Nutrition in Animals

(a) The main steps of nutrition in humans are ingestion, digestion, absorption, assimilation and egestion.

(b) The largest gland in the human body is liver.

(c) The stomach releases hydrochloric acid and digestive juices which act on food.

(d) The inner wall of the small intestine has many finger-like outgrowths called villi.

(e) Amoeba digests its food in the food vacuole.

(a) Digestion of starch starts in the stomach. (False) (It starts in the mouth).

(b) The tongue helps in mixing food with saliva. (True)

(c) The gall bladder temporarily stores bile. (True)

(d) The ruminants bring back swallowed grass into their mouth and chew it for some time. (True)

(a) Fat is completely digested in the:
(i) Stomach (ii) Mouth (iii) Small intestine (iv) Large intestine

(b) Water from the undigested food is absorbed mainly in the:
(i) Stomach (ii) Foodpipe (iii) Small intestine (iv) Large intestine

Villi: The finger-like outgrowths on the inner wall of the small intestine.

• Location: Inner wall of Small Intestine.
• Function: They increase the surface area for absorption of digested food.

Bile is produced in the Liver and stored in the **Gall Bladder**.

It helps in the digestion of Fats.

Cellulose.

Reason: Ruminants have a large sac-like structure called Rumen where certain bacteria are present. These bacteria can break down cellulose. Humans do not have these bacteria, so they cannot digest cellulose.

Glucose is the simplest form of sugar and can be easily absorbed by the blood. It does not need to be broken down further by digestion. Hence, it provides instant energy to the cells.

Similarity: Both have Holozoic mode of nutrition (Ingestion, Digestion, Absorption, Assimilation, Egestion).

Difference: Humans ingest food through mouth and have a complex digestive system. Amoeba ingests food using pseudopodia and digests it in a temporary food vacuole.

If we do not clean our teeth after eating, bacteria present in the mouth break down the sugars from leftover food and release acids. These acids gradually damage the teeth. This is called **Tooth Decay**.

ORS stands for Oral Rehydration Solution. It is a solution of sugar and salt in clean water, given to patients suffering from diarrhea to prevent dehydration.

• Ingestion: Taking food into the body.
• Digestion: Breaking down complex food into simple soluble substances.
• Absorption: Absorbing digested food into blood.
• Assimilation: Using absorbed food for growth and energy.
• Egestion: Removing undigested waste from the body.

• Buccal Cavity: Teeth chew food, Saliva breaks down starch into sugar. Tongue mixes saliva.
• Oesophagus: Pushes food down to stomach by peristalsis movement.
• Stomach: Releases HCL (kills bacteria), Mucus (protects lining), and Digestive Juices (break down proteins).
• Small Intestine: Complete digestion of carbohydrates, fats and proteins takes place here. Receives bile from liver and pancreatic juice from pancreas. Villi absorb nutrients.
• Large Intestine: Absorbs water and minerals from undigested food.
• Anus: Expels faecal matter.

• They quickly swallow grass and store it in **Rumen**.
• In rumen, food is partially digested and called **Cud**.
• Later, cud returns to mouth in small lumps and animal chews it. This is **Rumination**.
• Grass is rich in **Cellulose**. Ruminants have bacteria in rumen to digest cellulose (which humans lack).

• Single-celled organism found in pond water.
• Pushes out **Pseudopodia** (false feet) to capture food.
• Food is trapped in a **Food Vacuole**.
• Digestive juices are secreted into vacuole to break down food.

• Starfish eats animals covered by hard shells of calcium carbonate. It pops out its stomach to eat!
• Saliva breaks down Starch into Sugar.
• The length of small intestine is about 7.5 meters.