Nutrition in Animal.

 Nutrition in Animals

Definition: Nutrition is the process by which animals take in and use food to sustain their growth and development.

Types of Nutrition: There are different types of nutrition in animals, including holozoic nutrition, parasitic nutrition, and saprophytic nutrition.

Process of Nutrition

The process of nutrition in animals involves five stages: ingestion, digestion, absorption, assimilation, and egestion.

Ingestion: The intake of food into the body.

Digestion: The breakdown of food into simpler substances.

Absorption: The uptake of soluble substances produced during digestion by the tissues in the body.

Assimilation: The use of simple substances to build complex substances required by the body.

Egestion: The elimination of undigested food from the body.

Nutrition in Amoeba

Amoeba is a single-celled organism that obtains its nutrients by ingesting food particles.

The process of nutrition in Amoeba involves the formation of a food vacuole, digestion, absorption, and egestion.

Human Digestive System

The human digestive system consists of the alimentary canal and other organs such as the gall bladder, pancreas, and liver.

The digestive system breaks down food into simpler substances that can be absorbed and used by the body.

Types of Teeth

There are four different types of teeth:

incisors, canines, premolars, and molars.

Each type of tooth has a specific function, such as biting, tearing, or grinding food.

Digestion in Humans

Digestion starts in the mouth, where food is mixed with saliva that contains digestive enzymes.

The food then passes through the esophagus into the stomach, where it is mixed with digestive juices that break down proteins.

Further digestion takes place in the small intestine, where enzymes from the pancreas and bile from the liver are released.

Absorption and Assimilation

The nutrients absorbed in the blood are transported to the rest of the body.

The final product of carbohydrate digestion, glucose, is broken down into carbon dioxide and water in the cells to release energy.

Amino acids are used for repairing worn-out cells and tissues.

Egestion

The undigested food is eliminated from the body through the anus.

The large intestine absorbs water and minerals, and the remaining waste is stored in the rectum until it is eliminated.

Nutrition in Ruminants

Ruminants are animals that have a four-chambered stomach and digest plant-based foods.

The digestive system of ruminants involves ingestion, digestion, absorption, and egestion.

Ruminants have a unique digestive system that allows them to break down and extract nutrients from plant-based foods.

Class 8 chapter 15:Natural phenomena

 Some Natural Phenomena

### Introduction

Natural phenomena are events that occur in nature, often governed by physical laws.

Understanding natural phenomena can help us appreciate the complexity and beauty of the natural world.

### Lightning

1. Formation: Lightning is a massive electrostatic discharge that occurs during thunderstorms.

2. Safety precautions: During lightning storms, it's essential to take safety precautions like avoiding tall objects and staying indoors.

### Earthquakes

1. Causes: Earthquakes are caused by the movement of tectonic plates in the Earth's crust.

2. Effects: Earthquakes can cause destruction, tsunamis, and loss of life.

3. Precautions: During earthquakes, it's essential to take precautions like dropping to the ground and taking cover.

### Conclusion

Natural phenomena like lightning and earthquakes can be fascinating and awe-inspiring, but they also pose significant risks. Understanding these phenomena can help us appreciate the natural world and take necessary precautions.

Chemical effect of electric current.

 

Introduction

Electric current can cause chemical changes in certain substances.

These chemical changes can be used for various applications.

Electrolysis

1. Definition: Electrolysis is the process

of using electric current to cause a chemical change in a substance.

2. Examples: Electrolysis of water, electroplating, and extraction of metals.

Electroplating

1. Definition: Electroplating is the process of depositing a thin layer of a material on an object using electrolysis.

2. Applications: Electroplating is used to protect metals from corrosion, improve appearance, and enhance durability. 

Chemical Effects of Electric Current

1. Decomposition: Electric current can cause decomposition of certain substances.

2. Chemical reactions: Electric current can initiate chemical reactions, leading to the formation of new substances.

Applications

1. Electroplating: Used for decorative and protective purposes.

2. Purification of metals: Used to purify metals like copper and zinc.

3. Extraction of metals: Used to extract metals like aluminum and sodium.

Conclusion

Electric current can cause significant chemical changes in substances, and understanding these effects is crucial for various applications. 

Chapter 12 :Friction

 

Friction

Introduction

Friction is a force that opposes motion between two surfaces in contact.

Friction helps us to walk, hold objects, and stop vehicles.

Types of Friction

1. Static friction: Friction that acts on objects that are not moving.

2. Kinetic friction: Friction that acts on objects that are moving.

3. Rolling friction: Friction that acts on objects that are rolling.

Causes of Friction

1. Surface roughness: Friction is caused by the roughness of surfaces in contact.

2. Interlocking of surfaces: Friction is also caused by the interlocking of surface irregularities. 

Effects of Friction

1. Heat generation: Friction generates heat, which can be useful or harmful.

2. Wear and tear: Friction causes wear and tear of surfaces, leading to damage.

Reducing Friction

1. Lubricants: Using lubricants like oil or grease to reduce friction.

2. Smoothening surfaces: Making surfaces smooth to reduce friction.

3. Using wheels or rollers: Using wheels or rollers to reduce friction.

Conclusion

Friction is an essential force that affects our daily lives. Understanding friction and its effects can help us to reduce it and make o ur lives easier.