Important Questions (1 mark): Diversity in Living Organisms - UPSC MCQ

The Smallest Taxon
The smallest taxon in the classification system is the species. Here is a detailed explanation:
Taxonomy and Classification System
- Taxonomy is the science of classification, which involves organizing and categorizing organisms based on their characteristics.
- The classification system consists of a hierarchical structure called a taxonomic hierarchy.
- The taxonomic hierarchy includes several levels, or taxa, which are arranged from broad to specific categories.
The Smallest Taxon: Species
- The species is the most specific and smallest taxon in the classification system.
- It refers to a group of individuals that share common characteristics and can interbreed to produce fertile offspring.
- Species are identified by their unique scientific names, which consist of a genus name followed by a specific epithet.
- For example, Homo sapiens is the scientific name for humans, where Homo represents the genus and sapiens represents the specific epithet.
Other Taxa
- Above the species level, there are several larger taxa in the classification system, including genus, family, order, class, phylum, kingdom, and domain.
- Each taxon represents a broader category that includes multiple species or groups of organisms.
- For example, the genus is a higher taxon that includes several closely related species.
- The order is an even higher taxon that includes multiple genera.
- The class is a broader taxon that includes multiple orders, and so on.
Conclusion
- In summary, the smallest taxon in the classification system is the species.
- It represents the most specific category and consists of individuals that share common characteristics and can interbreed.
- Above the species level, there are several larger taxa that encompass broader categories of organisms.

An organism that can live and grow in the presence of oxygen is called an aerobe.
Explanation:
Aerobes are organisms that can survive and thrive in the presence of oxygen. They have the ability to use oxygen for various metabolic processes, such as respiration, which is essential for their growth and survival.
Here are some key points to understand about aerobes:
1. Definition: An aerobe is an organism that can carry out aerobic respiration, utilizing oxygen as the final electron acceptor in the electron transport chain.
2. Oxygen Requirement: Aerobes require oxygen for their metabolic processes. They have specific enzymes and pathways to efficiently use oxygen for energy production.
3. Metabolism: Aerobes possess mitochondria, which are the powerhouses of the cell and allow them to generate energy through oxidative phosphorylation. This process produces a large amount of ATP, which is the primary energy currency of the cell.
4. Examples: Many organisms, including humans, animals, plants, and most bacteria, are aerobes. They are adapted to live in environments with abundant oxygen.
5. Benefits of Oxygen: Oxygen provides a higher energy yield compared to anaerobic metabolism. It allows organisms to efficiently extract energy from organic molecules and perform complex metabolic processes.
In conclusion, an organism that can live and grow in the presence of oxygen is called an aerobe. They have evolved to utilize oxygen for their metabolic needs and are found in various ecosystems, including terrestrial and aquatic environments.

Unicellular Green Alga

Among the options given, the unicellular green alga is Chlamydomonas.

Explanation:

• Spirogyra: Spirogyra is a filamentous green alga, not a unicellular one. It is composed of long, thread-like chains of cells.


• Fern: Ferns are not algae, they are a group of vascular plants that reproduce via spores.


• Cycas: Cycas is a genus of gymnosperms, which are seed-producing plants. They are not algae.


• Chlamydomonas: Chlamydomonas is a unicellular green alga commonly found in freshwater environments. It has a single, spherical cell with two flagella for movement.

Therefore, the correct answer is option D: Chlamydomonas.

There are two main groups of non-flowering plants. Plants that use spores to reproduce and plants that use seeds to reproduce. The non-flowering plants that use seeds are called gymnosperms. Gymnosperm means "naked seeds". They are called this because their seeds are open to the air with no covering such as the seeds of flowering plants. One of the major groups of gymnosperm plants is the conifer. Fern is a spore producing plant. Ferns produce spore casings on the underside of their leaves. These look like brown spots. At some point the casings dry out and the spores are released into the air. 

Non-Chlorophyllous Heterotrophic Plants
There are several types of non-chlorophyllous heterotrophic plants. These plants are unable to produce their own food through photosynthesis and rely on obtaining nutrients from other sources. The options given in the question are as follows:
A: Algae
- Algae are photosynthetic organisms that contain chlorophyll and are capable of producing their own food through photosynthesis. Therefore, algae are not non-chlorophyllous heterotrophic plants.
B: Fungi
- Fungi are non-chlorophyllous heterotrophic plants. They obtain nutrients by absorbing them from their surroundings. Fungi play essential roles in decomposition and nutrient cycling in ecosystems.
C: Bryophytes
- Bryophytes, including mosses and liverworts, are non-vascular plants that lack true roots, stems, and leaves. They obtain nutrients through direct absorption from their environment. Therefore, bryophytes are non-chlorophyllous heterotrophic plants.
D: Pteridophytes
- Pteridophytes, such as ferns and horsetails, are vascular plants that have true roots, stems, and leaves. They possess chlorophyll and are capable of photosynthesis. Therefore, pteridophytes are not non-chlorophyllous heterotrophic plants.
Conclusion:
The correct answer is B: Fungi. Fungi are non-chlorophyllous heterotrophic plants that obtain nutrients by absorbing them from their surroundings.

