RBSE Solutions Class 12 Biology Chapter 40 Important and Common Human Diseases

RBSE Class 12 Biology Chapter 40 Multiple Choice Questions

 

Question 1. In which of the following disease, deformities in fingers are generated?
(a) Tetanus
(b) Leprosy
(c) Tuberculosis
(d) Pneumonia
Answer: (b) Leprosy
In simple words: Leprosy is a disease that can cause changes and deformities, especially in the fingers and other body parts. It affects the skin, nerves, and limbs.

🎯 Exam Tip: When identifying diseases by symptoms, remember specific signs like 'deformities in fingers' are key clues for conditions like leprosy.

 

Question 3. Kala-azar disease is caused by -
(a) Entamoeba histolytic
(b) Leishmania
(c) Trypanosoma
(d) Plasmodium
Answer: (b) Leishmania
In simple words: Kala-azar is a disease caused by a type of parasite called Leishmania. This parasite spreads through sandfly bites.

🎯 Exam Tip: Remember the specific pathogens or vectors for common diseases like Kala-azar, as these are often tested.

 

Question 4. Malaria is caused by biting of the following mosquito.
(a) Male Anopheles
(b) Female Anopheles
(c) Culex
(d) Tsetse fly
Answer: (b) Female Anopheles
In simple words: Malaria spreads when a female Anopheles mosquito bites a person. Male mosquitoes do not spread malaria.

🎯 Exam Tip: Distinguish between male and female mosquitoes in disease transmission, as only females of certain species act as vectors.

 

Question 5. Guinea-Worm disease is caused by -
(a) Dracunculus
(b) Ascaris
(c) Enterobius
(d) Taenia
Answer: (a) Dracunculus
In simple words: The Guinea-Worm disease is caused by a type of worm called Dracunculus. It is a painful parasitic infection.

🎯 Exam Tip: Associate specific parasitic worms with the diseases they cause, such as Dracunculus with Guinea-Worm disease.

 

Question 7. Which of the following is a genetic disease?
(a) sickle cell Anaemia
(b) Haemophilia
(c) Colour Blindness
(d) All of the options
Answer: (d) All of the options
In simple words: Sickle cell anemia, haemophilia, and color blindness are all conditions that a person gets because of genes passed down from their parents. These are not caught like infections.

🎯 Exam Tip: Understand the characteristics of genetic diseases, which are inherited and not caused by external factors like bacteria or viruses.

RBSE Class 12 Biology Chapter 40 Short Answer Type Questions

 

Question 1. What do you understand by contagious diseases? Give two examples.
Answer: Contagious diseases are illnesses that can easily spread from one person to another through direct contact. This means if you touch an infected person or things they have touched, you can also get sick. Examples include Ringworm and Conjunctivitis (pink eye).
In simple words: Contagious diseases are those that spread quickly from sick people to healthy people by touching or being close.

🎯 Exam Tip: When defining medical terms, always provide clear examples to illustrate your understanding, as examples demonstrate practical knowledge.

 

Question 2. Write a short note on Acquired Immuno Deficiency Syndrome.
Answer:
Acquired Immuno Deficiency Syndrome (AIDS):
1. General:
AIDS is a serious viral disease caused by the Human Immunodeficiency Virus (HIV). HIV is also known as HTLV-3 or LAV and belongs to the retrovirus family. This virus was identified by Montagnier in 1982. HIV primarily targets and destroys helper T-lymphocytes, which are crucial for the body's immune system. The virus is not stable in the air and cannot survive outside the body for long. Once inside, it actively destroys infected CD4+ T-cells, which are vital components of immunity formed in the thymus during childhood. The immune system becomes severely weakened.

2. Structure:
The HIV virus has a complex structure, enclosed by a phospholipid bilayer membrane. This membrane has specific proteins called GP-120 and GP-41 embedded within it, which help the virus attach to host cells. Inside this membrane, there are two identical single strands of RNA. Each RNA molecule is associated with an enzyme called reverse transcriptase, which allows the virus to convert its RNA into DNA once it infects a cell. Surrounding the RNA molecules are two protein layers: an inner layer of P-24 proteins and an outer layer of P-17 proteins. There are two main subtypes of HIV, HIV-1 and HIV-2, with HIV-1 being the primary cause of AIDS.

3. Modes of Infection of HIV:
HIV can spread from person to person through several main ways. It can be transmitted through direct blood contact, for example, by sharing contaminated needles for injection. Sexual contact is a common route of transmission. A pregnant mother who has HIV can also pass the virus to her unborn baby in the uterus, as the virus can cross the placental barrier. Additionally, the virus is found in colostrum, which is the first milk produced by mothers, meaning it can be transmitted during breastfeeding. Historically, a large percentage of transmission, sometimes up to 80%, was noted in specific high-risk groups.

