CBSE Important Questions for Class 11 Biology Biological Classification - 2025-26

Very Short Questions and Answers (1 Marks Questions)

1. Nostoc and Anabaena have specialised cells called heterocysts. What is the function of these cells?

Ans:  Assist in the nitrogen fixation process.

2. Which group comprises single-celled eukaryotes only.

Ans: Kingdom Protista comprises single-celled eukaryotes.

3. Which organisms are the chief producers in oceans?

Ans: Diatoms are the chief producers in oceans.

4. Name the fungus which causes disease in wheat  (i)rust  (ii) Smut.

Ans: (i) Puccinia, (ii) Ustilago are the fungus that causes disease in wheat.

5. Which ascomycetes have been used extensively in biochemical and genetic work.

Ans: Neurospora used in biochemical and genetic work.

6. Who introduced the five-kingdom classification of organisms?

Ans:  R.H. Whittaker (1969) introduced the five kingdoms.

7. To which kingdom do the multicellular decomposers belong?

Ans: Kingdom fungi - multicellular decomposers.

8. Expand PPLO.

Ans: Pleuropneumonia like organisms stands for PPLO.

9. Name the five kingdoms in which the organisms are grouped together?

Ans: Monera, Protista, Fungi, Plantae & Animalia -5 kingdoms

10. Which organisms are known as "Jokers of plant kingdom"

Ans: 2 Mycoplasma

11. In which class of fungi sexual reproduction does not occur?

Ans: Deuteromycetes - sexual reproduction does not occur.

12. Who is known as the "Father of classification"?

Ans: Carolus Linnaeus - Father of classification

13. Name the fungus from which LSD drug is obtained?

Ans: Claviceps purpurea is the name of fungus.

14. It is advised to grow one pulse crop in between two main crops in the same field. Why?

Ans: To increase the fertility of the soil so it is advised to grow one pulse crop in between two main crops in the same field.

15. Define experimental taxonomy?

Ans: It is the process of identifying evolutionary units within a species by determining their genetic origin through experimentation.

16. Name the fungus that causes the rust of wheat?

Ans:  Puccinia graminis tritici is the fungus that causes the rust of wheat.

17. What are distributed organisms that have not been included under any kingdom?

Ans: Virus & Viroids has not been included in any kingdom.

Short Questions and Answers (2 Marks Questions)

1. How are alt bacteria classified on the basis of their shapes?

Ans: Coccus (red-shaped Bacillus), Bacillus (red-shaped Bacillus) (spherical). Spirillum (comma-shaped) and Vibrium (spiral-shaped).

2. What is the mode of reproduction in bacteria?

Ans: Mostly by fission; spore production in difficult conditions. By transferring DNA from one person to another, sexual reproduction is possible.

3. Why are red tides caused and why are they harmful?

Ans: Dinoflagellates such as Gonyaulax have a rapid multiplication rate. They are dangerous because they emit chemicals that destroy aquatic animals.

4. Viruses and viroids differ in structure and the diseases they cause. How?

Ans: Viruses can have either RNA or DNA molecules enclosed in a protein coat, whereas viroids are free RNA molecules with low molecular weight and no protein coat. Viroids are smaller than viruses in size. Viruses infect only plants, but viroids infect all living things. Viroids lack a protein coat, whereas viruses have a protein covering or coat called capsid that surrounds the genetic material.

5. Which class of Kingdom fungi has both unicellular as well as multicellular members?

When is a fungus called coprophilous?

Ans: On dung, Ascomycetes Yea-n (Unicellular), Pen cilium (Multicellular), and Coprophilous moans fungus flourish.

6. What is the basis of modern classification?

Ans: Modern taxonomy is founded on the following principles:

(i) Relationship between evolution.

(ii) The genetic codes of different species are similar.

(iii) Characteristics of the environment.

