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(i) The fluids secreted by major and minor salivary glands constitute saliva. 

(ii) Saliva is slightly acidic and its pH is 6.8 

(iii) Saliva is a mixture of water and electrolytes (Na⁺ K⁺,Cl⁻, HCO₃⁻) derived from blood plasma, mucous, serous fluids and salivary amylase or ptyalin enzyme and lysozyme (antibacterial agent), secreted by salivary glands. 

(iv) Ions of thiocyanate are also present in saliva.

(b) (P – ii ) ( Q – iv ) ( R – i ) (S – iii)

Identify the odd one sucrase.

Jaundice is caused due to hepatitis viral infection.

When digestion takes place in a cavity of alimentary canal, lined by cells it is known as extracellular digestion.

1. I asked my teachers, “Why is he working outside?” 

2. He asked me, “Is the world so poor that it cannot give me a toy and a book, instead of forcing me to take a gun or a tool?”

Sometimes chyme is squeezed into oesophagus. This causes burning of some cells and is called heart burn.

Castillo, Caraballo and Luis Rengifo were the three shipmates whom Velasco saw.

He was a bold and confident person who was not ready to give up till the end.

No. The life raft was almost two meters away and it was very heavy in that lurching sea and he had to row against the wind. So he was unable to reach Herrera.

Correct Answer is: (c) Dentin

Piles / haemorrhoids

The dilations of colon are called Haustra.

Caraballo, with Castillo clinging to his neck was struggling hard to swim towards the raft.

Caraballo had vanished with Castillo hanging on to his neck.

Enterokinase.

Swallowing of food is called deglutition.

Intestinal glands: These are formed by the surface epithelium of the small intestine. 

These are of two types: Crypts of Lieberkuhn and Brunner's glands. 

(i) (a) The crypts of Lieberkuhn are simple, tubular structure which occur throughout the small intestine between the villi. 

(b) They secrete digestive enzymes and mucus. 

(c) The mucus is secreted by the goblet cells. 

(d) These crypts have at the base paneth cells and argentaffin cells. 

(ii) (a) The Brunner's glands are found only in the duodenum and are located in the submucosa. 

(b) They secrete a little enzyme and mucus. 

(c) The mucus protects the duodenal wall from getting digested. 

(d) Digestion of most of nutrients take place in the duodenum under the action of various enzyme.

Rice contains starch. The digestion of starch takes place in the mouth or buccal cavity. The saliva contains salivary amylase enzyme, which converts about 30 percent of starch into maltose, isomaltose and dextrin. The pancreatic juice also contains amylase, which acts upon the remaining starch and changes it into glucose and fructose. The intestinal juice also acts upon maltose, isomaltose and converts them into glucose.

When milk reaches the stomach, protein digestion starts. Pepsin stimulates the digestion of proteins in milk. HCI activates pepsinogen into pepsin. It hydrol ses soluble casein into paracasein to make solid curd, i.e., coagulation of milk. Reinin, a milk coagulating enzyme is secreted as pro-rennin but in presence of HCl it is hydrolysed into active rennin. Rennin hydrolyses casein into paracasein to milk coagulation.

Amador Caraballo and Castillo had almost reached the raft when a huge wave struck.

Later, the narrator un-derstood that they had vanished with the waves.

The main constituents of food are carbohydrates, proteins, nucleic acids and fats.

The old worn out red blood corpuscles are broken down in the liver cells. Their haemoglobin is changed into bile pigments.

Velasco tried to row towards Rengifo to rescue him. However, he was not successful. He sank forever less than two meters from the oar.

The detoxifies toxic substances Liver.

Differences between chylomicrons and micelles:

The food which has been digested and absorbed by the blood passes through the liver. If a person who has consumed some poisonous substance, its traces would naturally go to the liver. Hence liver cells are chemically examined during post mortem to know the contents of the cells of liver.

Apart from bile secretion, the liver also performs several funactions. 

• Destroys aging and defective blood cells. 
• Stores glucose in the form of glycogen or disperses glucose into the blood stream with the help of
• pancreatic hormones.
• Stores fat soluble vitamins and iron.
• Detoxifies toxic substances.
• Involves in the synthesis of non-essential amino acids and urea.

