Biological Classification Class 11 Important Questions

The classification of different organisms on the basis of their morphology and anatomy is called biological classification. Different botanists came up with their own approaches and criteria for classification but the most widely accepted model of biological classification was proposed by an eminent scientist, R.H. Whittaker. He presented a five-kingdom classification which was based on parameters such as cell structure, body size, method of nutrition and reproduction.

CBSE Class 11 Biology Chapter 2 explains the biological classification system in detail. One of the most important features of this system is that it follows the evolutionary sequence of living organisms. The organisms are classified into different taxa or levels like Kingdom, Phylum, Division, Class, Order, Family, Genus and Species. The five kingdoms are as follows:

1. Kingdom Monera
2. Kingdom Protista
3. Kingdom Fungi
4. Kingdom Plantae
5. Kingdom Animalia.

In this article, we have mentioned important questions of Biological Classification with concepts in the form of very short, short, long and very long answer type questions for CBSE Board and NEET exams.

---

Very Short Answer Type Questions (1 Mark)

Ques: How is the five-kingdom classification more advantageous than the two-kingdom classification?

Ans: The five-kingdom biological classification is based on the following criteria:

• The structure of the cell
• The structure of the body
• The mode of nutrition
• The kind of reproduction and
• Phylogenetic relationships among different organisms and kingdoms.

The two-kingdom biological classification is categorized as Kingdom Plantae and Kingdom Animalia. 

Ques: Who proposed the five-kingdom biological classification?

Ans: RH Whittaker proposed the five-kingdom biological classification. The five kingdom classification includes Monera, Protista, Fungi, Plantae and Animalia.

Ques: What are the similarities between virus particles and non-living objects?

Ans: Virus particles are intermediate between living and non-living things. They behave like living things inside their hosts and like non-living crystals outside their host cells. They resemble non-living things in the following aspects:

• Inert nature without living activities.
• They cannot reproduce themselves.

Ques: Mention the main difference between a virus and a viroid?

Ans: A virus contains protein coal called the capsid and a core containing the genetic material. That genetic material may be either DNA or RNA. But, the viroid contains only genetic material, but a protein coat.

Ques: What are the eukaryotic kingdoms of the five-kingdom biological classification proposed by RH Whittaker?

Ans: The organisms with cells containing a true nucleus are called eukaryotic organisms. There are four eukaryotic divisions in five kingdom biological classification of RH Whittaker which are as namely- Protista, Fungi, Plantae, and Animalia.

Ques: State whether the chemosynthetic bacteria are autotrophic or heterotrophic?

Ans: The chemosynthetic bacteria are autotrophic because they prepare their own food in the presence of sunlight by the process of Photosynthesis. 

Ques: What are the economic uses of archaebacteria and heterotrophic bacteria?

Ans: Archaebacteria converts milk into curd and cheese and produces methane gas in biogas plants. Heterotrophic Bacteria improve the fertility of the soil by nitrogen fixation, ammonification and nitrification. Example: Rhizobium bacteria.

Read More:

---

Short Answer Type Questions (2 Marks)

Ques: Why are both autotrophic cyanobacteria and heterotrophic bacteria classified under eubacteria of the kingdom Monera?

Ans: The similarities between autotrophic cyanobacteria and heterotrophic bacteria are as follows:

• They do not have a true nucleus with a nuclear membrane.
• DNA is directly present in the cytoplasm without a protein coat.
• All the ribosomes are of the 70S type.
• All the membranous organelles are absent.

Ques: How can a farmer improve his crop yield by using cyanobacteria in his agricultural fields?

Ans: Blue-green algae that belong to the kingdom monera are also called cyanobacteria. Cynobacteria are capable of fixing atmospheric nitrogen into ammonia due to the presence of specialized cells called heterocysts.  After the death and decay of their filaments, a lot of nitrate-nitrogen is mixed up with the soil. Crop plants can absorb this nitrate nitrogen, grow vigorously, and produce more grains.

Ques: Why is Trypanosoma included in the kingdom Protista?

Ans: Trypanosoma is a unicellular organism. It consists of a true nucleus with a nuclear membrane. It also consists of membranous organelles. So, it is a unicellular eukaryote. All unicellular eukaryotic organisms are included in the kingdom Protista. The other features of Trypanosoma are the presence of nuclear endosomes, granular food particles, and binary fission.

Ques: What are the differences between three fruiting bodies produced by different ascomycetes fungi?

Ans: The fruiting bodies of ascomycetes are called ascocarps. There are three types. The differences between apothecium, perithecium, and cleistothecium are as follows:

Ques: Why is Neurospora extensively used in genetic experiments?

Ans: Neurospora is used in genetic experiments for three reasons. 

(1) It can easily be grown in a nutrient medium containing simple organic substances, mineral salts, vitamins, and hormones in the lab. 

(2) Its life cycle is very short. 

(3) It is very easy to introduce mutations in Neurospora by using X-rays.

Ques: Define the terms ‘phycobiont’ and ‘mycobiont’?

Ans: The symbiotic association between an alga and a fungus in a biological classification is called Lichen. Phycobiont is considered as the algal component whereas the fungal component is represented by mycobiont. In this permanent symbiosis, the fungus mycelium absorbs and supplies water and mineral nutrients to the alga. The alga prepares food by photosynthesis and supplies it to the fungus.

Ques: Why are some flowering plants in biological classification parasitic?

Ans: Some plants become parasitic to absorb water, minerals, foot materials from other plants, as they do not have chlorophyll to manufacture food. Cuscuta, Cassytha, Orobanche, Loranthus, and Striga are parasitic plants.

Ques: Why do polluted water bodies show more numbers of Nostoc and Oscillatoria under the microscope?

