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CBSE Notes Class 7 Science Chapter 9 Life Processes in Animals
All living organisms perform certain basic activities to stay alive. These activities are called life processes. In animals, important life processes include nutrition, respiration, circulation, excretion, and movement. This chapter helps students understand how these processes take place in animals and how different organs work together to keep the body functioning properly.
Students learn about nutrition, respiration, circulatory system and excretion. Organs like the kidneys play an important role in this process. Movement and response to stimuli are also discussed, showing how animals react to changes in their surroundings.
This system helps transport oxygen, nutrients, and waste materials throughout the body. This CBSE Class 7 Science chapter builds a strong foundation for understanding human biology and encourages students to take care of their health.
1.0Download CBSE Class 7 Science Chapter 9 Notes: Free PDF
Get the CBSE Class 7 Science Chapter 9 – Life Processes in Animals Notes PDF to learn about breathing, digestion, circulation, and excretion. The information is presented in a clear and organised way. Helps students review important biology ideas in a useful way.
2.0Life Processes in Animals Class 7 Science Chapter 9 – Revision Notes
Animals need food and oxygen to release energy. Nutrition, respiration, circulation and excretion work together to maintain the body's functions.
Key Concepts
- Life Processes: Basic activities that living organisms perform to stay alive, such as nutrition, respiration and excretion.
- Nutrition: The process of taking in food and using it for energy, growth and repair.
- Digestion: The breakdown of complex food into simpler substances that the body can absorb.
- Absorption: The movement of digested nutrients into the blood.
- Respiration: The process of releasing energy from food.
- Circulation: The transport of oxygen, nutrients and waste materials through the blood.
- Excretion: The removal of waste products formed inside the body.
Nutrition in Animals
- Animals obtain food from plants or other animals to meet their energy and nutritional needs.
- Digestion breaks down complex food into simpler substances that the body can absorb and use.
- The human digestive system includes the mouth, oesophagus (food pipe), stomach, small intestine, large intestine and anus. The liver and pancreas help in digestion.
- Digestion begins in the mouth, where teeth break food into smaller pieces and saliva begins the digestion of starch.
- Food moves through the oesophagus to the stomach by peristaltic movements, which are wave-like contractions of muscles.
- In the stomach, food mixes with digestive juices. The acidic environment helps digestive enzymes act on proteins.
- The small intestine is the main site of complete digestion and absorption. Digestive juices from the liver, pancreas and intestinal wall help break down food.
- The inner walls of the small intestine contain finger-like projections called villi, which increase the surface area for absorption.
- The large intestine absorbs water from undigested food. The remaining waste leaves the body through the anus.Testing for Starch in Food
- Iodine solution is used to test for starch in food.
- When iodine is added to food containing starch, it turns blue-black.
- Saliva contains an enzyme called ptyalin, which starts breaking down starch in the mouth.
- Chewing rice mixes it with saliva. Comparing the rice before and after chewing helps demonstrate the action of saliva on starch.
Digestion in Ruminants
- Animals such as cows, buffaloes and sheep are called ruminants because they bring partially digested food back into the mouth and chew it again.
- This process is called rumination.
- Ruminants have a four-chambered stomach consisting of the rumen, reticulum, omasum and abomasum.
- Their digestive system helps them digest plant food containing cellulose.
Respiration in Animals
- Respiration releases energy from food. In aerobic respiration, glucose breaks down using oxygen and produces carbon dioxide, water and energy.
- Breathing is the physical process of taking air into and out of the lungs.
- Inhalation: Air enters the lungs, the chest cavity expands and the diaphragm moves downward.
- Exhalation: Air moves out of the lungs, the chest cavity becomes smaller and the diaphragm moves upward.
- The exchange of oxygen and carbon dioxide takes place in tiny air sacs called alveoli in the lungs.
- Aerobic respiration uses oxygen, while anaerobic respiration occurs without oxygen.
- Different animals have different respiratory organs. Earthworms breathe through their skin, insects use tracheal tubes, fish use gills and humans use lungs.
Circulation in Animals
- The circulatory system transports oxygen and nutrients to body cells and helps carry waste materials away.
- The heart pumps blood throughout the body.
- Blood vessels carry blood between the heart and different body parts.
- Circulation connects the digestive and respiratory systems with the rest of the body by transporting absorbed nutrients and oxygen to cells.
Excretion in Animals
- Excretion removes waste products formed during body activities.
- The kidneys filter the blood and remove waste substances and excess water to form urine.
- The urinary system includes the kidneys, ureters, urinary bladder and urethra.
- Urine travels from the kidneys through the ureters to the urinary bladder. It leaves the body through the urethra.
- The lungs also help remove carbon dioxide during exhalation.
How Life Processes Work Together
- Nutrition supplies nutrients to the body.
- Respiration releases energy from food.
- Circulation transports oxygen and nutrients to cells.
- Excretion removes waste products formed inside the body.
- These processes depend on one another to keep the body functioning properly.
3.0Chapter 9 Terminologies to Know – Life Processes in Animals
- Nutrition: Taking in food and using it for body functions.
- Ingestion: Taking food into the body.
- Digestion: Breaking complex food into simpler substances.
- Absorption: Taking digested nutrients into the blood.
- Assimilation: Using absorbed nutrients for energy, growth and repair.
- Egestion: Removing undigested food from the body.
- Peristalsis: Wave-like muscle movements that push food through the digestive tract.
- Rumination: Bringing partially digested food back into the mouth for chewing.
- Alveoli: Tiny air sacs in the lungs where gases are exchanged.
- Excretion: Removing waste products formed inside the body.
4.0Learning Guide for Class 7 Science – Life Processes in Animals
Experiments and Observations:
- Action of Saliva on Starch: Add iodine to plain boiled rice (tube A) and to chewed boiled rice (tube B).
- Observation: Tube A turns blue-black because starch is present. Tube B shows little or no colour, because saliva has changed the starch into sugar.
- Chapati Tastes Sweet: Chew a small piece of chapati for a minute. It tastes sweet because salivary amylase turns starch into sugar.
- Model of Breathing: Use a bell jar, a rubber sheet (diaphragm) and a balloon (lungs).
- Observation: Pulling the sheet down fills the balloon, like inhalation. Pushing it up empties the balloon, like exhalation.
- Exhaled Air and Lime Water: Blow into lime water and compare with ordinary air passed through lime water.
- Observation: Lime water turns very milky with exhaled air, so it has more carbon dioxide.
Everyday Examples:
- Mouth watering at the thought of food.
- Choking when we talk while eating.
- Droplets on a mirror when we breathe on it.
- A cow chewing quietly after eating.
Revision Tips:
- Iodine turns blue-black with starch.
- Lime water turns milky with carbon dioxide.
- Diaphragm flat means inhalation. Diaphragm dome-shaped means exhalation.
- Breathing is physical. Respiration is chemical and releases energy.
Safety Rules:
- Do not swallow lime water. Blow gently and never suck through the straw.
- Brush your teeth twice a day and rinse your mouth after meals.
- Do not talk or laugh while eating.
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8.0Key Features of Chapter 9: Life Processes in Animals
- Basic Life Processes: This includes things like eating, breathing, moving blood, and getting rid of waste.
- Digestive System: Provides you how the body breaks down and absorbs food.
- Respiratory System: The respiratory system is what we use to breathe and move oxygen and carbon dioxide around.
- Circulatory System: Tells how blood moves oxygen and nutrients around the body.
- Excretory System: These are the system that gets rid of waste from the body.
- Coordination: Talks about how the nervous system controls basic body functions.