Different Ways of Taking Food: Ingestion in Humans and Amoeba

Sample Questions

Ques. Write a note on digestion system parts in humans. (5 Marks)

Ans. Humans take in food from the mouth, then digest it in the digestive system, and then utilize it. The unused substance is considered as waste and it was given out as excreta. The digestion begins from the buccal cavity, then the esophagus, also known as the food pipe.

Mouth and buccal cavity: Intake of food is from the mouth, also called ingestion. Using the teeth humans break complex substances into small substances. Each tooth rooted in separate sockets Saliva in the mouth helps to break down starch into sugar. The tongue is a fleshy muscular organ attached to the back floor of the buccal cavity and is free in the front.

Esophagus: It runs along the neck and chest. The moment of the wall of the food pipe help to push the food downwards

Stomach: It is a thick-walled bag in the shape of a flattened J and is the widest part of the alimentary canal. The inner lining of the stomach secretes mucus along with hydrochloric acid and other digestive juices.

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Small intestine: It is 7.5meters long and largely coiled. It gets its secretion from the pancreas and liver. Digested food is passed into the blood vessels of the small intestine, this is called absorption. The inner walls of the small intestine have finger-like projections called the villi. 

Large intestine: It is shorter and wider as compared to the small intestine. It is 1.5 meters in length.It absorbs water and salts from undigested food. The waste then passes through the rectum. 

Ques. Write the different modes of ingestion with examples. (4 Marks)

Ans. 

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Ques. How are ingestion and digestion different? (3 Marks)

Ans. Ingestion is the way food or drinks are taken in by an organism. In other words, the process of consuming food into the digestive system. Due to different anatomy, the method of digestion is different for every species of organism. The two most common methods are chewing and swallowing. Humans ingest food through the mouth and chew to break the complex substances into simpler ones for better digestion. 

Humans take in food from the mouth, then digest it in the digestive system, and then utilize it. The unused substance is considered as waste and is given out as excreta. The digestion begins from the buccal cavity, then the esophagus, also known as the food pipe. The food then passes to the stomach, then the small intestine, then to the large intestine. In the end, the waste is excreted out from the anus.

Ques. Write a note on digestion in grass-eating animals. (3 Marks)

Ans. Cows and buffaloes swallow the grass and store it in a part of their stomach called the rumen. Here the food is semi-digested. The patricianly digested food is called a curd. Later when the cow is resting the curd is returned to the mouth in small lumps. 

It is then chewed by the cow. This process is called rumination and the animal is known as the ruminant. The grass is rich in cellulose, bacteria present in the rumen help to digest it. Humans can’t digest cellulose. Animals like horses and rabbits have large sac called caecum having the bacteria needed for digestion. 

Ques. Draw and write a note on digestion in Amoeba. (4 Marks)

Ans. Amoeba is a single-cell organism commonly found in pond water. They have a cell member, nucleus, and small bubble-like vacuoles in their cytoplasm. They keep changing their shape while moving. 

It forms finger-like projections called pseudopodia for movement and to capture food. The pseudopodia are used to engulf food. They feed on microscopic organisms. The food is then trapped in the food vacuole. Digestive juices there break the food into simpler substances. Then the digested food is absorbed. Undigested food is expelled out by the vacuole. 

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Ques. Explain the absorption process in the small intestine. (4 Marks)

Ans. The small intestine is 7.5meters long and largely coiled. It gets its secretion from the pancreas and liver. Bile juice is secreted by the liver, it plays an important role in the digestion of fats. While pancreatic juices help in digesting carbohydrates, fats, and proteins. Carbohydrates get broken into glucose, fats are broken into fatty acids and glycerol. While proteins are broken into amino acids. 

Digested food is now passed into the blood vessels of the small intestine, this is called absorption. The inner walls of the small intestine have finger-like projections called the villi. Villi helps to increase the surface area of absorption. Singular projections are called villus and each villus has a network of thin small blood vessels close to the surface. The blood vessels transport the absorbed substances to different organs of the body, where they build complex substances like proteins, which is called assimilation.

Ques. Write a note on digestive enzymes in the small intestine. (4 Marks)

Ans. Secretin- a hormone that is secreted by S cells of the small intestine (duodenum) in response to the acidity developed in the gastric chyme. It helps to maintain the pH level in the intestine.

Cholecystokinin- It is a peptide secreted by the ‘I cells’ in the small intestine containing high fat and protein. It is also responsible for decreasing gastric activity and allowing the pancreatic juices to neutralize the acidic content of the gastric chyme.

Gastric Inhibitory Peptide- This peptide is produced by the mucosal cells present in the small intestine and is responsible for minimizing gastric motility.

Motilin- This hormone increases gastrointestinal motility.

Maltase- It converts maltose into glucose.

Sucrase- It converts sucrose into glucose and fructose.

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