Free Biodiversity and Variety of Life MCQs with Answers

111. Which the following are likely to be present in deep sea water?

• A. Bluegreen algae
• B. Saprophytic fungi
• C. Archaebacteria
• D. Eubacteria

Explanation: Archaebacteria belong to a group of prokaryotic organisms called Monera. These include the methanogens, which produce methane; the thermoacidophilic bacteria, which live in extremely hot and acidic environments (such as hot springs); and the halophilic bacteria, which can only function at high salt concentrations and are abundant in the world's oceans.

112. Pigment containing membranous extensions in some cyanobacteria are:

• A. Pneumatophores
• B. Chromatophores
• C. Heterocysts
• D. Basal bodies

Explanation: Chromatophore is a pigmented lamellar or vesicular structure that can be isolated from disrupted photosynthetic bacteria or cyanobacteria. Their plasma membrane may be projected in folds into the cytoplasm forming lamellae that have, therefore, double unit membrane structure. The pigments and most of the enzymes required for the light-induced electron transport and phosphorylation processes of photosynthesis are located in the plasma membrane and lamellae.

113. Why is a capsule advantageous to a bacterium?

• A. It protects the bacterium from desiccation.
• B. Provides pathogenicity to bacteria.
• C. It allows bacterium to "hide" from host's immune system.
• D. It allows the bacterium to attach to the surface.

Explanation: A bacterial capsule is advantageous to a bacterium, particularly in terms of pathogenicity, for the following reasons:1. **It protects the bacterium from desiccation:** This protective capsule helps pathogens survive outside of a host. When a bacterium is expelled from a host, it may face harsh environmental conditions, including drying out (desiccation). The capsule acts as a shield, retaining moisture and preventing the bacterium from drying up, enhancing its ability to persist in the environment and potentially infect new hosts.2. **It allows the bacterium to "hide" from the host's immune system:** Pathogenic bacteria often possess capsules composed of materials that are not easily recognized by the host's immune system. This camouflage effect makes it difficult for immune cells to detect and eliminate the bacterium. By "hiding" from the immune system, the bacterium can establish infections and continue to cause disease.3. **It allows the bacterium to attach to a surface:** Bacterial capsules can aid in adhesion to host tissues and surfaces. This is a critical step in the pathogenic process. For instance, many pathogenic bacteria need to adhere to host cells or tissues to initiate an infection. The capsule can facilitate this attachment, allowing the bacterium to colonize and establish infections in the host.In the context of pathogenicity, these advantages of a bacterial capsule contribute to the bacterium's ability to evade host defenses, survive in various environments, and initiate infections within the host's body.

114. Which one of the following is true for fungi?

• A. They lack a rigid cell wall.
• B. They are heterotrophs.
• C. They lack nuclear membrane.
• D. They are phagotrophs.

Explanation: The true statement for fungi among the options is:"They are heterotrophs."Explanation of each statement:1. "They lack a rigid cell wall": This statement is false. Fungi do have a rigid cell wall, primarily composed of a complex sugar called chitin. The cell wall provides structural support and protection to fungal cells.2. "They lack nuclear membrane": This statement is false. Fungi, like most eukaryotic organisms, have a well-defined nucleus enclosed by a nuclear membrane. This membrane separates the genetic material from the cytoplasm of the cell.3. "They are phagotrophs": This statement is false. Fungi are not phagotrophs. They are saprophytic or parasitic heterotrophs. Fungi obtain nutrients by secreting enzymes that break down organic matter in their environment, and then they absorb the resulting small organic molecules. This process is distinct from phagotrophy, which involves engulfing and digesting whole particles.So, the correct statement is that fungi are heterotrophs because they obtain their nutrients by consuming organic matter in various forms.

