Free Biodiversity and Variety of Life MCQs with Answers

121. In eubacteria, a cellular component that resembles eukaryotic cell is:

• A. Plasma membrane
• B. Nucleus
• C. Ribosomes
• D. Cell wall

Explanation: Plasma membrane of eubacteria resembles plasma membrane of eukaryotic cell. But nucleus, ribosomes and cell wall are little different in eukaryotic cell in their structure and organization from eubacterial cell. Plasma Membrane: The plasma membrane, also known as the cell membrane, is a structure shared by both eubacteria (prokaryotes) and eukaryotic cells. It serves as a selective barrier that controls the passage of substances in and out of the cell, just like in eukaryotic cells. Nucleus: Eubacteria do not possess a true nucleus. Unlike eukaryotic cells, which have a distinct membrane-bound nucleus housing their genetic material, eubacteria have a nucleoid region where their DNA is located, but it lacks a membrane. Ribosomes: Ribosomes are cellular structures responsible for protein synthesis. Both eubacteria and eukaryotic cells have ribosomes, but there can be some differences in their ribosome structure and organization. Cell Wall: Eubacteria typically have a cell wall, which is a rigid outer layer providing structural support and protection to the cell. This is a feature shared with some eukaryotic cells, such as plant cells and fungi, but not all eukaryotic cells have cell walls.

122. Which one of the following organisms is not an eukaryote?

• A. Paramecium caudatum
• B. Escherichia coli
• C. Euglena viridis
• D. Amoeba proteus

Explanation: 1. Paramecium caudatum: Paramecium caudatum is a eukaryotic organism. Eukaryotes are characterized by having a true nucleus enclosed within a membrane, and Paramecium fits this description.2. Escherichia coli: Escherichia coli, commonly known as E. coli, is a prokaryotic organism. It is a bacterium, which means it lacks a true nucleus and other membrane-bound organelles. Instead, its genetic material is found in a single circular chromosome in the cytoplasm.3. Euglena viridis: Euglena viridis is a eukaryotic organism. It is a single-celled organism with a well-defined nucleus and other membrane-bound organelles, which are characteristics of eukaryotes.4. Amoeba proteus: Amoeba proteus is also a eukaryotic organism. Like Paramecium and Euglena, it possesses a true nucleus enclosed by a nuclear membrane, confirming its classification as a eukaryote.So, among the options provided, Escherichia coli is the one that is not a eukaryote. It is a prokaryotic bacterium.

123. The pathogen Microsporum responsible for ringworm disease in humans belongs to the same kingdom of organisms as that of

• A. Taenia, a tapeworm
• B. Wuchereria, a filarial worm
• C. Rhizopus, a mold
• D. Ascaris, a round worm

Explanation: Rhizopus, a mold:Rhizopus is a genus of fungi, specifically a type of mold. Molds are also classified under the kingdom Fungi, similar to Microsporum.

124. Virus envelope is known as:

• A. Capsid
• B. Virion
• C. Nucleoprotein
• D. Core

Explanation: The nucleic acid of a virus is surrounded by a protein coat called the capsid. The capsid is composed of protein subunits called capsomeres. In some viruses, the capsid is covered by an envelope, which usually consists of some combination of lipids, proteins and carbohydrates.

125. Single celled eukaryotes are included in:

• A. Protista
• B. Fungi
• C. Archaea
• D. Monera

Explanation: Protista is a kingdom in the classification of life forms. It consists of a diverse group of eukaryotic microorganisms that are primarily single-celled but can also be multicellular.Protists include various organisms like amoebas, paramecia, diatoms, and algae. Many of these single-celled eukaryotes do not fit neatly into the other major kingdoms (Animalia, Plantae, and Fungi).

126. Some hyperthermophilic organisms that grow in highly acidic (pH 2) habitats belong to the two groups:

• A. Eubacteria and archaea
• B. Cyanobacteria and diatoms
• C. Protists and mosses
• D. Liverworts and yeasts

