ancestry when evaluating evolutionary relationships.

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Assertion: Euglena cannot be classified on the
basis of two kingdom system.

Reason: Euglena is a plant due to presence of
chlorophyll.

View answer and explanation

Correct option: C

If Assertion is true but Reason is false

The assertion is true, but the reason is false. Euglena's classification is complex, but it's not *just* because of chlorophyll.

Solution approach

Correct Answer + Core Reason: If Assertion is true but Reason is false. Euglena's classification is complex, and the presence of chlorophyll is not the sole reason.

Step-by-Step Solution:

Step 1: Analyze the assertion: Euglena possesses characteristics of both plants (chlorophyll) and animals (motility, lack of cell wall in some conditions), making it difficult to classify under a strict two-kingdom system.

Step 2: Analyze the reason: While Euglena does contain chlorophyll, this is not the only reason it's difficult to classify. Its animal-like characteristics also contribute to the difficulty.

Step 3: Determine if the reason correctly explains the assertion: The reason is false because Euglena's classification is not solely based on the presence of chlorophyll.

Why other options are wrong:
- Option A: The reason is false, so it cannot be the correct explanation of the assertion.
- Option B: The reason is false.
- Option D: The assertion is true.

Key Concepts:
- Classification of organisms
- Characteristics of Euglena
- Two-kingdom system

Memory Aids:
- Remember that Euglena has both plant-like and animal-like characteristics.

Quick Tips:
- Consider all aspects of an organism when determining its classification.

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Five Kingdom System of classification suggested by R.H. Whittaker is not based on

View answer and explanation

Correct option: A

Absence of a well defined nucleus

Option A (Absence of a well defined nucleus) is correct because Whittaker's classification was based on cell structure complexity, mode of nutrition, reproduction, and phylogenetic relationships, not solely on the absence of a nucleus.

Solution approach

Correct Answer + Core Reason: Absence of a well defined nucleus. Whittaker's classification considers other factors more directly.

Step-by-Step Solution:

Step 1: Recall the criteria used by R.H. Whittaker for his five-kingdom classification.

Step 2: Whittaker's classification was based on:
- Cell structure (prokaryotic vs. eukaryotic)
- Body organization (unicellular vs. multicellular)
- Mode of nutrition (autotrophic vs. heterotrophic)
- Reproduction (sexual vs. asexual)
- Phylogenetic relationships (evolutionary history)

Step 3: While the presence or absence of a nucleus (prokaryotic vs. eukaryotic) is a factor in cell structure, the classification is not *solely* based on this.

Why other options are wrong:
- Option B: Mode of reproduction is a key criterion in Whittaker's classification.
- Option C: Mode of nutrition is a key criterion in Whittaker's classification.
- Option D: Complexity of body organization is a key criterion in Whittaker's classification.

Key Concepts:
- Whittaker's five kingdom classification
- Criteria for classification

Memory Aids:
- Remember the key criteria: Cell structure, Body organization, Nutrition, Reproduction, Phylogeny.

Quick Tips:
- Understand the basis of Whittaker's classification.

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Contagium vivum fluidum concept of virus was proposed by

View answer and explanation

Correct option: B

MW Beijerinck

Option B (MW Beijerinck) is correct because he proposed the 'Contagium vivum fluidum' concept.

Solution approach

Correct Answer + Core Reason: MW Beijerinck. MW Beijerinck proposed the \'Contagium vivum fluidum\' concept of virus.

Step-by-Step Solution:

Step 1: The question asks who proposed the \'Contagium vivum fluidum\' concept.

Step 2: Recall that MW Beijerinck demonstrated that the infectious agent in tobacco mosaic disease was a \'contagium vivum fluidum\' (soluble living germ).

Why other options are wrong:
- Option A: DJ Ivanowsky discovered that the infectious agent could pass through bacteria-proof filters.
- Option C: Stanley crystallized the Tobacco Mosaic Virus (TMV).
- Option D: Robert Hooke is known for his work on cells, not viruses.

Key Concepts:
- History of virology
- Contagium vivum fluidum
- MW Beijerinck

Memory Aids:
- Beijerinck = Fluid

Quick Tips:
- Remember the key contributions of different scientists to the field of virology.

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The disease caused by Trypanosoma is

View answer and explanation

Correct option: B

Sleeping sickness

The correct answer is B (Sleeping sickness) because Trypanosoma is a protozoan parasite that causes African sleeping sickness.