7. Give one example of a fungus as a source of antibiotics?

Ans: Penicillium is the genus from which the antibiotic penicillin is derived. Green and blue moulds are examples of Penicillium. The bacteria Penicillium chrysogenum is used to make the antibiotic penicillin.

8. How are viroids different from viruses?

Ans:

9. Explain the phylogenetic system of classification?

Ans: The phylogenetic system of classification is based on species' evolutionary relationships. It reflects the fundamental interdependence of creatures. It is neither static nor dynamic.

Its origins are incomplete fossil records due to the difficulty of formation, exposure, discovery, and investigation.

10. What is the basis of Whittaker's system of classification?

Ans: Whittaker based his classification on the following three criteria :

(i) Structure of cell i-e. prokaryotic Vs. Eukaryotic organization.

(ii) Unicellular Vs. multicellular organisms

(iii) Different modes of nutrition - parasitic, autotrophic or heterotrophic

11. Find out what do the terms "algal bloom" & "red tides" signify?

Ans:

(I)Algal bloom is a term used to describe the rapid growth of algae in a water body as a result of nutrient enrichment.

(II) Crimson dinoflagellates, such as Gonyaulux, multiply rapidly, making the sea appear red. It's known as red tide.

12. Why are some fungi grouped under "fungi imperfecti"?

Ans: Asexual reproduction is widespread in fungus. A portion of the mycelium is fragmented into minute pieces that grow into new mycelium, however sexual reproduction occurs in some fungus. Fungi imperfecti refers to a group of fungi that reproduces entirely by asexual spores rather than sexual spores.

13. Explain "Numerical taxonomy".

Ans: The employment of technology approaches in taxonomy is referred to as numerical taxonomy. The characters that can be seen are investigated. For computers, they are given numbers and codes like (+) and (-). (-). The computer-processed data assigns a score to each taxon based on the number of unit characters they possess.

14. What are the demerits of the five kingdom classification?

Ans: Below given are the demerits of five kingdom classification:-

(i) Autotrophic and heterotrophic organisms are included in the kingdom monera & Protista.

(ii) Phylogenetic lineages in lower organisms are not well-defined or well-defined.

(ii) From protists, multicellular groups have emerged.

15. Give scientific name of species of fungus:

(a) Produces a plant disease.

Ans: Phytophthora infestans, which causes potato late blight.

(b) Is edible

Ans:  Agaricus campestris - A mushroom that can be eaten.

(c) A source of antibiotic

Ans: Penicillium notatum is an antibiotic-producing fungus.

(d) Used in the manufacture of ethanol.

Ans: Saccharomyces cerevisiae is a yeast that is used to make ethanol.

16. Compare salient features of Monera & Protista.

Ans:

17. State an economically important use of

(i) Heterotrophic bacteria.

Ans: Heterotrophic bacteria are mostly decomposers. Some are beneficial in the production of curd milk, nitrogen fixation, and other processes, whereas others are pathogens that cause sickness.

(ii) Archaebacteria.

Ans: production.Archaebacteria, bacteria that make biogas from cow dung, for example.

18. Write the importance of the classification of organisms.

Ans. (i) With millions of plants known today, classification is essential for the systematic study of living beings.

(ii) All organisms do not live in the same place.

(iii) Studying all creatures at the same time is impossible.

(iv) It aids in the understanding of evolutionary links between various groups.

(v) It makes each creature easier to distinguish and identify.

19. What are insectivorous plants? Give an example.

Ans: Carnivorous plants are insectivorous plants. They catch insects to supplement nitrogen requirements in the diet. These are green plants that have had their leaves modified to trap insects in order to overcome a nitrogen shortage. For example, the 

pitcher plant (Nepenthes) has had its leaf blade modified into a pitcher.

Long Questions and Answers (3 Marks Questions)

1. Who gave live Kingdom classification? What were the criteria used for such classification?

Ans: Whittaker, R., and Whittaker, H. Classification criteria Phylogenetic relationships, cell structure, thallus arrangement, method of nourishment, reproduction.

