Biology: Biological Classification (Solved Examples Part 1)

Master 'The Living World' with 20-25 solved examples in this comprehensive blog, designed for NEET and Olympiad aspirants. Covering essential topics like biological classification, the diversity of life, and the characteristics of living organisms, this guide provides step-by-step solutions for better understanding. Perfect for strengthening your grasp of key concepts, these solved examples will help boost your problem-solving abilities and exam preparation. Ideal for NEET, Olympiads, and other competitive exams, this blog will ensure you're well-prepared to succeed.

1. In which of the following fungi an intervening dikaryotic stage occurs during the life cycle?
A. Aspergillus
B. Mucor
C. Albugo
D. Rhizopus

Solution:

Dikaryotic stage is feature of ascomycetes and basidiomycetes member i.e., Aspergillus (Ascomycetes).

Correct Answer:A

2. Which of the following is an example of amoeboid protozoans?

A . Trypanosoma

B . Paramecium

C . Gonyaulax

D . Entamoeba

Solution:

Amoeboid protozoans are organisms that live in freshwater, seawater or moist soil. They move and capture their prey by putting out pseudopodia (e.g. Amoeba). Some of them such as Entamoeba are parasites.

Correct Answer : D

3. In bacteria, plasmid is

A . extra chromosomal material

B . main DNA

C . non functional DNA

D . repetitive gene.

Solution:

Plasmids are semi-autonomous molecules and exist in cells as extrachromosomal genomes, although some plasmids can be inserted into a bacterial chromosome, where they become a permanent part of the bacterial genome.

Correct Answer : A

4. Bacterial structure and behavior are respectively:-

A . Simple, Simple

B . Complex, Simple

C . Simple, Complex

D . Complex, Complex

Solution:

Structure of bacteria is simple but behavior in different conditions changes; so, behavior is complex

Correct Answer : C

5. Anoxygenic photosynthesis is characteristic of

A . Rhodospirillum

B . Spirogyra

C . Chlamydomonas

D . Ulva

Solution:

In Rhodospirillum, electron donor is organic compound instead of water hence no oxygen is released, i.e., anoxygenic photosynthesis occurs. In other plants water is used as electron donor and H + and O2 are produced during photolysis of water.

Correct Answer : A

6. The two-kingdom classification of the living world was considered inadequate, because:

A . It does not provide for a clear cut demarcation between prokaryotes and eukaryotes

B . It includes fungi under plant kingdom though they are saprotrophic and store glycogen

C . In this classification position of euglenoid is not fixed

D . All of the above

Solution:

The question asks why the two-kingdom classification of living organisms is considered inadequate.

Let’s break down the options:

A. It does not provide for a clear demarcation between prokaryotes and eukaryotes.

- This is true, as the two-kingdom system treats all organisms as either plants or animals, which doesn't clearly differentiate between these groups.

B. It includes fungi under the plant kingdom though they are saprotrophic and store glycogen.

- This is also accurate. Fungi are quite distinct from plants, yet they were classified as plants in this system.

C. In this classification, the position of euglena (euglenoids) is not fixed.

- This statement is correct as well; euglena have characteristics that could place them in either the plant or animal category, leading to confusion.

D. All of the above.

- Since all the previous statements are correct, this is the right choice.

So, the answer is indeed D (All of the above).

Correct Answer : D

7. Choose the incorrect statement from following

A . Mycoplasma can survive without oxygen

B . In slime moulds spores are dispersed by air current

C . Dinoflagellates are chief producers in the oceans

D . Pellicle is responsible for flexible body in Euglenoids

Solution:

Diatoms produce long-chain fatty acids and are an important source of energy-rich molecules. They are the food source of the entire aquatic food web including zooplanktons, aquatic insects, fishes and whales. Hence, they are known as the chief producers of oceans.

Correct Answer : C

8. Viruses are no more "alive" than isolated chromosomes because

A . they require both RNA and DNA

B . they both need food molecules

C . they both require oxygen for respiration

D . both require the environment of a cell to replicate

Solution:

A virus is a small infectious agent that replicates only inside the living cells of other organisms, using their cellular machinery. Viruses can infect all types of life forms, from animals and plants to microorganisms, including bacteria and archaea. Isolated chromosomes also require the environment of a cell or cellular machinery to replicate.

Correct Answer : D

9. Chrysophytes, Euglenoids, Dinoflagellates and Slime moulds are included in the Kingdom

A . Fungi

B . Animalia

C . Monera

D . Protista

Solution:

Protista is a kingdom of unicellular eukaryotic organisms. It includes photosynthetic protists (dinoflagellates, chrysophytes and euglenoids), consumer decomposer protists (slime moulds) and protozoan protists.

