Page 23 - Ripples SCIENCE 7 - TEJPUR Edition 2024 Answer Key

8. Differentiate between digestive canal and digestive system.

Ans. The digestive canal, also known as the alimentary canal, is the continuous, hollow
tube that runs from the mouth to the anus through which food travel during digestion.

It includes the mouth, oesophagus, stomach small intestine, large intestine, rectum
and anus.

On the other hand, the digestive system comprises the digestive canal as well as
salivary glands, liver, gall bladder and pancreas which produce enzyme and other

substances that aid in breaking down food.
G. Long-answer questions.

1. Explain the process of digestion in humans with the help of a diagram.
Ans. Digestion in humans : The process of digestion in humans involves several steps,

transforming food into nutrients the body can use.
• Ingestion: The process starts when food is taken into the mouth. Here, it is

chewed by teeth and mixed with saliva, which contains enzymes that start
breaking down carbohydrates.

The chewed food, called bolus, is
swallowed and moves down the

food pipe through a process called
peristalsis. When the food reaches

the stomach, it is mixed with gastric
juices including hydrochloric acid and

enzymes that further break down
proteins. The food now becomes a

semi-liquid mixture chyme.
• Absorption: The chyme moves into

small intestine, where complete
digestion and absorption of food

occurs. In small intestine, the food
mixes with digestive juices from the

pancreas (that provides pancreatic
juices) and bile from the gall bladder ( that helps digest fats).

The walls of the small intestine has finger-like projections called villi, that help
in the absorption of nutrients from the digested food.

• Assimilation : In this process, the absorbed food is used for producing energy
and growth. For example, amino acids are used by the cells for the synthesis of

proteins, which are needed for growth and repair.

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