4. Symptoms of AIDS:
People with AIDS often show certain symptoms as their immune system weakens significantly. These can include swollen lymph nodes, prolonged and persistent coughing, and heavy, unexplained sweating, especially at night. In later stages, an individual with AIDS may also develop specific opportunistic infections, such as Pneumocystis carinii pneumonia, and certain cancers like Kaposi's sarcoma, which are rare in people with healthy immune systems. These symptoms are signs that the body's defenses are failing.
In simple words: AIDS is caused by the HIV virus, which attacks the body's defense cells. It has an outer and inner structure with RNA inside. The virus spreads through blood, sexual contact, from mother to baby, and breastfeeding, leading to symptoms like swollen glands, coughing, and sweating.

🎯 Exam Tip: When describing a disease like AIDS, ensure you cover its cause (pathogen), structure (key components), modes of transmission, and characteristic symptoms clearly to earn full marks. Remember that the virus mainly targets and destroys immune cells.

 

Question 3. Write short notes on:
1. Amoebiasis
2. Malaria
3. Guinea worm disease
4. Cancer
Answer:
1. Amoebiasis:
Amoebiasis, also known as amoebic dysentery, is an infection caused by a tiny parasitic organism called Entamoeba histolytica. This parasite infects the intestines.

Symptoms:
When infected, the parasite in its active form (trophozoite) enters the intestinal wall. It releases enzymes that break down tissue, causing cells to separate. This process creates small ulcers filled with mucus in the affected parts of the intestine. These ulcers can burst, releasing mucus, and sometimes blood, which then passes out with stool. Patients typically do not have a fever, but they suffer from ongoing diarrhea and severe abdominal cramps throughout the day. The continuous loss of fluids and nutrients can make patients feel very weak.

Mode of Infection:
This disease primarily spreads through consuming food and water that are contaminated with the parasite. Flies can also play a role in carrying the parasite and spreading the infection.

Prevention:
To prevent amoebiasis, it is crucial to drink only boiled water, ensuring it is free from contamination. It is also important to avoid eating uncovered food, as it can easily be exposed to contaminants.

Treatment:
Several medicines are available for treating amoebiasis, including Amitine, Fusegilin, and Metronidazole. These drugs help to kill the parasite and alleviate the symptoms.
In simple words: Amoebiasis is a tummy infection caused by a tiny bug called Entamoeba histolytica. It causes diarrhea and stomach pain, and spreads through dirty food and water. We can prevent it by drinking boiled water and eating covered food.

🎯 Exam Tip: For diseases, always mention the causative agent, common symptoms, how it spreads (mode of infection), ways to prevent it, and possible treatments for a complete answer.

 

Answer (continued):
2. Malaria:
Malaria is a severe disease caused by various types of Plasmodium parasites, including Plasmodium vivax (the most common type), Plasmodium falciparum (the most dangerous type), Plasmodium malariae, and Plasmodium ovale. These parasites are responsible for the different forms of malaria.

Transmission & Life Cycle:
The malaria disease spreads when an infected female Anopheles mosquito bites a human. The Plasmodium parasite has a complex life cycle that involves two hosts: humans and mosquitoes. This cycle is divided into three main stages:

• Schizogony (Asexual): This stage takes place inside humans, specifically in the liver cells and red blood cells. It involves rapid multiplication of the parasite and is further divided into phases like the pre-erythrocytic, exoerythrocytic (both in liver), erythrocytic (in red blood cells), and post-erythrocytic (back in liver cells).
• Gamogony (Sexual): This phase begins in humans, where male and female gametocytes (early sexual forms) are produced. It is then completed within the female Anopheles mosquito after she feeds on an infected person.
• Sporogony (Asexual): This stage occurs in the stomach of the female Anopheles mosquito, leading to the formation of infective forms.

The infective stage for humans is called the sporozoite. When an infected mosquito bites, these sporozoites enter the human bloodstream. They quickly travel to the liver, where they multiply. After a period, they are released from the liver and infect red blood cells. Inside the red blood cells, they multiply further, causing the cells to burst. The bursting of these red blood cells releases a toxic substance called haemozoin, which triggers the characteristic symptoms of malaria like shivering, chills, and fever.

