Biology Test - 6

The correct answer is Cancer.

Key Points

• Oncogenes are associated with Cancer.
• Oncogenes are the genes causing cancer.
• Carcinogens are the chemical causing cancer.
• Oncogenic viruses are the viruses that cause cancer.
  • Human papillomavirus, Epstein-Barr virus, and hepatitis B virus are a few oncogenic viruses.
  • Such viruses have the ability to induce tumours in the animals they infect.
  • When these viruses infect cultured cells, they cause transformation.

Additional Information

• Tuberculosis:
  • India is committed to eliminating tuberculosis from the country by 2025, five years ahead of the global target by the World Health Organisation (WHO) i.e. 2030.
  • To align with the ambitious goal, the programme has been renamed from the Revised National Tuberculosis Control Programme (RNTCP) to National Tuberculosis Elimination Programme (NTEP).
• Hepatitis:
  • It is caused by a virus.
  • The word hepatitis refers to any inflammation of the liver — the irritation or swelling of the liver cells from any cause.
  • It can be acute (inflammation of the liver that presents with sickness — jaundice, fever, vomiting) or chronic.
• Typhoid:
  • Typhoid is an infectious bacterial disease that mainly spreads through contaminated food or water.
  • It is a serious disease spread through contaminated food and water causing high fever, abdominal pain and diarrhoea.
  • It can also spread due to poor hygienic conditions.
  • The major symptoms of this disease are characterized by high fever, loss of appetite and diarrhoea.
  • Typhoid fever is caused by Salmonella typhi bacteria.
  • In the Typhoid Widal test, a type of blood test is done to Identifies antibodies against Salmonella antigens.

Concept:

• Plasmodium is a protozoan that causes the disease malaria. There are different plasmodium varieties like P. vivax, P. malaria, and P. falciparum
• P. falciparum is the most fatal one.
• Plasmodium requires two hosts to complete its Life cycle:

1. Human
2. Female Anopheles Mosquito

Explanation:

• The infective stage of malarial parasite plasmodium is ''Sporozoite''

The life cycle of Plasmodium: 

Ist phase in the Human:

• The infected female Anopheles mosquito transfers the sporozoites i.e. an infectious form of plasmodium to the human body by biting.
• The sporozoites reach the liver cells and multiply themselves and become merozoites.
• These merozoites now attack the red blood cells and soon they get transformed into the trophozoites.
• They reproduce asexually in the RBCs producing male & female gametes.
• After this, they rupture the RBCs and release a toxin called hemozoin, which is responsible for high recurring fever, chills, and shivering.

IInd phase in Mosquito:

• The plasmodium again enters the Female Anopheles mosquito when it bites another infected person.
• Now the male and female gametes get fertilized in the mosquito's intestine and migrate to the salivary glands.

Additional Information

• Cyst: It represents a stage in the life cycle of protozoans where a thick wall develops around them that helps them to withstand harsh and unfavourable conditions.

The correct answer is All of the above.

Key Points

• A wide range of organisms belonging to bacteria, viruses, fungi, protozoans, helminths, etc. could cause diseases in man. Such disease-causing organisms are called pathogens
• Salmonella typhi is a pathogenic bacterium that causes typhoid fever in human beings. Hence, Statement 1 is correct.
  • These pathogens generally enter the small intestine through food and water contaminated with them and migrate to other organs through blood.
  • Sustained high fever (39° to 40°C), weakness, stomach pain, constipation, headache, and loss of appetite are some of the common symptoms of this disease.
  • Intestinal perforation and death may occur in severe cases. Typhoid fever could be confirmed by the Widal test 
• Bacteria like Streptococcus pneumonia and Haemophilus influenza are responsible for the disease pneumonia in humans which infects the alveoli (air-filled sacs) of the lungs. Hence, Statement 2 is correct.
  • As a result of the infection, the alveoli get filled with fluid leading to severe problems in respiration.
  • The symptoms of pneumonia include fever, chills, cough, and headache.
  • In severe cases, the lips and fingernails may turn grey to bluish in colour. 
  • A healthy person acquires the infection by inhaling the droplets/aerosols released by an infected person or even by sharing glasses and utensils with an infected person. 
  • Dysentery, plague, diphtheria, etc. are some of the other bacterial diseases in man. 
• Some of the human diseases are caused by protozoans too. Plasmodium, a tiny protozoan is responsible for this disease.
  • Different species of Plasmodium (P. vivax, P. malaria, and P. falciparum) are responsible for different types of malaria. Hence, Statement 3 is correct.
  • Of these, malignant malaria caused by Plasmodium falciparum is the most serious one and can even be fatal. 