2. What is the sexual cycle in kingdom fungi?

Ans: The steps are as follows:  

(i) Plasmogamy fusion of two motile or nonmotile gametes protoplasm.

(ii) Karyogamy is the fusion of two nuclei.

(iii) Zygotic Meiosis, which results in the formation of haploid spores.

(iv) Dikaryophase in ascomycetes and basidiomycetes, where two nuclei per cc (dikaryon) are found before karyogamy.

3. Some symbiotic organisms are very good pollution indicators and are composed of a chlorophyll-us and a non- chlorophyll-us member. Describe them.

Ans: Lichen is a symbiotic connection between algae and fungi that results in the formation of lichen. Algae chlorophyceae and fungi ascomycetes are the most common. Because they only grow in clean places, they operate as pollution indicators because they do not grow in polluted areas. For instance, consider the case of industrial melanism.

4. Explain sexual reproduction in bacteria?

Ans: Bacteria can not reproduce sexually, yet they exhibit genetic recombination in three ways:

(i) Conjugation: Lederberg and Tatum discovered it. The presence of a plasmid called F-factor in cells identifies the donor or male call. The donor cell has hollow cylindrical sex Pilli that adhere to the recipient bacteria. With the help of sex pilli, the donor and receiver make physical contact. The recipient cell receives a plasmid or a plant of donor DNA.

(ii) Griffith was the one who discovered it. It includes the death of a bacterial donor cell, which causes its DNA to be released into the external media, where it is broken and integrated into metabolically active cells. Recombination occurs when a recipient cell incorporates donor DNA and expresses all of its characteristics alongside those of the donor cell.

(iii) Zinder and Lederberg were the first to discover transduction. A virus is used to deliver donor genes to the recipient. A phage promotes bacterial lysis and integrates bacterial genes into phages before being released and infecting additional bacterial genes.

5. Discuss the salient features of viruses with the help of a diagram?

Ans: Viruses have the following characteristics:

(i) They are a fraction of the size of bacteria.

(ii) They can be filtered 

(iii) They can reproduce in host cells by utilising the host cell's enzymes and metabolic machinery.

(iv) Their genetic substance is DNA/RNA.

(v) These organisms are obligate parasites, self-replicating, and non-cellular.

(vi) They have a capsid protein covering that protects the nucleic acid.

(vii) They produce plant diseases such as mosaic, leaf curling, leaf role, vein clearing, and so on.

General diagram of a Virus

Viral protein capsid

6. Distinguish between bacteria & cyanobacteria?

Ans: 

7. Why is the natural system of classification better than the artificial system of classification?

Ans: Natural selection studies evolutionary tendencies and phylogeny using all available data, including fossils, in addition to bringing out natural links. It is superior to an artificial classification system for the following reasons:

(i) This method reveals organisms' natural relationships.

(ii) Only connected organisations of the group are included here.

(iii) It prevents the mixing of unrelated organisms.

(iv) It depicts the evolutionary relationships and origins of various taxa.

8. Give a comparative account of classes of kingdom fungi on the basis of mode of nutrition & mode of reproduction.

Ans:

9. Discuss different systems of classification briefly.

Ans: There are three types of fungus.

(i) Phycomycetes: Their mycelium is multinucleated and aseptate. Asexual reproduction is accomplished using aplanospores, while sexual reproduction is accomplished through isogamy or oogamy. These can be found in wet or damp areas, such as mucor Albugo.

(ii) Ascomycetes: They are septate unicellular or multicellular mycelium. Conidia are asexual spores that develop in chains. Ascospores, which are carried in a cup-shaped structure called asci, are used for sexual reproduction in yeasts like Penicillium and Aspergillus.

