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By going through these CBSE Class 12 Chemistry Notes Chapter 9 Coordination Compounds, students can recall all the concepts quickly.

Coordination Compounds Notes Class 12 Chemistry Chapter 9

Coordination Compounds or complex compounds are usually formed by the transition metals ¡n which the metal atoms or ions are bound to a number of anions or neutral molecules Chlorophyll, haemoglobin and vitamin B12 are coordination compounds of magnesium, iron and cobalt respectively.

Wernet’s Theory of Coordination Compounds:
Alfred Werner, a Swiss chemist proposed the concept of a primary valence and a secondary valence for a metal ion. Werner in 1998 propounded his theory of coordination compounds.

The main postulates are:

1. In coordination compounds metals show two types of linkages (valences) primary and secondary.
2. The primary valences are normally ionisable and are satisfied by negative ions.
3. The secondary valences are non-ionizable. These are satisfied by neutral molecules or negative ions. The secondary valence is equal to the coordination number and is fixed for a metal.
4. The ion.s/groups bound by the secondary linkages to the metal have characteristic spatial arrangements corresponding to different numbers.

Such spatial arrangement is called coordination polyhedra. The species within the square bracket are coordination entities or complex part and the ions outside the coordination entities or complex part are called counter ions.

Werner further postulated that octahedral, tetrahedral, and square planar geometrical shapes are more common in coordination compounds of transition metal.

[CO(NH₃)₆]³⁺, [Cr(H₂O)₆]³⁺, [Cr Cl (NH₃)₅]²⁺, [COCl₂(NH₃)₄]⁺ are octahedral complexes [NiCO)₄] and [PtCl₄]^2- are tetrahedral and square planar respectively.

Difference between a double salt and a complex: Both double salts, as well as coordination compounds, are formed by the combination of two or more stable compounds in a stoichiometric ratio.

1. KCl + MgCl₂ + 6 H₂O → KCl. MgCl₂. 6H₂0 (carnallite)
2. FeSO₄ + (NH₄)₂SO₄ + 6 H₂O → FeSO4. (NH₄)₂ SO₄. 6H₂O (Mohr’s salt)
3. 4 KCN + Fe (CN)₂ → K₄[Fe(CN)₆]
4. CoCl₃ + 6 NH₃ → [Co(NH₃)₆]Cl₃

1 and 2 are examples of double salts
3 and 4 are examples of coordination compounds.

Double salts lose their identity in aqueous solutions. They dissociate into simple ions completely when dissolved in water.

Coordinate complexes retain their identity both in the solid-state and in aqueous solutions. For example [Fe (CN)₆]^4- does not dissociate into Fe²⁺ and CN^– ions.

→ Coordination Sphere: The central atom/ion and the ligands attached to it are enclosed in a square bracket is collectively called the Coordination sphere. For example in K₄[Fe (CN)₆], [Fe(CN)₆]^4- is coordination sphere and ionisable group K⁺ written outside the coordination group is called Counterion.

→ Coordination Polyhedron: The spatial arrangement of the ligand atoms which are directly attached to the central atom/ion defines polyhedron about the central atom/ion [Co(NH₃)₆]³⁺, [Ni (CO)₄] and [Pt Cl]^2- are respectively octahedral, tetrahedral and square planar coordination polyhedra.

(Shapes of different coordination polyhedra. M = Central metal/ ion and L = a unidentate ligand)

→ Oxidation Number of Central Atom: The oxidation number of the central atom in a complex is defined as the charge it would carry if all the ligands are removed along with the electron pairs that are shared with the central atom. Oxidation no. of copper in [Cu (CN)₄]^3- is + 1 and it is written as Cu (I).

→ Coordination Entity/Complexion: A coordination entity constitutes a central metal atom or ion bonded to a fixed number of ions or molecules. For example, [CoCl (NH₃)₃] is a coordination entity in which the cobalt ion is surrounded by three ammonia molecules and three chloride ions. Other examples are [Ni (CO)₄], [PtCl, (NH₃)₂], [Fe (CN)₆]^3-, [CO(NH₃)₆]³⁺.

→ Central atom/ion: In a coordination entity, the atom/ion to which a fixed number of ions/ groups are bound in a definite geometrical arrangement around it, is called the central atom or ion. For example, the central atom/ion in the coordination entities: [NiCl₂ (H₂O)₄], [COCl(NH₃)₅]²⁺, [Fe(CN)₆]^3- are Ni²⁺, CO³⁺ and Fe³⁺, respectively. These central atoms/ions are also referred to as Lewis acids.

→ Ligands: The ions or molecules bound to the central atom/ion in the coordination entity are called ligands. These may be simple ions such as Cl, small molecules such as H₂O or NH₃, larger molecules such as H₂NCH₂CH₂NH₂ or N (CH₂ CH₂ NH₂)₃ or even macromolecules, such as proteins. When a ligand is bound to a metal ion through a single donor atom, as with Cl^–, H₂O or NH₃, the ligand is said to be unidentate.

When a ligand can bind itself through two donor atoms as in H₂NCH₂CH₂NH₂ (ethane-1,2-diamine) or C₂O₄^2- (oxalate), the ligand is said to be bidentate, and when several donor atoms are present in a single ligand as in N (CH₂CH₂NH₂)₃, the ligand is said to be polydentate. Ethylenediaminetetracetate ion (EDTA^4-) is an important hexadentate ligand. It can bind through two nitrogen and four oxygen atoms to a central metal ion.

When a di- or polydentate ligand uses its two or more donor atoms to bind a single metal ion, it is said to be a chelate ligand. The number of such ligating groups is called the denticity of the ligand. Such complexes,
called chelate complexes tend to be more stable than similar complexes containing unidentate ligands. The ligand, which can ligate through two different atoms is called ambidentate ligand. Examples of such ligands are the NO₂^– and SCN^– ions. NO₂^– ion can coordinate either through v nitrogen or through oxygen to a central metal atom/ion

→ Coordination Number: The coordination number (CN) of a metal ion in a complex can be defined as the number of ligand donor atoms to which the metal.is directly bonded. For example, in the complexions, [PtCl₆]²⁺ and [Ni(NH₃)₄]²⁺ the coordination number of Pt and Ni are 6 and 4 respectively. Similarly, in the complexions, [Fe(C₂O₄)₃]^2- and [Co(en)₃]³⁺, the coordination number of Fe and Co both is 6 because C₂O₄^2- and en (ethane-1, 2-diamine) are bidentate ligands.

It is important to note here that the coordination number of the central atom/ ion is determined only by the number of sigma bonds formed by the ligand with the central atom/ion. Pi bonds, if formed between the ligand and the central atom/ion, are not counted for this purpose.

Homoleptic and Heteroleptic Complexes [Co(NH₃)₆]³⁺ in which metal is bound to only one kind of donor group, i.e., NH₃ is called homoleptic complex. [Co(NH₃)₄ Cl₂]⁺ complex in which a metal is bound to more than one kind of donor groups is called heteroleptic complex.