Explanation: Explanations for each of the given options:1. Eubacteria and Archaea: - Eubacteria and Archaea are two distinct domains of microorganisms. Some hyperthermophilic organisms that grow in highly acidic (pH 2) habitats can belong to these groups.Eubacteria are a diverse group of bacteria that can thrive in extreme environments, including highly acidic conditions.Archaea are also single-celled microorganisms, and some of them are known to be hyperthermophiles, meaning they can live in extremely high-temperature environments, including acidic ones.2. Cyanobacteria and Diatoms: - Cyanobacteria are a group of photosynthetic bacteria that are often found in various environments, including acidic habitats. They can tolerate a range of pH levels.Diatoms are a type of photosynthetic microalgae, and while they are not typically associated with highly acidic conditions, some diatom species can adapt to a wide range of pH levels.3. Protists and Mosses: - Protists are a diverse group of eukaryotic microorganisms, including single-celled organisms like amoebas and algae. Some protists can be found in acidic environments.Mosses are small, non-vascular plants that typically grow in moist and shaded habitats. They are not typically associated with highly acidic conditions.4. Liverworts and Yeasts: - Liverworts are small, non-vascular plants similar to mosses. They can grow in a variety of habitats but are not specifically known for thriving in highly acidic environments.Yeasts are unicellular fungi and are not typically associated with highly acidic habitats. They are commonly used in various industrial and scientific applications.In summary, Eubacteria and Archaea are more likely to include hyperthermophilic organisms adapted to highly acidic conditions. The other options may have representatives that can tolerate acidic environments to some extent, but they are not as specialized for extreme acidity as Eubacteria and Archaea.

127. One of the freeliving, anaerobic nitrogen fixer is:

• A. Beijernickia
• B. Rhodospirillum
• C. Rhizobium
• D. Azotobacter

Explanation: Rhodospirillum is a free living photosynthetic anaerobic nitrogen fixing nonsulphur bacteria. It is capable of synthesizing its organic food in presence of light and in absence of O2 by a process known as bacterial photosynthesis. Beijernickia and Azotobacter are free living but aerobic nitrogen fixing bacteria. Rhizobium is a symbiotic nitrogen fixing bacteria.

128. Give below is the diagram of a bacteriophage. In which one of the options all the four parts A, B, C and D are correct?

• A. Tail fibres, Head, Sheath, Collar
• B. Sheath, Collar, Head, Tail fibres
• C. Head, Sheath, Collar, Tail fibres
• D. Collar, Tail fibres, Head, Sheath

Explanation: A-Head, B-Sheath, C-Collar, D-Tail fibre

129. Black(stem) rust of wheat is caused by:

• A. Alternaria solani
• B. Ustilago nuda
• C. Puccinia graminis triticina
• D. Xanthomonas oryzae

Explanation: Certainly, I can provide explanations for the options you listed in the context of black stem rust of wheat:1. Alternaria solani: Alternaria solani is a fungus that causes early blight in tomatoes and potatoes. It is not the causal agent of black stem rust in wheat.2. Ustilago nuda: Ustilago nuda is a fungus that causes loose smut in barley. It is not responsible for black stem rust in wheat.3. Puccinia triticina: Puccinia triticina, also known as wheat leaf rust, is the primary pathogen responsible for black stem rust in wheat. It's a fungal rust disease that affects the leaves, stems, and grains of wheat plants.4. Xanthomonas oryzae: Xanthomonas oryzae is a bacterial pathogen that causes bacterial leaf blight in rice and does not relate to black stem rust in wheat.In summary, black stem rust of wheat is primarily caused by Puccinia triticina, a fungal pathogen that affects wheat plants. The other options listed do not cause black stem rust in wheat.

130. Phylogenetic system of classification is based on:

• A. Morphological features
• B. Chemical constituents
• C. Floral characters
• D. Evolutionary relationships

Explanation: Certainly, here's an explanation of each of the options you mentioned in the context of phylogenetic classification:1. **Morphological Features**: This aspect of classification is based on the physical characteristics of organisms, such as their shape, size, structure, and other visible traits. Taxonomists use these features to group organisms that share similar physical characteristics into the same taxonomic category. For example, animals with backbones are classified as vertebrates based on their morphological feature of having a spinal column.2. **Chemical Constituents**: Some organisms have distinct chemical compounds or constituents that are unique to their group. These chemicals can be used for classification. For instance, the presence of specific chemical compounds in the cell walls of bacteria, like peptidoglycan, is a key feature used to differentiate between two major groups of bacteria, the Gram-positive and Gram-negative bacteria.3. **Floral Characters**: Floral characters are specific to plants and refer to the characteristics of their flowers. These characters can include features like petal number, arrangement of floral parts, and other flower-related traits. Botanists use floral characters to classify plants into various taxonomic groups, including families, genera, and species.4. **Evolutionary Relationships**: This is a fundamental concept in phylogenetic classification. Instead of focusing solely on superficial characteristics, phylogenetic classification aims to group organisms based on their evolutionary history. It considers the genetic and ancestral relationships between species. This approach often involves the use of molecular data, such as DNA and RNA sequencing, to construct phylogenetic trees that depict the evolutionary connections between different organisms.Phylogenetic classification is primarily concerned with understanding the evolutionary history and genetic relationships between organisms, making it a more accurate and dynamic system of classification compared to classifications based solely on superficial features.