Answer:
The pteridophyte among the given options is D: Fern.
Explanation:
Pteridophytes are a group of vascular plants that reproduce and disperse through spores. They do not produce flowers or seeds. Among the options given, only Ferns belong to the group of pteridophytes. Let's discuss each option in detail:
A: Ulothrix
- Ulothrix is a genus of filamentous green algae. It belongs to the group of algae, not pteridophytes.
B: Rhizopus
- Rhizopus is a genus of bread molds. It belongs to the group of fungi, not pteridophytes.
C: Marchantia
- Marchantia is a genus of liverworts. It belongs to the group of bryophytes, not pteridophytes.
D: Fern
- Ferns are a group of pteridophytes. They have well-developed vascular tissues and reproduce through spores. Ferns are characterized by their large leaves called fronds.
Therefore, the correct answer is D: Fern.

Companion cells are specialised parenchyma cells which are present adjacent to a sieve tube in the phloem of flowering plants. These cells are present in the angiosperms. These cells are absent in the pteridophytes and gymnosperms. Pinus is a gymnosperm and is devoid of the companion cell. The xylem of gymnosperms consists of tracheids for conducting sap as vessels are absent.

Phanerogams:
- Phanerogams refer to plants that produce seeds.
- They are also known as "seed plants" because they have reproductive structures called seeds.
- Gymnosperms and angiosperms are both types of phanerogams.
Gymnosperms:
- Gymnosperms are a group of plants that bear naked seeds, meaning their seeds are not enclosed within a fruit.
- They include plants such as conifers, cycads, and ginkgoes.
- Gymnosperms are typically woody and have needle-like or scale-like leaves.
- They are adapted to various environments and can be found in both temperate and tropical regions.
Angiosperms:
- Angiosperms are a group of plants that bear enclosed seeds within a fruit.
- They are the most diverse and widespread group of plants, with over 300,000 known species.
- Angiosperms include flowering plants such as trees, shrubs, herbs, and grasses.
- They have specialized structures for reproduction, including flowers, which attract pollinators, and fruits, which aid in seed dispersal.
Therefore, the correct answer is A: Phanerogams, as both gymnosperms and angiosperms are included in this group of seed plants.

Maize is a Monocot angiospermic plant
Explanation:
- Maize, also known as corn, is a cereal grain that belongs to the family Poaceae.
- It is a flowering plant, which means it is an angiosperm.
- Angiosperms are characterized by having seeds enclosed in a fruit or ovary.
- Maize is a monocot angiosperm, meaning it belongs to the monocotyledonous group of flowering plants.
- Monocots are characterized by having one cotyledon or seed leaf in their embryos.
- Other examples of monocots include rice, wheat, and barley.
- Maize plants have long, narrow leaves with parallel veins, another characteristic feature of monocots.
- The flowers of maize are borne in dense clusters known as inflorescences.
- Maize is an economically important crop and is widely cultivated for its edible kernels, which are used in various food products and animal feed.
- It is also used for biofuel production and as a raw material in the manufacturing industry.
In conclusion, maize is a monocot angiospermic plant belonging to the family Poaceae.