115. Maximum nutritional diversity is found in the group:

• A. Fungi
• B. Animalia
• C. Monera
• D. Plantae

Explanation: Nutritional diversity refers to the range of nutritional strategies and sources of food organisms within a particular group can utilize. Here's an explanation of the options:1. **Fungi**: Fungi are known for their nutritional diversity. They can be saprophytic, decomposing dead organic matter; parasitic, obtaining nutrients from other organisms; or mutualistic, forming symbiotic relationships with plants. Some fungi are even involved in predation, capturing and consuming small animals. This variety of nutritional modes makes fungi one of the most nutritionally diverse groups.2. **Animalia**: While animals display a wide range of feeding strategies, they are generally more limited in their nutritional diversity compared to fungi. Animals are primarily classified as heterotrophs, meaning they obtain nutrients by consuming other organisms, whether through predation, herbivory, or parasitism. While there are variations in how they obtain food, it is not as diverse as the nutritional strategies seen in fungi.3. **Monera**: Monera is an outdated taxonomic group that used to encompass all prokaryotes, including bacteria and archaea. Prokaryotes are primarily heterotrophic, relying on different sources of organic matter as their food. While there is some diversity in the types of organic matter they can utilize, it doesn't match the nutritional diversity found in fungi.4. **Plantae**: Plants are primarily autotrophic, meaning they produce their own food through photosynthesis. They can also be classified as photoheterotrophic if they supplement their diet with some organic compounds. While plants show diversity in their ability to adapt to different environments and growth forms, their nutritional diversity is relatively limited compared to fungi.So, among the options, the group with the maximum nutritional diversity is **Fungi**.

116. The most abundant prokaryotes helpu l to humans in making curd from milk and in production of antibiotics are the ones categorised as:

• A. Cyanobacteria
• B. Archaebacteria
• C. Chemosynthetic autotrophs
• D. Heterotrophic bacteria

Explanation: 1. **Cyanobacteria:** Cyanobacteria, also known as blue-green algae, are photosynthetic prokaryotes that can be found in various environments, including freshwater and marine ecosystems. While they are not directly involved in making curd from milk, they can be important in the production of oxygen and fixing nitrogen in certain ecosystems. They are not typically used in antibiotic production.2. **Archaebacteria:** Archaebacteria, a type of prokaryotic microorganism, are known for their ability to thrive in extreme environments, such as hot springs and deep-sea hydrothermal vents. While they have unique metabolic pathways and are used in biotechnology research, they are not commonly associated with curd production or antibiotic production.3. **Chemosynthetic autotrophs:** Chemosynthetic autotrophs are organisms that use inorganic compounds as an energy source to produce organic compounds. They are not typically involved in making curd from milk. These organisms are more commonly found in extreme environments like hydrothermal vents and are not typically used in antibiotic production.4. **Heterotrophic bacteria:** Heterotrophic bacteria are prokaryotes that obtain energy by consuming organic compounds. In the context of curd production, certain species of heterotrophic bacteria play a crucial role in fermentation, converting lactose in milk to lactic acid, which is essential in curd formation. Additionally, many antibiotics, such as penicillin, are produced by various heterotrophic bacteria.Therefore, the prokaryotes most relevant to curd production and antibiotic production are typically **heterotrophic bacteria**. They are responsible for the fermentation process in curd production and are used in the production of antibiotics.

117. Which one single organism or the pair of organisms is correctly assigned to its or their named taxonomic group?

• A. Paramecium and Plasmodium belong to the same kingdom as that of Penicillium.
• B. Lichen is a composite organism formed from the symbiotic association of an algae and a protozoan.
• C. Yeast used in making bread and beer is a fungus.
• D. Nostoc and Anabaena are examples of protista.

Explanation: Let's examine each statement:1. **Paramecium and Plasmodium belong to the same kingdom as that of Penicillium:** This statement is incorrect. Paramecium and Plasmodium belong to the Kingdom Protista, while Penicillium belongs to the Kingdom Fungi. They are not in the same kingdom.2. **Lichen is a composite organism formed from the symbiotic association of an algae and a protozoan:** This statement is partially incorrect. Lichens are composite organisms formed from the symbiotic association of an alga or cyanobacterium with a fungus, not a protozoan. Lichens are classified as mutualistic associations between a photosynthetic partner (alga or cyanobacterium) and a fungal partner.3. **Yeast used in making bread and beer is a fungus:** This statement is correct. Yeast, commonly used in baking bread and fermenting beer, is indeed a type of fungus. It belongs to the Kingdom Fungi.4. **Nostoc and Anabaena are examples of protista:** This statement is incorrect. Nostoc and Anabaena are both examples of cyanobacteria, which belong to the Kingdom Bacteria, specifically in the phylum Cyanobacteria. They are not classified as protists.In summary, the correct assignment is that **yeast used in making bread and beer is a fungus.** The other statements have inaccuracies regarding the taxonomic groups of the organisms mentioned.