→ Nomenclature of Coordination Compounds: The formulae and names for coordination entities are based on the recommendations of the International Union of Pure and Applied Chemistry (IUPAC).

Formulae of Mononuclear Coordination Entities:
The following rules are applied while writing the formulae:

1. The central atom is listed first.
2. The ligands are then listed in alphabetical order. The placement of ligand in the list does not depend upon its charge.
3. Polydentate ligands are also listed alphabetically. In the case of abbreviated ligand. The first letter of the abbreviation is used to determine the position of the ligand in alphabetical order.
4. The formula for the entire coordination entity, whether charged or not, is enclosed in square brackets. When ligands are polyatomic, their formulae are enclosed in square brackets. When ligands are polyatomic their formulae are enclosed in parenthesis. Ligand abbreviations are also enclosed in parenthesis.
5. There should be no space between the names of the ligands and the metal within a coordination sphere.
6. When the formula of a charged coordination entity is to be written without that of the counter ion, the charge is indicated outside the square brackets as a right superscript with the number before the sign. For example, [Co(CN)₆]^3-, [Cr (H₂O)₆]³⁺ etc.
7. The charge of the cations is balanced by the charge of the anions.

Note: The 2004 IUPAC draft recommends that ligands will be sorted alphabetically, irrespective of the charge.

The naming of Mononuclear Coordination Compounds Rules:

1. The cation is named first.
2. The ligands are named in alphabetical order before the name of the central atom/ion.
3. Names of the anionic ligands end in – O. No special ending for neutral ligands .and cationic ligands. Aqua for H20, amine for NH₃, carboxyl for CO and nitrosyl for NO, cyano for CN^–, Oxo for O^2-.
4. Prefixes mono, di, tri etc. are used to indicate the number of individual ligands in the coordination entity. When the names of the ligands include a number, then the terms bis, tris takes are used, the ligand to which they refer is placed in parenthesis. For example, [NiCl₂ (P Ph₃)] is named as dichloro bis (triphenylphosphine) nickel (II).
5. The oxidation number/state of the metal in cation, anion or neutral coordination entity is indicated by a Roman numeral in parenthesis.
6. If the complexion is an anion, the name of the metal ends with -ate. For example Cr in [Cr(CN)6]^3- is chromate,
7. The neutral complex molecule is named the same as that of the complex cation.

Note: The 2004IUPAC draft recommends that anionic ligands will end with – ido so that chloro would become chloride, etc.

Examples:

1. Cr [(NH₃)₃ (H₂O)₃]Cl₃: triamine tri aqua chromium (III) chloride.
2. [Co (H₂N CH₂CH₂NH₂)3]₂ (SO₄)₃: tris (ethane -1,2 di-ammine) Cobalt (III) sulphate.
3. [Cr(H₂O)6] Cl₃: Hexaaquachromium (111) chloride.
4. [Ag(NH₃)₂] [Ag(CN)₂]: diammine silver (I) dicyano argentate (I).

→ Isomerism in Coordination Compounds: Isomers are two or more compounds that have the same chemical formula, but different arrangements of atoms.
1. Stereoisomerism:
(a) Geometrical isomerism,
(b) Optical isomerism.

2. Structural Isomerism:
(a) Linkage isomerism,
(b) Coordination isomerism,
(c) Ionisation isomerism,
(d) Solvate isomerism.

Stereoisomers have the same chemical formula and chemical bonds but they have different special arrangements. Structural isomers have different bonds.

→ Geometrical Isomerism: It arises in heteroleptic complexes due to different possible geometric arrangements of the ligands. If in square planar complex [MX₂L₂], the two ligands X are on the same side and two ligands L are on the other, it is called CIS-isomer. If the two ligands X and L are opposite to each other, it is called a Trans-Isomer.

Example: [Pt (NH₃)₂ Cl₂]: diammine dichloroplatinum (II)

Octahedral complexes [CO(NH₃)₄Cl₂]⁺ and [Co{en)₂Cl₂]⁺ exist as cis and trans isomers.

2. Optical isomerism: The isomers which rotate the plane polarised light equally but in opposite directions are called optical isomers. The isomer which rotates the plane polarised light to right is called dextrorotatory (designated as d-) while the one which rotates the plane of polarised light to the left is called laevorotatory (designated as 1). The main requirement for optical activity is that the molecule/ion should not have a plane of symmetry.

For example, complexes such as [Co(en)₃]³⁺ and [Cr(ox)₃]^3- exist as optical isomers.

Another example of the optical isomers is shown by the complex [Co(en)₂ Cl₂]⁺.

2. Structural Isomerism: They are further divided into:
1. Linkage Isomerism: It arises in a coordination compound containing ambidentate ligand. The complex [CO(NH₃)₅(NO₂)]Cl₂ exists in two forms: the red form in which the nitrite ligand is bound through oxygen (- ONO) and the yellow form in which nitrate is bound through nitrogen (-NO₂). ,

2. Coordination Isomerism: It arises due to the interchange of ligands between cationic and anionic entities of different metal ions present in a complex. For example
[CO(NH₃)₆] [Cr (CN)₆] and [Cr (NH₃)₆] [CO(CN)₆]

3. Ionisation Isomerism: This isomerism arises when the counter ion m a complex salt is itself a potential ligand and can displace a ligand which can then become the counter ion.
(a) [CO(NH₃)₄O₂]NO₂ gives NO₂^– ions in solution and [CO(NH₃)₄ Cl(NO₂)]Cl which gives Cl ions in solution.

(b) [CO(NH₃)₅ SO₄] Br which gives a ppt. with AgNO₃ [of AgBr] and [Co (NH₃)Br[ SO₄ which gives ppt. with Bad2 solution.

4. Solvate or Hydrate Isomerism: It is similar to ionisation isomerism with the only difference that water (H₂O) is involved as a \ solvent. For example aqua complex Cr[(H₂O)₆]Cl3 – violet and its solvate isomer [Cr(H₂O)₅ Cl] Cl₂. H₂O – grey-green.

Bonding in Coordination Compounds:
There are two theories,
1. Valence Bond Theory for Bonding in Coordination Compounds: This theory was developed by Linus Pauling in 1930.
The basic assumptions of the theory are:
(a) The central metal atom in the complex must make available a number of empty orbitals equal to its coordination number for accommodating the electrons from ligands.
(b) The appropriate atomic orbitals (s, p, d) of the metal hybridise to give a new set of equivalent hybrid orbitals which are directed towards the ligand sites.
(c) The d orbitals used for hybridization may be either inner (n – 1)d orbitals or outer nd orbitals.
(d) The hybrid orbitals of the metal overlap with the filled orbitals of\the ligands to form coordinate bonds.

Thus, With the help of V.B. theory, the geometry of the complex can be predicted if the number of unpaired electrons is known. Alternatively, the number of unpaired electrons can be predicted from the known geometry of the complex.