Option 1 is correct, i.e. Typhoid fever.

• Typhoid fever: 
  • It can be diagnosed with the Widal test. 
  • Widal test is named after Georges-Fernand Widal (inventor). 
  • The test detects agglutinating antibodies against the O and H antigens of Salmonella Typhi Bacteria.

Extra facts: 

• To diagnose Tuberculosis, a blood test is sufficient to find the bacteria.
• AIDS can be diagnosed by ELISA-Enzyme-Linked Immunosorbent Assay.
• The study of Cancer is Oncology.

The correct answer is option [3] i.e., Gastrointestinal and urogenital tracts -Physiological barriers

Key Points

• Every day we are exposed to a large number of infectious agents.
• However, only a few of these exposures result in disease.
• This is due to the fact that the body is able to defend itself from most of these foreign agents.
• This overall ability of the host to fight the disease-causing organisms, conferred by the immune system is called immunity.
• Immunity is of two types: (i) Innate immunity and (ii) Acquired immunity.

​Explanation:

​Innate immunity:

• It​ is a non-specific type of defense, that is present at the time of birth.
• This is accomplished by providing different types of barriers to the entry of foreign agents into our body.
• Innate immunity consists of four types of barriers. These are-​
  1. ​​​Physical barriers: Skin on our body is the main barrier that prevents entry of the micro-organisms. Mucus coating of the epithelium lining the respiratory, gastrointestinal, and urogenital tracts also helps in trapping microbes entering our body.
  2. Physiological barriers: Acid in the stomach, saliva in the mouth, tears from eyes–all prevent microbial growth.
  3. Cellular barriers: Certain types of leukocytes (WBC) of our body like polymorpho-nuclear leukocytes (PMNL-neutrophils) and monocytes and natural killer (a type of lymphocytes) in the blood as well as macrophages in tissues can phagocytose and destroy
     microbes.
  4. Cytokine barriers: Virus-infected cells secrete proteins called interferons which protect non-infected cells from further viral infection.

Acquired immunity:​

• It is pathogen-specific. It is characterized by memory.
• This means that our body when it encounters a pathogen for the first time produces a response called primary response which is of low intensity.
• Subsequent encounter with the same pathogen elicits a highly intensified secondary or anamnestic response.
• This is ascribed to the fact that our body appears to have the memory of the first encounter.
• The primary and secondary immune responses are carried out with the help of two special types of lymphocytes present in our blood, i.e., B-lymphocytes and T-lymphocytes.
• The B-lymphocytes produce an army of proteins in response to pathogens into our blood to fight with them. These proteins are called antibodies.

Immunoglobulin (Ig): These are the protein molecules also called antibodies. These act against the foreign antigens entering the body, and neutralizes them.

• An antibody has a Y-shaped structure. 
• Each antibody molecule consists of four polypeptide chains, two are long called heavy (H) chains while the other two are short called light (L) chains. Hence, an antibody is represented as H2L2.
• Antibodies can be classified into five types IgA, IgM, IgE, IgG & IgD.

Explanation:

• IgE: IgE is produced in plasma cells. It is primarily found in mammals.
• It constitutes 0.05% of the total Ig in serum. It has a molecular weight of 200,000 daltons
• It mediates hypersensitive or allergic reactions like dust allergy, pollen allergy, etc that cause symptoms like sneezing, coughing, itchy eyes, etc.
• When the body encounters an IgE-specific antigen, the IgE gets attached to the mast cells which causes a release of powerful chemical mediators like histamine from the mast cells and an allergic reaction is initiated.

Additional Information

IgE antibodies:

• It is involved in triggering the immune system to attack the parasite that infects the cells.
• It is also involved in triggering allergic reactions.

IgG antibodies:

• Up to 75% of antibodies in the blood are of this type.
• Its main function is to provide protection against reinfection with microorganisms that have previously encountered the immune system.

IgM antibodies:

• It is involved in the initial immune response to an infection and is one of the first antibody isotypes produced by B lymphocytes.

The correct answer is Spleen.

Key Points

• Spleen
  • ​The spleen is the largest organ of the lymphatic system.
  • It keeps all the body fluids balanced.
  • It is made up of red pulp tissue that filters the old and damaged red blood cells, whereas, the white pulp tissue consists of the B and T cells that help to fight infections.
  • The spleen is a bean-shaped organ that stores erythrocytes, lymphocytes, and phagocytes.
  • The spleen recycles the old and damaged red blood cells and the white blood cells are stored.
  • It also helps to fight against bacteria that cause diseases such as meningitis and pneumonia.