(iii) Basidiomycetes: These fungi are known as club fungus because of the basidium, which is a club-shaped terminal of mycelium. They have septate mycelium and produce basidiospores, which are asexual spores. For example, mushroom smut

10. What are the different groups of fungi?

Ans: There are several classification systems:

(i) Artificial Classification: It simply considers a few easily observable traits and ignores anatomical linkages.

(ii) Natural Classification: It is based on organisms' natural affinities. It makes use of both external and internal characteristics.

(iii) Phylogenetic Classification: This classification is based on evolutionary relationships between organisms, i.e., organisms belonging to the same group have a common ancestor.

(iv) Phenotypic Classification: To prevent problems establishing evolutionary relationships, various criteria and procedures are used to classify organisms.

CBSE Class 11 Biology Chapter-2 Important Questions - Free PDF Download

Introduction - Biological Classification Class 11 

Vedantu offers a step by step guidance on the solutions of each chapter. The guidelines are prepared by the latest syllabus, which leaves no doubt about the solutions provided. It provides reliable and accurate NCERT Solutions for class 11 biology chapter 2. These NCERT solutions are not only confined to specific books, rather it covers all such important topics and subject. Students can download the free pdf form in a hassle-free manner. All the important topics are easily covered in class 11 chapter 2 - Biological classification 

Biological Classification Chapter 2 - Benefits of Important Questions and Answers

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• Class 11 Chapter 2 - Biological classification PDF not only provides important questions and topics, but it also gives a great insight into the whole chapter at the time of revision.

Biological Classification - Chapter 2 Class 11 Biology: Topics Covered in This Chapter 

Biological classification Class 11 Chapter 2 explains the different classifications of kingdoms. Biologist Linnaeus classified organisms based on two kingdoms - Animalia for animals and Plantae for plants. Biologist H. Whittaker stated five kingdoms of classification. Each of the kingdoms is discussed precisely in the following content in a better and easy-to-understand format. 

Biological Classification - Chapter 2 Class 11 Biology: Summary of the Chapter 

Biological Classification Class 11 Chapter 2 important topics include the following heads. We will discuss these in brief to get a clear understanding of the concept. The important topics include the following:

1. Biological classification

2. Taxonomy

3. Importance of taxonomy

4. Classification and Evolution

5. Classification of the Animal kingdom

6. Classification of plants

Organisms are classified in accordance with their ranks. Here are eight ranks used to classify organisms. These ranks are named as follows:

1. Domain

2. Kingdom

3. Phylum

4. Class

5. Order

6. Family

7. Genus

8. Species

For example, to classify humans, the following basis is used:

1. Domain - Eukaryota

2. Kingdom - Animalia

3. Phylum - Chordata

4. Class - Mammalia

5. Order - Primates

6. Family - Hominidae

7. Genus - Homo

8. Species - Homo Sapiens

Taxonomy deals with the naming, describing, and classification of living organisms including plants as well. Here classification is based on behavioural, biochemical, and genetic variations. 

The taxonomy also helps in the classification of species which further makes the understanding more precise and clear. Here is an incident from 1996 which will clarify the importance of taxonomy.

In 1996, a deadly fungus named Tilletia Indica was widely spread in wheat crops and caused a disease named Karnal bunt. This fungus impacted enormously and resulted in declining economic conditions. All exports were restricted which resulted in a billion-dollar loss. From here on taxonomists played their role, they observed the wheat crop and concluded that the blackening of the wheat crop is due to different fungi. After this evaluation, the billion-dollar crisis changed to a stable economic condition.

Classification and evolution: Biodiversity refers to the diversity of living things on Earth which is home to around 8 million known species. Some of the classifications are similar in body design but differ in other characteristics. Over time, different species evolved from one or more ancestors. From where have these species come? This is known as Evolution. Evolution took place and resulted in biodiversity. The Earth grounds more than 8 million species out of which some are known and some still unknown. Evolution says that life forms that exist today are far better than it they existed in early life forms. The organisms which existed years ago undergo certain changes for better survival and new life forms have arisen from them. Older organisms have simple body designs while young organisms have more complex body designs. Even though evolution took place, some sort of species still has their ancestral body designs and didn’t change completely. Whereas another set of species completely took a new body design, different from their ancestors.

