NCERT Solutions for Class 11 Biology Chapter 2 (Biological Classification) – Free PDF Download

Biological Classification NCERT Solutions: Download PDF

Chapter 2 explains how living organisms are grouped into categories based on specific features. Students can download the Class 11 Biology Chapter 2 Biological Classification question answer PDF from the link given below. Understanding these classifications becomes simpler when students follow these solutions.

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Also Read,

• NCERT Notes for Class 11 Biology: Biological Classification

Get the Class 11 Biology Chapter 2 Biological Classification Solutions (Exercise Questions)

The detailed answers to this chapter are given below. These answers are prepared by subject experts that follows the NCERT guidelines closely. Students can refer to the Class 11 Biology Chapter 2 Biological Classification question answer to gain clarity.

Q1. Discuss how classification systems have undergone several changes over a period of time.

Answer:

How we classify living things has shifted as we understand more. Aristotle initially classified plants according to appearances and animals according to blood, but that wasn't effective either. Linnaeus created a two-kingdom system, but it wasn't effective either. Thus, scientists developed a 5-kingdom system, which is implemented nowadays.

Q2. State two economically important uses of: (a) heterotrophic bacteria, (b) archaebacteria

Answer:

(a) In what way are heterotrophic bacteria beneficial?

• They decompose dead matter, which is good for the soil.

• They provide plants with nitrogen.

• They are employed in producing curd (yogurt).

(b) In what way are archaebacteria useful?

• They produce gobar gas (biogas), which is employed as fuel.

• They assist in obtaining minerals from rocks.

• They produce an enzyme that is used in DNA technology.

Q3. What is the nature of cell walls in diatoms?

Answer:

Diatoms are single-celled algae with unique and intricate cell walls. The cell walls, known as frustules, are made of silica (silicon dioxide), the same material from which glass is made. A frustule is made up of two wrapped-around halves that look like a petri dish or soapbox, which are very similar to one another. This creates a protective layer and support framework for diatoms. The silica in the cell walls is extremely hard and resistant to rot, so the frustules will survive long after the diatom has died. Millions of years later, the frustules accumulate on the ocean floor and form huge diatomaceous earth deposits. Diatomaceous earth is utilized for several purposes, including as a filtering medium, an abrasive in toothpaste, and an insecticide. Their optical properties are also studied in nanotechnology for the intricate patterns on diatom cell walls.

Q4. Find out what the terms algal bloom and red tides signify.

Answer:

1. Algal Bloom: A rapid growth of algae in a water body, giving color to the water. Algal blooms will reduce the concentration of oxygen in water, causing fish and other aquatic organisms to die.

2. Red Tide: When a type of dinoflagellate (Gonyaulax) explodes, giving a reddening of seawater. They emit poisons capable of killing fish.

Q5. How are viroids different from viruses?

Answer:

Viroids and viruses are both causative agents, but they have a wide variation in structure and complexity. Viruses are intricate particles with a nucleic acid genome (DNA or RNA) covered by a protein shell referred to as a capsid. Viruses may also contain an outer lipid-protein envelope. Viruses infect a variety of organisms, ranging from bacteria and plants to animals. Viroids, however, are far more basic in composition. They have only a minute, ring-shaped RNA molecule with no protein cover. Due to their basic structure, viroids are much smaller than viruses. Viroids are found to infect mostly plants and cause different diseases that can influence crop production and agricultural output. The absence of a protein coat in viroids increases their resistance to degradation and enables them to replicate directly in the host cell.

Q6. Describe briefly the four major groups of Protozoa.

Answer:

Protozoa are divided into four categories based on the method of movement:

• Amoeboid Protozoa – They occur in water and moist soil and move and consume food using pseudopodia (false feet). Example: Amoeba.

• Flagellated Protozoa – They have whip-like bodies called flagella to move. Some are parasites, and others exist freely. Example: Trypanosoma (sleeping sickness).

• Ciliated Protozoa – They are moving with extremely short hair-like bodies called cilia and have two nuclei. Example: Paramecium.

• Sporozoa – They do not have cilia and flagella. They reproduce through spores and are usually parasites. Example: Plasmodium (that causes malaria). Classification of Protozoa is a fundamental chapter of the Biological Classification.

Q7. Plants are autotrophic. Can you think of some plants that are partially heterotrophic?

Answer:

Most plants are autotrophic and nourish themselves by synthesizing food in the process of photosynthesis, but certain plants are partly heterotrophic. The Pitcher Plant (Nepenthes) is green and photosynthetic but survives in nitrogen-free soil. It obtains nitrogen by digesting insects trapped using its pitcher leaves. As it makes its food but also digests insects to obtain nutrients, it is partly heterotrophic. These enchanting plants contribute further information to Plantae in Biological Classification.

Q8. What do the terms phycobiont and mycobiont signify?

Answer:

"Phycobiont" and "mycobiont" are terms used to explain the two components of a lichen. Lichens are an association between fungi and algae.

Phycobiont is the algal partner, which produces food for the lichen by the process of photosynthesis.

Mycobiont is the fungal partner, which gives support and protection, and absorbs water and minerals from the surroundings. These symbiotic associations are an interesting feature of Biological Classification.

