Disease and its Causes Questions in English

(N/A) Symptoms that help in identifying that a baby is sick include:
- Redness of eyes
- Drooping of eyes
- Continuous crying
- High body temperature (fever)
$(b)$ Signs that help indicate the specific sickness in a baby:
- High fever,headache,muscular pain,and shivering indicate malaria.
- Loose motions and stomach pain indicate diarrhea.
- Redness and persistent rubbing of eyes indicate eye flu (conjunctivitis).
- Pale skin,yellow urine,and yellowing of eyes indicate jaundice.
- Doctors suggest laboratory tests if there is fever without other clear symptoms to identify the specific nature of the sickness.

(D) Elephantiasis, also known as filariasis, is a disease characterized by the thickening of the skin and underlying tissues, especially in the legs and male genitals. It is caused by parasitic filarial worms, specifically $Wuchereria \text{ } bancrofti$ and $Wuchereria \text{ } malayi$. These worms are transmitted to humans through the bite of infected mosquitoes. Therefore, the correct option is $D$.

(A) Typhoid is a bacterial disease caused by the bacterium $Salmonella$ $typhi$.
$AIDS$ is caused by the $HIV$ virus.
Dengue is caused by the Dengue virus.
Influenza is caused by the Influenza virus.
Therefore,Typhoid is the correct answer as it is not a viral disease.

(B) Cholera is caused by the bacterium $Vibrio \text{ cholerae}$.
Anthrax is caused by the bacterium $Bacillus \text{ anthracis}$.
Tuberculosis is caused by the bacterium $Mycobacterium \text{ tuberculosis}$.
Influenza is a viral disease caused by the influenza virus. Therefore, it is not a bacterial disease.

(D) The question asks to identify the disease $NOT$ caused by bacteria.
$A$, $B$, and $C$ (Typhoid, Anthrax, and Tuberculosis) are all caused by bacteria.
Typhoid is caused by $Salmonella \text{ } typhi$.
Anthrax is caused by $Bacillus \text{ } anthracis$.
Tuberculosis is caused by $Mycobacterium \text{ } tuberculosis$.
Malaria is caused by a protozoan parasite of the genus $Plasmodium$.
Therefore, the correct answer is $D$.

(A) The correct answer is $A$ (Malaria).
$1$. Malaria is caused by protozoans of the genus $Plasmodium$ (e.g.,$Plasmodium$ $vivax$,$Plasmodium$ $falciparum$).
$2$. Influenza is a viral disease caused by the influenza virus.
$3$. $AIDS$ ($Acquired$ $Immuno$ $Deficiency$ $Syndrome$) is caused by the $HIV$ ($Human$ $Immunodeficiency$ $Virus$),which is a retrovirus.
$4$. Cholera is a bacterial disease caused by the bacterium $Vibrio$ $cholerae$.

(B) Kala-azar,also known as visceral leishmaniasis,is caused by the protozoan parasite $Leishmania$ $donovani$.
It is transmitted to humans through the bite of an infected female sandfly.

(B) The statement 'Peptic ulcers are caused by eating acidic food' is incorrect. Peptic ulcers are primarily caused by a bacterium known as $Helicobacter \text{ } pylori$, not by dietary acidity. While stress and spicy food can exacerbate symptoms, they are not the root cause.

(N/A) Acute diseases are those that last for a very short period of time. Examples: Viral fever,Common cold.
$(b)$ Chronic diseases are those that last for a long time,even as much as a lifetime. Examples: Elephantiasis,Tuberculosis $(TB)$.
$(c)$ Infectious diseases are caused by biological agents (pathogens) and can spread from an infected person to a healthy person. Examples: Smallpox,Chickenpox.
$(d)$ Non-infectious diseases are not caused by pathogens and do not spread from one person to another. Examples: Diabetes,Goitre.

(N/A) The two diseases caused by protozoans and their causal organisms are:
$(i)$ Malaria: Caused by the protozoan $Plasmodium$.
$(ii)$ Sleeping sickness: Caused by the protozoan $Trypanosoma$.
(Alternatively,Kala-azar caused by $Leishmania$ is also a correct example.)

(N/A) $(i)$ The bacterium that causes peptic ulcers is $Helicobacter \, pylori$.
$(ii)$ This pathogen was discovered for the first time by Robin Warren and Barry Marshall in $1982$.

