LIFE PROCESSES
INTEXT QUESTIONSTopic - 1, Life processes
Ans: In multicellular organisms, all the cells may not be in direct contact with the surrounding environment. So, diffusion is insufficient to meet the oxygen requirements of large multicellular organisms.
Ans:- (i) Movement : It is the major criterion . It may be incurred through locomotion (running ,walking etc.), action of body parts (e.g., chewing of cud by cow), breathing , growth ( in plants), maintenance and repair of cellular structures and molecular movement in metabolic reactions.
(ii)Requirement of food for performing life processes.
(iii) Respiration and utilisation of the inhaled oxygen for oxidation of food.
(iv) Display of growth and development.
(v) expulsion of metabolic wastes (Excretion).
Ans: (i)An autotrophic organism (like a green plant) uses outside raw materials such as carbon dioxide, water and minerals alongwith sunlight to make its own food by the process of photosynthesis.
(ii) A hetrotrophic organism (like an animal) uses outside raw materials such as readymade organic food to grow, develop, synthesise proteins and other substances needed in the body.
(iii) Most of the organisms use oxygen (of air) as outside material for breaking down food and releasing energy for themselves in a process called respiration.
Ans: Nutrition, Respiration, Transport, excretion, Control and coordination, Growth, Movement and Reproduction.
Ans: The basic functions performed by living organisms to maintain their life on this earth are called life processes.
The basic life processes common to all the living organisms are;,br>
- Nutrition
- Respiration
- Transport
- Excretion
- Control and Coordination
- Growth
- Movement
- Reproduction
Topic - 2, Nutrition
Ans:-
| s.no. | Autotrophic Nutrition | Heterotrophic Nutrition |
|---|---|---|
| 1. | Food is synthesised from simple inorganic raw materials such as CO2 and water. | Food is obtained directly or indirectly from autotrophs.This food is broken down with the help of enzimes. |
| 2. | Presence of green pigments (chlorophyll ) is necessary. | No pigment is required . |
| 3. | Food is generally prepeared during day time. | Intake of food takes place at any time. |
| 4. | All green plants and some bacteria have this type of nutrition. | All animals and fungi have this type of nutrition. |
Ans : CO2 and water are the raw materials required for potosynthesis. Terrestrial plants get CO2 from environment through stomata and water from the soil through roots and transport to leaves. Aquatic plants take up CO2 that is present in dissolved form in water . Water is simply absorbed by the parts of the aquatic plant submerged in water.
Ans: The acid (hydrochloric acid ) secreted inside the the stomach makes the medium acidic which is necessary for the activation of enzyme pepsin. It converts inactive propepsin into active pepsin.Also, hydrochloric acid kils any bacteria which may enter the stomac along with food.
Ans: Disestive enzymes convert the large and insoluble food molecules into small water soluble molecules in the process of digetion.
For example , pancreas secretes enzymes like amylase, trypsin and lipase. The enzyme amylase breaks down the starch, trypsin breaks down the proteins and lipase breaks down the emulsified fats into simple sugars, amino acids and fatty acids respectively.
Ans : The inner lining of small intestine has millions of tiny finger like projections called villi.The presence of villi gives the inner walls of the small intestine a very large surface area for absorption of digested food.The villi are richly supplied with blood vessels which take the absorbed food to each and every cell of the body.
Topic - 3, Respiration
Ans: Air contains about 21% of oxygen while water has less than 1% oxygen in dissolved state.
Aquatic organisms use oxygen dissolved in surrounding water. Since air dissolved in water has fairly low concentration of oxygen , the aquatic organisms have much faster rate of breathing.
Terrestrial organisms take oxygen from the oxygen - rich atmosphere through respiratory organs. Hence, they have much less breathing rate than aquatic organisms and a terrestrial organism is able to get several times more oxygen than an aquatic organism in one breath.
Ans : First step of breakdown of glucose(C6H12O6) takes place in the cytoplasm of cells of all organisms.This process is called glycolysis. This process yields a three carbon molecule compound called pyruvate(CH3-CO-COOH).Further breakdown of pyruvate takes place in different ways in different organisms.
(i) Anaerobic respiration : The anaerobic respiration in plants (like yeast) produces ethanol (CH3-CH2-OH) and carbon dioxide (CO2) as end products.
(ii) Aerobic respiration : In aerobic respiration breakdown of pyruvate takes place in presence of oxygen to give rise three molecules of carbon dioxide and water .The release of energy in aerobic respiration is much more than in anaerobic respiration.
(iii) Lack of oxygen : Sometimes when there is lack of oxygen especially during physical exercise , in our muscles, pyruvate is converted into lactic acid [ CH3-CH(OH)-COOH ]. Formation of lactic acid in muscles causes cramp.
Ans: (i) Transport of oxygen : Haemoglobin present in the blood takes up the oxygen from the air in the lungs. It carries the oxygen to tissues which are difficient in oxygen before releasing it.
(ii) Transport of carbon dioxide : Carbon dioxide is more soluble in water. Therefore, it is mostly transported from body tissues in the dissolved form in our blood plasma to lungs. Here, it diffuses from blood to air in the lungs.
Ans :Lungs are soft, spongy structures located in the thoracic cavity. Each lung is enclosed in a double - walled sac called pleura. Within the lungs, the air passage(wind pipe) divides into smaller and smaller tubes, called bronchi which in turn form bronchioles. The bronchioles terminate in balloon - like structures , called alveoli. The alveoli present in the lungs provide maximum surface for exchange of gases. The alveoli have very thin walls and contain an extensive network of blood vessels to facilitate exchange of gases.
Topic - 4, Transportation
Ans: Transport system in human beings consists of heart, blood and blood vessels.
(i) Heart : It is the muscular organ which pumps and receives the blood.
(ii) Blood : It is a fluid connective tissue. It consists of plasma, RBC, WBC and blood platelets.
Plasma transports food, CO2 and nitrogenous wastes in dissolved form. RBCs transport respiratory gases and hormones.WBCs protect the body from infections and platelets prevent the loss of blood at the time of injury by forming blood clots.
(iii) Vessels : They are subdivided into -
(a) Arteries : Carry blood from heart to different body parts.
(b) Veins : Transport blood towards heart from various body parts.
(c) Capillaries : Site of exchange of materials between blood and living cells through tissue fluid.
Ans : Mammals and birds are warm blooded animals. They constantly use energy to maintain their body temperature. They have higher energy needs and so they require more oxygen to produce energy. Thus, it is important that their oxygenated blood does not get mixed up with deoxygenated blood .
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