Symptoms:
The release of haemozoin along with merozoites into the blood causes recurring malaria symptoms, known as paroxysm. These include:

• Rigour stage: The patient experiences severe chills and uncontrollable shivering.
• Fibril stage: During this stage, the body temperature rises sharply, reaching very high levels, typically between 104-106°F (40-41°C).
• Defervescent stage: This stage follows the fever, usually within six hours of the rigour stage, and is marked by profuse sweating as the body temperature begins to fall back to normal.

Medicines:
Quinine, extracted from the bark of the Cinchona tree, is one of the oldest and most well-known treatments for malaria. This tree grows in regions like Peru, Sri Lanka, and Java. Other effective medicines include Nivaquin, Resochin, Camaquin, Chloroquine, Paludrin, Plasmaquin, Daraprim, Mapacrine, Sulfadoxine, and Pyrimethamine. Modern treatment often involves a single dose of 750 mg of Sulfadoxine combined with 37.5 mg of Pyrimethamine.

Prevention:
The National Malaria Eradication Programme (NMEP) employs three main strategies to control malaria: eliminating mosquitoes, preventing new infections, and treating existing patients.

• Mosquito Larvae Destruction: A biological control method involves using fish that eat mosquito larvae, such as Stickleback, Gambusia, Minnows, Trout, and Channa. These are known as larvicidal fish.
• Chemical Control: Allethrin is a newer chemical used in various commercial mosquito repellents and insecticides, like "All Out" and "Goodknight." Other common insecticides include Pyrethrum, BHC (Benzene Hexachloride), and DDT (Dichlorodiphenyltrichloroethane).
• Personal Protection: Avoiding mosquito bites by using nets and repellents is crucial.

In simple words: Malaria is caused by tiny Plasmodium bugs spread by female Anopheles mosquitoes. The bugs go through different stages in humans and mosquitoes. It causes fever, chills, and sweating. We treat it with medicines like Quinine and prevent it by killing mosquitoes and avoiding bites.

🎯 Exam Tip: When explaining disease cycles, use clear steps and identify the different stages and hosts involved. Always include prevention and treatment methods.

 

Answer (continued):
3. Guinea Worm Disease (Dracunculiasis):
Guinea worm disease, also known as Dracunculiasis, is a parasitic infection caused by the Dracunculus medinensis worm. The disease starts when people drink water contaminated with tiny water fleas that carry the worm larvae.

Symptoms:
When the female worm is ready to lay its eggs, it creates a very painful blister on the skin, most often on the legs or feet, through which it tries to emerge. The area around this emerging worm becomes very itchy and inflamed. The worm also releases toxic substances that form small ulcers or blisters on the skin. Through these blisters, the worm's tail end comes out to release its young. This whole process causes severe local inflammation, swelling, and pain. After the worm has emerged, these blisters usually heal within a few days. The worm can sometimes be very long.

Treatment:
The primary treatment for Guinea worm disease involves carefully and slowly removing the worm from the body. In many communities, this is done by gently wrapping a small part of the worm around a stick and gradually pulling it out a few centimeters each day over several weeks. This method needs to be performed with extreme caution because if the worm breaks inside the body, it can lead to severe pain, swelling, and further infection. In some cases, surgical removal may be necessary. Preventing contamination of drinking water is the best long-term solution.

🎯 Exam Tip: For parasitic diseases, know the specific parasite, its life cycle stage causing symptoms, and traditional or modern methods of removal and prevention.

 

Answer (continued):
4. Cancer:
Cancer is a complex and serious disease characterized by the uncontrolled growth and division of cells in the body. While normal cells divide in a regulated manner, cancerous cells lose this control, leading to the formation of abnormal masses called tumors. This disease can affect almost any organ or tissue.

Types of Tumors:
Tumors are broadly classified into two types:

• Benign Tumors: These are non-cancerous growths. They usually remain localized at their original site and do not spread to other parts of the body. Benign tumors are generally not life-threatening.
• Malignant Tumors: These are cancerous tumors. They have the ability to invade surrounding tissues and spread to distant parts of the body through a process called metastasis, forming new secondary tumors. Malignant tumors are harmful and can be fatal.

Causes of Cancer (Carcinogens):
Factors that can transform normal cells into cancerous cells are known as carcinogens. These include:

• Radiations: Both ionizing radiation (like X-rays and gamma rays) and non-ionizing radiation (like ultraviolet or UV rays) can damage DNA and contribute to cancer development.
• Physical Stimuli: Chronic physical irritation or inflammation over a long period can also increase cancer risk. For example, the use of a traditional warming device called Kangri in Kashmir has been linked to certain cancers.
• Chemical Factors: Various chemical substances are known carcinogens. These can include hormones like testosterone and estrogen, nicotine and other compounds in tobacco products, certain heavy metals, and substances like mustard gas.
• Biological Factors: Some viruses, termed oncoviruses (e.g., Epstein-Barr virus, Human Papillomavirus, SV-40 virus), and specific genes called oncogenes (proto-oncogenes that have mutated) can lead to cellular changes that result in cancer.