Taxonomy: The Branch of Biology Dealing with Identification, Nomenclature, and Classification of Organisms
Taxonomy is a crucial branch of biology that focuses on the identification, nomenclature, and classification of organisms. It plays a vital role in organizing and understanding the vast diversity of life on Earth. Let's delve deeper into the concept of taxonomy and why it is important:
1. Definition of Taxonomy:
- Taxonomy is the science of classification, naming, and categorizing organisms based on their similarities and relationships.
- It involves the use of various techniques, including morphological, anatomical, physiological, biochemical, and genetic characteristics, to establish evolutionary relationships and create a systematic hierarchy of living organisms.
2. Importance of Taxonomy:
- Facilitates Identification: Taxonomy provides a standardized system for identifying and naming organisms, which is essential for effective communication in the scientific community. It allows researchers to precisely refer to specific organisms, avoiding confusion and ambiguity.
- Reveals Evolutionary Relationships: By studying the similarities and differences between organisms, taxonomy helps uncover evolutionary relationships and provides insights into their shared ancestry. This information is crucial for understanding the history of life on Earth and the processes that have shaped it.
- Aids Conservation Efforts: Taxonomy plays a vital role in biodiversity conservation. By identifying and classifying species, scientists can assess their conservation status, identify endangered or threatened species, and develop strategies for their protection and management.
- Supports Agricultural and Medical Sciences: Taxonomy is important in agriculture and medicine, as it helps identify pests, pathogens, and disease-causing organisms. This knowledge allows for the development of effective control measures and the advancement of medical research and treatment.
- Assists in Ecological Studies: By categorizing and studying organisms within their ecological context, taxonomy contributes to understanding ecosystem dynamics, species interactions, and the overall functioning of ecosystems.
3. Taxonomic Hierarchy:
- Taxonomy follows a hierarchical system of classification, ranging from broad categories to specific groups.
- The main taxonomic ranks, in descending order, are: Domain, Kingdom, Phylum, Class, Order, Family, Genus, and Species.
- Each rank represents a level of similarity and relationship between organisms.
- The classification is based on shared characteristics and evolutionary history.
4. Taxonomic Tools and Techniques:
- Taxonomy employs a range of tools and techniques to aid in the identification and classification of organisms.
- Traditional methods include detailed morphological observations, anatomical dissections, and examination of reproductive structures.
- Modern techniques utilize molecular biology, DNA sequencing, and genetic analysis to determine evolutionary relationships and establish taxonomic groupings.
In conclusion, taxonomy is a fundamental branch of biology that deals with the identification, nomenclature, and classification of organisms. It provides a systematic framework for understanding the diversity of life and plays a critical role in various scientific disciplines, conservation efforts, and ecological studies.

Who is known as the father of taxonomy?
The father of taxonomy is Carl Linnaeus. He is a renowned Swedish botanist, physician, and zoologist who is widely regarded as the father of modern taxonomy. Linnaeus developed the binomial nomenclature system, which is still used today in the classification and naming of organisms. Here is a detailed explanation of his contributions and why he is considered the father of taxonomy:
1. Carl Linnaeus's early life and education:
- Carl Linnaeus was born on May 23, 1707, in Sweden.
- He showed an early interest in plants and nature, which led him to pursue studies in medicine and botany.
2. Linnaeus's development of binomial nomenclature:
- Linnaeus introduced the binomial nomenclature system, which assigns a unique two-part name to each species.
- The first part of the name represents the genus, while the second part indicates the specific epithet.
- This system provides a standardized and universal way of identifying and naming organisms, reducing confusion and enabling better communication among scientists.
3. Linnaeus's classification system:
- Linnaeus developed a hierarchical classification system that groups organisms based on their similarities and differences.
- He classified organisms into a hierarchical structure that includes kingdoms, classes, orders, families, genera, and species.
- This system, known as the Linnaean system, forms the basis of modern taxonomy and provides a framework for organizing and studying biodiversity.
4. Linnaeus's contributions to the field of taxonomy:
- Linnaeus's work revolutionized the study of biology by providing a standardized system for naming and classifying organisms.
- His meticulous observations and detailed descriptions of plants and animals laid the foundation for modern taxonomy and systematics.
- Linnaeus's classification system has been widely adopted and is still used by scientists worldwide.
In conclusion, Carl Linnaeus is known as the father of taxonomy due to his groundbreaking contributions to the field. His development of binomial nomenclature and hierarchical classification system revolutionized the way organisms are named, classified, and studied. His work continues to be influential and forms the basis of modern taxonomy.

Introduction:
Binomial nomenclature is a system of naming species in which each species is given a unique two-part scientific name. This system was introduced by Carolus Linnaeus, a Swedish botanist and physician, in the 18th century. Linnaeus is often referred to as the "Father of Modern Taxonomy" for his contributions to the field of classification and naming of organisms.
Explanation:
The correct answer to the question "Binomial nomenclature was introduced by" is D: Carolus Linnaeus. Here is a detailed explanation of the options:
A: John Ray - John Ray was an English naturalist who made significant contributions to the fields of botany and zoology. However, he did not introduce binomial nomenclature.
B: A.P. de Candolle - Augustin Pyramus de Candolle was a Swiss botanist who made important contributions to the understanding of plant classification and systematics. However, he did not introduce binomial nomenclature.
C: A.L. de Jussien - Antoine Laurent de Jussieu was a French botanist who developed a natural classification system for plants. However, he did not introduce binomial nomenclature.
D: Carolus Linnaeus - Carl Linnaeus, also known as Carolus Linnaeus, was a Swedish botanist, physician, and zoologist who is best known for his work in developing the binomial nomenclature system. He introduced this system in his book "Systema Naturae" in 1735.
In conclusion, binomial nomenclature was introduced by Carolus Linnaeus, making option D the correct answer.