118. Which one of the following microbes forms symbiotic association with plants and helps them in their nutrition?

• A. Azotobacter
• B. Aspergillus
• C. Glomus
• D. Trichoderma

Explanation: The microbe that forms a symbiotic association with plants and aids in their nutrition is **Glomus**. Here's an explanation of all the options:1. **Azotobacter:** Azotobacter is a free-living nitrogen-fixing bacterium. It doesn't form symbiotic associations with plants but can contribute to nitrogen availability in the soil.2. **Aspergillus:** Aspergillus is a common filamentous fungus, but it is not typically known for forming symbiotic relationships with plants. Instead, it's often associated with various types of decomposition and growth in non-symbiotic environments.3. **Glomus:** Glomus is a type of mycorrhizal fungus. It forms a mutualistic symbiotic association with the roots of most plants. This association, known as arbuscular mycorrhiza, enhances the plant's ability to absorb water and essential nutrients, particularly phosphorus, from the soil. It's a crucial contributor to plant nutrition.4. **Trichoderma:** Trichoderma is a genus of fungi known for its ability to act as a biocontrol agent against plant pathogenic fungi. It can help protect plants from certain diseases but doesn't typically form direct symbiotic relationships with plants for nutritional benefits.So, the correct option is **Glomus** when it comes to forming a symbiotic association with plants and assisting in their nutrition.

119. In the five kingdom classification, Chlamydomonas and Chlorella have been included in:

• A. Protista
• B. Algae
• C. Plantae
• D. Monera

Explanation: In order to develop phylogenetic classification, R.H. Whittaker (1969), an American taxonomist, divided all the organisms into five kingdoms. Whittaker has used five criteria for delimiting the different kingdoms. (i) Complexity of cell structure, prokaryotic and eukaryotic (ii) 19 Complexity of body structure or structural organization, unicellular and multicellular. (iii) Mode of nutrition which is divergent in multicellular kingdoms. (iv) Ecological life style like producers (plantae), decomposers (fungi) and consumers (animalia), (v) Phylogenetic relationship. When such characteristics were considered, the fungi were placed in a separate kingdom - Kingdom Fungi. All prokaryotic organisms were grouped together under Kingdom Monera and the unicellular eukaryotic organisms were placed in Kingdom Protista. Kingdom Protista has brought together Chlamydomonas, Chlorella (earlier placed in Algae within Plants and both having cell walls) with ParamoeciumandAmoeba(which were earlier placed in the animal kingdom which lack cell wall). It has put together organisms which, in earlier classifications, were placed in different kingdoms. This happened because the criteria for classification changed

120. Which one of the following also act as as a catalyst in a bacterial cell?

• A. 5S rRNA
• B. snRNA
• C. hnRNA
• D. 23S rRNA

Explanation: Among the options you provided, 23S rRNA also acts as a catalyst in a bacterial cell. Here's an explanation of each option:1. 5S rRNA: 5S ribosomal RNA is a component of the ribosome, which is involved in protein synthesis in both bacterial and eukaryotic cells. It plays a structural role in the ribosome but does not act as a catalyst.2. snRNA (small nuclear RNA): snRNAs are a class of RNA molecules found in the nucleus of eukaryotic cells. They are involved in processes like pre-mRNA splicing and do not typically act as catalysts.3. hnRNA (heterogeneous nuclear RNA): hnRNA is an intermediate molecule in the processing of pre-mRNA in eukaryotic cells. It undergoes modifications to become mature mRNA and does not act as a catalyst.4. 23S rRNA: 23S ribosomal RNA is part of the large subunit of the bacterial ribosome. It has peptidyl transferase activity, which catalyzes the formation of peptide bonds during protein synthesis. This catalytic activity makes it an essential component for the translation of genetic information into proteins in bacterial cells.So, 23S rRNA is unique among the options in that it acts as a catalyst in a bacterial cell, specifically in the ribosome during protein synthesis.