(A-D) Hepatitis targets the liver.
$(b)$ Fits or unconsciousness targets the brain.
$(c)$ Pneumonia targets the lungs.
$(d)$ Fungal disease targets the skin.

(N/A) When the functioning or the appearance of one or more systems of the body changes for the worse,it produces certain abnormal signs of the disease. These visual or felt changes in human beings are called symptoms. Symptoms provide an indication of the presence of a particular disease.
Example $(i)$: Lesions on the skin are symptoms of chickenpox.
Example $(ii)$: Cough is a symptom of a lung infection.

(N/A) $AIDS$ stands for Acquired Immuno Deficiency Syndrome.
$AIDS$ is caused by the $HIV$ virus, which enters the body through sexual contact, blood transfusion, or other means.
Once inside, the virus spreads to the lymph nodes throughout the body and severely damages the immune system.
Because the immune system is compromised, the body can no longer fight off minor infections.
Consequently, simple infections like a common cold can escalate into pneumonia, or a minor gut infection can lead to severe diarrhoea and blood loss.
Since $AIDS$ does not present a single specific set of symptoms but rather manifests as a complex collection of various diseases and symptoms resulting from a weakened immune system, it is classified as a 'Syndrome' rather than a single disease.

(B) Nitrogen-fixing bacteria,such as $Rhizobium$,possess an enzyme called nitrogenase which is responsible for the fixation of atmospheric nitrogen into ammonia. This enzyme is highly sensitive to oxygen and is inactivated in its presence. Therefore,these bacteria require an anaerobic environment (oxygen-free) to function effectively,often provided by the protein leghemoglobin in root nodules.

(A) Non-infectious diseases are caused by factors that are not external pathogens like microbes.
These causes are typically internal or intrinsic to the body.
Examples include genetic disorders,hormonal imbalances,nutritional deficiencies,and lifestyle-related issues.
Unlike infectious diseases,these cannot be transmitted from one person to another through contact or vectors.

(N/A) $(i)$ Kala-azar is caused by the protozoan parasite $Leishmania$ $donovani$.
$(ii)$ Sleeping sickness is caused by the protozoan parasite $Trypanosoma$ $brucei$.

(A) If the bacteria enter through the nose,they travel to the lungs and cause pulmonary tuberculosis.
$(b)$ If the bacteria enter through the mouth,they can affect the gut lining and potentially spread to other organs like the liver.

(N/A) The worm found in the human small intestine is the Roundworm, scientifically known as $Ascaris lumbricoides$.
$(b)$ The bacteria responsible for causing acne is $Staphylococcus$ (specifically $Staphylococcus epidermidis$ or $Staphylococcus aureus$ strains).
$(c)$ The protozoan responsible for sleeping sickness is $Trypanosoma$ (specifically $Trypanosoma brucei$).
$(d)$ The disease caused by the protozoan $Leishmania$ is Kala-azar (also known as visceral leishmaniasis).

(N/A) $(i)$ If the lungs are infected,the person typically experiences symptoms such as a persistent cough,chest pain,and breathlessness or difficulty in breathing.
$(ii)$ If the stomach is infected,the person typically experiences symptoms such as stomach ache (abdominal pain),loose motions (diarrhea),and vomiting.

$(a)$ Mosquito bite/Skin
$(b)$ Brain
$(c)$ Sexual organs/Blood
$(d)$ Lymph nodes/Immune system
$(e)$ Nose/Mouth (Respiratory tract)
$(f)$ Lungs

(N/A)

Acute disease	Chronic disease
$(i)$ Lasts for a short period. Causes major effects on general health in a very short time.	$(i)$ Lasts for a long period. It takes a long time to cause major effects on general health.
$(ii)$ No long-term feeling of tiredness.	$(ii)$ One feels tired all the time.
$(iii)$ Weight loss does not occur and one does not become short of breath.	$(iii)$ Weight loss occurs and one becomes short of breath.

(D) $(i)$ Virus: Common cold and Influenza.
$(ii)$ Bacteria: Typhoid and Cholera.
$(iii)$ Protozoa: Malaria and Kala-azar.

(N/A) The statement implies that the site of infection is not always determined by the entry point of the pathogen. Pathogens often travel through the body to reach specific target organs.
Examples:
$(a)$ $AIDS$ causing virus: Enters through sexual contact or blood transfusion,but spreads to lymph nodes throughout the body.
$(b)$ Japanese encephalitis: The virus enters the blood through a mosquito bite but specifically targets and reaches the brain.
$(c)$ Malaria: The protozoan $Plasmodium$ enters the blood through a mosquito bite,travels to the liver,and then infects the $RBCs$ (Red Blood Cells).