Solution approach

Correct Answer + Core Reason: Sleeping sickness is caused by Trypanosoma.

Step-by-Step Solution:

Step 1: Recall the diseases caused by different protozoans.

Step 2: Trypanosoma is a genus of parasitic flagellate protozoa.

Step 3: Trypanosoma brucei causes African sleeping sickness, transmitted by the tsetse fly.

Step 4: The disease affects the nervous system, leading to sleep disturbances and eventually coma.

Why other options are wrong:
- Option A (Yellow fever): Yellow fever is caused by a virus transmitted by mosquitoes.
- Option C (Kala azar): Kala azar is caused by Leishmania, another protozoan parasite.
- Option D (Hey fever): Hey fever is an allergic reaction to pollen.

Key Concepts:
- Protozoan diseases
- Trypanosoma
- Sleeping sickness

Memory Aids:
- Trypanosoma = Tsetse fly = Sleeping sickness

Quick Tips:
- Remember the vector and causative agent for each disease.

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State whether the given statements are true or false
I. Bacteria shows both autotrophic and heterotrophic nutrition
II. Some of the bacteria are autotrophic. They may be photosynthetic autotrophic or chemosynthetic autotrophic
III. Heterotrophic nutrition involves the obtaining of readymade organic nutrients from outside sources

View answer and explanation

Correct option: C

I, II and III are true

Option C (I, II and III are true) is correct because all three statements accurately describe bacterial nutrition.

Solution approach

Correct Answer + Core Reason: I, II and III are true because bacteria exhibit both autotrophic and heterotrophic nutrition, with autotrophs being either photosynthetic or chemosynthetic, and heterotrophs obtaining nutrients from external sources.

Step-by-Step Solution:

Step 1: Statement I: Bacteria show both autotrophic and heterotrophic nutrition. This is true; some bacteria can produce their own food (autotrophic), while others obtain it from external sources (heterotrophic).

Step 2: Statement II: Some bacteria are autotrophic, either photosynthetic or chemosynthetic. This is also true; photosynthetic bacteria use sunlight, while chemosynthetic bacteria use chemical energy.

Step 3: Statement III: Heterotrophic nutrition involves obtaining readymade organic nutrients from outside sources. This is the definition of heterotrophic nutrition.

Step 4: Conclusion: All three statements are true.

Why other options are wrong:
- Option A: Incorrect because statement III is also true.
- Option B: Incorrect because statements II and III are true.
- Option D: Incorrect because it is incomplete. Option C is the correct answer.

Key Concepts:
- Autotrophic nutrition
- Heterotrophic nutrition
- Photosynthetic autotrophs
- Chemosynthetic autotrophs

Memory Aids:
- Autotrophs = Self-feeding, Heterotrophs = Other-feeding

Quick Tips:
- Remember the different types of bacterial nutrition.

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In the light of recent classification of living organisms into three domains of life (bacteria, archaea and eukarya), which one of the following statement is true about archaea?

View answer and explanation

Correct option: B

Archaea have some noble features that are absent in other prokaryotes and eukaryotes

Option B (Archaea have some noble features that are absent in other prokaryotes and eukaryotes) is correct because archaea possess unique characteristics not found in other prokaryotes or eukaryotes.

Solution approach

Correct Answer + Core Reason: Archaea have some noble features that are absent in other prokaryotes and eukaryotes. Archaea possess unique characteristics not found in other prokaryotes or eukaryotes.

Step-by-Step Solution:

Step 1: Recall the three domains of life: Bacteria, Archaea, and Eukarya.

Step 2: Understand the key characteristics of Archaea. Archaea have unique features such as:
- Ether-linked lipids in their cell membranes
- Lack of peptidoglycan in their cell walls
- Ribosomal RNA sequences distinct from Bacteria and Eukarya
- Ability to live in extreme environments (e.g., high temperature, high salinity)

Step 3: These features distinguish Archaea from both Bacteria (other prokaryotes) and Eukarya.

Why other options are wrong:
- Option A: Archaea resemble eukarya in all respects is incorrect because Archaea and Eukarya have significant differences.
- Option C: Archaea completely differ from both prokaryotes and eukaryotes is incorrect because Archaea share some similarities with both.
- Option D: Archaea completely differ from prokaryotes is incorrect because Archaea *are* prokaryotes, but with unique features.