Association between Algae and Fungi
The association between algae and fungi is known as Lichen. Lichens are composite organisms consisting of a symbiotic relationship between a fungus and an alga or cyanobacterium. This relationship is mutually beneficial, as both partners contribute to the survival and growth of the lichen.
The algae partner, usually a green alga or a cyanobacterium, provides the lichen with photosynthetic capabilities. It produces organic nutrients through photosynthesis, which are then utilized by the fungus.
The fungus partner provides the lichen with a protective structure and obtains nutrients from the environment. It absorbs moisture and minerals from the surroundings, providing a suitable habitat for the algae or cyanobacterium.
The association between algae and fungi in lichens is essential for their survival and success in various habitats. They can be found in diverse environments, including deserts, forests, tundra, and even on rocks and walls.
Lichens have a significant ecological role as pioneers in colonizing bare or disturbed habitats. They contribute to soil formation, nitrogen fixation, and provide food and shelter for various organisms.
In conclusion, the association between algae and fungi is known as lichen. This symbiotic relationship allows lichens to thrive in various environments and play important ecological roles.

Each scientific name in binomial nomenclature consists of two names, also called descriptors or epithets. The first word is the generic epithet and describes the genus that an animal belongs to. The second word is the specific epithet and refers to the species of the organism. Typically, the words have a Latin base and describe the genus or species with references to traits that are specific to the group. When written, the text of a scientific name is usually italicized or underlined, to clarify that it is a scientific name written in binomial nomenclature. The generic epithet is always capitalized, while the specific epithet is written in lower-case. In some older documents, both may be capitalized. Typically, the full name should be written out. However, when discussing many species of the same genus, the generic name is sometimes abbreviated to the first letter, still capitalized.

Taxonomic Term Substituted for Any Rank in Classification:
- The taxonomic term that can be substituted for any rank in the classification is Taxon.
Explanation:
- Taxonomy is the science of classifying and naming organisms based on their characteristics and relationships.
- Taxonomy uses a hierarchical system of classification that includes various ranks, such as kingdom, phylum, class, order, family, genus, and species.
- Each rank represents a different level of classification, with species being the most specific and kingdom being the most general.
- However, sometimes a more general term is needed that can be used to refer to any rank in the classification.
- In such cases, the term "taxon" is used. A taxon is a group of organisms at any particular rank or level in the classification hierarchy.
- It can refer to a kingdom, phylum, class, order, family, genus, species, or any other rank.
- The term "taxon" is a general term that encompasses all levels of classification and can be used to describe any group of organisms, regardless of their rank.
- Therefore, the taxonomic term that may be substituted for any rank in the classification is "taxon."

Algae belong to Thallophytes
Algae are a diverse group of photosynthetic organisms that belong to the kingdom Plantae. They are primarily aquatic organisms that can be found in freshwater, saltwater, and even in damp soil. Algae can range in size from microscopic unicellular organisms to large multicellular seaweeds.
Some key points about algae and their classification:
1. Thallophytes: Algae belong to the division Thallophyta, which is a group of plants that lack true stems, roots, and leaves. Thallophytes include both algae and fungi.
2. Bryophytes and Pteridophytes: Bryophytes include mosses, liverworts, and hornworts, while pteridophytes include ferns, horsetails, and clubmosses. These groups are distinct from algae and have different characteristics.
3. Algae characteristics: Algae are photosynthetic organisms that contain chlorophyll and other pigments that allow them to convert sunlight into energy. They have simple structures and lack true roots, stems, and leaves. Algae reproduce through various methods, including asexual reproduction (cell division) and sexual reproduction (fusion of gametes).
4. Classification of algae: Algae are classified into several divisions based on their characteristics, including Chlorophyta (green algae), Rhodophyta (red algae), Phaeophyta (brown algae), and Bacillariophyta (diatoms), among others.
In conclusion, algae belong to the division Thallophyta, which is a group of plants that includes algae and fungi. Algae are not classified as bryophytes or pteridophytes.

Algae are eukaryotic organisms that have no roots, stems, or leaves but do have chlorophyll and other pigments for carrying out photosynthesis. Algae can be multicellular or unicellular and are characterized by the green colour slippery appearance and spread during rainy seasons.

