Introduction
Animals require food for their energy and growth. But, they are not capable of making food by themselves. Therefore, they have to depend on the plant kingdom for their food and nutrition. Every animal, directly or indirectly depend on plants for their nutritional needs. However, the requirements of different components of nutrients is not in equal quantity in an animal body. Some nutrients are required in very less quantity, wherein some are required in large quantity. The nutrients, which are required in less quantity in an animal body are called micronutrients or trace elements. For example, minerals and vitamins. Micronutrients are called protective food as they provide the nutrients for the body to fight disease. The nutrients, which are required in large quantity in an animal body are called macro nutrients. For example, carbohydrates, fats, proteins and water. In this chapter, we will study about the requirement of nutrients and its utilization in animals.
Feeding and Digestion in Microorganism
Microorganisms are living organisms. They require food for energy and reproduction. Some bacteria can prepare its own food, hence, they have autotrophic mode of nutrition. Some bacteria depend on other organism for their food, therefore, they have heterotrophic mode of nutrition. For example, a well-known microorganism Amoeba is single celled found in pond water. Amoeba can change its shape and position. It has finger like structure, called pseudopodia, which is used to capture the food.
Look at the following picture of food digestion in an Amoeba:
Amoeba feeds on microscopic organisms. It pushes its pseudopodia to the food particle, engulfs it and food particle is trapped in a food vacuole. Foods are digested by the digestive enzyme secretes by the vacuole. Undigested food is expelled outside by the vacuole.
There are wide varieties of microorganisms, some are useful for us, and some are not. Bacteria present in human digestive system helps in the digestion process.
They feed on food taken by us.
Amoeba feeds on which one of the following types of organism?
(a) Microscopic organisms
(b) Plants
(c) Amoeba can eat big mammals
(d) All of these
(e) None of these
Answer: (a)
Explanation
Amoeba feeds on microscopic organisms. Therefore, option (A) is correct and rest of the options is incorrect.
Consider the following statements:
Statement 1: AII microorganisms have autotrophs mode of nutrition.
Statement 2: All microorganisms have heterotrophs mode of nutrition.
Which one of the following is correct about the above statements?
(a) Statement 1 is true and 2 is false
(b) Statement 1 is false and 2 is true
(c) Both statements are false
(d) Both statements are true
(e) None of these
Answer: more... 
Feeding and Digestion process of a Grass (Plant) Eating Animal
Depending upon the food habit, animals are classified into three categories:
(i) Herbivores
(ii) Carnivores
(iii) Omnivores
The animals those who eat plants and plant's products only are known as herbivores. Animals that eat only flesh of other animals are called carnivores. And the animals that eat both plants and plant's products are called omnivores. Therefore, the grass eating animals come in the category of herbivores. Herbivores are also called primary consumer as they feed on plants and plant's products directly.
Look at the following picture of digestive system of a herbivores or grass eating animal:
These animals graze and take food through the mouth. In mouth food is mixed with saliva , secreted by the salivary glands. Teeth and tongue help in the process. This food is then transported from the mouth to the stomach, through esophagus. The largest part of the stomach is called rumen. Enzymes are secreted by the bacteria and protozoa in the rumen of the goat, for digestion. Fiber eaten by the goat is broken down into smaller substance in the rumen. It also helps to build proteins and all vitamin B needed by the goat. Undigested or partially digested food is then transported into the reticulum. Food is back transported from reticulum into the mouth for re chewing that is called chewing of cud. Vitamins are digested and absorbed by small intestine and the undigested food is expelled outside.
Which one of the following organs covers largest area in the digestive system of a grass eating animal?
(a) Small intestine
(b) Large intestine
(c) Rumen
(d) All of these
(e) None of these
Answer: (c)
Explanation
Rumen is the largest organ in the digestive system of the grass eating animal. Therefore, option (C) is correct and rest of the options is incorrect.
Which one of the following parts in the digestive system of the grass eating animal transports the partially digested food back into the mouth for re-chewing?
(a) Reticulum
(b) Rumen
(c) Large intestine
(d) All of these
(e) None of these
Answer: (a)
Explanation
Reticulum in the stomach of a grass eating animal transports partially digested food back into the mouth for re-chewing. Therefore, option (A) is correct and rest of the options is incorrect. 
Feeding and Digestion in a Human Body
Feeding and digestion in a human body starts from mouth. Food particle from the mouth is transported into stomach through the food pipe and thereafter to small intestine. After the absorption of nutrients, undigested food is transported to large intestine where small amount of salt and water is absorbed.
Look at the following picture of digestive system in the human body:
Mouth part of the Digestive System
Mouth of the human body is called buccal cavity.