Correct Answer : D

10. Select incorrect statement w.r.t. slime moulds

A . The body as Plasmodium is formed after aggregation in suitable conditions

B . Differentiation of plasmodium occurs in unfavourable conditions

C . Represents holophytic mode of nutrition

D . These are holocarpic

Solution:

Slime molds grow on dead and decaying twigs and leaves having phagotrophic (Heterotrophic) mode of nutrition.

Correct Answer : C

11. A free living nitrogen fixing cyanobacterium which can also form symbiotic association with the water fern Azolla is

A . Tolypothrix

B . Chlorella

C . Nostoc

D . Anabaena

Solution:

Anabaena is a free living nitrogen fixing cyanobacterium which can form symbiotic association with the water fern Azolla.

Correct Answer : D

12. Which of the following statement is incorrect?

A . Conidia are produced exogenously and ascospores endogenously.

B . Yeasts have filamentous bodies with long thread-like hyphae.

C . Morels and truffles are edible delicacies.

D . Clauiceps is a source of many alkaloids and LSD.

Solution:

Exceptionally yeasts are unicellular fungi. Fungi are multicellular mainly heterotrophic eukaryotes having septate or aseptate hyphae.

Correct Answer : B

13. Which one of the following statements is wrong?

A . Eubacteria are also called false bacteria.

B . Phycomycetes are also called algal fungi.

C . Cyanobacteria are also called bluegreen algae.

D . Golden algae are also called desmids.

Solution:

Eubacteria are also called true bacteria

Correct Answer : A

14. Common type of asexual spores in zygomycetes and ascomycetes are respectively

A . Thick walled and thin walled

B . Endospore and exospore

C . Motile and non-motile

D . Thin walled and thick walled diploid

Solution:

In zygomycetes asexual spore are either motile zoospores or nonmotile aplanospore produced endogenously within sporangium while in ascomycetes conidia produced exogenously on conidiophore which are non motile in nature.

Correct Answer : B

15. Which group of fungi is commonly known as imperfect fungi?

A . Phycomycetes

B . Ascomycetes

C . Basidiomycetes

D . Deuteromycetes

Solution:

Deuteromycetes is commonly known as fungi imperfecti due to absence of perfect sexual stage. They are classed by the colour and structure of the conidia. Since most of the conidia structures look like ascomycetes type, they are believed to be derived from ascos which does not have the ability to reproduce sexually.

Correct Answer : D

16. What is true for cyanobacteria?

A . Oxygenic with nitrogenase

B . Oxygenic without nitrogenase

C . Non oxygenic with nitrogenase

D . Non oxygenic without nitrogenase

Solution:

Cyanobacteria are oxygenic photosynthetic bacteria. It has the ability to synthesize its own food in presence of oxygen. It has the ability to fix atmospheric nitrogen. It converts nitrogen into ammonia.

Correct Answer : A

17. Which one of the group of Archaebacteria are responsible for the production of bio gas?

A . Halophils

B . Thermoacidophils

C . Methanogenes

D . All of the above

Solution:

Methanogens are the type of archaebacteria which are responsibe for production of biogas by decomposition of dung

Correct Answer : C

18. Which of the following statements is correct for dinoflagellates flagella?

A . A single flagellum lies in the transverse groove between the cellplates.

B . A single flagellum lies in the longitudinal groove between the cell plates.

C . Two flagella, one lies longitudinally and the other transversely in a furrow between the wall plates.

D . Flagella are absent.

Solution:

Dinoflagellates are mostly marine and photosynthetic organism. They appear yellow, green, brown, blue or red depending on the main pigments present in their cells. Most of them have two flagella; one lies longitudinally and the other transversely in a furrow between the cell plates.

Correct Answer : C

19. Which of the following is the smallest living cell and can live without oxygen?

A . Mycoplasma

B . Mycorrhiza

C . Euglena

D . Tгурanosoma

Solution:

Mycoplasma are the simplest or smallest known organisms that completely lack a cell wall and can survive without oxygen.

Correct Answer : A

20. In which kingdom would you classify the archaea and nitrogen fixing organisms, if the five kingdom system of classification is used?

A . Plantae

B . Fungi

C . Protista

D . Monera

Solution:

Whittaker's classification includes five kingdom classification system. The five kingdoms include Monera, Protista, Fungi, Plantae, and Animalia. Monera includes Eubacteria and Archaea. They include non-nucleated unicellular organisms. They are prokaryotes. They have a cell wall. They have no membrane bound organelles and true nucleus.

Correct Answer : D