Grade 7 Science - Respiration in Organisms

'S Grade 07 U Chapter Notes YJ B  'S Class Notes U Respiration in Organisms YJ Grade 7 B 65  Topics to be Covered Respiration 1.1 Aerobic Respiration 1.2 Anaerobic Respiration 'S Breathing 2.2 Resp...

'S Grade 07 U Chapter Notes YJ B  'S Class Notes U Respiration in Organisms YJ Grade 7 B 65  Topics to be Covered Respiration 1.1 Aerobic Respiration 1.2 Anaerobic Respiration 'S Breathing 2.2 Respiratory Tract U 2.3 Inhalation vs Exhalation Breathing in Other Animals 3.1 Cockroach YJ 3.2 Earthworm 3.3 Fish 3.4 Frog Respiration in Plants B 66  Mind Map In Yeast In Muscle Cells Inhalation Vs Respiratory Aerobic Anaerobic Exhalation Tract 'S Respiration Breathing U YJ Respiration in Organisms B Respiration in Breathing in Plants Other Animals Stomata Roots Cockroach Frog Earthworm Fish 67  1. Respiration The cells require energy to perform various functions, and it is provided by the process known as respiration. The food we consume has stored energy, which is released during respiration. This process of breakdown of food in the cell with the release of energy is known as cellular respiration. Cellular Respiration 'S Digested Oxygen food U Blood Blood Energy + Water + CO2 YJ 1.1 Aerobic Respiration 1.2 Anaerobic Respiration Anaerobic respiration occurs in the absence of oxygen. a) In anaerobes like Yeast, food is broken down into B In aerobic respiration, food alcohol and carbon is broken down in the dioxide. presence of oxygen. Glucose → Energy + Alcohol + CO2 Glucose + O2 → Energy + H2O + CO2 b) In our muscle cells, during heavy exercise, anaerobic respiration yields Lactic acid and energy. Glucose → Energy + Lactic Acid 68  2. Breathing Breathing involves taking in oxygen-rich air (inhalation) and giving out carbon dioxide-rich air (exhalation) with the help of respiratory organs. 2.1 Respiratory Tract Path taken by air in the respiratory tract: 'S Nostrils → Nasal Cavity → Pharynx → Trachea → Lungs Lungs are present in the chest cavity, which is surrounded by ribs. The diaphragm forms the floor of U the cavity. Nostril Nasal cavity Pharynx YJ Trachea Ribs Lungs Diaphragm B Fun Fact The number of times a person breathes in a minute is termed as breathing rate. It is normally 15-18 times a minute and increases to 25 times during heavy exercise. 69 2.2 Inhalation vs Exhalation Inhalation Exhalation The ribs move up and The ribs move down outwards and inwards Diaphragm moves down Diaphragm moves up Space in the chest cavity Space in the chest cavity 'S increases and air rushes decreases and air is into the lungs. pushed out of the lungs. U Air Moves in Air Moves out Ribs move Ribs move YJ outwards inwards Diaphragm Diaphragm moves down moves up B Activity When a person breathes through a straw placed in a container with freshly prepared lime water, the lime water turns milky. Lime water The cause of this is the CO2 experiment present in the exhaled air. 70  3. Breathing in Other Animals 3.1 Cockroach Cockroaches have small openings on the sides of their bodies called spiracles. They also possess a network of tubes called the trachea. Oxygen enters through the spiracles into the tracheal tubes and diffuses into the body tissues. Similarly, 'S carbon dioxide from the cells move out through the spiracles. U Tracheae Spiracles YJ 3.2 Earthworm Earthworms breathe through their moist skin. B The moist skin of earthworms helps the gases easily pass through them. O2 CO2 71 3.3 Fish Gills in fish help them to use oxygen dissolved in the water. Gills are projections of the skin. Gills They are supplied with blood vessels for exchange of gases. 'S 3.4 Frog Frogs have a pair of U lungs like human beings. They can also breathe Skin through their moist skin YJ underwater. 4. Respiration in Plants B CO2 Plants also take in oxygen from the air to break down O2 CO2 glucose to CO2 and H2O. O2 In leaves, tiny pores called stomata allow this exchange of gases. Open In roots, the air is taken up stomata from air spaces present between the soil particles. 72