Additional Information

• Tonsil
  • Tonsils are the two lymph nodes located on each side of the back of your throat.
  • They function as a defence mechanism and help prevent your body from getting an infection.
  • When it becomes infected, the condition is called tonsilitis.
• Thymus
  • The thymus gland is a very unique organ that is at its largest in children and shrinks away as the body grows older.
  • It is about 2.5 to 5 cm wide, 4 to 6 cm long, and 1cm thick at birth.
• Lymph node
  • A lymph node, or lymph gland, is a kidney-shaped organ of the lymphatic system, and the adaptive immune system.
  • A large number of lymph nodes are linked throughout the body by the lymphatic vessels.

The correct answer Helper T-lymphocytes.
Key Points

• Human Immuno Deficiency (HIV) is a virus that attacks cells in the body.
• Human Immuno Deficiency is a member of a group of viruses called a retrovirus.
• It has an RNA genome enclosed in an envelope.
• AID (Acquired Immuno Deficiency Syndrome) is caused by Human Immuno Deficiency.

Explanation-
HIV infection- 

• The HIV virus mainly affects the Helper T-lymphocytes (immune cells of the human body).
• After getting HIV into the body of a person, the virus enters the macrophages.
• Here, RNA is replicated to form viral DNA by enzyme reverse transcriptase.
• The viral DNA now gets incorporated into the host cell's DNA and directs the infected cells to produce viruses.
• The macrophages continue to produce virus particles.
• The virus particles enter Helper T-lymphocytes (T_H cells) in the blood, where they continue to replicate and produce viral progenies.
• The virus released in the blood also affects the other Helper T-lymphocytes.
• Thus, the number of Helper T-lymphocytes progressively decreases in the body of the infected persons.
• With the decrease in the number of T-cells, immunity also decreases.
• The person is unable to produce any immune response.

Thus, HIV mainly infects Helper T-lymphocytes.

Additional Information

Following preventive measures are used to prevent the spread of HIV infection.

• Making blood from blood banks safe from HIV.
• Ensure the use of only disposable needles and syringes.
• controlling drug abuse.

Enzyme-linked immunosorbent assay (ELISA) is the widely used diagnostic test for AIDS.

Cocaine is obtained from the Erythroxylum plant.

Key Points

• Coca alkaloid or cocaine is obtained from the coca plant Erythroxylum coca, native to South America.
• It interferes with the transport of the neuro-transmitter dopamine.
• Cocaine, commonly called coke or crack is usually snorted.
• It has a potent stimulating action on the central nervous system, producing a sense of euphoria and increased energy.
• An excessive dosage of cocaine causes hallucinations.

Additional InformationPoppy plant

• Opioids are drugs, which bind to specific opioid receptors present in our central nervous system and gastrointestinal tract.
• Heroin, commonly called smack is chemically diacetylmorphine which is a white, odorless, bitter crystalline compound.
• This is obtained by acetylation of morphine, which is extracted from the latex of poppy plant Papaver somniferum.
• Generally taken by snorting and injection, heroin is a depressant and slows down body functions.

Cannabis plant

• Cannabinoids are a group of chemicals, which interact with cannabinoid receptors present principally in the brain.
• Natural cannabinoids are obtained from the inflorescences of the plant Cannabis sativa.
• The flower tops, leaves, and the resin of the cannabis plant are used in various combinations to produce marijuana, hashish, charas, and ganja.
• Generally taken by inhalation and oral ingestion, these are known for their effects on the cardiovascular system of the body. 

Atropa plant

• Scientific name of belladona is Atropa Belladona.
• Atropa Belladona belong to solanaceae family.
• Belladonna drug is obtained from the leaves of this plant.
• The plant is a perennial herb.
• Belladona is used extremely to relieve pain.

Concept:

• When drugs & alcohol are taken for purposes other than medicinal use or taken in amounts that impair the physiological, psychological & physical functions of the body is called drug abuse, and the individual doing it is called a drug addict.
• Drugs belong to various categories like Opioids, Cannabinoids, Coco alkaloid, Hallucinogens, etc.

Explanation:

• Drug addiction can be defined as the psychological attachment to certain effects like euphoria, temporary feeling of well-being, produced by excess usage of drugs & alcohol.
• The characters shown by the body due to the abrupt discontinuation of drugs or alcohol are called withdrawal symptoms
• Withdrawal symptoms include:

1. Anxiety
2. Shakiness
3. Nausea
4. Sweating

​Additional Information 

• Reasons for alcohol & drug abuse in adolescents:

1. Curiosity and need for adventure, excitement & experiment
2. To escape stress, depression & frustration
3. Unstable or unsupportive family structure.