Teeth in the mouth breakdown the injected food into small pieces with the help of saliva, which is secrete by salivary glands. Saliva breaks down the starch into sugars. The functions of different teeth are different. Two pairs of teeth at the front in each jaw are called incisor. Incisors work for biting and cutting of the food. A pair of teeth which is called canine works for piercing and tearing the food. There are four pairs of teeth in each jaw which work for chewing and grinding called premolars and molars respectively.
Look at the following picture of different types of teeth in the mouth of the human body:
Mouth of a human body has a tongue for tasting the injected food. Taste buds on the tongue sense the taste of the injected food and send it to the brain for identification of the kinds of taste. Specific area on the tongue senses the specific taste as shown in the picture below.
Look at the following picture of structure of tongue in the mouth of the human body:
There are huge amount of taste buds on the tongue of the human body. Salty and sweet taste buds are located at the front of the tongue. Sour taste buds are on both sides of the tongue and bitter taste buds are on the back side of the tongue. Taste buds from the tongue can disappear due to the smoking, not eating enough vitamins, head injury and effect of radiation.
Digestion of Food in the Stomach of a Human Body
Partially digested food enters into the stomach through oesophagus or food pipe. Wall of the food pipe pushes the injected food downwards into the stomach. When food pipe unable to push the injected food downward, it is vomited out. Stomach secretes, mucous, hydrochloric acid and digestive juice.
Hydrochloric acid kills bacteria present in the injected food entered into the stomach through the food pipe.
Function of Small and Large Intestine
Now food enters into the small intestine from the stomach, Villi on the wall of the more... 
Answer Figures
Solution: (d) Note the direction of arrow which changes alternately. The dots are also changing alternately. Hence we are looking for a figure in which the arrow points down and the dots positioned as in figure (b).
Example 2:
Problem Figures
Answer Figures
Solution:(b) The four boxes are changing position in the following way: At first, middle boxes change position (diagonally) and extreme boxes remain stationary, then extreme boxes change position and middle boxes remain stationary and so on.
Example 3:
Problem Figures
Answer Figures
Solution: (c) The same figures rotates up-side-down in alternative figures.
Example 4:
Problem Figures
Answer Figures
Solution: (d) The figures is rotated at 90° (in four directions) and the fifth figure in the series will be same as the first figure.
Examples 5:
Problem Figures
Answer Figures
Solution: (a) The bigger ball's diameter more... | Shape | Total no. of sides | Perimeter |
| 1. Square | 4 | 4\[\times \]length of a side |
| 2. Rectangle | 2 length 2 width | 2\[\times \]length + 2 \[\times \]width = 2 (length + width) |
| 3. Triangle (Equilateral) | 3 | 3\[\times \]length of a side |
| 4. Triangle (isosceles) | 2 equal 1 unequal | 2\[\times \]length of equal sides + 1 length of different side |
| 5. Triangle (Scalene) | 3 (all unequal) | Sum of all unequal sides |
OA & OB are arms O is vertex
SUPPLEMENTARY ANGLES
Two angles are said to be supplementary if the sum of their measures is \[180{}^\circ \] Thus, \[\angle A\] and \[\angle B\] are supplementary if \[\angle A+\angle B=180{}^\circ \]
Example: If \[\angle A=60{}^\circ \] and \[\angle B=120{}^\circ \] then \[\angle A\] and \[\angle B\] are supplementary. Since\[\angle A+\angle B=180{}^\circ \]
COMPLEMENTARY ANGLES
Two angles are said to be complimentary if the sum of their measures is\[90{}^\circ .\]
Example: If \[\angle A=46{}^\circ \] and \[\angle B=44{}^\circ \] then \[\angle A\] and \[\angle B\] are complementary, since \[\angle A+\angle B=90{}^\circ .\]
ADJACENT ANGLES
Two angles with same vertex, one common arms and the other arms lying on opposite sides of common arm are called adjacent angles.
In the figure \[\angle BOC\] and \[\angle AOB\] are adjacent angles.
LINEAR PAIR OF ANGLES
Two adjacent angles are said to form linear pair of angles if their non-common arms are two opposite rays,
\[\angle AOC\]and\[\angle BOC\]are two adjacent angles. Their non-common arm OA and OB are two opposite rays.
Two important results are obtained from linear pair of angles.
1. The sum of all angles formed on the same side of a line at a given point on the line is \[180{}^\circ \]\[\,\angle AOC+\angle COB=180{}^\circ .\]
The sum of all angles around a point is\[360{}^\circ .\] Thus\[\angle AOB+\angle BOC+\angle COD+\angle DOA=360{}^\circ \]
VERTICALLY OPPOSITE ANGLES
When two lines intersect on a point four angles are formed. Angle 1 is vertically opposite to angle 3. Angle 2 is vertically opposite to angle 4.
Note: If two lines intersect to each other vertically opposite angles are equal.
PARALLEL LINES
Two lines or line segment in a plane which do not intersect and the perpendicular distance between them remain constant are called parallel lines.
TRANSVERSAL
A line which intersects two or more more... 
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