Test: Classification Systems (NCERT) - NEET MCQ

Numerical Taxonomy which is now easily carried out using computers is based on all observable characteristics. Number and codes are assigned to all the characters and the data are then processed. In this way each character is given equal importance and at the same time hundreds of characters can be considered. Cytotaxonomy that is based on cytological information like chromosome number, structure, behaviour and chemotaxonomy that uses the chemical constituents of the plant to resolve confusions, are also used by taxonomists these days.

Line in NCERT: "Cytotaxonomy that is based on cytological information like chromosome number, structure, behaviour and chemotaxonomy that uses the chemical constituents of the plant to resolve confusions, are also used by taxonomists these days."

natural classification systems developed, which were based on natural affinities among the organisms and consider, not only the external features, but also internal features, like ultrastructure, anatomy, embryology and phytochemistry. Such a classification for flowering plants was given by George Bentham and Joseph Dalton Hooker.

Line in NCERT: "As against this, natural classification systems developed, which were based on natural affinities among the organisms and consider, not only the external features, but also internal features, like ultra-structure, anatomy, embryology and phytochemistry."

To solve the given question, the correct answer is:

- (i) - Artificial
- (iii) - Phylogenetic

Explanation:

- The blank in the first statement refers to systems that assign equal weight to vegetative and sexual characteristics, which aligns with the concept of artificial systems in taxonomy.
- The third statement suggests systems that assume organisms within the same taxa share a common ancestor, which best fits the idea of phylogenetic systems.

Line in NCERT: "Such systems were artificial; they separated the closely related species since they were based on a few characteristics. Also, the artificial systems gave equal weightage to vegetative and sexual characteristics; this is not acceptable since we know that often the vegetative characters are more easily affected by environment." "Number and codes are assigned to all the characters and the data are then processed." "This assumes that organisms belonging to the same taxa have a common ancestor."

• A. Artificial - Q. Gross morphological characters
  Artificial classification systems use easily observable characteristics for classification, which are primarily gross morphological characters.

• B. Phylogenetic - P. Evolutionary relationships
  Phylogenetic classification is based on evolutionary relationships among organisms.

• C. Chemotaxonomy - R. Chemical constituents of plants
  Chemotaxonomy involves the classification of organisms based on their chemical constituents, such as specific compounds found in plants.

• D. Cytotaxonomy - S. Chromosome number, structure, and behavior
  Cytotaxonomy uses chromosome number, structure, and behavior as features for classification.

So, the correct answer is:

1. A - Q, B - P, C - R, D - S

To explain the concept of Numerical Taxonomy based on the provided options:

- Carried out using computers: Numerical Taxonomy is a method that involves the classification of organisms based on quantitative measurements of their observable characteristics. Using computers streamlines the analysis of vast amounts of data efficiently.

- Based on all observable characteristics: Numerical Taxonomy considers all available observable traits or characteristics of organisms for classification, allowing for a comprehensive analysis.

- Number and codes assigned to all the characters: In this method, each observable characteristic is assigned a numerical code, facilitating data organization and comparison.

Therefore, the correct answer "All of these (D)" encompasses the essence of Numerical Taxonomy, involving computer-based analysis, consideration of all observable characteristics, and the assignment of numerical codes to each characteristic.

Line in NCERT: "Numerical Taxonomy which is now easily carried out using computers is based on all observable characteristics. Number and codes are assigned to all the characters and the data are then processed."

• Cytotaxonomy integrates cytological information
• Chromosome number, structure, and behavior are crucial
• Chromosome number aids in species identification.
• Chromosome structure reveals genetic relationships.
• Chromosome behavior during cell division offers insights.                                                                                         

Option D is correct (All of these)

Line in NCERT: "Cytotaxonomy that is based on cytological information like chromosome number, structure, behaviour and chemotaxonomy that uses the chemical constituents of the plant to resolve confusions, are also used by taxonomists these days."

Numerical taxonomy evaluates resemblances and differences or primitiveness and advancement through statistical methods based on a large number of characters obtained from all disciplines of biology. This is followed by assigning them number and code of computer like plus (+) minus (-) followed by computer analysis.

