Life process notes class 10 science (Part - 2)

RESPIRATION

The process of releasing energy from food is called Respiration. It involves taking in O2 into the cells, using it for releasing energy by burning food and then eliminated the waste products from body of human. It is essential process for life because it provides energy for carrying out the entire organism alive.

Breathing and Respiration

·       The mechanism by which organism obtain O2 from air and release CO2 is called as breathing. While respiration includes breathing and oxidation of food in cells of organism to release energy.

·       Breathing is physical process while respiration is a biochemical process that requires many enzymes.

·       Breathing involves with the lungs. While the respiration involves with the mitochondria of cells where food is oxidised.

·       Respiration is just opposite to the photosynthesis. Because photosynthesis makes food by using CO2, water and sunlight and releasing O2 where as respiration breaks food (like glucose) by using O2 and release CO2, water and energy.

Energy produced during respiration is stored in the form of ATP molecules in the cell of body of human.

·       ADP + IP + Energy ATP (from respiration)(stored energy in cells)

·       ATP ADP + IP + Energy (for use in cell)

Initial steps of glucose breakdown occur in the cytosol and results in the production of pyruvic acid (1 molecule of glucose give rise two molecules of pyruvic acid.)

·       This pathway does not require oxygen. Fate of pyruvic acid determined by the presence or absence of O2. when O2 is not available pyruvic acid breakdown as an aerobically to produce either – ethyl alcohol and H2O in case of yeast and plant body or lactic acid in case of animal body cells this is three carbon compound.

If oxygen is available pyruvic acid enters in mitochondria and breakdown aerobically and proceeds the kerb cycle. It results the complete breakdown of pyruvic acid resulting in the release of CO2 & H2O.

Types of Respiration

1.    Aerobic respiration is that which carried out in the presence of oxygen. Here the glucose molecule completely breakdown into CO2 and water. It produces large amount of energy that stored in the form of ATP molecules. Mitochondria are the sites of aerobic respiration in the cells.

Glucose Glycolysis Pyruvic acid kerb cycle CO2 + H2O + 38ATP

(1 molecule) In cytosol (2-molecules) presence of O2

2.    Anaerobic respiration is that which takes place in absence of O2. Microscopic bacteria and some yeast obtain energy by this method. In this glucose breakdown into the ethanol and CO2 and release energy. This energy is then used by m/o. It produces much less energy.

Glucose glycolysis Pyruvic acid yeast femantation C2H5OH + CO2 + 2ATP

(1-molecule) In cytosol (2- molecules) absence of O2.

At some time anaerobic respiration takes place in human muscles mainly during vigorous physical exercise when oxygen gets used up faster in muscle cells than supplied by blood.

Glucose Glycolysis Pyruvic acid absence of O2 2lactic acid + 2ATP (1 molecule) In cytosol (2-molecule) Muscles

Respiration in plants

Respiration in plants occurs at a slow rate. On the other hand, respiration in animals occurs at a much faster rate. During respiration in plants, there is a little transport of respiratory gases from one part of the plant to the other. On the other hand, respiratory gases are usually transported over long distances inside an animal during respiration.

Respiration in roots

Air presents in b/w the particles of soil. Roots of plants take the O2 required for respiration by the process of diffusion. Oxygen diffuses in root hairs and reaches all other cells of root for respiration. Carbon-di-oxide gas is produced in the cells of root during the respiration moves out through the same root hairs by process of diffusion.

It is noted that land plant die if their roots remain water logged for a considerable time. This is because too much water expels O2 from soil particle. Due to this, oxygen is not available to roots for aerobic respiration so roots respire an-aerobically, producing the alcohol that kill the plant body.

Respiration in stems

The hard and woody stems of big plants or trees do not have stomata. In woody stems bark has lenticles for gaseous exchange. The oxygen from air diffuses into the stem of a woody plant through lenticles and reaches all the inner cells of the stem for respiration. CO2 produced are also diffuse out through it.

Respiration in leaves

Exchange of respiratory gases in the leaves takes place by the process of diffusion through the stomata. Oxygen from air diffuses in respiration in leaves occurs during the day time as well as at night. On the other hand photosynthesis occurs only during the day time.

Day time when photosynthesis occurs O2 is produced. Leaves use some of this O2 for respiration and rest of O2 diffuses out into air during day time, CO2 produced by respiration is all used up in photosynthesis by leaves. Even more CO2 is taken in from air. Thus net gas exchange in leaves during day time is; O2 diffuse out & CO2 diffuse in.

Night time when no photosynthesis occurs and hence no O2 is produced, O2 from air diffuses into leaves to carry to carry out respiration and CO2 produced by respiration diffused in and CO2 diffused out.

Respiration in Animals

·       In simple cellular (unicellular) animals like amoeba respiration takes place by the simple diffusion of gases through cell membrane.

·       Earthworm used their skin to absorb O2 from air and remove CO2.

·       Aquatic animals like fish, prawn have gills as respiratory organs which extract O2disolved in water.

·       Insect like grasshopper, cockroach, housefly & a mosquito have tiny holes called spiracles on their body and air tubes called trachea for respiration.

·       Respiratory organs of land animals such as man, birds, lizard, dog, and frog etc, are the lungs.

Respiration in Human being

Respiratory system in human being consists of two components: - Respiratory tract & Respiratory organs.

a)   The respiratory tract acts as a passage way for fresh air to flow from outside to the lungs and produced air from lungs to the exterior. Respiratory tract includes external nostrils nasal cavities, pharynx larynx & trachea. Respiratory tract is not concerned with the gaseous exchange. Trachea has rings of cartilage that prevent collapse of trachea.

b)  Respiratory organs are lungs which provide surface for exchange of gases. Lungs are pair in number, and lies in thoracic cavity. Lungs remain enclosed by pleura. In lungs major bronchi further divide into secondary bronchi which in tertiary bronchi and finally into bronchioles. Each bronchioles divides into smaller alveolar ducts that enter in air sac

Respiratory system is closely surrounded by the network of blood capillaries.

Voice box

It is also called larynx. It is an enlarged upper part of trachea, before puberty, it is similar in both series. In males it protrudes out and often called Adam’s apple, Vibration in vocal cord result in production of sound which is converted into speech by help of tongue.

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