Know Biology With Scientific Reasons (homeostasis)


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Know Biology With Scientific Reasons (homeostasis)

  1. 1. Chapter 1 Homeostasis Osmoregulation + Excretion + Thermoregulation ⇓ HOMEOSTASISBiological reasons 1 Dr Sajid Ali Talpur
  2. 2. 1. Why plant cell does not burst even if placed in hypotonic solution? Ans. it is so because of the presence of the cell wall which as a result of turgidity develops pressure potential which as a result resists more water flow and thus preventing cell burst.2. Why marine protozoa do not contain contractile vacuole? Ans. because they are osmoconformers ( i.e. isotonic to their environment and do not exhibit osmoregulation) and since contractile vacuoles are used to expel out surplus water to maintain osmoregulation.3. Why one feels more appetite during cold conditions? Ans. Since in winter our body temperature tends to drop consequently hypothalamus becomes alert so as to enhance basal metabolic rate by consuming food as a result of thyroxine secretion so we are compelled to take more food.4. Why guttation is common in the plants growing in the tropical rain forest? Ans. since guttation involves exudation of water in drops or large quantity and it is common in tropical rain forests due to abundant water and low transpiration. Biological reasons 2 Dr Sajid Ali Talpur
  3. 3. 5. Why do plants not excrete nitrogenous wastes like animals? Ans. Because unlike their nutrition is neither proteineous nor nitrogenous secondarily their most of the waste products are reutilized.6. Why the stem and leaves of xerophyte plants become succulent? Ans. because they are the dwellers of water scarce areas so make most of the rainy season and store water for dry weather.7. Why hydrophytes do not have cuticle on their leaves? Ans. Since cuticle is used for the sake of water conservation but hydrophytes being surrounded by plenty of water don’t require cuticle, also the absence of cuticle promotes transpiration.8. Why birds, insects and reptiles excrete uric acid? Ans. Because elimination of uric acid requires a little water (i.e. the excretion of 1g of uric acid requires 1ml of water) and since they are the dweller of the water deficient areas so have switched over their excretory material to uric acid.9. How the excretion of ammonia is beneficial for aquatic animals? Ans. Being a gas firstly it diffuses swiftly secondly its elimination requires plenty of water thus the animals get rid of excess water too. Biological reasons 3 Dr Sajid Ali Talpur
  4. 4. 10. Why most of the fresh water animals produce dilute urine? Ans. Because they live in a hypotonic environment and such an external environment causes inflow of water. Subsequently to maintain osmoregulation they excrete dilute urine.11. What happens to animal cell if placed in hypotonic solution? Ans. It is burst due to over inflow of water (endosmosis)12. Why protozoan cell being animal cell does not burst even if placed in hypotonic solution? Ans. Because of the presence of contractile vacuole, protozoan easily expels excess water and protects itself from rupture.13. How shockwave lithotripsy is more advantages than ultrasonic lithotripsy? Because ultrasonic lithotripsy is more painful and ultrasonic probe is inserted through a telescopic tube while in shock wave lithotripsy shock waves are easily focused on the stones from outside the body.14. How juxtamedullary nephron is superior to cortical nephron in case of water conservation. Ans. It is so because juxtamedullary nephron has longer loop of henle which firstly causes development of ions in medulla , consequently exosmosis from collecting duct, passing concentrated urine and helping to conserve water Biological reasons 4 Dr Sajid Ali Talpur
  5. 5. 15. How vasoconstriction helps in thermoregulation? Ans. Vasoconstriction means narrowing of blood vessels towards skin in such a condition the blood does not reach the skin surface and the colder environment does not affects such a deeper blood.16. Why does filtration occur only at glomerulus part but not at any other? Ans. Because of the sieve like nature of bowman’s capsule’s walls and the raised pressure due to diminished capillaries also promotes filtration but any other part is not so modified.17. Why in plant cells during winter ice crystals are formed on cell wall instead of cytosol? Ans. Because plant cells produce unsaturated fatty acids which are mustered upon cell wall instead of cytosol.18. Why certain leaves are called excretophore? Ans. Because they accumulate excess chemicals and fall off in autumn.19. How liver is assistant of blood? Ans. Itl helps by producing various proteins like prothrombin, fibrinogen, albumin etc which help in clotting and sustain blood pressure.20. Why the urine passing from human body is hypertonic to body fluids? Ans. Because of the presence of higher number of ions across the medulla and due to the presence of Biological reasons 5 Dr Sajid Ali Talpur
  6. 6. counter current multiplier and as a result of ADH secretion the most of the water is reabsorbed from collecting duct thus turning urine hypertonic to body fluids.21. How the analysis of composition of urine comes in handy to inspect the disorders? Ans. It is helpful in such a manner that its altered composition indicates abnormalities like the presence of glucose is the indication of diabetes mellitus since the normal urine does not contain glucose. Biological reasons 6 Dr Sajid Ali Talpur
  7. 7. Biological reasons 7 Dr Sajid Ali Talpur