Students are suggested to go through all notes which include Class 11 Chapter 2 important questions and topics. The notes provided by Vedantu expert teachers are in an easy-to-understand form and cover most of the important topics of this chapter. Students are also suggested to keep visiting the Vedantu website for a timely revision of important questions and topics. Memorising all leads to mugging up the answers without even understanding what the chapter is trying to explain to us. One needs expert guidance and teachers to get a better understanding. Vedantu ensures credible teachers who teach in an interactive manner.

Biological Classification - Chapter 2 Class 11 Biology:  Extra Important Questions (For Practice)

Below are four solved questions and answers which are regarded as important in this chapter. One can practice with these questions and answers before their examination. 

1. What is the advantage associated with Five-kingdom Classification over Two-kingdom Classification?

Ans. The five-kingdom classification that we see today was not the initial classification of living organisms. Carolus Linnaeus came up with two kingdom classifications which included kingdom Plantae and kingdom Animalia. The two-kingdom classification did not last for very long as because of its size it ignored major parameters while classifying. Here, there was no differentiation between Eukaryotes and prokaryotes. Neither unicellular and multicellular nor photosynthetic and non-photosynthetic were bifurcated. Organising all organisms either in plants or animals’ heads was not sufficient as there were organisms that cannot be either grouped as plants or animals.

These confusions led to the formation of a new mode of classification. It took into account cell structure, the presence of the cell wall, mode of reproduction, and nutrition. It led to the five-kingdom classification which included the following:

1. Kingdom Monera

2. Kingdom Protista

3. Kingdom Fungi

4. Kingdom Plantae

5. Kingdom Animalia

2. What are the approaches to improve crop yield?

Ans. In order to improve the crop yield, the following approaches are adopted:

1. Crop Variety Improvement - Plant breeding helps the farmers to select desired properties of crops and cross them to produce new varieties. It results in more plant properties which further help in feeding the growing population. It also helps in the production of disease-resistant crops.

2. Crop Production Management - Farming in India ranges from small farms to vast farms. Different farmers have different sizes of land depending upon the availability of resources, money, place, and access to information and technology. The crop results depending upon the inputs. It includes no cost, low cost, and even high-cost production practices.

3. Nutrient Management - As humans, plants require nutrients for their growth and development. There are certain macronutrients and micronutrients required depending upon the quantity. The farmers should be very much aware and educated of the nutrients required. Both very little and very much nutrients are harmful for crop production.

3. What will be an example of an insectivorous plant?

Ans. The Venus flytrap is an example of an insectivorous plant. 

4. Give an example of a parasitic plant.

Ans. The Corpse Flower is an example of a parasitic plant.

Tips to Study Biology for Class 11 Biology Examination

The following are some tips that can be incorporated into your study routine if you want to excel in your Biology exam:

1. Study the concepts properly with total understanding. 

2. Read the theories, and make notes.

3. Follow the class explanations.

4. Revise regularly.

5. Make diagrams to study better. 

6. Memorise the difficult names by writing them in a notepad and then re-writing it another copy. 

7. Practice with sample question papers.

Conclusion

The Class 11 Biology Biological Classification chapter is a crucial chapter that introduces students to the diversity of living organisms on Earth. It covers topics such as the classification of organisms based on their characteristics, the binomial nomenclature system, and the different kingdoms of life. Students should pay close attention to this chapter and practice solving questions to gain a thorough understanding of the concepts. Vedantu provides comprehensive study materials, including notes, sample papers, and solutions to previous year question papers, to help students prepare for their exams. By mastering the concepts covered in this chapter, students can develop a deeper appreciation for the diversity of life and understand the importance of classification in the study of Biology.

Related Study Materials for Class 11 Biology Chapter 2

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