The correct option is A.
In Whittaker's five kingdom classification, The kingdoms Monera and Protista include unicellular organisms. Kingdom Monera includes all prokaryotic unicellular organism like Bacteria and Archaebacteria, while kingdom Protista includes all eukaryotic unicellular organisms like Amoeba, Euglena, Paramoecium etc

The correct answer is C as Ribosomes contain large quantities of ribonucleic acid.

Glycocalyx is:
- Glycocalyx consists of:
- Glycoproteins: These are proteins that have carbohydrate chains attached to them.
- Glycolipids: These are lipids that have carbohydrate chains attached to them.
- Oligosaccharide part of glycolipids and glycoproteins:
- The glycocalyx includes the oligosaccharide part of glycolipids and glycoproteins. Oligosaccharides are short chains of carbohydrates.
- Lipid and protein parts of glycolipids:
- The glycocalyx includes both the lipid and protein parts of glycolipids. Lipids are hydrophobic molecules that make up the lipid bilayer of the cell membrane.
- Mucopolysaccharides attached to cell wall:
- Mucopolysaccharides are long chains of carbohydrates that are attached to the cell wall. They are not part of the glycocalyx.
Therefore, the correct answer is B: Oligosaccharide part of glycolipids and glycoproteins. The glycocalyx is composed of glycoproteins and glycolipids, specifically the oligosaccharide part of these molecules.

Ribosome exist as free structures that float throughout the cytoplasm of the cell. they do not have membranes, which allows them to pick up translational RNA released from the nucleus and grab onto free amino acids in order to produce protein chains.

Protein synthesis occurs on the ribosome.
Protein synthesis is the process by which cells build proteins. It involves the transcription of DNA into RNA and the translation of RNA into proteins. The ribosome is the cellular organelle responsible for the translation phase of protein synthesis.
Here are the key points explaining why protein synthesis occurs on the ribosome:
1. Ribosomes are the site of translation:
- Translation is the process of converting the information carried by the mRNA (messenger RNA) into a sequence of amino acids, which form a protein.
- Ribosomes are the cellular structures where translation takes place.
- They are composed of ribosomal RNA (rRNA) and proteins.
2. mRNA is read by ribosomes:
- mRNA carries the genetic information from the DNA to the ribosomes.
- The ribosomes read the sequence of nucleotides in the mRNA and use this information to synthesize a specific protein.
- The reading of the mRNA by ribosomes occurs in a process called codon recognition, where each three-nucleotide codon corresponds to a specific amino acid.
3. tRNA delivers amino acids to the ribosome:
- Transfer RNA (tRNA) molecules are responsible for carrying amino acids to the ribosome during translation.
- Each tRNA molecule has an anticodon that is complementary to the codon on the mRNA.
- The anticodon of the tRNA binds to the codon on the mRNA, and the corresponding amino acid is added to the growing protein chain.
4. Ribosomes facilitate the formation of peptide bonds:
- The ribosomes catalyze the formation of peptide bonds between the amino acids, linking them together to form a protein chain.
- The ribosome moves along the mRNA, reading the codons and adding the corresponding amino acids in the correct order.
In conclusion, protein synthesis occurs on the ribosome, which is responsible for translating the genetic information carried by mRNA into a sequence of amino acids, ultimately forming proteins.

The term protoplasm was coined by Purkinje.
Purkinje, a Czech anatomist and physiologist, is credited with coining the term "protoplasm" in 1839. This term was used to describe the jelly-like substance found within living cells, which was later recognized as the essential living material responsible for carrying out vital functions in organisms.
Key points to note about the term protoplasm and its origin:
- Definition of protoplasm: Protoplasm refers to the colloidal living substance present in cells, consisting of a mixture of proteins, nucleic acids, lipids, and other organic and inorganic compounds. It is responsible for various cellular processes, including metabolism, growth, and reproduction.
- Purkinje's contribution: Jan Evangelista Purkinje, also known as Johannes Evangelista Purkinje, was a prominent scientist who made significant contributions to the fields of anatomy, physiology, and histology. In 1839, he introduced the term "protoplasm" while studying the structure and function of cells.
- Importance of the term: Purkinje's introduction of the term protoplasm was a pivotal moment in the history of biology. It helped shift the focus of scientific research towards the study of cellular structures and processes, laying the foundation for the field of cell biology.
- Recognition of protoplasm as the living substance: Purkinje's identification of protoplasm as the essential living material within cells paved the way for further discoveries and understanding of cellular biology. It led to the recognition that cells are the basic units of life and that protoplasm is responsible for the vital functions and organization of living organisms.
In summary, Purkinje, a renowned anatomist and physiologist, coined the term "protoplasm" in 1839. This term describes the living substance found within cells and has played a crucial role in the development of cell biology as a scientific discipline.