Kupffer cells.

Glisson’s capsule.

No, all the other shipmates were drowned.

(d) liver cirrhosis

The sun was hot and metallic.

The Velasco splashed water on his head as he had lost his cap and the sun was burning his head and skin.

The arrangement of teeth in each half of the upper and lower jaw in the order of I, C, P and M can be represented by the dental formula. The dental formula of man is 2123 / 2123.

Velasco was startled because he saw a halfmoon shaped wound on the lower part of his knee.

The vestibule is slit like space bounded externally by lips and internally by the gums and teeth.

A gold ring, a watch, a chain with a medal of the Virgin of Carmen, keys to his locker, three business cards, etc were the items in the list of his belongings.

Solving the MCQ Questions of Why Do We Fall Ill. MCQ Questions can be of extreme help as you will be aware of all the concepts. These MCQ Questions pave for a quick revision of the Chapter thereby helping you to enhance subject knowledge. 

Students can solve these MCQ Questions for Class 9 with Answers and assess their preparation level. Students are advised to practice the Class 9 Science MCQ Questions of Why Do We Fall Ill available here. MCQ Questions for Class 9 Science with Answers are prepared as per the Latest Exam Pattern.

Students can clear up NCERT Class 9 MCQ Questions Science with answers to understand their preparation level.

Practice MCQ Questions for class 9 Chapter-Wise

1. Which one of the following is not a viral disease?

(a) Dengue
(b) AIDS
(c) Typhoid
(d) Influenza

2. Which one of the following causes kala-azar?

(a) Ascaris
(b) Trypanosoma
(c) Leishmania
(d) Bacteria

3. Vectors can be defined as

(a) animals carry the infecting agents from sick person to another healthy person
(b) microorganisms which cause many diseases
(c) infected person
(d) diseased plants

4. Which disease is not transmitted by mosquitoes?

(a) Dengue
(b) Malaria
(c) Brain fever or encephalitis
(d) Pneumonia

5. Viruses, which cause hepatitis, are transmitted through

(a) air
(b) water
(c) food
(d) personal contact

6.  Sleeping sickness is caused by ..........., a protozoan.

(a) Trypanosoma
(b) Euglena
(c) Plasmodium
(d) Amoeba

7. Suzan’s grandfather is suffering from tuberculosis. In which category will you put his disease?

(a) Chronic and acute both
(b) She cannot predict anything from this information.
(c) Chronic
(d) Acute

8. The vector for Yellow fever is:

(a) Mosquito
(b) Flea
(c) Housefly
(d) Rat

9. Which of the following bacteria cause peptic ulcer?

(a) Helicobactor chlolecystus
(b) Helicobactor salomonis
(c) Helicobactor pylori
(d) Helicobactor hepaticus

10. Jaundice is a disease of 

(a) kidney
(b) liver
(c) pancreas
(d) duodenum

11. Which one of the following has a long term effect on the health of an individual?

(a) Common cold
(b) Chicken pox
(c) Chewing tobacco
(d) Stress

12.  A condition of failure of function of kidney to form urine is

(a) Creatinine
(b) Hematuria
(c) Alkaptoneuria​
(d) Anuria

13. You are aware of Polio Eradication Programme in your city. Children are vaccinated because

(a) Vaccination kills the polio causing microorganisms
(b) Prevents the entry of polio causing organisms in the body
(c) It creates immunity in the body
(d) All of above

14. Cholera is an infectious, fatal disease caused by the bacterium which lives and multiplies in the small intestine. The disease sometimes occurs in epidemic form. Which of the following is not a reason for the spread of the disease?

(a) Breeding of the flies on the garbage heaps
(b) Use of spices in food
(c)Drinking the contaminated water
(d) Consuming the contaminated food

15. TAB-vaccine is used to provide immunity against Typhoid for a period of three years.What is the correct abbreviation of TAB?