The common types of geometries and hybrid orbitals used are:

The theory may be illustrated by two important examples:
1. [CO(NH₃)₆]³⁺ and [COF₆]^3-. In these complexes, Co (III) has six d- electrons. The first complexion is diamagnetic and the second has paramagnetic character due to four unpaired electrons. In the [CO(NH₃)₆]³⁺ complex, the two 3d electrons get paired up with the other two leaving two vacant orbitals and these vacant orbitals get d²sp³ hybridized. In the second [COF₆]^3- complexes, the 3d electrons are not disturbed and the outer 4d orbitals are used for hybridization.


[CO(NH₃)₆]³⁺ is called an inner orbital or low spin or spin paired complex. The paramagnetic octahedral complex [COF₆]^3- is failed outer orbital or high spin or spin-free complex.

In a tetrahedral complex one s and three p-orbitals are hybridized to form four equivalent orbitals oriented tetrahedrally, e.g., [Ni Cl₄]^2-.

It is paramagnetic. (High spin complex).

In the square planar complexes, the hybridisation involved is dsp². An example is [Ni(CN)₄]^2-. Here nickel is in a + 2 oxidation state and has the electronic configuration 3d⁸.

It is a diamagnetic complex.

Magnetic properties of Coordination Compounds: For metal ions with up to three electrons in the d-orbitals like Ti³⁺ (d); V³⁺ (d²); Cr³⁺ (d³) two vacant d orbitals are available for octahedral hybridisation with 4s and 4p orbitals. The magnetic behaviour of these free ions and complex is similar.

When more than three 3d electrons are present, the required pair of 3d orbitals for octahedral hybridisation is not directly available (as a consequence of Hund’s rule). Thus, for d⁴ (Cr²⁺, Mn³⁺), d⁵ (Mn²⁺, Fe³⁺), d⁶ (Fe²⁺, CO³⁺) cases, a vacant pair of d orbitals results only by the pairing of 3d electrons which leaves two, one and zero unpaired electrons respectively.

The magnetic data agree with maximum spin pairing in many cases, especially with coordination compounds containing d⁶ ions. However, with species containing d⁴ and d⁵ ions, there are complications. [Mn (CN)₆]^3- has a magnetic moment of two unpaired electrons while [MnCl₆]^3- has a paramagnetic moment of four unpaired electrons. [Fe(CN)₆]^3- has a magnetic moment of a single unpaired electron while [FeF₆]^3- has a paramagnetic moment of five unpaired electrons. [COF₆]^3- is paramagnetic with four unpaired electrons while [Co(C₂O₄)₃]^3- is diamagnetic.

This apparent anomaly is explained by valence bond theory in terms of the formation of inner orbital and outer orbital coordination entities. [Mn(CN)₆]^3-, [Fe(CN)₆]^3- and [Co(C₂O₄)₃]^3- are inner orbital complexes involving d² sp3 hybridisation, the former two complexes are paramagnetic and the latter diamagnetic. On the other hand, [MnCl]^3-/ [FeF₆]^3- and [COF₆]^3- are outer orbital complexes involving sp³d² hybridisation and are paramagnetic corresponding to four, five and four unpaired electrons.

Limitations of Valence Bond Theory:

1. It involves a no. of assumptions.
2. It does not give a quantitative interpretation of magnetic data.
3. It does not explain the colour shown by coordination compounds.
4. It does not explain the thermodynamic or kinetic stabilities of co-ordinate compounds.
5. It does not make exact predictions regarding the tetrahedral and square planar structures of 4-coordination complexes.
6. It does not distinguish between weak and strong ligands.

2. Crystal Field Theory: This theory envisages the metal ligand to be purely ionic arising.from electrostatic interactions between the metal and ligand. Ligands are treated as point charges in case of anions or dipoles in case of neutral molecules. The five d orbitals in an isolated gaseous metal atom/ion have the same energy, i.e., they are degenerate.

On the arrival of the ligands, these d-orbitals split up. Those orbitals which lie on the direct path of the ligands are repelled more than those which lie away from the path of approaching ligands. This pattern of splitting depends upon the nature of the crystal field.

A. Crystal Field splitting into Octahedral Coordination Entities: In an octahedral complex when the six ligands approach the metal atom/ ion, out of five d-degenerate orbitals, three-d orbitals (d_xy, d_yz, d_zx) which lie away from the path of the approaching ligands (∵ they lie in between the axes) are repelled less than those two d-orbitals (d_x²–y² and d_z²) which lie on the direct path [they lie in between the axes].

Thus the degeneracy of the five d-orbitals are lost and these d-orbitals split up. This splitting gives two sets of orbitals -12 set of three orbitals of lower energy and eg set of two orbitals (d_x²–y² and d_z²) of higher energy. It is called Crystal Field Splitting and the difference of energy is denoted by Δ₀ (o -for octahedral complex). The energy of two eg orbitals is raised by \(\frac{3}{5}\) Δ₀ and that of the three t_2g will decrease by \(\frac{2}{5}\) Δ₀.

The crystal field splitting, Δ0, depends upon the field strength of the ligands which is in the order:
I^– < Br < SCN^– < Cl^– < S^2- < F^– < OH^– < C₂O₄^2- < H₂O < NCS^– < edta^4- < NH₃ < en < CN^– < CO such a series is called spectrochemical series.

In d¹ complexes, the single d-electron occupies the lower t_2g orbital. In d² and d³ coordination entities, the d-electrons occupy the three t_2g orbitals singly in keeping with Hund’s Rule.

For d⁴ ions, two different patterns are possible:

1. the 4th electron could either enter the lower energy t_2g level and pair with an existing electron, or
2. it could occupy the higher energy e_2g level. It depends upon two factors:
   (a) The magnitude of crystal field splitting energy Δ₀.
   (b) The pairing energy P [energy required for electron pairing in a single orbital).

1. If Δ₀ < P, the 4th electron enters one of the eg orbitals. Ligands for which Δ₀ < P is known as Weak field ligands and form high spin complexes.

Crystal Field Splitting of d-orbitals in an Octahedral complex

2. If Δ₀ > P, the 4th electron occupies a lower energy t_2g orbital. Ligands producing this effect are known as strong field ligands and form low spin complexes.

Calculations show that d⁴ to d⁷ coordination entities are more stable for the strong field as compared to weak field cases.

B. Crystal Field Splitting into Tetrahedral Coordination Entities: In tetrahedral complexes, splitting of d-orbitals is such that it is opposite to that of octahedral complexes. The eg set of d-orbitals of the metal ion is lower in energy and the t_2g set has higher energy. Moreover, the value of Δt [t for tetrahedral complex] is smaller than Δ0 (Δt = \(\frac{4}{9}\) Δ₀) for the same ligands and metal-ligand distances. Consequently, the orbital splitting energies are not sufficiently large for forcing pairing of electrons, i.e., electrons prefer to remain unpaired and thus low spin complexes are rarely observed in tetrahedral complexes.

d-orbitals splitting in tetrahedral crystal field

Colour in Coordination Compounds: Formation of coloured complexes is .the characteristic property of transition elements. It can be explained readily on the basis of crystal field theory, taking an example of an octahedral complex of [Ti (H₂O)₆]³⁺ in which the metal ion Ti³⁺ is a 3d¹ system.

