Microbiology

Step 1: Understanding vectors.
Vectors are DNA molecules used to transfer foreign genes into host cells during genetic engineering.
Step 2: Examples of vectors.
Plasmids, bacteriophages (like lambda phage), and cosmids are commonly used vectors.
Step 3: Identifying the non-vector.
Mosquito is a biological organism, not a molecular cloning vector.

Step 1: Understanding bacterial genomes.
Mycobacterium genitalium has the smallest bacterial genome, with a genome size of around 580,000 base pairs, making it the smallest known genome of a free-living organism.
Step 2: Analyzing the options.
(A) Methanococcus jannaschii: Incorrect. This bacterium has a larger genome compared to Mycobacterium genitalium.
(B) Mycobacterium genitalium: Correct. It has the smallest bacterial genome known.
(C) Haemophilus influenzae: Incorrect. Haemophilus influenzae has a larger genome than Mycobacterium genitalium.
(D) Saccharomyces cerevisiae: Incorrect. Saccharomyces cerevisiae is a yeast, and its genome is much larger than Mycobacterium genitalium.
Step 3: Conclusion.
The correct answer is (B) Mycobacterium genitalium, as it has the smallest known bacterial genome.

Step 1: Understanding oxidative phosphorylation.
Oxidative phosphorylation occurs in the electron transport system (ETS) of mitochondria.
Step 2: ATP yield from one glucose.
NADH and FADH generated during glycolysis, link reaction, and Krebs cycle donate electrons to ETS.
Step 3: Total ATP count.
Complete aerobic respiration of one glucose molecule yields a total of 38 ATP molecules.
Step 4: Conclusion.
Hence, the correct answer is thirty eight ATP.

Step 1: Understanding ribosome structure.
Ribosomes are composed of rRNA and proteins and consist of two subunits.
Step 2: Role of magnesium ions.
Magnesium ions (Mg ) help maintain ribosomal structure by binding the two subunits together.
Step 3: Importance in protein synthesis.
Without Mg , ribosomal subunits dissociate and protein synthesis cannot occur.
Step 4: Conclusion.
Therefore, magnesium is the essential binding agent in ribosomes.

Step 1: Identifying bacterial appendages.
Bacteria possess various appendages such as flagella (for movement), fimbriae (for attachment), and pili (for genetic exchange). However, bacteria do not have cilia, which are present in eukaryotic cells.
Step 2: Analyzing the options.
(A) flagella: Incorrect, flagella are present in many bacteria and are used for movement.
(B) fimbriae: Incorrect, fimbriae are hair-like appendages that bacteria use for attachment.
(C) cilia: Correct, cilia are not found in bacteria, they are found in eukaryotic cells.
(D) pili: Incorrect, pili are present in bacteria and play a role in DNA transfer during conjugation.
Step 3: Conclusion.
The correct answer is (C) cilia, as they are not found in bacteria.

Step 1: Understanding pyruvate conversion.
Pyruvate is converted into acetyl CoA inside the mitochondria by the pyruvate dehydrogenase complex before entering the Krebs cycle.
Step 2: Nature of the reaction.
During this process, one carbon atom is removed as carbon dioxide and pyruvate is oxidized, hence the reaction is called oxidative decarboxylation.
Step 3: Evaluation of options.
(A) Oxidative decarboxylation: Correct — this accurately describes the reaction.
(B) Oxidative dephosphorylation: Incorrect — not related to pyruvate conversion.
(C) Oxidative phosphorylation: Incorrect — it occurs in the electron transport chain.
(D) Oxidative dehydration: Incorrect — no water removal occurs here.
Step 4: Conclusion.
The conversion of pyruvate into acetyl CoA occurs through oxidative decarboxylation.

Step 1: Understanding prokaryotic cells.
Prokaryotic cells lack a true nucleus and membrane-bound organelles. They include bacteria and cyanobacteria.

Step 2: Analysis of given organisms.
Anabaena and Nostoc are cyanobacteria and hence prokaryotic.
Streptococcus is a bacterium and is prokaryotic.
Paramoecium is a unicellular eukaryote with a true nucleus.

Step 3: Conclusion.
Therefore, the organism which is not prokaryotic is Paramoecium.

Step 1: Understanding blood vessels.
Arteries, veins and capillaries have distinct structural and functional roles.
Step 2: Evaluating the statements.
Pulmonary artery carries deoxygenated blood from heart to lungs, unlike other arteries.
Step 3: Identifying the incorrect statement.
Thus, the statement that pulmonary artery contains oxygenated blood is incorrect.

Step 1: Activation of pepsinogen.
Pepsinogen is converted into active pepsin in the presence of hydrochloric acid (HCl) in the stomach.
Step 2: Protein digestion.
In acidic medium, pepsin digests proteins into peptones and proteoses.
Step 3: Correct identification.
Thus, A is HCl and B is pepsin.