Key Concepts:
- Three domains of life
- Archaea
- Bacteria
- Eukarya

Memory Aids:
- Archaea = \"ancient,\" often found in extreme environments.\"

Quick Tips:
- Know the key differences between the three domains.

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The following is comparable to a professional
dinner guest

View answer and explanation

Correct option: C

Parasite

Option C is correct because a parasite, like a professional dinner guest, benefits at the expense of the host.

Solution approach

Correct Answer + Core Reason: Parasite. A parasite benefits at the expense of its host, similar to a professional dinner guest who benefits from the host's hospitality.

Step-by-Step Solution:
Step 1: Analyze the given options and their ecological relationships.
Step 2: Define the terms:\nA. Competitive organism: An organism that competes with others for resources.\nB. Commensal: An organism that benefits from another without harming or benefiting the other.\nC. Parasite: An organism that benefits at the expense of another (the host).\nD. Predator: An organism that hunts and kills another for food.
Step 3: Relate the terms to the analogy of a professional dinner guest:\nA professional dinner guest benefits from the host's food and hospitality, similar to how a parasite benefits from its host. The host may or may not be harmed, but the parasite is definitely benefiting.

Why other options are wrong:
- Option A: Competitive organism - A dinner guest is not necessarily competing with the host.
- Option B: Commensal - A parasite harms the host, unlike a commensal organism.
- Option D: Predator - A parasite doesn't kill the host immediately like a predator does.

Key Concepts:
- Ecological Relationships
- Parasitism
- Commensalism
- Predation

Memory Aids:
- Remember \"Parasite = Professional Dinner Guest\" - both benefit at the expense of another.

Quick Tips:
- Understand the different types of ecological relationships and their characteristics.

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Find the odd one w.r.t. the fungi imperfecti

View answer and explanation

Correct option: D

Penicillium

Penicillium is the odd one out because it is classified under Ascomycetes, while the others are Deuteromycetes.

Solution approach

Correct Answer + Core Reason: Penicillium. Penicillium is classified under Ascomycetes, while Alternaria, Colletotrichum, and Trichoderma are Deuteromycetes (Fungi Imperfecti).

Step-by-Step Solution:

Step 1: Recall the classification of each fungus.

Step 2: Alternaria, Colletotrichum, and Trichoderma are all members of Deuteromycetes (Fungi Imperfecti), a group of fungi where sexual reproduction is not known or has not been observed.

Step 3: Penicillium, on the other hand, is classified under Ascomycetes, where sexual reproduction has been observed.

Why other options are wrong:
- Option A: Alternaria is a Deuteromycete.
- Option B: Colletotrichum is a Deuteromycete.
- Option C: Trichoderma is a Deuteromycete.

Key Concepts:
- Classification of fungi
- Deuteromycetes (Fungi Imperfecti)
- Ascomycetes

Memory Aids:
- Deuteromycetes are \"imperfect\" because their sexual stage is unknown.

Quick Tips:
- Know the defining characteristics of different fungal classes.

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Viroids have

View answer and explanation

Correct option: A

ssRNA not enclosed by protein coat

Option A (ssRNA not enclosed by protein coat) is correct because viroids are characterized by having a single-stranded RNA molecule without a protein coat.

Solution approach

Correct Answer + Core Reason: ssRNA not enclosed by protein coat. Viroids are small, circular, single-stranded RNA molecules without a protein coat.

Step-by-Step Solution:

Step 1: Recall the structure of viroids.

Step 2: Viroids are infectious agents that consist only of a small, circular, single-stranded RNA molecule.

Step 3: They lack a protein coat (capsid), which distinguishes them from viruses.

Why other options are wrong:
- Option B: Viroids do not contain DNA.
- Option C: Viroids do not contain DNA and lack a protein coat.
- Option D: Viroids do not contain double-stranded RNA and lack a protein coat.

Key Concepts:
- Viroids
- Structure of viroids
- Differences between viroids and viruses

Memory Aids:
- Viroids = RNA without a coat.

Quick Tips:
- Remember that viroids are simpler than viruses, lacking a protein coat.

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Which is the only kingdom occupied by BGA, nitrogen fixing bacteria and methanogenic bacteria in five kingdom classification?

View answer and explanation

Correct option: C

Monera

The correct answer is C (Monera) because BGA (blue-green algae), nitrogen-fixing bacteria, and methanogenic bacteria are all prokaryotes, which are classified under the Kingdom Monera.

