Selina Concise Class 9 Biology Chapter 11 Digestive System Solutions
Digestive System
A. Solution:
1.
Answer: c) Stomach into intestine.
Explanation- Pylorus is the opening of the stomach into intestine and it is also known as Gate-keeper.
2.
Answer: a) HCL and pepsin.
Explanation- Inner lining of stomach secretes gastric juice. It is colourless and contains water, salts, HCl and pepsin enzyme.
3.
Answer: c) Colon.
Explanation- Large intestine absorbs water from the digested food and it does not secrete any enzyme. Colon is a part of large intestine.
4.
Answer: c) Premolars, molars – Grinding.
Explanation- Premolars and molars both are responsible for the crushing or grinding of food.
B. Solution:
1.
Answer:
Explanation- The dental formula of normal human adult is:
2, 1, 2, 3
————- = 32, Permanent teeth with 4 wisdom teeth
2, 1, 2, 3
2.
Answer:
Explanation- The following reflexes takes place when a person chews and swallows food:
- Saliva secretion takes place while chewing.
- While chewing, tongue is pressed on the upward side.
3. Solution:
A.
B.
Answer:
ii) Both the statements are wrong.
C. Solution:
1.
Answer:
When naturally occurred food items undergoes breakdown and converted into diffusible form, then it is called as Digestion. The food items are large compounds and cannot be utilized in the body. The food item should be in absorbable form and for this digestion is necessary. For digestion process, digestive system is required.
2.
Answer:
End product of the digestion of starch is Maltose.
End product of the digestion of proteins is Small peptides and amino acids.
End product of the digestion of Fats is Fatty acids and glycerol.
3.
Answer:
No enzymes are required to digest vitamin because the original form of vitamins is absorbed by the cell. They are absorbed by digestive tract directly and transported to the cell by blood. The vitamins are of two types i.e. some are water soluble and some are fat soluble so absorbed by the cell as it is.
4.
Answer:
The foot material or items that we eat are in the complex form. The absorption of food for the body is essential for growth and health. For this, the complex food should be in simple form. Chewing of food helps to break complex food into simple substances. The saliva which is secreted during chewing will help to moisten food. The enzymes of saliva helps in the breakdown of carbohydrates. Hence, chewing is necessary and helpful in digestion.
5.
Answer:
Rectum is 15 cm long and opens at anus. It is a temporary storage for undigested food. A circular muscle (sphincter) is present at anus and it remains closed except passing time of bowels. This is the function of rectum.
6.
Answer:
Roughage consists of cellulose and it is a dietary fibre. It is undigested material of the body. Our body does not contain of cellulose digesting enzyme. Green leafy vegetables and fruits are example of Roughage.
7.
Answer:
Following are the two ways in which ileum of mammal is adapted for the absorption of digested food:
- Ileum has more surface area and is long.
- It is single cells epithelium.
- Ileum slows food movement because it is narrow. While slowing food movement, it allows absorption.
8.
Answer:
Stomach secretes hydrochloric acid or HCl and its functions are:
- While eating, if any germ enters stomach then HCl kills them.
- It helps in the activation of pepsin which act on proteins.
D. Solution:
1.
Answer:
The vegetarian menu of dinner which contains all the necessary nutrients will include chapati or rice which contains Carbohydrates, Cereals, Green leafy vegetables, Fruits, Milk, Fat, Brown sugar.
2.
Answer:
Main characteristics of Enzymes:
- Enzymes are also known as proteins.
- It always forms same product at the end from the fixed substrate.
- Its best temperature range is 35° C to 40° C.
- It is useful again and again. It acts as Catalyst.
- It is specific and acts on one type of substance.
3.
Answer:
Small intestine is coiled in the abdomen. It has three regions Duodenum, Jejunum and Ileum. Small intestine is an important part because the absorption of digested food occurs here. The intestinal juices are secreted by glandular cells between the villi. The small intestine helps in both digestion and absorption.
It receives bile and pancreatic juices in the duodenum. So, small intestine is an important organ in the digestive system.
4.