The t_2g set is lower in energy and the eg set is higher in energy. The rotary 3d1 electron prefers to remain in t_2g set in the ground state. If the light corresponding to a yellow-green region of white light is absorbed by this complex, it will excite the electron from the t_2g set to the next available eg
set[t_2g e_g° → t°_2g e_g¹ ]. Thus the complex appears violet.

The transition of an electron in [Ti(H₂O)₆]³⁺ complex

The colour of the complexes is explained by crystal field theory due to the d-d transition of the electron. Removal of the ligands does not cause crystal field splitting and hence the complex becomes colourless,
e.g., where CuSO₄.5H₂0 [Complex: [Cu (H₂O)4]²⁺. SO₄^2-. H₂O] is blue in colour due to absorption of the red region of white light, anhydrous CuSO₄ s white. Removal of water from [Ti(H₂O)₆]Cl₃ on heating renders it colourless.

The influence of the ligand on the colour of a complex may be illustrated by considering the [Ni (H₂O)₆]²⁺ complex, which forms when nickel (II) chloride is dissolved in water. If the identity ligand, ethane- 1, 2-diamine (en) is progressively added in the molar ratios en: Ni, 1:1, 2:1,3:1 the following series of reactions with associated colour changes occur.

Limitations of Crystal Field Theory:

1. As ligands are assumed to be point charges, anionic ligands are expected to have a greater splitting effect. However, actually, they are found to be at the lower end of the spectrochemical series.
2. It does not take into account the covalent character of bonding between the ligand and the central atom/ion.
3. Though OH^– ion in the spectrochemical series lies below H₂O and NH₃, yet it produces a greater splitting effect.

→ Bonding in Metal Carbonyls: The homoleptic carbonyls (compounds containing carbonyl ligands only) are formed by most of the transition metals. Tetracarbonylnickel (o), viz., [Ni (CO)₄] is tetrahedral, Penta carbonyl iron (o) is trigonal bipyramidal while Hexa carbonyl chromium (o) is octahedral.

Stability of Coordination Compounds: Consider the reaction
M + 4 L → ML₄
Stability constant (on Equilibrium constant)
K = \(\frac{\left[\mathrm{ML}_{4}\right]}{\left[\mathrm{M} \mid[\mathrm{L}]^{4}\right.}\)

The numerical value of the stability constant is a measure of the stability of the complex in the solution.

Importance And Applications of Coordination Compounds: These compounds are widely present in the mineral, plant and animal world. They play important functions in analytical chemistry, metallurgy, biological systems, industry and medicine.
1. Hardness of water is estimated by simple titration with Na₂ EDTA. The Ca²⁺ and Mg²⁺ ions present in hard water make stable complexes with EDTA.

2. Metallurgical extraction of silver and gold make use of complex formations. Gold can be extracted from [Au (CN)₂]^– complex by the addition of zinc.

3. Purification of Nickel can be achieved by Mond’s process by converting impure nickel to complex [Ni (CO)₄] which decomposes to yield pure nickel.

4. Chlorophyll, the green pigment present in plants responsible for photosynthesis, is a coordination compound of Magnesium. Haemoglobin, the red blood pigment of blood that acts as an oxygen carrier is a coordination compound of iron. Vitamin B₁₂, Cyanocobalamin, the anti-pernicious anaemia factor, is a cord in. m compound of cobalt.

5. Coordination comp us are used as catalysts for many industrial processes. Rhodium complex [(Ph₃P) RhCl]. a Wilkinson catalyst is used for the hydrogenation of alkenes.

6. Articles can be electroplated with silver and gold much more smoothly and evenly from a solution of complexes Ag (CN)₂]^– and [Au (CN)₂]^– than from a solution of simple metal ions.

7. In black and white photography, the developed film is fixed by washing with hypo solution which dissolves the under-composed AgBr to form a complex io,n [ Ag (S₂O₃)₂]^3-.

8. Cis-platin is used for the treatment of cancer. Excess of copper and iron are removed by the chelating ligands D-penicillamine and desferrioxamine B via the formation of coordination compounds. EDTA is used in the treatment of lead poisoning

By going through these CBSE Class 12 Physics Notes Chapter 14 Semiconductor Electronics: Materials, Devices and Simple Circuits, students can recall all the concepts quickly.

Semiconductor Electronics: Materials, Devices and Simple Circuits Notes Class 12 Physics Chapter 14

→ A solid behaves like a good conductor if there is no forbidden gap.

→ A solid behaves as a semiconductor if its forbidden gap is small am behaves as an insulator if its bandgap is large.

→ In an intrinsic semiconductor, the electrical conductivity is determined only by thermally generated charge carriers. Their number is very small so the thermal conductivity is low.

→ Doping of semiconductors with a small amount of impurity changes their conductivity highly.

→ The majority of charge carriers in the p-type and n-type semiconductors are holes and electrons respectively.

→ Electron mobility is higher than that of holes.

→ At low temperatures, the free electrons remain in the V.B. of the semiconductor. As the temperature rises, electrons cross over to the conduction band.

→ Both n and p-semiconductors are neutral.

→ For an intrinsic semiconductor,
n_e = n_h = n_i

→ At higher temperatures, the conductivity of the semiconductor increases due to the increase in the number density of the charge carriers.

→ The potential barrier in the Ge diode is about 0.3 V and that of the Si diode is about 0.7 V.

→ Potential barrier opposes the forward current and supports the reverse current. ‘

→ The width of the depletion layer is of the order of 10^-6 m = 1 pm.

→ The electric field set up across the potential barrier is of the order of 3 × 10⁵ Vm^-1 for Ge and 7 × 10⁵ Vm^-1 for Si.

→ The current gain for CE configuration (β) ranges from 20 to 200.

→ For full wave rectifier, the minimum number of d iodes required is two.

→ The p-n junction can be assumed as a capacitor having the depletion layer acting as a capacitor.

→ Semiconductor devices are current controlled devices.

→ The semiconductor devices are temperature sensitive devices.

→ After the breakdown, the reverse current does not depend on the reverse voltage.

→ The junction diode has a unidirectional flow of current.

→ Due to unidirectional current characteristics a junction diode is used as a rectifier.

→ In a photodiode, light is made to fall on the junction so that current is proportional to the intensity of incident light.

→ The LED emits light energy due to recombination of electrons and holes at the junction.

→ In solar cell, sun’s energy is converted into electrical energy.

→ There are two junctions in a transistor. Emitter-base junction is always forward biased and the base-collector junction is always reverse biased.

→ The input resistance of the transistor is always lesser than that of
the output (collector) resistance.

→ α: It is always less than unity.

→ β > > α.

→ Common emitter configuration is most commonly used.

→ The energy in the tank circuit is alternatively stored in the electric field of the capactior and the magnetic field around the inductor.

→ In a binary number system only two numbers 0 and 1 are used.

→ Positive or high values are represented by 1 while the low values are represented by 0.

→ AND, OR and NOT gates are the basic gates.

→ NAND or NOR gates are called the basic building blocks of the digital circuits.

→ NAND gate : It is a combination of AND gate followed by a NOT gate.

→ NOR gate: It is the combination of OR gate followed by the NOT gate.

→ Dynamic resistance or a.c. resistance of a diode: It is defined as the ratio of the change in applied voltage to the change in the current of the diode.

→ Current gain: It is defined as the ratio of the output current to the input current.

→ α : It is defined as the ratio of change in collector current to the change in emitter current.
β : It is the ratio of change in collector current to the change in base current.

→ Logic gate is a circuit which has one or more than one inputs and only one output.

→ AND gate: It is the logic curcuit in which the output is high if both the inputs are high and the output is low if one or both the inputs are low.

→ OR gate: It is a logic circuit having output high if one or both the inputs are high and the output is low if both the inputs are low.

→ NOT gate: It has high output if input is low and vice-versa.

Important Formulae

→ Frequency of L.C. oscillation is given by
v = \(\frac{1}{2 \pi \sqrt{\mathrm{LC}}}\)

→ Dynamic resistance of junction diode is given by
r_d = \(\frac{\Delta \mathrm{V}}{\Delta \mathrm{I}}\)

→ Current flowing through the semiconductor is given by ”
I = I_e + I_h
= eA (n_e μ_e + n_h μ_h)

→ The conductivity of the semiconductor is given by
σ = e(n_e μ_e + n_h μ_h)

→ For intrinsic semiconductor, n_e × n_h = n_i²
where ni = intrinsic carrier concetration, ne, nh are electron and hole carrier density.

→ Mobility is given by, μ = \(\frac{v_{\mathrm{d}}}{\mathrm{E}}\)
I_e = I_b + I_c

→ β = I_c/I_b = d.c current gain for CE. amplifier.

→ The α and β are related as
β = \(\frac{\alpha}{1-\alpha}\)

→ β_ac = \(\left(\frac{\Delta \mathrm{I}_{c}}{\Delta \mathrm{I}_{\mathrm{b}}}\right)_{\mathrm{V}_{\mathrm{ce}}=\mathrm{Constant}}\)

→ Voltage gain, AV = \(\frac{\Delta \mathrm{V}_{\mathrm{o}}}{\Delta \mathrm{V}_{\mathrm{i}}}\) = B_ac × \(\frac{\mathrm{R}_{\text {out }}}{\mathrm{R}_{\text {in }}}\)

→ Resistance gain = \(\frac{\mathrm{R}_{\mathrm{out}}}{\mathrm{R}_{\mathrm{in}}}\)

→ Power gain = \(\frac{\Delta P_{\mathrm{o}}}{\Delta \mathrm{P}_{\mathrm{i}}}=\frac{\Delta \mathrm{V}_{\mathrm{o}} \times \mathrm{I}_{\mathrm{o}}}{\Delta \mathrm{V}_{\mathrm{i}} \times \mathrm{I}_{\mathrm{i}}}\)
= A_v × current gain

→ α = d.c. current gain for C.B. amplifier
= \(\frac{\mathrm{I}_{\mathrm{c}}}{\mathrm{I}_{\mathrm{e}}}\)

→ g_m = Transconductance = \(\frac{\Delta \mathrm{I}_{\mathrm{c}}}{\Delta \mathrm{V}_{\mathrm{eb}}}\)
= \(\frac{\beta}{R_{\text {in }}}\)

→ Input resistance, r_i = \(\left(\frac{\Delta V_{\mathrm{be}}}{\Delta \mathrm{I}_{\mathrm{b}}}\right)_{\mathrm{V}_{\mathrm{ce}}=\mathrm{Constant}}\)

→ Output resistance, r₀ = \(\left(\frac{\Delta \mathrm{V}_{\mathrm{ce}}}{\Delta \mathrm{I}_{\mathrm{c}}}\right)_{\mathrm{I}_{\mathrm{b}}=\mathrm{Constant}}\)

Here we are providing Class 11 Biology Important Extra Questions and Answers Chapter 22 Chemical Coordination and Integration. Important Questions for Class 11 Biology are the best resource for students which helps in Class 11 board exams.

Class 11 Biology Chapter 22 Important Extra Questions Chemical Coordination and Integration

Chemical Coordination and Integration Important Extra Questions Very Short Answer Type

Question 1.
What is an endocrine gland?
Answer:
The gland without duct, which secretes hormones, is called the endocrine gland.

Question 2.
What are hormones?
Answer:
The endocrine glands secrete chemical substances which affect various body activities in target organs, by reaching there through blood.

Question 3.
Expand the term BMR.
Answer:
Basal Metabolic Rate.

Question 4.
Which hormone is responsible for the metamorphosis of tadpoles into adult frogs?
Answer:
The hormone thyroxine secreted by the thyroid gland is responsible for the metamorphosis of tadpoles into adult frogs.

Question 5.
What is castration?
Answer:
The surgical removal of the testis is called castration.

Question 6.
What is adrenal virilism?
Answer:
The hypersecretion of sex corticoids causes the development of external male characters in females, called adrenal virilism.

Question 7.
What condition is caused due to failure of production of [ testosterone?
Answer:
Eunuchoidism.

Question 8.
What function do glucagons have?
Answer:
It causes the formation of glucose from the breakdown of glycogen and from amino acids.

Question 9.
Name the gland which functions as both the endocrine and exocrine?
Answer:
Pancreas.

Question 10.
Name the hormone which is antidiuretic in its effect.
Answer:
Vasopressin (ADH) secreted by the posterior pituitary.

Question 11.
Why pituitary is called, “master gland”?
Answer:
Because it controls most of the other endocrine glands.

Question 12.
How are pheromones different from hormones?
Answer:
Hormones affect the same individual but pheromones affect another individual of the community.

Question 13.
Give one example of the effect of pheromones in Insects.
Answer:
Pheromones from female moths attract males from 3 – 4 km distance.

Question 14.
How is iodine important to our body?
Answer:
Iodine is required for thyroxine secretion. Deficiency of iodine leads to goiter.

Question 15.
Name the gland which is both exocrine and endocrine.
Answer:
Pancreas.

Question 16.
Write any two hormones which are chemically different.
Answer:
Insulin hormone is made of proteins and testosterone is made of steroids.

Question 17.
Write the full form of ACTH. What is its role?
Answer:
Andreno-Cortico-Trophic Hormone.
ACTH stimulates the secretion of the adrenal cortex.

Question 18.
Write names and sources of hormones regulating the plasma Ca⁺ level.
Answer:
Parathormone produced by parathyroids.

Chemical Coordination and Integration Important Extra Questions Short Answer Type

Question 1.
Work out the contrast between diabetes Mellitus and diabetes insipidus.
Answer:
Diabetes Mellitus: It is the disorder in which blood sugar is present well beyond the renal threshold, consequently glucose is present in urine. It is caused due to deficiency of insulin hormone.

Diabetes insipidus: It is the disorder in which hypotonic urine is excessively excreted. It is caused by the deficiency of the secretion of the ADH hormone.

Question 2.
Differentiate between estrogen and progesterone.
Answer:

Estrogen	Progesterone
(1) It is secreted by the ovary.	(1) It is secreted by the Corpuslutem of the ovary.
(2) It acts on and develops female secondary organs.	(2) It maintains endometrium during pregnancy.

Question 3.
Differentiate the action of insulin and glucagon.
Answer:

Insulin	Glucagon
(1) It is secreted by beta cells of islet of Langerhans of the pancreas.	(1) It is secreted by alpha cells of islet of Langerhans of the pancreas
(2) It converts soluble glucose into insoluble glycogen.	(2) It converts glycogen into glucose.

Question 4.
Name and state briefly the functions of the hormones secreted by the adrenal cortex.
Answer:
Mainly the hormones secreted by the adrenal cortex are:

1. Glucocorticoids: These regulate the metabolism of carbohydrates, fats, and proteins.
2. Mineralocorticoids: These maintain the sodium, potassium level in the blood.
3. Sex corticoids: These stimulate the development of external sex characters like male patterns of body hair distribution. Androstenedione and dehydroepiandrosterone are sex corticoids.

Question 5.
Differentiate between hormones and pheromones.
Answer:

Hormones	Pheromones
1. These are the chemicals released by the endocrine glands.	1. These are the chemicals released by exocrine glands.
2. These are the result of biological changes in the body.	2. These are the result of behavioral and developmental changes.
3. Biological changes are the manifestation of the individual self.	3. Changes are after perception of these by the members of the same species.
4. These are released into the bloodstream	4. These are released into the environment.

Question 6.
Describe different disorders caused by thyroid hormone imbalance.
Answer:
Other than simple goiter, the main thyroid hormone imbalances are:

1. Cretinism: Hypoactivity of thyroxine in children causes poor physical and mental development, low metabolism. The affected individual is potbellied and pigeon-chested.
2. Myxedema: Hypoactivity of thyroxine in adults causes poor physical and mental development, low metabolism, puffy appearance, and reproductive failure.
3. Grave’s disease: (exophthalmic goiter) Hyperactivity of thyronine causes increased metabolism, bulging of eyeballs, emaciation, and restlessness.

Question 7.
State different functions of thyroid hormones.
Answer:

1. These affect the metabolism.
2. These maintain BMR (Basal Metabolic Rate).
3. These affect physical growth.
4. These affect the development of mental faculties.
5. These affect the process of differentiation.
6. Affect metamorphosis in tadpoles.

Question 8.
State chief characteristics of the hormones.
Answer:

1. The effect produced is marked even in minute concentrations.
2. Directly sent to target organs through blood circulations.
3. Storage is not possible.
4. The target organ is distantly placed from the organ in which these are produced.
5. These are secreted as a response to some sort of stimulus.
6. Chemicals are biological in origin, i.e., biogenic, e.g., amine, peptides, steroids, etc.

Question 9.
Differentiate between hormones and enzymes.
Answer:

Hormones	Enzymes
1. Produced by gland distant from target organ.	1. Produced at the site of action.
2. Maybe steroids, amines, or peptides.	2. Proteinaceous in nature.
3. Consumed during the action.	3. Not used up during the auction.
4. Do not catalyze the specific reaction.	4. Catalyses specific reaction.
5. Affect the activity of enzymes	5. Does not affect the activity of hormone production.

Question 10.
Describe in brief different disorders caused by the adrenal cortex.
Answer:
Different disorders related to the adrenal cortex are:

1. Addison’s disease: Atrophy or destruction of adrenal cortex causes failure of secretion of minerals corticoids and glucocorticoids leads to low blood Na⁺, high plasma K⁺ and urinary Na⁺, bronze skin pigmentation.
2. Cushing’s syndrome: Increased production of cortical causes low’ plasma K⁺, high plasma Na⁺, rise in blood pressure and volume.
3. Aldosteronism: Hyperactivity of aldosterone cause Na+ and K+ conditions like Cushing’s syndrome, muscular weakness.
4. Adrenal virilism: Hypersecretion of sex corticoids causes the development of male-type external features in female-like beard and mustache, low pitch male voice, and mensural cessation.

Question 11.
Why do you suppose the brain goes to the trouble of synthesizing releasing hormones, rather than simply directing the production of the pituitary hormones immediately?
Answer:
Hormones secreted by the posterior lobe of the pituitary gland are actually synthesized by the neurons in the hypothalamus and stored in their axon ends in the posterior lobe for release, when required.

The pituitary was called the Master endocrine gland, because of the number of hormones it produces and the control it exercises over other endocrine glands. However, it itself is under control of the releasing hormones secreted by the hypothalamus of the brain. Thus there is a chain of disorders, the hypothalamus directs the pituitary output, which controls the secretion of hormones by other endocrine glands.

Question 12.
Which endocrine gland is controlled by the secretion of other endocrine glands?
Answer:
The thyroid gland is the only endocrine gland that is controlled by the secretion of another endocrine gland. It stores its secretary product in large quantity.

Homopothalamus, in response to some external stimulus, produces a thyrotropin-releasing hormone (TRH) for the secretion of the thyrotrophic hormone. The thyrotropin-releasing hormone stimulates the anterior pituitary lobe to secrete thyrotrophic hormone. The latter, in turn, stimulates the thyroid gland to produce thyroxine, thereby restoring the normal blood- thyroxine level.

Question 13.
How is the communication among the parts of an organism accomplished?
Answer:
The endocrine system functions in a hierarchical manner. The hypothalamus produces releasing or inhibiting hormones, which travel in neurosecretory cells to the anterior pituitary, where they control the production of its hormones.

Hypothalamus also produces two hormones which are stored in and released from the posterior pituitary level. Many hormones are regulated by negative feedback controls. In such a Control, an excess of the hormone or the product of hormone-induced response suppresses the synthesis or release of that hormone until the level returns to normal.

In positive feedback control, the hormone causes an event or process that increases the production of this hormone. Thyroid and steroid are lipid-soluble hormones and readily pass through the plasma membrane of a target cell into the cytoplasm.

There they bind to the specific intracellular receptors and binds to specific regulatory sites on the chromosomes. The binding alters proteins, forming a complex that enters the nucleus the pattern of gene expression, initiating the transcription of some genes (DNA) while repressing the transcription of others. This results in the production of specific RNA, translation products, proteins, and enzymes. In this way communication among the parts of an organism accomplished.

Question 14.
Discuss the role of the hypothalamus and pituitary as a coordinated unit in maintaining physiological processes.
Answer:
The hypothalamic-pituitary axis consists of the hypothalamus and pituitary gland. The hypothalamus is a part of the brain and consists of several masses of grey matter called Hypothalamic nuclei. These are located in the white matter in the floor of the third cerebral vesicle of the brain; neurons of these hypothalamic nuclei control the pituitary gland.

The pituitary gland is a small pea-shaped gland situated below the hypothalamus and connected to the brain by a stalk. The pituitary is divided into anterior, posterior, and intermediate lobes. It secretes a number of hormones.

Question 15.
Why is the endocrine system considered a chemical extension of the nervous system?
Answer:
The human endocrine system and functioning of their hormones, including their role as chemical messenger and regulators. Also, it is related to the hypothalamic-hyperphysical axis and feedback controlling mechanism. These two systems operate in a co-ordinate way on many occasions. Many important functioning of the endocrine system is under the control of the nervous system. Hence the endocrine system is considered as a chemical extension.

Question 16.
What are the seven principal hormones produced by the anterior pituitary? What function does each serve?
Answer:

Hormone	Function
1. Somatotropin or growth hormone	1. It stimulates body growth.
2. Thyrotropin or thyroid-stimulating hormone.	2. Release of thyroid hormones.
3. Corticotropin or Adreno-corticotropin hormone	3. Release of gluco-corticoids and mineralo corticoids hormones of adrenal cortex.
4. Follicle-stimulating hormone (FSH).	4. Growth of ovarian follicle and estrogens secretions in females and spermatogenesis in males.
5. Prolactin Hormone	5. Milk secretion from mammary glands.
6. Luteinizing hormone (LH)	6. It stimulates the ovaries to secrete the female sex hormone- progesterone.
7. Melanocyte -stimulating hormone (MSH)	7. Melanocyte-stimulating hormone-releasing hormone. The target organ is skin pigment cells.

Question 17.
What hormones are secreted by the posterior pituitary gland? What function do they serve? Where are these hormones actually produced? How these hormones are transported to the region from which they are released?
Answer:
1. Vasopressin: Released from the axon terminals of hypothalamic neurons into the blood in the posterior lobe of the pituitary. It reduces the volume of urine by increasing the reabsorption of water from the urine, collecting tubules, and collection ducts in the kidney, hence called Antidiuretic hormone.

2. Oxytocin: It is released from the axon terminals of hypothalamic neurons into the blood in the posterior lobe of the pituitary due to the distension of the uterus by the full-term fetus.

It helps in childbirth. It is also known as milk ejection hormone.

Question 18.
What are the examples of antagonistic hormones associated with basal metabolism? How does each pair function?
Answer:
Para hormone (PTH) and thyroid hormone calcitonin act agonistically to regulate the calcium phosphorous balance in the blood. The release of parathormone increases the blood calcium to normal by drawing calcium from the bones into the plasma, by increasing calcium absorption in the digestive tract, and by reducing loss of calcium in the urine. It lowers calcium-phosphorus balance and is necessary for the growth of bones and teeth.

Calcium is vital for blood clotting, muscle tone, and for normal nervous activity. It is also needed for the activities of many enzymes.

Question 19.
What two hormones are produced by the adrenal medulla? What non-hormonal function do they serve?
Answer:
The hormone Adrenaline and Nor-adrenaline are secreted by the adrenal medulla.
Function: These hormones act on organs and tissues supplied by sympathetic fibers and produce effects like those of sympathetic stimulation.

Question 20.
From what chemical compounds are ail steroid hormones derived? Mention at least two examples of steroidal hormones.
Answer:
The adrenal cortex is the outer layer of the adrenal gland. It secretes steroidal hormones. Examples, Glucocorticoids, and mineralocorticoids.

The adrenal cortex produces steroid hormones through the modification of cholesterol.

Question 21.
In general, how the steroid hormones affect changes in their target cells?
Answer:
Steroid hormones have minor differences, the various hormones have strikingly different functions. They bind to different receptors in the target cell and affect sets of chemical reactions.

Cortical steroids can be grouped into three functional categories.

1. Mineralocorticoids: They regulate saltwater balance through their effect on kidney and blood pressure.
2. Glucocorticoids: They regulate carbohydrate, protein, and lipid metabolism.
3. Ganado corticoids: It is a sex hormone and helps chemically and functionally to the sex.

Question 22.
What hormones are produced when the body’s blood glucose levels drop below normal? How do these hormones act to return the level to normal? What hormone is produced when the body’s blood glucose levels become elevated? How does this hormone act to return the level to normal?
Answer:
B-cells secrete insulin.
T-cells secrete somatostatin.

These two hormones regulate the level of glucose in the blood:

1. When the blood glucose level becomes excessive, insulin acts on the three target tissues: liver, muscle, and adipose cells. Insulin causes the liver to take up glucose and convert it into glycogen and fat. It facilitates the liver to take up glucose in the muscle and adipose cells causing the levels of the glucose in the blood lowered.
2. Somatostatin: acts as a paracrine, to inhibit the secretion of glycogen and insulin, decreases secretion, mortality, and absorption in the digestive tract.

Question 23.
What is diabetes? What is the ultimate hormonal deficiency in these diseases? How does this affect an individual’s ability to use glucose? What are some possible treatments for adult-onset diabetes?
Answer:
Diabetes mellitus is a group of disorders that lead to an increase in the level of glucose in the blood. The deficiency of insulin hormone causes diabetes mellitus.

In this disease, the patient cannot use or store glucose. Thus, glucose accumulates in the blood from where it is excreted by kidneys in die urine.

Glucose increases the osmotic pressure of urine, causing loss of water from the body in urine. This produces excessive thirst. Degradation of fats increases, producing ketone bodies such as acetoacetate and acetone. Blood cholesterol rises, injuries may change into gangrenes. Healing power is ^ impaired leading to the damage of tissues.

A diabetic person has blurred vision and is weak, tired, irritable, nauseated, and underweight. In extreme cases, the patient may pass into a coma and die.

Treatment: Administration of insulin gives relief by lowering blood glucose levels.
Diabetes caused by insufficient insulin production is called Insulin-dependent diabetes.
Diabetes due to a person’s ability to use insulin is termed as insulin ) independent diabetes. It is more common than insulin-dependent diabetes.
Diabetes mellitus may also be caused by the failure of insulin to move glucose from the blood into the cells for storage or consumption.

This is due to the defective insulin receptors or cell surfaces, starving the cells of glucose, or to an abnormality in pancreatic protein amylin, which regulates insulin’s activity.

Chemical Coordination and Integration Important Extra Questions Long Answer Type

Question 1.
What are thyroids? Describe the disorders of thyroids hor¬mones.
Answer:
The thyroid gland is situated in the neck close to the trachea in human beings. It consists of two elongated oval lobes joined together by a narrow band called ISTHMUS. It highly vascular organ and contains many- spherical or oval sac-like follicles.

Cells of the follicle secrete jelly-like semi-fluid called Colloid of Thyroid stored in the lumen of the follicle. This contains iodinated forms of an amino acid called THYRONINE. When required, two thyroid hormones, THYROXINE, and TRIIODOTHYRONINE are released from the colloid to the blood.

(a) and (b) Thyroid gland

Disorders:

1. Failure of the thyroid from infancy or childhood causes a disease called cretinism. In it, there is slow body growth and mental development. There is also a low metabolic rate.
2. The deficiency of thyroid hormones in adults produces Myxedema. The patient shows a puffy appearance and lacks intelligence, lateness, and initiative. There is also a low metabolic rate.
3. The deficiency of iodine produces enlargement of thyroids causing Iodine Deficiency to Goitre.
4. Some thyroid enlargement is accompanied by a bulging of the eyeball.
   The disease is called Grave’s Disease or Exophthalami Goitre. The excessive amount of thyroid is secreted. ,

Question 2.
Give an account of the primary male sex organ in man and mention briefly the functions of the hormone testosterone.
Answer:
The testis is the primary sex organ. There are pair of tests. Each testis is covered by a thick connective tissue sheath, Tunica Albuginea. Both testes normally remain suspended in a pouch called Scrotum outside the abdominal cavity. Each testis consists of many small and highly convoluted tubules, called seminiferous tubules, constituting its spermatogenic tissue.

Cells lining the tubules give rise to spermatozoa, which are released into the lumen of the tubule. These are present groups of polyhedral cells.

Interstitial cells of Leydig in the connective tissue around the seminiferous tubules. This constitutes the endocrine tissue of the testis. These cells secrete Testosterone into the blood. Somniferous tubules unite to form a large number of straight tubules, which open into irregular cavities in the posterior part of the testis. The vasa efferentia arise from these cavities and conduct spermatozoa out from the testis.

Functions of Testosterone:

1. It stimulates the growth and development of male secondary sex organs (prostate, seminal vesicles, and penis).
2. It stimulates and maintains the normal function of secondary sex organs in reproduction.
3. It also stimulates and maintains the development of external male characters such as beards, mustaches, and low-pitch male voices in males and combs and wattles in cock.
4. It also stimulates the formation of sperms in the testes.
5. It promotes the growth of many body tissues including bones and muscles.

T.S. of testis of an adult man

Question 3.
Distinguish between
(a) Follicle-stimulating hormone and luteinizing hormone.
Answer:
Follicle-stimulating hormone and luteinizing hormone:

Stimulating hormone (FSH)	Luteinizing hormone
(i) It stimulates the testes in the male to produce sperms.	(i) It stimulates the testes to secrete the male sex hormone.
(ii) It stimulates the ovaries in the female to produce ova.	(ii) It stimulates the ovaries to secrete the female sex hormone- progesterone.

(b) Somatostatin and somatomedin
Answer:
Somatostatin and somatomedin:

Somatostatin	Somatomedin
(i) It is secreted by the anterior lobe of the pituitary.	(i) It is secreted by the hypothalamus.
(ii) It stimulates body growth	(ii) It inhibits the secretion of the growth hormone from the anterior pituitary.

(c) Vasopressin and Oxytocin
Answer:
Vasopressin and Oxytocin:

Vasopressin	Oxytocin
(i) Vasopressin is released from the axon terminal of hypothalamic neurons into the blood in the posterior lobe of the pituitary due to the rise in blood osmotic pressure caused by the loss of water from the body.	(i) Oxytocin is released from the axon terminals of hypothalamic neurons into the blood in the posterior lobe of the pituitary due to distension of the uterus by the full-term fetus or due to the sucking of the breast by an infant.
(ii) It reduces the volume of urine by increasing the reabsorption of water from the urine in the distal convoluted tubules, collecting tubules, and collection ducts in the kidney, hence called Antidiuretic Hormone (ADH).	(ii) It helps in childbirth by causing uterine contractions at the end of pregnancy, hence called birth hormones.
(iii) It increases arterial blood pressure by causing constriction or narrowing of arterioles.	(iii) It causes the contractions of the mammary gland and muscles that help in the flow of stored milk from the mammary gland to the mouth of the sucking infant, hence called milk ejection hormone.

(d) Estrogen and progesterone
Answer:
Estrogens and Progesterone:

Estrogens	Progesterone
(i) These are secreted by the cells of maturing Grrafian follicle.	(i) Corpus luteum and placenta secrete progesterone.
(ii) Estrogen stimulates growth, maturation, and functions of female secondary sex organs at puberty.	(ii) Progesterone brings about most of the pregnancy changes such as uterine growth, attach¬ment of the embryo to the uterine wall, placenta formation.
(iii) These also develop and maintain external female sex characters like the high pitch female voice and the female pattern of body hair distribution.	(iii) No such action.

(e) Glucocorticoids and mineralcorticoids
Answer:
Glucocorticoids and Mineralocorticoids:

Glucocorticoids	Mineralocorticoids
(i) Glucocorticoids such as cortisols regulate the metabolism of carbohydrates, fats, and proteins.	(i) Mineralocorticoids such as Aldosterones regulate the metabolism of sodium and potassium.
(ii) These are secreted from the middle cellular layer (ZONA Fasciculate) of the adrenal cortex

(f) Diabetes mellitus and diabetes insipidus
Answer:
Diabetes mellitus and Diabetes insipidus:

Diabetes mellitus	Diabetes insipidus
(i) It is due to failure of insulin secretion.	(i) It is due to the failure of secretion of vasopressin.
(ii) The blood sugar is abnormally high and the glucose appears in the urine.	(ii) The blood sugar is normal and no glucose appears in the urine.
(iii) There are high blood cholesterol and ketone body formation.	(iii) There is no such phenomenon.

(g) Exophthalamia goiter and iodine deficiency goiter
Answer:
Exophthalmic Goitre and Iodine Deficiency goiter:

Exophthalmic Goitre	Iodine Deficiency goiter
(i) It is accompanied by a bulging of eyeballs, i.e., exophthalmos.	(i) It is accompanied by cretinism in children and myxedema in adults.
(ii) The thyroid is overactive and secretes an excessive amount of thyroid hormones.	(ii) The dietary deficiency of iodine causes the deficiency of thyroid hormones.

(h) Cretinism and dwarfism.
Answer:
Cretinism and dwarfism:

Cretinism	Dwarfism
(i) It is due to over secretion of so gonadotropin from childhood.	(i) It is due to the failure of secretion of somatotropin from an early age.
(ii) There is an abnormal elongation of all long bones.	(ii) There is stoppage of growth of long bones and of the body prematurely making the patient dwarf

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