NEET Biology Physics Chemistry question and answer by careeradvice.in

🟢Important Points of NCERT 🟢
✨✨✨✨✨✨✨✨✨✨✨✨
1. 1770 : Joseph Priestley - Essential role of air in growth of green plant.
2. 1774 : Joseph Priestley - Discovered O2.

3. 1831 : Robert Brown - Ist discovered and described nucleus.

4. 1838 : Schleiden (German Botanist) - Work on plants.
5. 1839 : Schwann(British Zoologist) - Work on both plants & animals.

6. 1855 : Rudolf Virchow - Omnis cellula-e-cellula (cells arises from
pre-existing cells).

7. Life originate from pre-existing life : Pasteur (Yeast).

8. Life originate from non-living (decaying & rotting matter) : Spontaneous
generation.

9. Life originate from pre-existing non-living organic molecules (RNA,
Protein)- Oparin (Russia) & Haldane (England)- Chemical Evolution.

10. 1856 - 1863 : Mendal experiment on garden pea. (7 years)
11. 1860 : Julius von Sachs - Developed hydroponics.

12. 1865 : Mendal published his work.

13. 1866 : Langdon Down - Down’s syndrome.

14. 1869 : Friedrich Meischer - Ist identified DNA and named it nuclein.

15. 1891 : Henking - Discovered X-body.

16. 1891 : Fossil discovered in Java - Homo erectus.

17. 1892 : Ivanowsky - Discovered virus.

18. 1898 : Beijerinek - Contagium vivum fluidum (infectious living fluid).

19. 1898 : Camillo Golgi - Discovered (observed) G.B.

20. 1900 : de Vries, Corre ns and von Tsche rmak inde pende ntly
rediscovered Mendel’s results.

21. 1902 : Chromosome movement during meiosis has been worked out.

22. 1905 : Law of limiting factor (Blackmann).

23. 1928 : Fredrick Griffith - Transforming experiment with Streptococcus
pneumoniae (Diplococcus).

24. 1935 : Stanley - Crystallised viruses.

25. 1937 : Ramde o Misra obtained Ph.D. in Ecology from Lee ds
university (U.K.).

26. 1938 : Coelocanth fish caught in South Africa.

27. 1945 : Fleming, Chain & Florey - Awarded Nobel prize.

28. 1950 : Watson obtained Ph.D. on a study of the effect of hard X-rays
on bacteriophage multiplication.

29. 1951 : Family planning programme started in India.

30. 1952 : Hershey & Chase-experiment on bacteriophage or Bacterial virus
gives unequivocal proof that DNA is the genetic material.

31. 1953 : Miller experiment - Methane, ammonia, hydrogen & water
vapour.

32. 1953 : Watson & Crick - Double helical structure of B-DNA &
replication scheme.

33. 1953 : Palade : Discovered ribosome.

34. 1954 : Ramachandran - Triple helical model of collagen, published
in Nature.

35. 1954 : Crick complete d Ph.D. on a thesis “X-rays diffraction :
polypeptides and proteins.

36. 1958 : Meselson & Stahl - Work on E.coli proves semiconservative
replication of DNA in prokaryotes.

37. 1958 : Taylor - Work on Vicia faba proves semiconservative replication
of DNA in eukaryotes.

38. 1960 : Katherine Esau - Published “Anatomy of Seed Plants.”

39. 1961 : Melvin Calvin - Nobel Prize.

40. 1962 : Watson, Crick and Wilikins - Nobel Prize.

41. 1963 : Wheat varieties (Sonalika & Kalyan sona) introduced.

42. 1963 : Two enzyme responsible for restricting growth of bacteriophage
in E.coli were isolated.

43. 1966 : Derivative of IR-8 & Taichung native-I introduced.

44. 1969 : Whittaker - Five kingdom classification.

45. 1971 : Govt. of India legalized MTP.

46. 1971 : Diener- Discovered Viroid(free RNA without capsid).

47. 1972 : Singer & Nicolson - Fluid mosaic model.

48. 1972 : Stanley Cohen & Herbert Boyer - Formed Ist recombinant DNA.

49. 1972 : Establishme nt of NCEPC - National Committe e for
Environmental Planning & Coordination.

50. 1974 : Water act.

51. 1980 : Joint forest management, (JFM).

52. 1981 : AIDS was Ist reported.

53. 1981 : Air act.

54. 1983 : Eli Lily (An American company) produces insulin in E.coli by
recombinant DNA technology.

55. 1984 : Establishment of MOEF : Ministry of Environment & Forest.

56. 1986 : Environment Protection Act.

57. 1987 : Montreal protocol. Held in Montreal, Canada.

𝗘𝗫𝗖𝗛𝗔𝗡𝗚𝗘 𝗢𝗙 𝗚𝗔𝗦𝗘𝗦

Alveoli are the primary sites of exchange of gases.

Gaseous Exchange in Lungs

● At alveoli level, gaseous exchange occur through respiratory membrane (diffusion membrane) which is 0.2 mm thick (total thickness is much less than a mm).

● 𝗜𝘁 𝗰𝗼𝗻𝘀𝗶𝘀𝘁 𝗼𝗳 𝘁𝗵𝗿𝗲𝗲 𝗹𝗮𝘆𝗲𝗿𝘀:

(i) Alveolar epithelium (thin squamous epithelium)

(ii) Basement substance in between them (composed of a thin basement membrane supporting the squamous epithelium and the basement membrane surrounding the single layer endothelial cells of capillaries)

(iii) Endothelium of alveolar blood capillaries

● Exchange of gases also occur between blood and tissues.

● O2 and CO2 are exchanged in these sites by simple diffusion mainly based on pressure/concentration gradient

● Pressure contributed by an individual gas in a mixture of gases is called partial pressure and is represented as pO2 for oxygen and pCO2 for carbon dioxide.

🛡Sexual Reproduction♻️

➖The sexual mode of reproduction comprises the process of combining DNA from two different individuals.
➖There are two germ-cells (responsible for producing a new organism); one is large and contains the food-stores whereas the other one is smaller and likely to be motile.
➖The motile germ-cell, normally, is known as the ‘male gamete’ and the germ-cell containing the stored food is known as the ‘female gamete.’

🔰Sexual Reproduction in Flowering Plants
➖As shown in the image given below, flowers have different parts, such as sepals, petals, stamens, and carpels. Among these, stamens and carpels are the reproductive parts and contain the germ-cells.
➖Stamen is the male reproductive part, which produces pollen grains (yellowish substance).
➖Carpel, which is present in the center of a flower, is the female reproductive part.
➖Carpel is made of three parts.
➖The bottom part, which is swollen, is the ovary; the middle part, which is elongated, is known as the style; and the terminal part, which may be sticky, is known as the stigma.
➖The ovary contains ovules and each ovule has an egg cell.
➖The male germ-cell that produced by the pollen grain fuses with the female gamete present in the ovule.
➖The fusion of the germ-cells or fertilization produces zygote, which is capable of growing into a new plant.
➖The flower, which contains either stamens or carpels, is known as unisexual, such as papaya, watermelon, etc.
➖The flower, which contains both stamens and carpels, is known as bisexual, such as Hibiscus, mustard, etc.

✅Reproduction in Human Beings✅
Human beings have typical sexual reproduction process where mature male and female mate to produce a new baby.

✍️Male Reproductive System
➖The male reproductive system produces the germ-cells; further, other part of the reproductive system delivers the produced germ-cells to the site of fertilization.
➖The formation of sperms or germ-cells takes place in the testes.
➖The formation of sperm typically requires a lower temperature than the normal body temperature.
➖The testes secrete hormone, namely testosterone that brings changes in the appearance of boys at the time of their puberty.
➖The formed sperms are then delivered through the vas deferens, which unites with a tube coming from the urinary bladder.
➖The urethra, likewise, acts as a common passage for both the sperms and urine.
➖The sperms are fluids that consist of mainly genetic material; it has a long tail that helps to move towards the female germ-cell.


✍️Female Reproductive System
➖The female germ-cells or eggs are produced in the ovaries.
➖The egg is transported from the ovary to the womb through a thin oviduct known as fallopian tube.
➖The two oviducts unite and form an elastic bag-like structure known as the uterus, which opens into the vagina through the cervix.
➖During the sexual intercourse, most likely, the egg and the sperm (zygote) get fertilized and implanted in the lining of the uterus.
➖The thickened lining (of the uterus) and richly supplied blood nourish the growing embryo (in the uterus).
➖The embryo receives nutrition from the mother’s blood with the help of a special tissue known as placenta.
➖Likewise, the development of a child inside the mother’s body, takes about nine months.

Important Notes - Electrochemical Cells

► An electrochemical cell can convert electrical energy to chemical energy and can also convert electrical energy to chemical energy. There are two types of electrochemical cells- Galvanic cell and Electrolytic cell.

► Cathodes are usually metal electrodes. It is the electrode where reduction takes place. The cathode is the positive electrode in a galvanic cell and a negative electrode in an electrolytic cell. Electrons move into the cathode.

► A half-cell is half of an electrochemical cell (electrolytic or galvanic), where either oxidation or reduction occurs. At equilibrium, there is no transfer of electrons across the half cells. Therefore, the potential difference between them is nil.

► A salt bridge is a device used to connect the oxidation and reduction half-cells of a galvanic cell (a type of electrochemical cell). Strong electrolytes are generally used to make the salt bridges in electrochemical cells. Since ZnSO4 is not a strong electrolyte, it is not used to make salt bridges.

► Emf of a cell is equal to the maximum potential difference across its electrodes, which occurs when no current is drawn through the cell. It can also be defined as the net voltage between the oxidation and reduction half-reactions.

► Cell potential is an intensive property as it is independent of the amount of material present. Gibbs free energy is defined for an electrochemical cell and is an extensive property as it depends on the quantity of the material.

► Electrode potential is the tendency of an electrode to accept or to lose electrons. Electrode potential depends on the nature of the electrode, temperature of the solution and the concentration of metal ions in the solution. It doesn’t depend on the size of the electrode.

► The salt bridge connects the two half-cell solutions to complete the circuit of the electrochemical cell. The electrolytes of the salt bridge are generally prepared in agar-agar or gelatin so that the electrolytes are kept in a semi-solid phase and do not mix with the half-cell solutions and interfere with the electrochemical reaction.

► A salt bridge is a junction that connects the anodic and cathodic compartments in a cell or electrolytic solution. It maintains electrical neutrality within the internal circuit, preventing the cell from rapidly running its reaction to equilibrium.

► A Voltaic or Galvanic cell is a type of electrochemical cell that converts chemical energy into electrical energy. Photovoltaic cells are used to convert light energy into electrical energy. An Electrolytic cell is a type of electrochemical cell that converts electrical energy into chemical energy. A fuel cell is an electrochemical cell that converts the chemical energy of a fuel and an oxidizing agent into electricity.

► For all spontaneous chemical reactions, the change in Gibbs free energy (ΔG°) is always negative. For a spontaneous reaction in an electrolytic cell, the cell potential (E°cell) should be positive.

► In an electrochemical cell, when an opposing externally potential is applied and increased slowly, the reaction continues to take place. When the external potential is equal to the potential of the cell, the reaction stops. Once the externally applied potential is greater than the potential of the cell, the reaction goes in the opposite direction and the cell behaves like an electrolytic cell.

► Primary cells cannot be used again and again. Since there is no fluid inside, these cells are also known as dry cells. The internal resistance is high and the chemical reaction is irreversible. Their initial cost is cheap.

► A secondary battery (a series of cells) is one which can be charged, discharged into a load, and recharged many times. Nickel-cadmium cell, Lead storage cell and Mercury cell are examples of secondary cells. Leclanche cell is an example of a primary cell