Life Processes

IMPORTANT NOTES

1. Every living organism has a need of nutrition as it is through nutrition that one obtains energy.

2. The process of intake and utilisation of nutrients (i.e. substances that either release energy or help in the manufacture of biomolecules) is known as nutrition.

3. Green plants are autotrophs as they synthesise their own food using sunlight, chlorophyll, carbon dioxide and water.

4. Photosynthetic equation 6CO2 + 12H2O sunlight chlorophyll --> C6H12O6 + 6H2O + 6O2

5. Chlorophyll is a light receiver which can trap solar energy within its molecule.

6. The site of chlorophyll activity is the special plant cell organelles called chloroplasts.

7. In humans the alimentary canal is basically a long tube extending from the mouth to the anus. When we eat something we like, our mouth ‘waters’. This watery fluid is called saliva secreted by the salivary glands.

8. The gastric glands present in the stomach wall of human, release hydrochloric acid, pepsin and mucus.

9. Tooth decay or dental carries causes gradual softening of enamel and dentine. Brushing the teeth after eating removes the dental plaque.

10. Factors that affect photosynthesis are
(i) Light,
(ii) Temperature,
(iii) Water, and
(iv) Carbon dioxide.

11. Animal nutrition shows a very wide range. Unicellular organisms like Amoeba obtain food by the process of phagocytosis. The human digestive system climaxes the evolutionary development of the digestive system with numerous glands, digestive juices and organs working together. The various steps of nutrition are ingestion, digestion, absorption and assimilation.

12. The energy-rich molecule in which energy is first captured is adenosine triphosphate or ATP.

13. Breathing is a physical process which involves inhalation and exhalation.

14. Respiration is a biochemical process which includes breathing and oxidation of food.

15. Respiration in the presence of oxygen is known as aerobic respiration.

16. Respiration that occurs in absence of oxygen is known as anaerobic respiration.

17. During aerobic respiration, food (glucose) is completely broken down into carbon dioxide and oxygen and energy is released in the form of ATP.

18. Aerobic respiration occurs in higher organisms including human being.

19. Anaerobic respiration occurs in certain bacteria, yeast and also in our muscles.

20. The muscles of vertebrate animals can continue working for a minute or two without oxygen.

21. Micro-organisms such as yeast and certain bacteria obtain their energy by anaerobic respiration which is termed fermentation.

22. Common type of fermentation is alcoholic fermentation which is performed by yeast.

23. Direct respiration is seen in unicellular organisms like Amoeba, Paramecium, bacteria and Chlamydomonas.

24. Diffusion is defined as the movement of a substance from a region of higher concentration to a region of lower concentration.

25. Rate of respiration in plants is much slower than in animals.

26. In higher plants, the exchange of gases occurs through stomata and lenticels.

27. Organs of respiration in animals are skin, trachea, gills, lungs, etc.

28. Thin-walled air sacs called alveoli are present in lungs.

29. The blood contains a pigment, haemoglobin, which helps in the transport of carbon dioxide and oxygen.

30. In human beings, four basic processes are involved in respiration—breathing, gaseous transport, tissue respiration and cellular respiration.

31. In the thoracic cavity, the lungs are bound by a convex muscular and elastic sheet called diaphragm.

32. Diffusion is a major method by which transportation of material occurs in single celled organisms like bacteria.

33. Diffusion is the movement of molecules from a region of higher concentration to that of lower concentration resulting in their uniform distribution.

34. The entire surface of the root is not associated with absorption of water and nutrients.

35. Only 1% to 2% of the total water absorbed by the roots, is used up in photosynthesis and metabolic activities.

36. The main process involved in the upward conduction of water and minerals is called transpiration.

37. Through transpiration pull, movement of water and minerals take place.

38. The transportation of food from the leaves to other plant parts is termed translocation.

39. In case of plants, xylem is made of tracheids and vessels. Both are thick walled with perforations in their cell wall.

40. Water and mineral salts are absorbed by root hair and are transported in the plant by xylem vessels which are long interconnected tubes.

41. Transpirational pull works as a suction force for the upward movement of the sap.

42. Long distance transportation of food material from the leaves to the other parts of the plant is known as ‘translocation’.

43. Phloem is the living tissue that translocates prepared food in aqueous solution. Phloem is made of living cells called ‘sieve tubes’.

44. In human beings the main transporter is the blood which flows in blood vessels and is pumped by the heart.

45. Blood Vessels 
Arteries (carry blood away from the heart)
Veins (carry blood  towards the heart)
Capillaries (Interconnectors between arterioles and veinules)

46. Blood Vessels
Plasma
Red blood cells
White blood cells
Platelets

47. Lymph: Lymph is also known as tissue fluid. It is another type of fluid involved in transportation. It is colourless and contains less protein. Some amount of plasma, proteins and blood-cells escape into intercellular spaces in the tissues in the form of lymph. It drains into lymphatic capillaries from the intercellular spaces. It drains excess fluid from the extra cellular space back into the blood. Lymph carries digested as well as absorbed fat from the intestine.

48. The pathway indicating the flow of blood within the human heart. The right half of the heart always has deoxygenated blood while the left half has only oxygenated blood. 

49. As the blood flows, a part of it gets filtered out of the capillary walls. This forms the lymph. Lymph — carries digested fats. — returns proteins and other fluids for circulation. — lymphocytes contribute towards immunity.

50. The waste products in animals include carbon dioxide, nitrogenous compounds like ammonia, urea and uric acid, bile pigments from the breakdown of haemoglobin, excess salts and vitamins.

51. The most poisonous of all waste by-products of metabolism is ammonia.

52. The kidneys extract urea from the blood and excrete it from the body as part of a liquid called urine.

53. Excretion of waste products is very simple and much less in plants as compared to animals.

54. Excretory system of human, mainly consists of a pair of kidneys, ureters, urinary bladder, urethra, etc.

55. Excretory organs in animals are lungs, skin, kidneys and liver.

56. An artificial kidney machine works on the principle of dialysis.

57. Dialysis is a process of separating small molecules from larger ones using a semipermeable membrane.

58. Bowman’s capsule is a cup shaped body enclosing glomerulus part of a nephron.

59. Glomerulus is a network of finely divided blood capillaries enclosed in Bowman’s capsule.

60. Structural and functional unit of kidney is nephron. The parts of a nephron are 
(a) a tuft of capillaries called ‘glomerulus’,
(b) Bowman’s capsule,
(c) extended tubular system and a collecting duct.

61. Carbon dioxide produced during respiration is carried by
(i) haemoglobin in the blood and,
(ii) water in which it gets dissolved.

62. The kidneys perform two major functions—
(i) help to remove toxic wastes like urea from the blood and thereby clean the blood,
(ii) control water balance and levels of mineral salts in the body.

63. The filtration of blood for the removal of wastes can be done by an artificial kidney, in cases of renal failure. Such a system is called ‘Dialysis’.