Solution approach

Correct Answer + Core Reason: Monera is the kingdom occupied by BGA, nitrogen-fixing bacteria, and methanogenic bacteria.

Step-by-Step Solution:

Step 1: Recall the five kingdom classification system.

Step 2: Identify the characteristics of each kingdom: Monera, Protista, Fungi, Plantae, and Animalia.

Step 3: BGA (now known as cyanobacteria), nitrogen-fixing bacteria, and methanogenic bacteria are all prokaryotic organisms.

Step 4: Prokaryotic organisms are classified under the Kingdom Monera.

Why other options are wrong:
- Option A (Plantae): Plantae includes eukaryotic, multicellular organisms that perform photosynthesis.
- Option B (Protista): Protista includes eukaryotic, mostly unicellular organisms.
- Option D (Fungi): Fungi includes eukaryotic, heterotrophic organisms with chitinous cell walls.

Key Concepts:
- Five kingdom classification
- Prokaryotes vs. Eukaryotes
- Kingdom Monera

Memory Aids:
- Monera = prokaryotes

Quick Tips:
- Remember that prokaryotes lack a true nucleus and membrane-bound organelles.

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Select the wrong match.

View answer and explanation

Correct option: D

Red tide causing organism - Can fix

{CO}_2

as well as

{N}_2

Option D is the wrong match because while red tide causing organisms (dinoflagellates) can fix CO2, they are not typically known for fixing N2.

Solution approach

Correct Answer + Core Reason: Red tide causing organism - Can fix ${CO}_2$ as well as ${N}_2$ . Red tide organisms (dinoflagellates) can fix CO2 but generally do not fix N2.

Step-by-Step Solution:
Step 1: Analyze the given matches and their characteristics.
Step 2: Evaluate each match:\nA. Indicator of water pollution - Soap box like body: This refers to diatoms, which are good indicators of water quality and have silica cell walls that resemble soap boxes. This is a correct match.\nB. Malaria causing organism - Lack locomotory structure: This refers to sporozoans like Plasmodium, which cause malaria and lack locomotory structures. This is a correct match.\nC. Smallest cell - Wall less moneran: This refers to Mycoplasma, which are the smallest cells and lack a cell wall. This is a correct match.\nD. Red tide causing organism - Can fix ${CO}_2$ as well as ${N}_2$ : Red tide is caused by dinoflagellates. While dinoflagellates can perform photosynthesis and fix ${CO}_2$ , they are not typically known for fixing ${N}_2$ . Nitrogen fixation is more common in cyanobacteria.

Why other options are wrong:
- Option A: Indicator of water pollution - Soap box like body - This is a correct match for diatoms.
- Option B: Malaria causing organism - Lack locomotory structure - This is a correct match for sporozoans like Plasmodium.
- Option C: Smallest cell - Wall less moneran - This is a correct match for Mycoplasma.

Key Concepts:
- Characteristics of Different Organisms
- Ecological Roles
- Nitrogen Fixation

Memory Aids:
- Remember \"Diatoms = Soap Box\" and \"Mycoplasma = No Wall\"

Quick Tips:
- Know the key characteristics of different groups of organisms.

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Which of the following is not a character of Protista?

View answer and explanation

Correct option: A

Protists are prokaryotic

Option A (Protists are prokaryotic) is correct because protists are eukaryotic, not prokaryotic.

Solution approach

Correct Answer + Core Reason: Protists are prokaryotic. Protists are eukaryotic organisms, not prokaryotic.

Step-by-Step Solution:

Step 1: The question asks which of the given options is not a characteristic of Protista.

Step 2: Consider the characteristics of Protista:
- Eukaryotic (not prokaryotic)
- Some have cell walls
- Mode of nutrition can be autotrophic or heterotrophic
- Body organization is cellular

Step 3: Protists are eukaryotic, meaning they have a nucleus and other membrane-bound organelles.

Why other options are wrong:
- Option B: Some protists, like diatoms, have cell walls.
- Option C: Protists can be autotrophic (e.g., algae) or heterotrophic (e.g., protozoa).
- Option D: Protists are unicellular or simple multicellular organisms with cellular organization.

Key Concepts:
- Characteristics of Protista
- Eukaryotic vs. prokaryotic cells

Memory Aids:
- Protists = Eukaryotic

Quick Tips:
- Remember that protists are eukaryotic.

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