(N/A) The following table lists the diseases and their respective causative agents:

Disease	Causative Agent
$(a)$ Sleeping sickness	$Trypanosoma$ (Protozoan)
$(b)$ $SARS$	Virus
$(c)$ Kala-azar	$Leishmania$ (Protozoan)
$(d)$ Acne	$Staphylococcus$ (Bacteria)
$(e)$ $AIDS$	Virus $(HIV)$
$(f)$ Dengue fever	Virus
$(g)$ Malaria	$Plasmodium$ (Protozoan)
$(h)$ Brain fever	Virus
$(i)$ Chickenpox	Virus
$(j)$ Polio	Virus

(N/A)

Signs of a disease	Symptoms of a disease
$(i)$ Signs are objective,definite indications of a disease that can be measured or observed by a physician.	$(i)$ Symptoms are subjective experiences reported by the patient,which indicate the presence of a disease.
$(ii)$ Signs are what doctors look for during a physical examination to diagnose a specific condition.	$(ii)$ Symptoms are what the patient feels (e.g.,pain,headache,nausea) and describes to the doctor.

(C) Many animals,particularly those that are ectothermic or have specific reproductive strategies,lay eggs that are highly sensitive to environmental temperature fluctuations. If the temperature deviates from the optimal range,the development of the embryo inside the egg can be severely hindered or stopped. Similarly,larvae (the immature form of many animals) are often soft-bodied and lack the complex thermoregulatory mechanisms of adults,making them extremely vulnerable to changes in temperature. Therefore,eggs and larvae are the most susceptible stages to temperature changes.

(A) Nitrogen-fixing bacteria,such as $Rhizobium$ and $Azotobacter$,possess an enzyme called nitrogenase which is responsible for the fixation of atmospheric nitrogen into ammonia. This enzyme is highly sensitive to oxygen and is irreversibly inactivated by it. Therefore,these bacteria require an anaerobic (oxygen-free) environment to function effectively. In contrast,ferns,$Chara$ (an algae),and mango trees are aerobic organisms that require oxygen for cellular respiration.

(N/A) disease is a state of physical or mental discomfort caused by the malfunctioning of any tissue,organ,or organ system.
Diseases can be classified into various types:
$(i)$ Based on duration:
- Acute diseases: Last for a short period,e.g.,$Common \ cold$.
- Chronic diseases: Last for a long period,e.g.,$Diabetes$.
$(ii)$ Based on cause:
- Infectious (Communicable): Caused by pathogens like bacteria,viruses,etc.,e.g.,$Tuberculosis$.
- Non-infectious (Non-communicable): Caused by internal factors or lifestyle,e.g.,$Cancer$.
$(iii)$ Based on origin:
- Congenital diseases: Present from birth,e.g.,$Down \ syndrome$.
- Acquired diseases: Developed after birth,e.g.,$Malaria$.

(N/A)

Viruses	Bacteria
$(i)$ They are very small.	They are larger in size compared to viruses.
$(ii)$ Non-cellular.	Single-celled.
$(iii)$ Have no metabolism of their own.	Have metabolism of their own.
$(iv)$ Do not take food by any method.	Take food by absorption.
$(v)$ Do not grow and do not divide.	Grow in size and divide to produce more bacteria.
$(vi)$ Command the host cell to produce viruses.	They can reproduce on their own.
$(vii)$ Can be crystallised.	Cannot be crystallised.
$(viii)$ All produce diseases in humans,animals,or plants.	Some are harmless,some are useful,and some cause diseases.

(D) Protozoans are single-celled eukaryotic organisms that can cause various diseases in humans.
$1$. Malaria is caused by protozoans of the genus $Plasmodium$.
$2$. Kala-azar (Leishmaniasis) is caused by the protozoan $Leishmania$ $\text{donovani}$.
Syphilis and Gonorrhoea are caused by bacteria. Allergy is an immune system response, and skin infections can be caused by bacteria or fungi. Cancer is a disease of uncontrolled cell growth, and $AIDS$ is caused by a virus $(HIV)$.
Therefore, the correct option is $D$.