Diagnosis:
Early detection of cancer is crucial and involves several methods:

• Observation of Symptoms: Doctors look for persistent symptoms like unusual swellings, non-healing sores or blisters, abnormal discharges from body openings, unexplained lumps, recurring indigestion or stomach irregularities, persistent constipation or diarrhea, sudden and unexplained weight loss, or chronic coughs and sore throats.
• Biopsy: A definitive diagnostic method where a small sample of suspicious tissue is surgically removed and examined under a microscope by a pathologist to identify cancerous cells. This helps determine the type and grade of cancer.
• Medical Imaging: Techniques such as X-rays, Computed Tomography (CT) scans, and Magnetic Resonance Imaging (MRI) are used to visualize internal organs, identify tumors, and assess their size and spread.
• Blood and Bone Marrow Examination: For certain cancers like leukemia (blood cancer), diagnosis may involve counting specific blood cell types or examining bone marrow. Specific antibodies against cancer-specific antigens can also be used for detection.

Treatment:
Cancer treatment plans are often multimodal, combining different approaches:

• Surgery: This involves the physical removal of the tumor and surrounding cancerous tissue. It is most effective when cancer is localized.
• Radiotherapy: High-energy radiation beams are directed at the tumor to destroy cancer cells or shrink tumors. It can be used alone or in conjunction with other treatments.
• Chemotherapy: This involves using powerful drugs that kill rapidly dividing cells, including cancer cells. Chemotherapy can have systemic side effects, such as hair loss (alopecia) and anemia, because it affects healthy rapidly dividing cells too.
• Targeted Therapy and Immunotherapy: These newer treatments specifically target cancer cells based on their genetic or molecular characteristics, or they boost the body's own immune system (e.g., using interferons) to fight off cancer.

In simple words: Cancer is when body cells grow out of control, forming lumps called tumors. It can be caused by radiation, certain chemicals, viruses, or genes. Doctors find it using scans and biopsies. Treatment includes cutting out the tumor, radiation, or medicines, and sometimes uses the body's own defenses.

🎯 Exam Tip: For comprehensive answers on diseases like cancer, always structure your response with clear headings covering definition, types, causes, diagnosis, and treatment. Providing specific examples for each point strengthens your answer.

 

RBSE Class 12 Biology Chapter 40 Essay Type Questions

 

Question 1. Name Non-communicable diseases. Explain any two of them in detail.
Answer:
Non-Infectious Diseases:
Non-infectious diseases are conditions that are not caused by infection from pathogens like bacteria, viruses, or parasites, and therefore, they cannot be spread from person to person. They usually develop due to a combination of genetic factors, lifestyle choices, and environmental exposures.

Cancer (Detailed Explanation):
Cancer is a broad term for a group of diseases characterized by abnormal cell growth with the potential to invade or spread to other parts of the body. Unlike normal cells, which follow a controlled cycle of growth and division, cancer cells divide without regulation. This uncontrolled multiplication often leads to the formation of masses of tissue called tumors. Cancer can originate in any part of the body.

Types of Tumors:
Tumors are typically categorized into two main groups:

• Benign Tumors: These are non-cancerous growths. They remain localized to their point of origin and do not invade nearby tissues or spread to distant sites. Benign tumors are generally not dangerous and can often be removed without recurrence.
• Malignant Tumors: These are cancerous tumors. They have the dangerous ability to infiltrate and destroy surrounding healthy tissues. Malignant cells can also break away from the original tumor and travel through the bloodstream or lymphatic system to form new tumors in other parts of the body, a process known as metastasis.

Causes of Cancer (Carcinogens):
The agents or factors that trigger the transformation of normal cells into cancerous ones are known as carcinogens. These include:

• Ionizing and Non-ionizing Radiations: Exposure to certain types of radiation, such as X-rays, gamma rays, and ultraviolet (UV) rays, can damage cellular DNA and contribute to cancer development.
• Physical Stimuli: Chronic physical irritation or inflammation over a long period can also increase cancer risk. For example, using traditional warming devices like the Kangri in Kashmir has been associated with skin cancers.
• Chemical Factors: Many chemical substances are known carcinogens. These can include hormones like testosterone and estrogen, nicotine and other compounds in tobacco products, certain heavy metals, and substances like mustard gas.
• Biological Factors: Certain viruses, termed oncoviruses (e.g., Epstein-Barr virus, Human Papillomavirus, SV-40 virus), and specific genes called oncogenes (proto-oncogenes that have mutated) can lead to cellular changes that result in cancer.

