Life Processes

1. What are life processes?

Processes such as nutrition, respiration, transport, and excretion that maintain an organism’s life.

2. Why isn’t visible movement the only sign of life?

Because many vital processes (e.g., molecular transport, respiration) occur invisibly even when an organism appears still.

3. Why do living organisms need continuous repair mechanisms?

Their highly organized structures tend to break down; molecular movement and energy are required to maintain and rebuild them.

4. Why must organisms obtain energy from their environment?

To fuel maintenance of order, growth, and all life processes; energy cannot be generated internally without a food source.

5. Define nutrition.

The process by which organisms obtain and utilize food for energy, growth, and repair.

6. Contrast autotrophic and heterotrophic nutrition.

Autotrophs synthesize their own food from inorganic sources (plants); heterotrophs consume other organisms (animals, fungi).

7. What raw materials do autotrophs require? What are their sources? What are their uses

1.Carbon dioxide, 2.water, 3.sunlight, 4.chorlophyll (for photosynthesis).

1.Atmospheric air through Stomata

2.Soil—>root—>xylem—>leaf

3.Sun

4.chlorplast—>green part of plants

1. Sorce of carbon and oxygen

2. Source of H

3. Energy source

4. Traps sunlight

8. Write the balanced equation for photosynthesis.

6CO2 + 12H2O ←→ C6H12O6 + 6O2 + 6H20

9. What is chlorophyll’s role in photosynthesis?

It absorbs light energy and converts it into chemical energy.

10. Where in a leaf does photosynthesis take place?

In chloroplasts within mesophyll cells.

11. What three major steps occur during photosynthesis?

Light absorption, water splitting (photolysis), and CO₂ reduction to glucose.

12. Why are stomata essential?

They allow CO₂ in for photosynthesis and release O₂ and water vapor.

13. How do guard cells regulate transpiration?

By swelling or shrinking to open or close stomatal pores, balancing gas exchange and water loss.

14. What is translocation?

Movement of sugars from leaves to other plant parts via phloem.

15. Explain saprophytic nutrition.

Fungi and some bacteria secrete enzymes onto dead matter, digest externally, and absorb nutrients.

16. Describe parasitic nutrition.

Parasites live on/in hosts, deriving nutrients at hosts’ expense (e.g., Cuscuta, tapeworm).

17. What is holozoic nutrition?

Ingestion and internal digestion of solid foods, as in most animals.

18. How does Amoeba feed?

Engulfs food by extending pseudopodia to form a food vacuole for digestion.

19. How does Paramecium obtain food?

Cilia sweep food into its oral groove, forming food vacuoles for digestion.

20. What experiment shows the action of salivary amylase?

Mix starch solution with saliva; iodine turns from blue-black to no color, indicating starch breakdown.

21. What is peristalsis?

Rhythmic contractions of digestive tract muscles that propel food forward.

22. Which organ produces pepsinogen, and what activates it?

Gastric glands secrete pepsinogen, activated to pepsin by HCl in the stomach.

23. Why does the stomach secrete mucus?

To protect its lining from acidic gastric juices.

24. What is the role of bile?

Emulsifies large fat droplets into smaller ones, increasing lipase action.

25. Where is bile produced and stored?

Produced in the liver, stored in the gallbladder.

26. Name two pancreatic enzymes and their functions.

Trypsin (digests proteins) and lipase (breaks down fats).

27. What are villi and why are they important?

Finger-like projections in the small intestine that increase surface area for absorption.

28. What enters blood capillaries in villi?

Glucose, amino acids, and other water-soluble nutrients.

29. How are fats absorbed?

Into lacteals (lymph capillaries) as fatty acids and glycerol, then into bloodstream.

30. What is egestion?

Removal of undigested food (feces) from the body via the anus.

31. Define respiration (biological).

Biochemical breakdown of food to release energy (ATP).

32. Differentiate breathing and cellular respiration.

Breathing is physical gas exchange; cellular respiration is metabolic ATP production.

33. What is aerobic respiration?

Oxygen-dependent oxidation of glucose to CO₂ and H₂O, yielding \sim38 ATP.

34. Write the equation for aerobic respiration.

C₆H₁₂O₆ + 6 O₂ \longrightarrow 6 CO₂ + 6 H₂O + energy

35. What is anaerobic respiration?

Oxygen-independent breakdown of glucose, producing less ATP and by-products like ethanol or lactic acid.

36. Name the products of yeast fermentation.

Ethanol and CO₂.

37. What accumulates in muscles during strenuous exercise?

Lactic acid, causing cramps and fatigue.

38. Where does glycolysis occur?

In the cytoplasm.

39. Where do the Krebs cycle and electron transport chain occur?

In mitochondria.

40. What is ATP and why is it called the energy currency?

Adenosine triphosphate stores energy in phosphate bonds and releases it upon hydrolysis.

41. How much energy is released by ATP hydrolysis?

\sim30.5 kJ/mol

42. Why do red blood cells have no mitochondria?

To maximize space for hemoglobin and prevent them from consuming the oxygen they transport.

43. What causes the alveoli to remain inflated?

Surfactant reduces surface tension; residual volume of air keeps alveoli open.

44. Explain gas exchange in alveoli.

O₂ diffuses into blood (high alveolar, low blood concentration); CO₂ diffuses out.

45. What mechanism drives inhalation?

Diaphragm contracts (flattens) and intercostals lift ribs, increasing thoracic volume, lowering pressure.

46. What drives exhalation?

Diaphragm and intercostals relax, decreasing volume, increasing pressure, pushing air out.

47. What is double circulation?

Blood flows through the heart twice: pulmonary circuit (to lungs) and systemic circuit (to body).