Answer: The largest organ in the body is Liver. It is reddish brown organ.
The following functions are of liver organ in the body:
- It helps in the regulation of sugar.
- It helps in the removal of nitrogen part by amino acid break down.
- Red blood cells of the foetal are synthesized.
- It acts as storage for iron copper and several vitamin.
5.
Answer:
a)
Peristalsis: Peristalsis is defined as contraction and relaxation of circular muscle of the gut which pushes the food.
b)
Omnivore: The organisms which eat or consume plants and animals are called as Omnivore.
c)
Pylorus: Pylorus is a passage that opens into the duodenum and present at the lower end of the stomach.
d)
Kilocalorie: Kilocalorie is the energy which is required to raise the temperature of 1kg of water by 1 Celsius and is a unit of energy.
e)
Assimilation: When the digested food is converted into body material then this conversion is called as Assimilation.
6.
Answer:
Enzymes which are present in the stomach and intestine with their functions:
- Stomach: Stomach contains pepsin enzyme. It helps proteins to become polypeptides.
- Small intestine: Duodenum of small intestine contains Amylopsin, Trypsin and Steapsin. The Amylopectin is responsible for the production of maltose. Trypsin produces peptides and amino acids. Steapsin works on emulsified fats and produces fatty acid and glycerol. Ileum of the small intestine contains Erepsin, Maltase, Sucrase and lactase. Erepsin produces amino acids. Maltase act on maltose for the production of glucose. Sucrase helps to produce glucose and fructose. Lactase helps in the production of glucose and galactose.
7.
Answer:
Following are the reasons why water is necessary for our body:
- Water helps to maintain body temperature.
- Water is basic element of blood and helps to carry nutrients, oxygen to the cell.
- Water is necessary for the digestion and absorption of food.
- In the saliva and mucous, water is major component.
8.
Answer:
Test for starch:
- Take a food item in the test tube.
- Add some water and boil it to make solution.
- Once solution become cool, add few drops of iodine to the solution.
- The solution will show blue-black color. This blue and black color indicated presence of starch.
Test for Protein:
- Take a test tube with food item. Take conc. nitric acid.
- Add some drops of dilute nitric acid to the test tube.
- Heat it gently.
- Rinse off acid by using water. Add some drops of ammonium hydroxide to it.
- The colour will change to yellow then orange and then red. Red color shows presence of protein.
E. Solution:
1.
Diagram- Internal structure of mammalian tooth with two roots.
2.
Answer:
When we swallow saliva, the larynx part gets pulled on the upward to bring it close to the back of the tongue. Opening is closed by epiglottis. After this, it goes to the oesophagus.
3.
Answer:
Organ |
Enzyme | Food acted upon |
Final product |
Stomach |
Pepsin | Proteins | Polypeptide |
Mouth | Amylase | Starch | Disaccharide |
Ileum | Maltose | Maltose |
Glucose |
4.
Answer:
a)
1- Enamel
2- Dentine
3- Pulp
4- Gum
5- Crown
6-Cement
b) Solution:
In the given figure of tooth, only one root is shown. So, it can be a canine s or incisor which is useful in biting.
c) Solution:
The part 3 is of pulp. It is soft connective tissue that contains pulp cavity of the tooth. Pulp includes lymph vessels, blood capillaries and nerve fibres.
d) Solution:
Total number of type tooth and its functions are given below:
- Type of tooth are incisors, canines, premolars and molars.
- Incisors are for cutting and biting. And number of teeth are eight. Canines are four in number and helps to hold food.
- Premolars are eight in number and it crushes or grinds food.
- Molars are twelve in number and useful in grinding of food.
5.
Answer:
a)
Total number of teeth which are present in the given dentition are 20 teeth.
b)
Canines are the type of tooth and it is helpful in holding food. So, the canines are absent in the given dentition. Hence the given dentition is of herbivore.
c) Solution:
2, 1, 2, 3
————– = 32, Permanent teeth with 4 wisdom teeth
2, 1, 2, 3
Here is your solution of Selina Concise Class 9 Biology Chapter 11 Digestive System
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