Diagnosis:
Detecting cancer early is vital for effective treatment. Diagnosis involves:

• Clinical Observation: Recognizing general symptoms like unexplained lumps, sores that do not heal, abnormal bleeding or discharge, persistent indigestion, sudden weight loss, or chronic cough.
• Biopsy: A definitive diagnostic method where a small sample of suspicious tissue is surgically removed and examined under a microscope for the presence of cancer cells. This helps determine the type and grade of cancer.
• Medical Imaging: Techniques such as X-rays, Computed Tomography (CT) scans, and Magnetic Resonance Imaging (MRI) are used to visualize internal organs, identify tumors, and assess their size and spread.
• Molecular and Blood Tests: Specific blood tests can detect tumor markers or abnormal cell counts (e.g., in leukemia). Advanced molecular biology tools can identify specific genetic mutations or protein markers associated with different cancers.

Treatment:
Cancer treatment plans are customized and often involve a combination of therapies:

• Surgery: This is performed to physically remove the tumor and surrounding cancerous tissue. It is most effective when cancer is localized.
• Radiotherapy: High-energy radiation beams are directed at the tumor to destroy cancer cells or shrink tumors. It can be used alone or in conjunction with other treatments.
• Chemotherapy: This involves using powerful drugs that kill rapidly dividing cells, including cancer cells. Chemotherapy can have systemic side effects, such as hair loss (alopecia) and anemia, because it affects healthy rapidly dividing cells too.
• Targeted Therapy and Immunotherapy: These newer treatments specifically target cancer cells based on their genetic or molecular characteristics, or they boost the body's own immune system (e.g., using interferons) to fight off cancer.

In simple words: Non-communicable diseases are not spread by germs. Cancer is one such disease where cells grow out of control, forming lumps called tumors that can spread. It is caused by things like radiation, chemicals, viruses, and genes. Doctors find it using tests and scans. Treatment includes cutting out the tumor, radiation, medicine, or using the body's own defense.

🎯 Exam Tip: When explaining non-communicable diseases like cancer in detail, remember to clearly define the disease, differentiate between tumor types, list various causes (carcinogens), describe diagnostic methods, and outline the different treatment options. Provide specific examples where possible to enhance your explanation.

 

Question 3. What are communicable diseases? Explain any two communicable diseases.
Answer: Infectious diseases are caused by germs like bacteria, viruses, and other small organisms. These diseases can easily spread from one person to another. They can be transmitted through air, food, water, direct body contact, or by insects that carry germs.

Here are two examples of communicable diseases:
1. **Leprosy (Hansen's Disease):** This disease is caused by the bacterium *Mycobacte-rium leprae*. It mainly affects the nervous system, muscles, and skin. Symptoms can take a long time to appear, usually between 1 to 7 years. Leprosy spreads through discharge from wounds, and close contact with an infected person can also transmit it. The disease causes deformities in fingers and toes. There are different types of leprosy, like tuberculoid (where the patient has good immunity and gets scales and twisted limbs) and lepromatous (where immunity is weaker, and bacterial cells form lumps and many wounds on the skin). To prevent spread, affected patients should be kept separate, and their clothes and belongings should not be shared.
2. **Tuberculosis (TB):** This infectious disease is caused by *Mycobacterium tuberculosis*. These bacteria most commonly infect the lungs, but they can affect any body part. TB spreads mainly through tiny droplets when an infected person coughs or sneezes, and also through contaminated water. The bacteria release a toxin called tuberculin that harms body tissues. Symptoms include a decrease in appetite, leading to weakness. Germs spread when an infected person coughs, spits mucus, or sneezes. When a healthy person breathes in these germs, they can get infected, especially if their immune system is weak. Sometimes, blood may appear in the sputum. Prevention involves taking special care, isolating the sick person, cleaning their clothes and utensils by boiling, and properly disposing of sputum and stool in the soil. Not sharing items like hookahs, beedis, or cigarettes also helps. Complete prevention is possible with the BCG (Bacille Calmette Guerin) Vaccine. These diseases highlight the importance of hygiene and public health measures.
In simple words: Communicable diseases are illnesses that spread from one person to another, often by germs. Examples like leprosy and tuberculosis show how different bacteria can cause serious health problems affecting various body parts and how important it is to prevent their spread.

🎯 Exam Tip: When explaining diseases, always mention the cause (pathogen), how it spreads (transmission), main symptoms, and possible prevention or treatment methods for full marks.