Line in NCERT: "Numerical Taxonomy which is now easily carried out using computers is based on all observable characteristics. Number and codes are assigned to all the characters and the data are then processed. In this way each character is given equal importance and at the same time hundreds of characters can be considered."

Modern phylogenetic classification systems are based on evolutionary relationships between organisms, assuming that organisms within the same taxa have a common ancestor.

Line in NCERT: "At present phylogenetic classification systems based on evolutionary relationships between the various organisms are acceptable."

Answer: c

The earliest systems of classification used only gross superficial morphological characters such as habit, colour, number and shape of leaves, etc. They were based mainly on vegetative characters or on the androecium structure (system given by Linnaeus). Such systems were artificial; they separated the closely related species since they were based on a few characteristics. Also, the artificial systems gave equal weightage to vegetative and sexual characteristics; this is not acceptable since we know that often the vegetative characters are more easily affected by environment.

In numerical taxonomy:
- I: Computers are used, considering all observable characters.
- II: Considers hundreds of characters equally.
- Correct answer: C: Both I and II are correct.

Explanation:
- I: Computers help process vast data efficiently.
- II: Equal weight ensures fair representation of all characters.

This method aids in accurate classification by leveraging technology for comprehensive analysis while ensuring fair treatment of individual traits.

Line in NCERT: "Numerical Taxonomy which is now easily carried out using computers is based on all observable characteristics. Number and codes are assigned to all the characters and the data are then processed. In this way each character is given equal importance and at the same time hundreds of characters can be considered."

Artificial systems of classification were based upon morphological characters (such as habit, habitat, colour, number and shape of leaves, etc.) for grouping of organisms, They were mainly based on vegetative characters or on the androecium structure. These systems separated the closely related species since they were based only on a few characteristics. This was not acceptable because vegetative characters are more easily affected by environment.

Line in NCERT: "the earliest systems of classification used only gross superficial morphological characters such as habit, colour, number and shape of leaves, etc. They were based mainly on vegetative characters or on the androecium structure (system given by Linnaeus). Such systems were artificial; they separated the closely related species since they were based on a few characteristics."

The earliest systems of classification used only gross superficial morphological characters such as habit, colour, number and shape of leaves, etc. They were based mainly on vegetative characters or on the androecium structure (system given by Linnaeus). Such systems were artificial; they separated the closely related species since they were based on a few characteristics. Also, the artificial systems gave equal weightage to vegetative and sexual characteristics; this is not acceptable since we know that often the vegetative characters are more easily affected by environment. As against this, natural classification systems developed, which were based on natural affinities among the organisms and consider, not only the external features, but also internal features, like ultrastructure, anatomy, embryology and phytochemistry. Such a classification for flowering plants was given by George Bentham and Joseph Dalton Hooker.

Line in NCERT: "As against this, natural classification systems developed, which were based on natural affinities among the organisms and consider not only the external features, but also internal features, like ultra-structure, anatomy, embryology and phytochemistry."

The earliest systems of classification used only gross superficial morphological characters such as habit, colour, number and shape of leaves, etc. They were based mainly on vegetative characters or on the androecium structure (system given by Linnaeus). Such systems were artificial; they separated the closely related species since they were based on a few characteristics.

Line in NCERT: "Such systems were artificial; they separated the closely related species since they were based on a few characteristics."

Artificial classification is based on morphological structures of the plant i.e. artificial classification focuses on external structure of the plants than their internal structure.
Hence the correct option is "A"

Line in NCERT: "the earliest systems of classification used only gross superficial morphological characters such as habit, colour, number and shape of leaves, etc."

 natural classification systems developed, which were based on natural affinities among the organisms and consider,not only the external features, but also internal features, like ultrastructure, anatomy, embryology and phytochemistry. Such a classification for flowering plants was given by George Bentham and Joseph Dalton Hooker.

Line in NCERT: "Such a classification for flowering plants was given by George Bentham and Joseph Dalton Hooker."