(a) Typhoid-Paratyphoid A and B Vaccine
(b) Typhoid-Partialtyphoid A and B Vaccine
(c)Typhoid-Peroxytyphoid A and B Vaccine
(d) Typhoid-Pertyphoid A and B Vaccine

16. Infectious diseases are the diseases that can spread from infected person to the healthy person. Which of the following can make you ill if you come in contact with an infected person?

(a) Genetic abnormality
(b) Blood cancer
(c) High blood pressure
(d) Sneezing and coughing

17. Which one of the following deficiency disease?

(a) Diabetes
(b) Malaria
(c) Goitre
(d) Tetanus

18. Identify a protozoan disease –

(a) Ringworm
(b) Measles
(c) Diphtheria
(d) Amoebiasis

19. BCG’ vaccine is given to infants for protection against –

(a) Diarrhoea
(b) Cholera
(c) Pneumonia
(d) Tuberculosis

20. Which one is not a sexually transmitted disease?

(a) AIDS
(b) Gonorrhoea
(c) Syphilis
(d) Diabetes.

Answer: 

1. Answer : (c) Typhoid

Explanation: Typhoid is a bacterial infection that can lead to a high fever, diarrhea, and vomiting. It can be fatal. It is caused by the bacteria Salmonella typhi. The infection is often passed on through contaminated food and drinking water, and it is more prevalent in places where handwashing is less frequent.

2. Answer : (c) Leishmania

Explanation: Kala azar is caused by bites from female phlebotomine sandflies—the vector (or transmitter) of the leishmania parasite. The sand flies feed on animals and humans for blood, which they need for developing their eggs.

3. Answer :(a) animals carry the infecting agents from sick person to another healthy person

Explanation:  A vector is an organism that does not cause disease itself but which spreads infection by conveying pathogens from one host to another. A "vector" in this sense is a vehicle for delivering genetic material such as DNA to a cell. 

4. Answer :  (d) Pneumonia

Explanation: Pneumonia is a disease that is not transmitted by the mosquitoes. Pneumonia refers to various pulmonary infections that are caused by viruses, fungi, and bacteria. The bacteria Diplococcus pneumoniae is the predominant causative agent of pneumonia.

5. Answer : (b) water

 Explanation: The hepatitis A virus is transmitted primarily by the faecal-oral route; that is when an uninfected person ingests food or water that has been contaminated with the faeces of an infected person. In families, this may happen through dirty hands when an infected person prepares food for family members.

6 . Answer : (a) Trypanosoma

Explanation:  African Trypanosomiasis, also known as “sleeping sickness”, is caused by microscopic parasites of the species Trypanosoma brucei. It is transmitted by the tsetse fly (Glossina species), which is found only in sub-Saharan Africa.

7. Answer : (c) Chronic

Explanation:  The most common types of chronic disease are cancer, heart disease, stroke, diabetes, and arthritis.

8. Answer : (a) Mosquito

Explanation: Yellow fever virus (YFV), an arthropod-borne virus in the genus Flavivirus of the family Flaviviridae, is the etiologic agent of yellow fever.

9. Answer : (c) Helicobactor pylori

Explanation: The most common causes of peptic ulcers are infection with the bacterium Helicobacter pylori (H. pylori) and long-term use of nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen (Advil, Motrin IB, others) and naproxen sodium (Aleve).

10. Answer : (b) liver

Explanation: Hepatocellular jaundice occurs as a result of liver disease or injury. Hemolytic jaundice occurs as a result of hemolysis, or an accelerated breakdown of red blood cells, leading to an increase in the production of bilirubin. Obstructive jaundice occurs as a result of an obstruction in the bile duct.

11. Answer : (c) Chewing tobacco

Explanation: It is a chronic disease that causes long term effects on an individual. Stress can be caused by many sudden changes and situations in our life. It is easy to handle and does not cause long-term effects on humans. 

12. Answer : (d) Anuria

Explanation: A condition of failure of the kidney to form urine is called Anuria or enuresis.

13. Answer : (c) It creates immunity in the body

Explanation: It is particularly critical that sick children and newborn babies are immunized because their immunity levels are lower than those of other children. All sick children and newborns should be immunized during the polio campaigns to give them the protection against polio that they desperately need.

