Free Biodiversity and Variety of Life MCQs with Answers

2411. Deafness is caused by excess use of:

• A. Tetracycline
• B. Streptomycin
• C. Levofloxacin
• D. Erythromycin

Explanation: The prolonged adminstartion of streptomycin causes hearing loss or deafness in humans especially in the high frequency range. Hence this option is correct.

2412. Bacteria play important role in:

• A. Nitrogen cycle
• B. Carbon cycle
• C. Urea cycle
• D. Water cycle

Explanation: Bacteria play many important roles in nitrogen cycle, while in carbon and urea cycle bacteria only have a single role. The role of bacteria in Nitrogen cycle is: NITROGEN FIXATION, AMMONIFACTION and DECOMPOSITION and DENITRIFICATION

2413. For sterilization, which of the following is used:

• A. Dry heat
• B. Moist heat
• C. Gamma rays
• D. All of these

Explanation: This is correct as sterilization uses many techniques which involve the use of gamma rays in some , moist heat in others and dry heat in the rest .

2414. Pesticide and insecticides are made up of:

• A. Physical agents
• B. Biological agents
• C. Chemical agents
• D. All of these

Explanation: Pesticides and insecticides are the chemicals which kill the unwanted pests and insects for the welfare of humans. In some cases a microorganism or a biological agent can also be used as a pesticide. But most of the insecticides and pesticides are chemical agents. Hence this is the correct option.

2415. What is the main role of bacteria?

• A. CO2 cycle
• B. Nitrogen cycle
• C. Phosphorus cycle
• D. All of above

Explanation: Bacteria play vita role(s) in all of the above mentioned cycles be it in the form of decomposition, nitrogen fixation , denitrification or converting phosphates to other organic forms.

2416. Rapid growth at exponential rate occurs in which phase of bacterial growth?

• A. Lag
• B. Log
• C. Stationary
• D. Decline

Explanation: Exponential Phase (Logarithmic Phase): In the exponential phase, the bacteria experience rapid and continuous growth at an exponential rate. Under favorable conditions with an abundant supply of nutrients, bacterial cells divide and multiply at their maximum rate during this phase.

2417. Which of the following refers to the region of RNA responsible for binding ribosomes during prokaryotic translation?

• A. TATA box
• B. Promoter
• C. Terminator
• D. Shine-Dalgarno sequence

Explanation: The correct answer is D) Shine-Dalgarno sequence. The Shine-Dalgarno sequence is a short RNA sequence found in the mRNA of prokaryotic cells, specifically in the 5' untranslated region (UTR). It is located upstream of the start codon (AUG) that signals the beginning of translation. The Shine-Dalgarno sequence base pairs with the complementary sequence on the 16S rRNA of the small ribosomal subunit during the initiation of translation. This interaction positions the ribosome correctly on the mRNA to start translation. The Shine-Dalgarno sequence is essential for the efficient initiation of translation in prokaryotic cells.

2418. Compound Microscope was first used by:

• A. A.V. Leeuwenhoek
• B. Pasture
• C. Janssen and Hans
• D. None of these

Explanation: It had long been suspected that small creatures exist which are too small to be seen with the naked eye. However, their discovery was linked to the invention of the microscope. A Dutch Scientist "Antonie van Leeuwenhoek" (1673) was the first to report the microbes such as bacteria and protozoa. He used a simple microscope to describe bacteria and protozoa with accurate drawings and descriptions and called these small creatures as "animalcules". He first observed small creatures in rainwater and then confirmed these in saliva, vinegar, infusions, and other substances.

2419. The nitrifyng bacteria are an example of which of the following?

• A. Heterotrophic Bacteria
• B. Saprotrophic Bacteria
• C. Chemosynthetic Bacteria
• D. Parasitic Bacteria

Explanation: Chemosynthetic bacteria obtain their energy by converting inorganic substances into organic compounds. Nitrifying bacteria are a type of chemosynthetic bacteria, as they obtain energy by oxidizing ammonia and nitrites to produce nitrates.

2420. DNA replication in bacteria occurs:

• A. Within nucleolus
• B. Prior to fission
• C. Just before transcription
• D. During SDuring S phase:

Explanation: DNA replication in bacteria occurs just before fission. Here's an explanation for each of the options you mentioned:1. Within nucleolus: The nucleolus is a substructure found within the nucleus of eukaryotic cells, not in bacteria. Bacteria lack a defined nucleus and nucleolus.2. Prior to fission: Bacterial DNA replication occurs just before the process of binary fission. Binary fission is the method by which bacteria reproduce, where a single bacterial cell divides into two genetically identical daughter cells. DNA replication is a crucial step in this process to ensure that each daughter cell receives a copy of the genetic material.3. Just before transcription: DNA replication and transcription are separate processes. DNA replication must occur before transcription in both bacteria and eukaryotic cells. Replication generates a copy of the DNA, while transcription is the process of synthesizing RNA from DNA.4. During S phase: The concept of an S phase is relevant to eukaryotic cell cycle regulation. In eukaryotic cells, the cell cycle is divided into phases, and S phase is the specific phase where DNA replication occurs. Bacteria do not undergo a defined cell cycle like eukaryotic cells, so they do not have an S phase.In summary, DNA replication in bacteria occurs prior to fission, ensuring that each daughter cell receives a complete copy of the genetic material, which is critical for their reproduction.