BIOLOGY [2 Mark Question Answer]

(i) Human Digestive System.
(ii) 1-mouth 2- esophagus 3- stomach 4- gall bladder 5- liver 6- pancreas 7- appendix 8- small intestine 9- large intestine 10-rectum 11-anus.

(i) Single Villus Enlarged
(ii) 1. Epithelium 2. Blood Capillaries 3. Lymphatic Capillary
(iii) The structure of the small intestine is designed for absorption of nutrients.

Test if a food item contains fat.
• Take a small quantity of the food item to be tested.
• Wrap the food item in a piece of paper and crush it.
• Straighten the paper.
• Dry the paper by keeping it in sunlight for a while.
• Observe the paper.
• An oily patch on the paper indicates the presence of fats in the tested food item.

Proteins can be tested by using the following methods. Take the given food sample and prepare its extract. Add the aqueous copper sulphate to the prepared food extract. A solution that turns violet in colour confirms the presence of protein in the foodstuff.

Dissolve the food item in water and take the solution in a test tube and add a few drops of benedict's solution in it. Heat it for a minute. A red precipitate will be formed at the bottom showing the presence of sugar in the given food item.

To know the presence of starch in any given sample of food, the iodine test can be performed. In this, iodine solution is used. In this, few drops of iodine solution is added to the food sample. If starch is present in a food item, it will turn blue-black colour.

Functions of the liver
• Production of bile, which helps carry away waste and break down fats in the small intestine during digestion.
• Production of certain proteins for blood plasma.
• Production of cholesterol and special proteins to help carry fats through the body.

When there is air in the pharynx, the vocal cords are vibrated and sounds are produced which allows the person to speak. When the person is eating or swallowing, the epiglottis is closed so that the food does not enter the tracheal tube. This is the reason that a person cannot swallow and talk simultaneously.

The four main types of teeth are:
• Incisors - Your incisors are eight teeth in the front center of your mouth (four on both bottom and top). ...
• Canines - Your canines are the next teeth that develop in your mouth. ...
• Premolars - Premolars are used for tearing and crushing food. ...
• Molars - Your molars are your largest teeth.

the arrangement, type, and number of the teeth in a particular species is dentition. The dental formula for the adult human beings is 2123/2123. There are 2 incisors, 1 canine, 2 premolars aand 3 molars in one row.

The walls of the small intestine absorb water and the digested nutrients into your bloodstream. As peristalsis continues, the waste products of the digestive process move into the large intestine.

The small intestine absorbs most of the nutrients in your food, and your circulatory system passes them on to other parts of your body to store or use. Special cells help absorbed nutrients cross the intestinal lining into your bloodstream.

A major digestive organ is the stomach. Within its mucosa are millions of embedded gastric glands. Their secretions are vital to the functioning of the organ. Most of the digestion of food takes place in the small intestine which is the longest part of the Gl tract.

From the esophagus, food then travels to the stomach, where it breaks down further with the help of the acids and powerful enzymes secreted by the stomach. This semi-digested food then travels down to the small intestine, where secretions from the liver, gallbladder, and pancreas further act on the food particles.

Lipase is an enzyme the body uses to break down fats in food so they can be absorbed in the intestines. Lipase is produced in the pancreas, mouth, and stomach.

Pepsin is a stomach enzyme that serves to digest proteins found in ingested food. Gastric chief cells secrete pepsin as an inactive zymogen called pepsinogen. Parietal cells within the stomach lining secrete hydrochloric acid that lowers the pH of the stomach. A low pH (1.5 to 2) activates pepsin.

Amylases digest starch into smaller molecules, ultimately yielding maltose, which in turn is cleaved into two glucose molecules by maltase. Starch comprises a significant portion of the typical human diet for most nationalities.

Dentin or dentine is a layer of material that lies immediately underneath the enamel of the tooth. It is one of the four major components of the tooth which comprises: The outer hard enamel. The dentin underneath the enamel. The dental pulp that lies soft and encased within the dentin.

Most carnivores have carnassial, or shearing, teeth that function in slicing meat and cutting tough sinews. The carnassials are usually formed by the fourth upper premolar and the first lower molar, working one against the other with a scissorlike action.

Diastema is a gap between your teeth. This can happen between any of your teeth. Because of its position, it's most noticeable when there's a gap between your upper front teeth.