Page 25 - Ripples SCIENCE 7 - TEJPUR Edition 2024 Answer Key

Liver: Liver produces bile, which is stored in the gall bladder and released into the

small intestine. Bile helps in the emulsification of fats, breaking them down into

smaller parts so that enzymes can act on them more efficiently.
Pancreas: Pancreas secretes pancreatic juice into the small intestine. This juice

contains a variety of digestive enzymes, such as amylase (for carbohydrates), lipase

(for fats) and proteases (for proteins), which further break down the food particles
into their constituent nutrients.

5. Discuss the role of small intestine in digestion.
Ans. The small intestine plays a crucial role in digestion. In small intestine, the digestion

of food continues with the help of digestive juices. These juices come from the

pancreas, liver and the walls of the small intestine itself.
Pancreatic juice contains enzymes that break down proteins, fats and carbohydrates.

Bile from the liver, stored in the gall bladder, helps in breaking down fats into smaller
forms, making them easier to digest.

Also, the structure of small intestine helps in digestion. It is lined with tiny, finger-like

projections, called villi, that increase the surface area for digestion. Villi help in the
absorption of nutrients.

As digested food passes through the small intestine, nutrients like glucose, amino acids

and fatty acids and glycerol are absorbed through villi and enter the bloodstream.
This allows the nutrients to be transported to various parts of the body.

The muscles of the small intestine contract and relax in a process called peristalsis

that helps to mix the digestive juices with food and push it along the intestine.
6. How do amoeba derives its nutrition from its surroundings? Explain with the help of

labelled diagram.
Ans. Amoeba moves around in its environment that can be water or moist soil. It can

detect food particles, such as bacteria or tiny plant matter, in its surroundings .

As it encounters a food particle, it extends parts of its cell membrane to surround and
engulf the food. These extensions are called pseudopodia, which means “false feet”.

Pseudopodia engulfs the food particle and form a food vacuole.
Once the food particle is inside the food vacuole, the amoeba releases digestive

enzymes into the vacuole. These enzymes break down the food particle into smaller,

soluble nutrients.
The digested nutrients are then absorbed. These nutrients provide the energy and

materials the amoeba needs for growth and other life processes.

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