Quiz On Helminths, Arthropods And Prions!

Explanation
Helminths are a multicellular group of parasitic worms, which includes various species such as roundworms, tapeworms, and flukes. The term "metazoa" refers to all multicellular animals, which encompasses helminths as well. Therefore, "Metazoa" is the correct answer to this question.

Explanation
Nematoda is the correct answer because they are known for their long, thin, unsegmented tube-like bodies. Cestoda refers to tapeworms, which have a flat, segmented body. Trematoda refers to flukes, which have a leaf-shaped body. While flukes and tapeworms are both types of helminths, they do not have the characteristic long, thin bodies described in the question.

Explanation
Roundworms have only longitudinal direction muscles used for sideways thrashing movement. This muscle arrangement allows them to move by contracting and relaxing their muscles in a wave-like motion, propelling them forward. Unlike flatworms, flukes, and tapeworms, roundworms do not have circular muscles that would allow them to move in a different manner. Therefore, roundworms are the only helminth in the given options that exhibit sideways thrashing movement through their longitudinal muscles.

Explanation
Tapeworms are flatworms that belong to the class Cestoda. Unlike other helminths such as flukes and digenea, tapeworms do not have a gut or body cavity. Instead, they absorb nutrients directly from their host's digestive system through their specialized structures called suckers and hooks. This adaptation allows tapeworms to live as parasites in the intestines of various animals, including humans. Larva, on the other hand, refers to the immature stage of an organism and is not a specific type of helminth.

Explanation
Feces is the correct answer because it is the bodily excrement that is commonly examined for ova (eggs) and parasites of helminths (worms). This is because the digestive system eliminates waste and toxins from the body through the feces, making it a suitable sample for detecting helminth infections. Saliva, urine, and mucous do not typically contain these ova and parasites, making them incorrect answers.

Explanation
During helminth infection, eosinophils are specifically increased. Eosinophils are a type of white blood cell that play a crucial role in the immune response against parasitic infections, such as helminths. They are particularly effective in combating helminth parasites due to their ability to release toxic granules that can kill the parasites. Therefore, an increase in eosinophil count is a characteristic immune response to helminth infection.

Explanation
Taeniasis refers to an infection caused by adult tapeworms in the gut. Tapeworms are parasitic flatworms that can infect humans when they consume undercooked or raw contaminated meat. Once inside the human gut, the tapeworms attach themselves to the intestinal wall and can cause symptoms such as abdominal pain, weight loss, and digestive issues. It is important to properly cook meat and maintain good hygiene to prevent taeniasis.

Explanation
Taeniasis is a parasitic infection caused by tapeworms. Tapeworms attach themselves to the host's intestines and absorb nutrients from the host's food. However, the amount of nutrients taken by taeniasis is minimal, meaning that it does not significantly affect the host's overall nutrient intake. Therefore, the statement that the amount of nutrients taken from the host by taeniasis is negligible is true.

Explanation
Schistosomiasis is a parasitic disease caused by blood flukes that primarily affect the intestines, lungs, liver, and blood vessels. It is considered one of the most important flukes involving development in these organs. The parasites enter the body through contaminated water and penetrate the skin, then migrate to the blood vessels surrounding the intestines and liver. They can cause inflammation, fibrosis, and damage to these organs, leading to severe complications such as liver cirrhosis, bladder and intestinal wall damage, and pulmonary hypertension. Schistosomiasis is a significant public health concern in many tropical and subtropical regions.

Explanation
Prions are misfolded proteins that can cause diseases, such as Creutzfeldt-Jakob disease and mad cow disease. Unlike viruses or bacteria, prions do not contain genetic material and cannot elicit an immune response. The immune system typically responds to foreign substances, such as viruses or bacteria, by producing antibodies to neutralize them. However, prions are composed of abnormal proteins that are not recognized as foreign by the immune system, therefore they do not trigger an immune response.

Explanation
The PrPc protein is predominantly expressed in nerve cells. This is because PrPc stands for "cellular prion protein," and prions are known to be primarily associated with neurodegenerative diseases. Therefore, it makes sense that the protein would be predominantly expressed in nerve cells, which are the primary cells affected by prion diseases.

Explanation
Prions are infectious proteins that can cause neurodegenerative diseases. The statement "large size" is not true regarding the properties of a prion. Prions are actually very small in size, consisting of misfolded proteins that can aggregate and cause damage to the nervous system. Their small size allows them to easily spread and infect other cells.

Explanation
The inoculation period of spongiform encephalopathies refers to the time it takes for symptoms to appear after an individual has been infected. The correct answer, "months to years," suggests that it can take a significant amount of time for symptoms to manifest. This is consistent with the nature of spongiform encephalopathies, which are slow-progressing diseases affecting the brain. The lengthy incubation period is a characteristic feature of these diseases, distinguishing them from other types of infections that may have shorter incubation periods.

Explanation
Prions are infectious proteins that can cause diseases such as Creutzfeldt-Jakob disease. They are highly resistant to traditional sterilization methods and can survive on contaminated surgical instruments. Therefore, if these instruments are not properly sterilized, they can spread prions to other patients during surgical procedures. This makes the statement "Prions can be spread by the use of contaminated surgical instruments" true.

Explanation
Lymphocytes are a type of white blood cell that play a crucial role in the immune response. They are responsible for recognizing and destroying foreign substances, including prions, in the body. After crossing the mucosa, lymphocytes can transfer prions into neural tissue as they migrate to different parts of the body. This process allows prions to spread and cause damage to the nervous system.