Ans: A water body suddenly turns green due to the rapid growth of algae. This is called an algal bloom. If you collect that water and observe it under the microscope, you can find a number of algal species including Nostoc and Oscillatoria.

---

Long Answer Questions (3 Marks)

Ques: What is Taxonomy? What is its scope?

Ans: The branch of science that deals with the nomenclature, identification, description, and classification of both living and extinct organisms are called taxonomy in biological classification chapter of class 11. The living organisms include bacteria, fungi, non-flowering plants, flowering plants, protozoans, helminth worms, annelids, arthropods, molluscs, echinoderms, and vertebrates. It is based on the external features, internal features, and phylogenetic relationships of organisms. The organisms are classified into different taxa or levels like Kingdom, Phylum, Division, Class, Order, Family, Genus and Species.

Ques: What are ‘pearls of the ocean’? What are their deposits?

Ans: Diatoms are nicknamed “pearls of the ocean”. They are so-called because of the ornamentations on their cell walls. The siliceous cell walls of diatoms are called the frustules. They are the chief autotrophs in the surface waters of oceans.

After death, diatom cells reach the bottom of the ocean and accumulate there for billions of years. These deposits are for the diatomaceous earth. It has a number of applications in different industries.

Ques: How are fungi useful in our daily lives?

Ans: Saprophytic fungi keep the earth and our surroundings clean by decomposing dead plants and animals. Fungal mycelium binds the soil particles together and improves the soil structure. Some fungi can be used in the biological control of pests and diseases. Edible mushrooms are rich in proteins and vitamins. Some fungi are cultured in labs to produce useful organic acids. Yeast is used in the bakery industry and also in the fermentation of carbohydrates into alcohol.

Ques: How are ‘fairy rings’ formed on the forest floor after heavy rains?

Ans: Soil consists of a thick mat for the mycelium of mushrooms. After heavy rains, nutrients in the soil get dissolved in soil moisture and are easily absorbed by mycelia. The mycelia grow in such a way that the central part gets exhausted and the peripheral part grows in diameter. The mycelia produce a ring of fruiting bodies called basidiocarps. They appear like fairy rings.

Ques: What are insectivorous and parasitic plants? Give some examples

Ans: The insect-eating plants are called insectivorous plants. They live in soils that are deficient in nitrogen, So, they depend on insects for available nitrogen. They are butterworts, pitcher plants, sundews, and venus flytrap. Plants that depend on other plants for water, minerals, and food are called parasitic plants. The roots of parasitic plants are called haustoria. Some of the parasitic plants are dodder, Orobanche, Loranthus, Striga.

---

Very Long Answer Questions (5 Marks)

Ques: What are the merits of the five-kingdom biological classification?

Ans: The merits of the five-kingdom biological classification are given below:

1. This system of classification proposed by RH Whittaker is more scientific, accurate, and natural with evolutionary relationships.
2. It takes into account the presence of the cell wall, nucleus, mode of nutrition, and reproduction into consideration.
3. In the five-kingdom classification, the living organisms are classified into different groups based on their similarities and evolutionary relationships.
4. The five-kingdom classification makes us understand the phylogeny and evolutionary origins of organisms.

Ques: How are bacteria classified in a biological classification system?

Ans: (i) Bacteria are classified on the basis of the shapes of cells

1. A rod-shaped bacterium is called bacillus.
2. A spiral-shaped bacterium is called the spirillum.
3. A comma-shaped bacterium is called the vibrio.
4. The spherical shaped bacterium is called the coccus.
5. A corkscrew-shaped bacterium is called the spirochaete.

(ii) Bacteria are classified on the basis of the nature of the cell wall

1. Gram-positive bacteria.
2. Gram-negative bacteria.

(iii) Bacteria are classified on the basis of the type of respiration

1. Aerobic bacteria or Aerobes in the presence of oxygen.
2. Anaerobic bacteria or Anaerobes in the absence of oxygen

(iv) Bacteria are classified on the basis of mode of nutrition

1. Autotrophic Bacteria: prepare their own food material
2. Heterotrophic Bacteria: cannot prepare their own food material

Ques: What are the different characteristic features of euglenoids?

Ans: The characteristic features of euglenoids are given as follows:

• They are unicellular organisms with a true nucleus.
• They are commonly found in freshwater bodies.
• The outer hard and tough cell membrane is called a pellicle.
• The anterior part of the cell has two flagella.
• There is a photosensitive eyespot near the flagella.
• They are autotrophic in nutrition due to the presence of a photosynthetic pigment called chlorophyll.
• In the absence of sunlight, euglenoids behave as heterotrophs.

Ques: What are the different asexual spores produced by algae?

Ans: Algae reproduce by asexual spores like zoospores, aplanospores, tetraspores, akinetes, exospores, and endospores.

• Zoospores: Motile spores are called zoospores. They are motile due to the presence of flagella. Chlamydomonas produces biflagellate zoospores, Ulothrix produces quadri-flagellate zoospores and Oedogonium produces multi-flagellate zoospores.
• Aplanospores: The non-motile spores produced inside the sporangium are called aplanospores. They are formed during unfavourable conditions. Eg., Microspora
• Tetraspores: These are haploid aplanospores formed on diploid plants in a tetrasporangia. Eg., Red algae
• Akinetes: Akinetes are thick-walled spores with abundant reserve food material. They are formed to tide over unfavourable conditions.
• Exospores: They are externally formed without a sporangium. Eg., Chamaesiphon
• Endospores: The protoplast of the mother cell divides to form many endospores. They are also called conidia or conidia. Eg., Dermocarpa.

---

Check-Out: