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2021-07-24 15:29:31 BIӨDIVΣЯƧƬIY ΛПD ᄃӨПƧΣЯVΛƬIӨП

𝐐𝐔𝐈𝐂𝐊 𝐑𝐄𝐕𝐈𝐒𝐈𝐎𝐍 𝐍𝐎𝐓𝐄𝐒
There are about 20,000 species of ants, 3,00,000 species of beetles, 28,000 species of fishes & 20,000 species of orchids

Term biodiversity was popularised by Edward wilson

India has 50,000 genetically different strains of rice and 1000 varieties of mango

Acc to IUCN (2004), No.of species discovered and described range about 1.5 million

Robert may estimate - total no.of species is around 7 million

More than 70% of species discovered are animals

More than 70% of animals are insects

Plants constitute not more than 22% of total species

Total no.of species of fungi is more than combined total of fishes, amphibians, reptiles and mammals

India occupy 2.4% of total land surface but they contribute 8.1% of total biodiversity

There are about 45,000 species of plants and twice as many animals are discovered in india

Acc to robert estimate...only 22% of total no.of species have been discovered


There are 1,00,000 plant species and more than 3,00,000 animals species are yet to be discovered in india

Columbia has 1400 species of birds...newyork - 105 species of birds, Greenland - 56 species

India has 1200 species of birds Amazonian rain forest in south

america has 1300 species of birds, 40000 species of plants, 427 amphibians, 427 mammals, 378 reptiles, more thab 1,25,000 invertebrates

The colonisation of tropical pacific island by humans has led to the extinction of 2000 species of native birds

Over 784 species have extincted in past 500 years ( 359 invertebrates, 338 vertebrates & 87 plants )

In last 20 years, 27 species disappeared

Around 15,500 species are facing threat of extinction

32% amphibians, 31% gymnosperms, 23% mammals, & 12% birds are facing threat of extinction Open / Comment

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2021-07-23 18:07:59 Notes on s-Block Elements:

Covalent Character:.

Small cation and large anion favors covalency.

Order: LiCl > NaCl > KCl > RbCl > CsCl & . LiI > LiBr > LiCl > LiF

Greater the charge on the cation greater is its polarizing power and hence larger is the covalent character: Na+CI- < Mg+2CI2 < AI+3 CI3

Greater the charge on the anion, more easily it gets polarized thereby imparting more covalent character to the compound formed eg covalent character increase in the order. NaCI < Na2SO4 < Na3PO4

c) Lattice Energies: Amount of energy required to separate one mole of solid ionic compound into its gaseous ions.

Greater the lattice energy, higher is the melting point of the alkali metals halide and lower is its solubility in water

d) Hydration Energy: Amount of energy released when one mole of gaseous ions combine with water to form hydrated ions.

M+ (g) + aq → M+ (aq) + hydration energy

X- (g) + aq → X- (aq) + hydration energy

Higher the hydration energy of the ions greater is the solubility of the compound in water.

The solubility of the most of alkali metal halides except those of fluorides decreases on descending the group since the decrease in hydration energy is more than the corresponding decrease in the lattice energy.

Due to high hydration energy of Li+ ion, Lithium halides are soluble in water except LiF which is sparingly soluble due to its high lattice energy.

For the same alkali metal the melting point decreases in the order

fluoride > chloride > bromide > iodide

For the same halide ion, the melting point of lithium halides are lower than those of the corresponding sodium halides and thereafter they decrease as we move down the group from Na to Cs.

The low melting point of LiCl (887 K) as compared to NaCl is probably because LiCl is covalent in nature and NaCl is ionic.

Anomalous Behavior of Lithium and diagonal relationship with Magnesium:

Li has anomalous properties due to

Very small size

High polarizing Power

Lithium show diagonal relationship with magnesium because both elements have almost same polarizing power.

The melting point and boiling point of lithium are comparatively high.

Lithium is much harder than the other alkali metals. Magnesium is also hard metal.

Lithium reacts with oxygen least readily to form normal oxide whereas other alkali metals form peroxides and superoxides.

LiOH like Mg (OH)2 is weak base. Hydroxides of other alkali metals are strong bases.

Due to their appreciable covalent nature, the halides and alkyls of lithum and magnesium are soluble in organic solvents.

Unlike elements of group 1 but like magnesium. Lithium forms nitride with nitrogen.6Li + N2 → 2Li3N

LiCl is deliquescent and crystallizes as a hydrate, LiCI2H2O. Other alkali metals do not form hydrates. also forms hydrate, MgCI2.8H2O .

Unlike other alkali metals lithium reacts directly with carbon to form an ionic carbide. Magnesium also forms a similar carbide.

The carbonates, hydroxides and nitrates of lithium as well as magnesium decompose on heating.
Li2CO3 → Li2O + CO2

MgCO3 → MgO + CO2

2LiOH → Li2O + H2O

Mg (OH)2 → MgO + H2O

4LiNO3 → 2Li2O + 4NO2 + O2

2Mg ( NO3)2 → 2Mg + 4NO2 +O2

The corresponding salts of other alkali metals are stable towards heat.
Lithium nitrate, on heating, decomposes to give lithium oxide, Li2O whereas other alkali metals nitrate decomposes to give the corresponding nitrite.

4LiNO3 → 2Li2O + 4NO2 + O2

2NaNO3 → 2NaNO2 + O2

2KNO3 → 2KNO2 + O2

Li2CO3, LiOH, LiF and Li3PO4 are the only alkali metal salts which are insoluble in water. The corresponding magnesium compounds are also insoluble in water.

Hydrogen carbonates of both lithium and magnesium can not be isolated in solid state. Hydrogen carbonates of other alkali metals can be isolated in solid state.

Sodium Hydroxide (NaOH):
a. Properties

NaOH is stable towards heat but is reduced to metal when heated with carbon

2NaOH + 2C → 2Na +2CO + H2

FeCl3 + 3NaOH →Fe(OH)3 + 3NaCl

NH4Cl + NaOH → NaCl + NH3 (pungent smell) + H2O Open / Comment

2021-07-23 14:46:40 Doubtnut ke Study Channels par ab sirf Instant doubt solving hi nahi
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2021-07-23 10:58:08 Some important points - Human Reproduction

• Uterus also called womb.

• Longest unstripped muscles of the body are found in the walls of uterus. (During pregnancy)

• Clitoris is a homologous to the penis in the male.

• Bartholin Glands : It is homologous to Cowper's gland of male

• A functional mammary gland is characteristic of all female mammals.

• The milk produced during the initial few days of lactation is called colostrum which contains antibodies (IgA) absolutely essential to develop resistance for the new-born babies.

•Liberation of sperms from Sertoli cells of seminiferous tubules is called spermiation.

• Liberation of sperms from testes is called semination.

• Liberation of sperms from body of male is called ejaculation .

•Mammalian sperms are transfered to vagina of female by the process called insemination.

• In 1 ml of semen, 20 to 120 millions of sperms are present in human being.

• Leydig's cells mature at 10 yrs. of age.

• In humans (and most vertebrates), the first polar body does not undergo meiosis II.

• The first polar body is, therefore, formed merely to get rid of unwanted chromosomes.

• 65-74 days are required to complete the cycle of spermatogenesis in human being. Open / Comment

2021-07-23 09:31:23

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2021-07-23 07:01:42 𝐌𝐧𝐞𝐦𝐨𝐧𝐢𝐜𝐬 and 𝐭𝐫𝐢𝐜𝐤𝐬 for 𝐟𝐮𝐧𝐠𝐢 𝐞𝐱𝐚𝐦𝐩𝐥𝐞𝐬.

𝐁𝐚𝐬𝐢𝐝𝐨𝐦𝐲𝐜𝐞𝐭𝐞𝐬-
𝐓𝐫𝐢𝐜𝐤:- Agar Usne Puccha To 𝐁𝐚𝐬.

𝐀𝐠𝐚𝐫- Agaricus (mushroom)

𝐔𝐬𝐧𝐞- Ustilago (rust fungus)

𝐏𝐮𝐜𝐡𝐡𝐚- Puccnia (smut fungus)

Ascomyce𝐭𝐞𝐬-
𝐓𝐫𝐢𝐜𝐤:- Yash and Astha ne Naya Pencil 𝐊𝐡𝐚𝐫𝐢𝐝𝐚

𝐲𝐚𝐬𝐡- Yeast

𝐀𝐬𝐭𝐡𝐚- 𝐀𝐬𝐩𝐞𝐫𝐞𝐠𝐢𝐥𝐥𝐮𝐬

𝐍𝐚𝐲𝐚- 𝐍𝐞𝐮𝐫𝐨𝐬𝐩𝐨𝐫𝐚

𝐩𝐞𝐧𝐜𝐢𝐥- Penecillium

Many 𝐦𝐞𝐦𝐛𝐞𝐫𝐬 like 𝐦𝐨𝐫𝐞𝐥𝐬 and 𝐛𝐮𝐟𝐟𝐥𝐞𝐬 are e𝐞𝐝𝐢𝐛𝐥𝐞 and are considered 𝐝𝐞𝐥𝐢𝐜𝐚𝐜𝐢𝐞𝐬.

𝐏𝐡𝐲𝐜𝐨𝐦𝐲𝐜𝐞𝐭𝐫𝐬-
𝐓𝐫𝐢𝐜𝐤𝐬:-RaMu Alu Pheco
Ra- Rhyzopus (bread mould)

𝐌𝐮- Mucor

𝐀𝐥𝐮- Albugo (parasitic fungi on mustard)

𝐏𝐡𝐞𝐜𝐨- Pythium

𝐃𝐞𝐮𝐭𝐞𝐫𝐨𝐦𝐲𝐜𝐞𝐭𝐞𝐬 _
𝐓𝐫𝐢𝐜𝐤𝐬:- 𝐀𝐂𝐓

𝐀- alterneria

𝐂- Collectotrichum

𝐓 - 𝐓𝐫𝐢𝐜𝐡𝐨𝐝𝐞𝐫𝐦𝐚



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2021-07-22 14:38:13 Doubtnut ke Study Channels par ab sirf Instant doubt solving hi nahi
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