(A) Typhoid is a bacterial disease caused by the bacterium $Salmonella \ Typhi$.
$AIDS$ is caused by the $Human \ Immunodeficiency \ Virus$ $(HIV)$.
Dengue is caused by the $Dengue \ virus$.
Influenza is caused by the $Influenza \ virus$.
Therefore,Typhoid is the only disease listed that is not viral.

(D) Microbes (microorganisms) are living organisms that are too small to be seen with the naked eye.
They include a wide variety of organisms such as viruses,bacteria,fungi,and protozoa.
Since both options $(a)$ (viruses and bacteria) and $(b)$ (fungi and protozoa) represent categories of microbes,option $(d)$ is the correct choice.

(C) Kala-azar,also known as visceral leishmaniasis,is a disease caused by protozoan parasites of the genus $Leishmania$.
These parasites are transmitted to humans through the bite of infected female phlebotomine sandflies.
$Ascaris$ is a genus of parasitic nematode worms (roundworms).
$Trypanosoma$ is a genus of kinetoplastids,a monophyletic group of unicellular parasitic flagellate protozoa,which causes diseases like sleeping sickness.
Bacteria are prokaryotic microorganisms that cause various diseases but are not the causative agents of kala-azar.

(A) Diseases caused by parasitic worms (helminths) are common in humans.
$1$. $Ascariasis$ is caused by the roundworm $Ascaris$ $lumbricoides$.
$2$. Many worms cause $Intestinal$ $infections$ by residing in the human gut.
$3$. $Elephantiasis$ (Filariasis) is caused by filarial worms such as $Wuchereria$ $bancrofti$.
Since all the listed options are diseases caused by different species of worms,the correct answer is $All$ $of$ $these$.

(B) The statement 'Peptic ulcers are caused by eating acidic food' is incorrect.
Scientific research, notably by Barry Marshall and Robin Warren, proved that peptic ulcers are primarily caused by the bacterium $Helicobacter \text{ } pylori$, not by acidic food.
High blood pressure is indeed linked to lifestyle factors like obesity and inactivity.
Cancers are often associated with genetic mutations or abnormalities.
Acne is primarily caused by $Propionibacterium \text{ } acnes$, not by $Staphylococci$ (which are typically associated with skin infections like boils or impetigo).
Therefore, option $B$ is the wrong statement.

(B) The statement is False.
Diseases that last for only short periods of time are known as acute diseases.
Chronic diseases are those that last for a long time,sometimes even for a lifetime (e.g.,diabetes or tuberculosis).

(TRUE) The statement is True.
Chronic diseases are illnesses that persist for a long duration,often for months or years. Because they last for a long time,they can cause significant,lasting damage to various organ systems,leading to severe long-term health consequences.
In contrast,acute diseases are short-lived and usually do not cause major long-term health complications,as the body typically recovers quickly.

(TRUE) The statement is True.
Diseases are rarely caused by a single factor. They typically result from a complex interaction of factors.
$1$. Immediate cause: The primary organism or factor that directly causes the disease (e.g.,a virus or bacteria).
$2$. Contributory cause: Factors that make an individual more susceptible to the disease,such as poor nutrition,lack of public health facilities,or genetic predisposition.
Therefore,most diseases have multiple causes rather than one single cause.

(FALSE) The statement is $False$.
High blood pressure and cancer are classified as non-communicable or chronic diseases.
$1$. High blood pressure is often caused by genetic factors,lifestyle choices (such as diet,lack of exercise,and stress),and age,rather than by infectious agents like bacteria or viruses.
$2$. Cancer is primarily caused by genetic mutations,environmental factors (such as carcinogens or radiation),and lifestyle factors,not by infectious agents (though some viruses can increase the risk of specific cancers,they are not the primary cause for most cases).
Therefore,these diseases are not caused by infectious agents.

(FALSE) The statement is $False$.
Viruses are obligate intracellular parasites,meaning they can only replicate and survive inside the living cells of a host. They are metabolically inactive outside the host cell.
Conversely,many bacteria are free-living organisms that can survive and reproduce in various environments outside of a host,such as soil,water,or decaying organic matter.

(B) Elephantiasis, also known as lymphatic filariasis, is a disease characterized by the thickening of the skin and underlying tissues, especially in the legs and male genitals.
It is caused by parasitic filarial worms, most commonly $Wuchereria$ $bancrofti$ or $Brugia$ $malayi$.
These parasites are transmitted to humans through the bite of infected mosquitoes.
Therefore, the correct option is $B$.