14.  Answer : (b) Use of spices in food

Explanation: A bacterium called Vibrio cholerae causes cholera infection. The deadly effects of the disease are the result of a toxin the bacteria produces in the small intestine. The toxin causes the body to secrete enormous amounts of water, leading to diarrhea and a rapid loss of fluids and salts (electrolytes).

15. Answer : (a) Typhoid-Paratyphoid A and B Vaccine

Explanation: The vaccine TAB is used for the prevention of Typhoid. This vaccine helps in preventing typhoid, paratyphoid A and the paratyphoid B.

16. Answer : (d) Sneezing and coughing

Explanation: Infectious diseases are transmitted from person to person by direct or indirect contact. Certain types of viruses, bacteria, parasites, and fungi can all cause infectious diseases. Malaria, measles, and respiratory illnesses are examples of infectious diseases.

17. Answer : (c) Goitre

Explanation: The most common cause of goiters worldwide is a lack of iodine in the diet.

18. Answer :(d) Amoebiasis

Explanation: Amoebiasis, a type of gastro, is a cause of diarrhoea among travellers to developing countries. It is caused by a parasite known as Entamoeba histolytica that infects the bowel. Amoebiasis most commonly affects young to middle-aged adults. Proper handwashing helps prevent the spread of amoebiasis.

19. Answer : (d) Tuberculosis

Explanation: Bacille Calmette-Guérin (BCG) is a vaccine for tuberculosis (TB) disease. This vaccine is not widely used in the United States, but it is often given to infants and small children in other countries where TB is common. BCG does not always protect people from getting TB.

20. Answer : (d) Diabetes

Explanation: Sexually transmitted diseases (STDs), or sexually transmitted infections (STIs), are infections that are passed from one person to another through sexual contact. The contact is usually vaginal, oral, and anal sex. But sometimes they can spread through other intimate physical contact.

Click here to more practice  MCQ Question of Why do we fall ill class 9

i = \(\frac{2}{2}\), c \(\frac{1}{1}\),pm = \(\frac{0}{0}\), m\(\frac{2}{2}\) x 2 = 20

It is responsible for the secretion of water and bicarbonate as well as inhibition of gastric mobility digestive enzymes as well as hormones secretes digestive enzymes as well as hormones.

The narrator resigned himself to the fact that he was alone at sea and had no food and water.

In the duodenum pancreatic juice and bile juice are discharged by the pancreas and liver respectively. The pancreatic juice is secreted by pancreas and is brought to the duodenum through pancreatic duct. The pancreatic juice contains three enzymes: i.e., Trypsin, Amylase and Lipase.

Bilirubin and biliverdin

I fell ill twice in the last one year. The disease, I first suffered from was diarrhoea and secondary the dengue fever.

(a) The changes I brought in my habits after suffering from these diseases to protect myself in near future are

(i) I will always drink clean, pure water and wash hands before eating anything.

(ii) I will live in clean surroundings where disease spreading vectors could not multiply. For example, mosquitoes.

(b) Pure drinking water should be available always. The intake of impure water is the main cause of many infectious diseases.

In the last one year, I had illness for two times. I was suffering from cold, dysentery and skin disease.
(a) As per the doctor’s advice we should take injections and medicines and nutritious food.
(b) Our surrounding should be clean, neat and tidy. We should drink filtered water, we must follow health tips such as exercises and walking etc.

Bile serves the following functions: 

(i) Sodium bicarbonate present in bile neutralizes HCl of chyme. 

(ii) Sodium glycocholate and sodium taurocholate break the large fat droplets into the smaller ones. 

(iii) Its salts help in the absorption of fat and fat-soluble vitamins. 

(iv) Bile pigments are excretory products.

(i) Salivary amylase or ptyalin hydrolyses starch into maltose isomaltose and α-dextrins.

Starch \(\underset{Amylase}{\stackrel{Salivery}{\rightarrow}}\) maltose + Isomaltose +  α− dextrins

(ii) Bicarbonate ions in saliva neutralise the acids in food. The lysozyme present in saliva act as anti-microbial agent and prevent infection by the microbes.

The absorbed nutrients finally reach the tissues which utilize them for their activities. This process is called assimilation.