The plant disease which is not caused by a fungus is

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The bacterium Xanthomonas campestris is the causative organism for the black rot in crucifers. The bacterium causes the darkening of the vascular tissues. X. campestris is an aerobic, Gram-negative rod shape bacterium. The bacterium infects plants belonging to the Brassicaceae (Cruciferae) family, i.e. cauliflower, cabbage, broccoli, kale, turnip, mustard, radish, oilseed rape, etc.

Characteristic of black rot of crucifers is the development of V-shaped chlorotic/necrotic lesions. The necrotic lesion extends from the leaf margins and blackens vascular tissues.

On the other hand, other diseases are caused due to fungus. (A) Brown rust of wheat is caused due to fungus Puccinia triticina, (B) Red rot of sugar cane is caused due to fungus Glomerella tucumanensis, and (C) Late blight of potato is caused due to fungus Phytophthora infestans.

During its formation bread, becomes porous due to release of CO2 by the action of:

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The Baker’s yeast or the Saccharomyces cerevisiae is the common strain of yeast used in the bakery industry for baking bread and other bakery products. Baker’s yeast serves as a leavening agent. The yeast ferments sugars present in the dough into carbon dioxide (CO2) and ethanol (C2H5OH). The released carbon dioxide helps in the rising of bread and the bread becomes softer and lighter.

The Baker’s yeast or the Saccharomyces cerevisiae is a unicellular fungus. They are  round/ovoid in shape and about 5–10 μm in diameter. Yeast reproduces by budding. The optimum temperature requires for the growth of Baker’s yeast is 30–35 °C or 86–95 °F.

Bacteria having clusters of flagella at both poles are known as

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A flagellum is a hairlike structure present in microorganisms. They are mostly used for mobility or swimming. In some cases, they may act as sensory organs to sense chemicals and the temperature of the outside environment. The number of flagella present in the bacteria may be one or more.

According to the number and arrangement of flagell in the bacterial cells, they may be

(i) Monotrichous: Bacteria with a single flagellum (V. cholerae)

(ii) Lophotrichous: Bacteria with many flagella at one place (H. pylori)

(iii) Apmphitrichous: Bacteria with a single or Cluster of flagella at both poles (A. faecalis)

(iv) Peritrichous: Bacteria with many flagella projecting in different directions (E.coli)

Which of the following human organs is affected by the consumption of aflatoxin, a food adulterant?

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The human organ that is affected by the consumption of aflatoxin is the Liver. Aflatoxins are mycotoxins. They are highly poisonous secondary metabolites substances synthesized by fungi belonging to the Aspergillus species. Aflatoxin is also acting as carcinogens and mutagens and causes liver cancer in humans.

The mold Aspergillus grows in soil, dead and decaying vegetation. The fungi also grow on various foodstuffs that are consumed by humans and animals such as wheat, rice, millet, sweetcorn, peanut, sesame seed, sorghum, etc. Upon consumption by humans and animals, they enter their bodies. If an animal consumes aflatoxin-contaminated food, there is a possibility that the toxin can pass to eggs, milk products, and meat.

The most toxic toxin is Aflatoxin B1. It is produced by the fungi Aspergillus parasiticus and A flavus. The other aflatoxins are aflatoxin G1, aflatoxin G2, aflatoxin B1, and aflatoxin B2. They can enter the body through mucous, respiratory, or cutaneous routes. Aflatoxin contains a coumarin ring and a lactone moiety. 

Adult humans show a high tolerance for aflatoxin. However, children are affected most due to the toxin. The higher dose of aflatoxin ingestion can cause acute hepatic necrosis called acute aflatoxicosis. Later the acute aflatoxicosis leads to liver cirrhosis or liver carcinoma. 

Who discovered an infectious agent that was to be a free RNA of low molecular weight, it also lacked protein coat. This agent caused potato spindle tuber disease?

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The Potato spindle tuber viroid (PSTVd) is the causative agent of potato spindle tuber disease. The Potato spindle tuber viroid was discovered by the Swiss-American plant pathologist Theodor Otto Diener. He discovered the Potato spindle tuber viroid in 1971. The host plant is potato (Solanum tuberosum). The Potato spindle tuber comprises 359 nucleotides.