48. Why is double circulation efficient?

It separates oxygen-rich and poor blood, maximizing O₂ delivery.

49. Name the four chambers of the heart.

Right atrium, right ventricle, left atrium, left ventricle.

50. What prevents backflow in the heart?

Valves: atrioventricular valves (tricuspid, bicuspid) and semilunar valves (pulmonary, aortic).

51. What is systolic pressure?

Blood pressure during ventricular contraction.

52. What is diastolic pressure?

Blood pressure during ventricular relaxation.

53. What is a normal adult blood pressure?

\sim120/80 mm Hg

54. What are arteries?

Vessels carrying blood away from the heart under high pressure; thick, elastic walls.

55. What are veins?

Vessels carrying blood toward the heart; have valves and thinner walls.

56. What are capillaries?

One-cell-thick vessels where exchange of gases, nutrients, and wastes occurs.

57. What is the function of plasma?

Transports nutrients, hormones, wastes, and CO₂ in dissolved form.

58. What do white blood cells do?

Defend the body against infection.

59. What do platelets do?

Initiate blood clotting to prevent blood loss.

60. What is lymph and its function?

Tissue fluid that drains into lymphatics, returning excess fluid to blood and aiding immunity.

61. What are lymph nodes?

Small glands that filter lymph and house lymphocytes for immune response.

62. Why is blood red?

Hemoglobin in RBCs binds O₂ and gives blood its red color.

63. How is CO₂ carried in blood?

As bicarbonate ions (\sim70%), bound to hemoglobin (\sim20%), and dissolved (\sim10%).

64. What adaptations do fish gills have for gas exchange?

Large surface area of lamellae and counter-current flow of water vs. blood.

65. Define transport in plants.

Movement of water, minerals, and food through xylem and phloem.

66. What comprises the xylem?

Vessels, tracheids, xylem parenchyma, and fibers.

67. What comprises the phloem?

Sieve tubes, companion cells, phloem parenchyma, and fibers.

68. What drives water absorption by roots?

Osmosis: soil water enters root hair cells with higher solute concentration.

69. What is root pressure?

Upward push of xylem sap due to continuous osmotic water entry in roots.

70. What is transpiration pull?

Suction created by water evaporation from leaves, drawing water upward.

71. How do trees transport water to great heights?

Combined root pressure (minor), capillarity, and transpiration pull (major).

72. What is capillarity?

Rise of water in narrow tubes (xylem) due to adhesion and cohesion.

73. Why do plants wilt if transpiration exceeds water uptake?

Loss of turgor pressure due to water deficit in cells.

74. How are sugars loaded into phloem?

Active transport into sieve tubes by companion cells, increasing osmotic pressure.

75. What is phloem sap?

A solution of sugars, amino acids, hormones, and minerals moving through phloem.

76. Why can phloem flow be bidirectional?

Source-sink relationships vary; sugars move from leaves (sources) to growth/storage sites (sinks).

77. What is the pressure-flow hypothesis?

Sugars loaded at source create high pressure; unloading at sink lowers pressure, driving flow.

78. How do deciduous trees use leaf fall for excretion?

They store waste materials in leaves and shed them, removing wastes from the plant body.

79. What excretory products do leaves release?

Gases (O₂, CO₂), water vapor, and latex in some species.

80. What are lenticels?

Spongy areas in bark that allow gas exchange in woody stems.

81. Define excretion.

Removal of metabolic waste products from the body.

82. What are the major excretory products in humans?

CO₂ (lungs), urea (kidneys), water, salts, and sweat (skin).

83. What structures comprise the human urinary system?

Two kidneys, two ureters, urinary bladder, and urethra.

84. What is a nephron?

The functional filtration unit of the kidney.

85. What is glomerular filtration?

Blood pressure forces plasma (minus proteins) through glomerular walls into Bowman’s capsule.

86. What is selective reabsorption?

Useful substances (glucose, amino acids, some salts, water) are reabsorbed into blood from the tubule.

87. What is tubular secretion?

Additional unwanted substances (drugs, H⁺, K⁺) are secreted from blood into the tubule.

88. What is the path of urine formation?

Bowman’s capsule → proximal tubule → loop of Henle → distal tubule → collecting duct → ureter → bladder → urethra.

89. How does ADH regulate urine concentration?

Anti-diuretic hormone increases water reabsorption in collecting ducts, producing concentrated urine.

90. Why is the loop of Henle important?

It establishes a concentration gradient in medulla, enabling water reabsorption in collecting ducts.

91. What is a dialysis machine?

An artificial kidney that filters wastes from blood when kidneys fail.

92. How often must dialysis be performed?

Typically 2–3 times per week, \sim4–5 hours per session.

93. What waste products do plants excrete?

O₂ (photosynthesis), CO₂ (respiration), water vapor, resins, latex, gums, and mineral salts into soil.

94. How do stem bark cells handle waste?

Store resins and gums in old xylem, isolating toxins from living tissues.

95. Why do some plants produce aromatic oils?

As metabolic by-products, sometimes serving defense or pollen attraction, later lost to the atmosphere.

96. What excretory role does transpiration play?

Removes excess water and dissolved minerals from leaves.

97. How do plant root exudates affect soil?

They release organic acids, enzymes, and wastes that can mobilize nutrients or inhibit microbes.

98. What happens to fallen leaves and fruit?

They decompose, returning waste compounds to the soil, completing the excretion cycle.

99. What is gutkha chewing’s effect on human excretion?

Increases toxin load, causing kidney strain and requiring more frequent detoxification.

100. Why does exercise increase breathing and sweating?

To expel excess CO₂ (respiration by-product) and regulate body temperature via sweat (excretion of water and salts).