Q9. Give a comparative account of the classes of Kingdom Fungi under the following:
(i) Mode of nutrition
(ii) Mode of reproduction

Answer:

A comparative account of the classes of Kingdom Fungi is as follows:

Q10. What are the characteristic features of Euglenoids?

Answer:

• Euglenoids are unicellular organisms that can behave as both plants and animals (mixotrophic).

• They lack a cell wall but possess a soft protein covering known as a pellicle, which provides them with shape and facilitates smooth movement.

• They possess chlorophyll and are capable of photosynthesis, but when in the dark, they behave like heterotrophs and obtain food from their environment.

• They swim through two flagella (whip-like appendages) at the front of their body.

• They possess a light-sensitive "eyespot" to detect sunlight for photosynthesis. All these features qualify them under Protista in Biological Classification.

Q11. Give a brief account of viruses with respect to their structure and the nature of their genetic material. Also, name four common viral diseases.

Answer:

Viruses are small particles that can only multiply within a living cell. They infect animals, plants, and even bacteria.

• Nucleic acid: The virus's genetic material, either DNA or RNA. It carries the instructions for producing more viruses.

• Capsid: A protein shell that encloses and covers the nucleic acid.

• Envelope: Certain viruses have an outer membrane known as an envelope, composed of lipids and proteins.

• Enzymes: Certain viruses have special enzymes with them that assist them in their reproduction within the host cell.

Common viral diseases:

• Common cold

• AIDS

• Swine flu

• Hepatitis

Q12. Organise a discussion in your class on the topic: Are viruses living or nonliving?

Answer:

Viruses are a mystery since they possess both the properties of living and non-living objects.

• They contain genetic material (DNA or RNA).

• They are capable of reproduction (but only within a host cell).

• They are capable of evolving and mutating over time.

• Why viruses may be thought to be non-living:

• They are not composed of cells.

• They cannot replicate on their own.

• They lack their metabolism (they are unable to generate their energy).

• They can be crystallized, such as non-living chemicals.

Also, check the NCERT Books and NCERT Syllabus here:

• NCERT Books Class 11 Biology

• NCERT Syllabus Class 11 Biology

• NCERT Books Class 11

• NCERT Syllabus Class 11

Approach to Solve Biological Classification Class 11 Question Answer

Given below are the steps that students can follow to answer the questions effectively. All the answers are prepared in clear and simple language.

1. Learn the meaning of biological classification, which categorises organisms based on their features and differences.

2. Study the five-kingdom system: Monera, Protista, Fungi, Plantae, and Animalia. All groups are well-explained in the Class 11 Biology Chapter 2 Biological Classification question answer.

3. Major characteristics such as cell structure, body organisation, nutrition, and reproduction need to be studied in detail.

4. Practice examples of each kingdom, e.g., bacteria for Monera or fungi for the Kingdom Fungi. Students can refer to the Class 11 Biology Chapter 2 Biological Classification Solutions to understand the concepts.

5. Practice the previous year's questions and other forms of questions given in the NCERT Solutions for Class 11. This makes the students familiar with the question pattern and difficulty level of the questions.

NCERT Solutions for Class 11: Subject-wise

• NCERT Solutions for Class 11 Maths

• NCERT Solutions for Class 11 Chemistry

• NCERT Solutions for Class 11 Physics

Important Question from NCERT Class 11 Biology Chapter 2

Given below is a multiple-choice question along with the explanation. This chapter helps students understand how organisms are grouped based on their characteristics. For more such questions, students can refer to the NCERT Solutions for Class 11 Biology Chapter 2 Biological Classification.

Question: Which one of the following is NOT a feature of the Kingdom Monera?

a. Prokaryotic cell organization

b. Membrane-bound organelles

c. Unicellular organisms

d. Both autotrophic and heterotrophic types of nutrition

Answer: The correct answer is option (b) Membrane-bound organelles

Explanation: Cells of the kingdom Monera are prokaryotic and do not contain membrane-bound organelles like mitochondria or a nucleus. They may be autotrophic (cyanobacteria) or heterotrophic (bacteria).

What Students Learn from Biological Classification NCERT Solutions?

Biological classification provides a systematic way to organize this diversity, making it easier to study and identify evolutionary relationships.

• Students understand how organisms are grouped based on their structural, functional, and evolutionary relationships.
• Biological Classification NCERT Solutions explain the principles and methods used to classify plants, animals, and microorganisms.
• Students explore different kingdoms, major phyla, and the distinguishing features of each group.
• Biological Classification class 11 question answer helps students practice identifying characteristics, solving exercises, and writing accurate answers in exams.
• Students gain knowledge about modern classification systems, including molecular and evolutionary relationships.

What Extra Should Students Study Beyond the NCERT for NEET?

To prepare for the NEET exam, students have to study some concepts beyond the NCERT. Along with these concepts, they can practice well-labelled diagrams given in the NCERT Solutions for Class 11 Biology Chapter 2 Biological Classification. Here is a table for all the important topics from the chapter:

Chapter-Wise NCERT Solutions for Class 11 Biology

Below mentioned are the Chapterwise solutions: