Food, Nutrition & Digestion (Chap- 5 ) Class - 9 & 10 / Biology Free Video Classes, Q/A & Worksheets

 Biology For 9 & 10 

(Chap-5)

 Food, Nutrition & Digestion

Q/A

Q.1. What are the mineral nutrients of plants?

Ans: Plants absorb certain elements from the soil, air and water for growth and nutrition. Plants can not live without these elements. These elements are called nutrients.

Q.2. How many essential mineral nutrients do plants use?

Ans: Plants use 16 essential mineral nutrients.

Q.3. What is a food pyramid?

Ans: Placing carbohydrates at the bottom and considering the quantities of vegetables, fruits, proteins, fats and oils successively, if we arrange these substances in successive tiers, it looks like a pyramid. This is called the ideal food pyramid.

Q.4. Why does Anemia occur?

Ans: Anemia is a general disease often occurring in children and females in our country. Anemia occurs when the density of haemoglobin is less than normal with respect to age and gender. This disease occurs due to the deficiency of the essential elements of food like iron, folic acid, or vitamin B -12. 

Q.5. Why does night blindness occur?

Ans: The disease Xerophthalmia occurs due to the deficiency of vitamin A. If the deficiency is not treated, the level and intensity of the disease increase. 

Q.6. Describe the structure of a tooth with diagram.

Ans: Structure of a tooth:

The tooth typically consists of three parts. As:

I) Crown : 

The part above the gum.

ii) Root: 

The inner part below the gum.

iii) Neck: 

The tooth between the crown and the root. Each tooth is composed of the following components:

a) Dentine: 

The main part of the tooth consists of hard substances.

b) Enamel: 

The crown is covered with enamel. Enamel is the hardest component of a tooth. Dentine and Enamelare composed of calcium phosphate, calcium carbonate and fluoride.

c) Pulp: 

Dentine surrounds a pulp cavity with blood vessels soft cells and nerves running through it. The blood supply nourishes dentine with nutrients and oxygen.

d) Cement: 

The main part of the tooth Dentine is covered with a thin covering, the cement. The tooth remains attached with the gums by means of this cement.

Q.7. What are the characteristics of a balanced diet?

Multiple Choice Questions.

1. Which of the following nutrients serve in a plant as a macronutrient?

a) Zinc

b) boron

c) chlorine

d) potassium

2. Chlorosis is caused by- 

i) nitrogen deficiency

ii) sulfur deficiency

iii) iron deficiency

Which one of the following is correct?

a) i & ii

b) i & iii

c) ii & iii

d) i, ii & iii

Read the stem and answer the questions number 3 and 4.
Five years old Sanjana can see all the writings in her book. But at night she can not see the writing clearly.

3. Which vitamin deficiency does Sanjana have?

a) vitamin A

b) vitamin B

c) vitamin C

d) vitamin D

4. To prevent this disease which food should Sanjana eat?

i) liver

ii) carrot

iii) Mola fish

Which one is correct?

a) i & ii

b) i & iii

c) ii & iii

d) i, ii & iii

Creative Questions

1. Dr. Raihan spends most of the time in the laboratory. So, his body weight is increasing. On the other hand, his younger brother Jahir is a regular player of the National Football Team. For that he has to play and take exercise daily.

a) What type of food is the source of nitrogen?

b) What do you mean by high protein? Explain it.

c) Which food should be in much quantity in Jahir's food chart? Explain.

d) Which type of food is not applicable for Dr. Raihan that is included in Jahir's food chart? Explain.

Ans:

a) Protein is the source of nitrogen.

b) Fish, meat, eggs, cheese, liver etc. are the source of animal protein. This kind of protein contains all the essential amino acid that’s why they are considered as high class protein. The energy value of this kind of food is very high.

c) Jahir’s daily food chart is written below according to their necessity –

Bean & kidney bean:

Amount : 30gm

It will fulfill his necessity of protein (7.2 gm), fat (0.1 gm), mineral (0.4 gm), carbohydrate (15.9 gm). It can provide 96 Kcal of energy.

ii) Egg/fish/ meat:

Amount : 30gm

Egg, fishes and meat are also full of calories and protein.

iii) vegetables: amount : 80gm

iv) Fat/oil: 

v) Milk: amount : 250 gm

All the above mentioned food should be in Jahir’s food chart because this food will help him to be physically fit and will cover all the nutrients that he needs.

2. Irfan Ali observed that the leaves of the grass in his garden were becoming yellow, and the leaves, flowers and buds of flowering plants were falling off plants. To solve these problems, he asked for help from a horticulturist, and the horticulturist suggested that Irfan Ali apply some essential nutrient elements in his garden.

a) What is a micronutrient?

b) What are the essential elements for plants? Explain.

c) Explain the causes of the problems found with the grass in Irfan's garden.

d) Evaluate the suggestions given by the horticulturist.

Digestion in the small intestine:

When the chyme enters the duodenum, two secretions, pancreatic juice from the pancreas and bile from the liver, are released through the bile from the pancreas, and bile from the liver, is released through the bile duct. Both of these secretions are alkaline in nature. Pancreatic juice neutralizes the acidity of the chyme. The enzymes of the pancreatic juice continue the digestion process of proteins and carbohydrates and start fat digestion. Bile neutralizes the acidity of the food and creates an alkaline medium. Bile salt, one of the constituents of bile, emulsifies fats, meaning it helps fat droplets to mix with water. It then becomes easier for the enzyme lipase to digest fats. The Lipase converts the fat droplets into fatty acids and glycerol.

Fats   ----------------------Lipase--------          Fatty acid    +  glycerol

Pancreatic juice contains trypsin, lipase and amylase. On the other hand, intestinal juice contains the enzymes, maltase, lactose, and sucrose. Trypsin, converts partly digested protein into amino acid and simple peptide.

    Polypeptide    ------------------Trypsin --------------   Amino acid    +  simple peptide

Amylase converts starch into simple glucose.

              Starch           --------------amylase------         glucose

Digestion:

The process whereby large food molecules are broken down into small, soluble, and diffusible molecules that can be absorbed into the body cells. The digestive system consists of the gut (alimentary canal) and the glands associated with it.

Food enters the body via the mouth which leads into the buccal cavity. Three pairs of salivary glands open into the buccal cavity and produced secretion called saliva which is emptied into the buccal cavity.

Phyrynx is a common passage for food and air. There is a possibility of food passing into the trachea during swallowing.

Oesophagus or gullet is a narrow, muscular tube containing from the pharynx through the thorax and the diaphragm to the stomach.

The stomach is a bag-like organ located in between the esophagus and the small intestine. Its wall is thick and muscular. It lies immediately beneath the diaphragm to the left side of the abdominal cavity. The inner surface of the stomach has numerous gastric glands.

The small intestine consists of a U-shaped duodenum, jejunum, and much-coiled ileum. 

Liver cells secrete bile, an alkaline greenish-yellow liquid containing bile salts. It aids in the digestion of fats. Bile is stored temporarily in the gall bladder.

The pancreas is a gland lying in the loop of the duodenum. It is connected to the duodenum by means of the pancreatic duct. It produces pancreatic juice which contains digestive enzymes. It secretes the hormone insulin which plays an important part in the control of the blood sugar level in the body and utilization of carbohydrates. 

The large intestine is shorter but much broader than the small intestine. The main function of the large intestine is to absorb water and mineral salts from the undigested food material. 

Digestive Glands:

The glands, whose secretion takes part in the digestion of food, are called digestive glands. The digestive glands in humans are as follows:

a) Salivary glands: 

There are three pairs of salivary glands. A pair of parotid glands, located in front of and below each ear, a pair of sub maxillary glands below the jaw and a pair of sub lingual glands the tongue open into the buccal cavity through various ducts. Salivary juice contains water and an enzyme named ptyalin.

b) Liver: 

The liver is situated just below the diaphragm on the right side of the stomach. It is the largest gland of the body and is deep brown in colour. The right lobe of the liver is larger than the left lobe. Each lobule contains numerous cells. These cells produce bile. Bile is alkaline in nature.

c) Pancreas:

the pancreas is an important mixed gland located obliquely at the back of the stomach. It contains the enzymes trpsin, lipase and amylase. These enzymes helps in the digestion of carbohydrates, proteins and fats.

d) Gastric glands:

The glands in the stomach wall are called gastric glands. The juice secreted from these glands (trypsin, lipase, amylase) is known as gastric juice.

e) Intestinal glands:

Villi, located in the wall of small intestine, contain intestinal glands. The secretion of these glands is known as intestinal juice.

Digestion in stomach:

When the food reaches the stomach, gastric juice is secreted from the inner wall. This juice contains the following main components.

Hydrochloric acid:

Hydrochloric acid destroys the germs coming with the food substances, converts inactive pepsinogen into active pepsin and creates an acidic medium to help its proper funcioning.

Pepsin:  

Pepsin is an enzyme which breaks protein into a compound named polypeptide which consists two or more amino acids.

Pancreatic juice neutralizes the acidity of the chyme. The enzymes of the pancreatic juice continue the digestion process of proteins and carbohydrate and starts fat digestion. It then becomes easier for the enzyme lipase to digest fats. The Lipase converts the fat droplets into fatty acid and glycerol.

  

Digestion of carbohydrates and fats do not occur in the stomach, because gastric juice does not contain any particular enzyme for the digestion of carbohydrates and fats.

Pancreatic juice contains trypsin, lipase and amylase. On the other hand, intestinal juice contains the enzymes, maltase, lactose and sucrose. Trypsin, converts partly digested protein into amino acid and simple peptide.

Constipation:

When stools become hard, or stool does not pass for two or more days, this condition is called constipation. 

Causes:

1. withholding bowel pressure

2. excessive water absorption from the undigested part of food in the colon

3. slow movement of the undigested part of the food through the alimentary canal

4. leading a lazy life

5. intestinal disorder 

6. slowing down of the contraction of colonic muscles

7. not eating food containing roughage

Effect:

a) Due to constipation the passing stool becomes difficult. This result in an uneasy feeling in the abdomen 

b) abdominal pain

c) tumours of the alimentary canal

Preventions:

a) eat fibrous food

b) drink enough water

c) regularly eat vegetables, fruits, apples, bananas, coconut, dates, oranges, papaya, pineapple eta.

d) make a habit of walking and passing of stool.

2. What is the function of Liver?

The liver is a chemical factory, a food store, and a central heating system. 

It stores glucose as glycogen. It changes this back to glucose when the body needs it.

It stores the minerals copper and potassium, as well as iron needed to make red blood cells.

It stores vitamins A, B, and D.

It makes bile, which is needed for digestion.

It takes some poisons from the blood and makes them harmless. These poisons come from germs, alcohol, and drugs.

It makes fibrinogen, which is needed for blood to clot in wounds.

It takes the goodness out of unwanted amino acids and changes what is left into a waste called urea. Urea is removed from your body by your kidneys.

 The liver produces bile. The ingredients of bile are mainly water, bile salt, cholesterol, and mineral salts. It is stored in the gall bladder. When necessary, the bile passes to the duodenum and takes part indirectly in digestion. There are no enzymes in the bile. 

Q.1. What is the structure of liver?

Ans: The liver is situated just below the diaphragm on the right side of the stomach. It is the largest gland of the body and is deep brown in colour. The right lobe of the liver is larger than the left lobe. The liver consists of four incomplete lobes. Each lobe consists of lobules. Each lobule contains numerous cells. These cells produce bile. Bile is alkaline in nature.

Different types of biochemical reactions take place in the liver. So, it is the organic laboratory. Beneath the liver the gall bladder is attached.