Theodor Otto Diener observed that in the causative organisms for potato spindle tuber disease is not a virus and only Theodor Otto Diener observed that the causative organisms for potato spindle tuber disease is not a virus and only consists of single-strand circular RNA. The causative organism also lacks a protein capsid and is very small in size as compared to the smallest known virus. He coined the term “viroid”. The Potato spindle tuber viroid was also the first viroid to be identified.

Fungi which cause thrush in humans

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Thrush or oral thrush is caused due to the infection of Candidiasis. The oral thrush is also known as oral candidiasis or oropharyngeal candidiasis. Oral thrush is a medical condition that arises due to the overgrowth of the fungus Candida albicans on the lining of the mouth.

The fungus Candida albicans can grow in the mouth, tongue, throat, and other parts of the body. In the mouth, the thrush appears as a white creamy lesion that looks like cottage cheese. Thrush causes irritation, redness, and pain in the mouth.

Thrush appears mostly in immune-compromised patients such as HIV/AIDS patients. However, it also appears in babies, toddlers, and older adults. Sometimes it appears in people with medications such as corticosteroids, antibiotics, and birth control pills. The symptoms of thrush include loss of taste, difficulty in swallowing, and sometimes fever.

Which of the following is a prokaryote?

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The genus Nostoc contains prokaryotic organisms. The genus Nostoc belongs to Cyanobacteria. Cyanobacteria are also known as “blue-green algae”. The most common example is the Nostoc commune. Swiss physician and philosopher Paracelsus coined the name “Nostoc”. Nostoc is found in moist rocks and soil as well as in the bottom of lakes and springs. Nostoc is also known as star jelly.

Cyanobacteria are prokaryotes. However, they possess photosynthetic apparatus (chlorophyll a and photosystem II) similar to the eukaryotes. Additionally, they also contain blue phycocyanin and red phycoerythrin pigments. Nostoc is filamentous cyanobacteria that fix atmospheric nitrogen (N2) through specialized cells called heterocysts. The filaments are made up of spherical or barrel-shaped cells. The cells are blue-green in color.


Hydrophobia is caused due to the infection of

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Hydrophobia or extreme fear of water fear arises due to the infection of Rabies. Rabies is a zoonotic, viral disease caused due to the Rabies virus (Rabies lyssavirus). The rabies virus is an enveloped virus with a negative-sense single-stranded RNA genome. The virus affects mammals such as dogs, humans, and bats. The rabies virus infects the central nervous system (CNS) of the host animal. This leads to severe neurological problems such as aggressive behavior and fear of water (hydrophobia). Hydrophobia is not a symptom of rabies-infected dogs. But the hydrophobia is a common feature seen in humans infected with rabies.

Rabies virus spreads to people from the saliva or a bite from the infected animals. The symptoms of rabies are fever, anxiety, confusion, hyperactivity, headache, nausea, and vomiting. Patients unable to swallow, excessive salivation, fear to drink fluids, hallucinations, and insomnia. If untreated, rabies is 100% fatal. Rabies is of two types: furious rabies and paralytic rabies.

Rabies usually lives on the saliva of the patients. Excessive salivation helps the virus to spread from one person to another or one animal to others. In the furious rabies form of the disease, the patients experience severe muscle spasms in the throat while drinking water or any fluid. The patients usually thought the spam on the throat is due to swallowing water. Thus, the patients start to fear water.

The first genome of a living organism sequenced in 1995 was:

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The first genome of a living organism sequenced in 1995 was the bacterium Haemophilus influenza. Haemophilus influenza is a gram-negative, facultatively anaerobic, coccobacillus bacteria. The bacterium is the first free-living organism, whose genome was sequenced. Before the sequencing of the H. influenza genome, Frederick Sanger and his team sequenced the full genome of virus phiX174.

The genome of H. influenza was sequenced at The Institute for Genomic Research, Maryland by American biotechnologist Craig Venter and his team. Now the institute is a part of J Craig Venter Institute. The strain of H. influenza bacteria used for the sequencing was Rd KW20. The DNA library for sequencing was provided by American microbiologist and Nobel laureate Hamilton Othanel Smith.

The genome of bacterium H. influenza consists of 1,830,138 bp of DNA. The genome contains 1604 protein-coding genes, 57 tRNA genes, 117 pseudogenes, and 23 other RNA genes. The sequencing was performed through the whole-genome shotgun. The study was published in Science magazine (1995). The Genome Sequence DataBase accession number for the whole genome sequence of H influenza is L42023>.