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(b) Egg cell and antipodal cells

A bisexual flower is emasculated to prevent self-pollination in the flower and it is bagged after emasculation to prevent contact of unwanted pollen grain with the stigma of the flower.

Dialogue by chemical components ,germinates to produce pollen tube,content move into pollen tube,grows through stigma, style reaches ovary , generative cell divide into two male gametes enters through micropyle, filiform apparatus guides the entry.

Stored pollens can be used as pollen banks in crop breeding programmes.

Sewage Treatment Plant.

(b) Micropyle

Pollen tube carries two male gametes.

Pollen tube, after reaching the ovary, enters the ovule through the micropyle and then enters one of the synergids through the filiform apparatus which guides the entry of pollen tube into egg cell.

The answer is (c) Root hair region

The answer is (a) Capillary water

The cells of an outer most layer (epiblema) of roots have their outer walls protruding out to form a tubular structure which passes through the interparticle spaces of soil particles. These are called root hairs. The cells of epiblema which produce root hair are called trichoblast

Sir J.C. Bose experimented on Desmodium gyrus.

Upward rise of water and dissolved minerals, absorbed by roots, to the top of the plant against gravitational force is called ascent of sap. This rise takes place against the gravitational force through the lumen of xylem elements.

Water absorption is affected by the following factors: 

1. Available soil water 

2. Soil aeration 

3. Soil temperature 

4. The concentration of soil solution 

1. Available soil water: 

Soil water present in the capillary spaces of soil particle is called available water as only this can be absorbed by roots. This is directly related to the structure of the soil. More is the amount of capillary water, higher is the rate of absorption of water. The rate of absorption is optimum when water in the soil is in the range of its field capacity or it’s water holding capacity. 

2. Soil aeration: 

• Absorption of water takes place rapidly in well-aeriated soils such as loam. 
• In waterlogged soils, the rate of absorption becomes slow or even becomes zero. 

3. Soil temperature: 

Rate of absorption is high when the temperature of the soil is in the range of 20° to 30°C. Rise in soil temperature beyond 30°C results into decrease in the rate of absorption. Low soil temperature decreases absorption and at the freezing temperature, it may become zero. 

4. The concentration of soil solution: 

• Presence of a greater amount of dissolved minerals in the soil increases the concentration of soil solution and under this condition, water absorption is greatly reduced. 
• Rate of water absorption is high when soil solution is very dilute i.e. the number of dissolved minerals is low. 
• The rate of absorption is very low in saline soils.

1. During circulation, blood passes twice through the heart, therefore it is called double circulation. 

2. (1) Pulmonary circulation which is from heart to lungs and back from lungs to heart. (2) Systemic circulation which is from heart to body and back from all body organs to the heart. 

3. Oxygenated blood is carried to the heart by pulmonary veins. Dexoygenated blood is carried to the lungs by pulmonary artery. 

4. Deoxygenated blood is carried to heart by superior and inferior vena cavae. Oxygenated blood is carried to the body organs by systemic or dorsal aorta.

(I) All alkali metals react with water, liberating H₂ and forming their hydroxides. 

2M + 2H₂O ---------->2MOH +H₂ 

(II) Alkali metals tarnish in air due to formation of an oxide or hydroxide on their surface. 

4Li +O₂-------->2Li₂ O 

2Na +O₂--------->Na 2O₂ 

(iii)All alkali metals react with hydrogen to form ionic hydrides. 

2M +H₂---------->2MH 

Ionization enthalpy of alkali metals decreases down the group because the size of metal atom increases due to the addition of new shells along with the increase in magnitude of nuclear charge.

The alkaline earth metals have low ionization enthalpies due to fairly large size of the atoms. Since the atomic size increases down the group, their ionization enthalpy decreases The first ionisation enthalpies of the alkaline earth metals are higher than those of the corresponding Group 1 metals. This is due to their small size as compared to the corresponding alkali metals. It is interesting to note that the second ionisation enthalpies of the alkaline earth metals are smaller than those of the corresponding alkali metals. 

(i) Ionization enthalpy (I E): I E of alkaline earth metals are higher than those of alkali metals of group 1. This is because the atoms of alkaline earth metals have smaller size (due to higher nuclear charge) as compared to the alkali metals. 

(ii) Basicity of oxides: The oxides of alkali and alkaline earth metals dissolve in water to form their respective hydroxides. These hydroxides are strong bases. The hydroxides of alkaline earth metals are less basic than of alkali metals of the corresponding periods. This is due to their 

(a) high ionization enthalpy 

(b) small ionic size and 

(c) dipositive charge on the ions. 

As a result M-O bond in these hydroxides is relatively stronger than that of corresponding alkali metals and therefore does not break. 

(iii) Solubility of hydroxides: Because of smaller size and higher ionic charge, the lattice enthalpies of alkaline earth metals are much higher than those of alkali metals and hence the solubility of alkali metal hydroxides is much higher than that of alkaline earth metals. However the solubility of the hydroxides of both alkali and alkaline earth metals increase down the group due to large decrease in their lattice enthalpies as compared to their hydration enthalpies.

Due to the small size, high ionization energy, and high sublimation energy of beryllium, its lattice and hydration energies are insufficient to provide complete charge separation and the formation of simple Be²⁺ ions. In all compounds therefore, even BeO and BeF₂, there is substantial covalent character in the bonding.

It reacts with dilute acid to liberate carbon dioxide. 

CaCO₃ + 2HCl ---->  CaCl₂ + CO₂ + H₂O

The alkaline earth metals readily react with acids liberating dihydrogen gas. 

M + 2HCl _→MCl₂ + H₂

1. Beryllium forms covalent compounds whereas other members form ionic compounds.

2. Beryllium does not exhibit coordination more than four orbitals in the valence shell. 

3. The oxide and hydroxide of beryllium are amphoteric in nature

1 1s² 2s² 

2 Beryllium 

3 Beryllium

It is mainly because of,

(i) its small size and high polarizing power,

(ii) relatively high electro negativity and ionization energy as compared to other members,

(iii) absence of vacant d-orbitals in its valence shell.

When mixed with water, the setting of cement takes place to give a hard mass. This is due to the hydration of the molecules of the constituents and their Rearrangement. The purpose of adding gypsum is only to slow down the process of setting of the cement so that it gets sufficiently hardened.

Since the atomic sizes of magnesium and calcium are smaller than that of sodium and potassium, calcium and magnesium form carbonates and hydroxides with higher lattice energies. Thus, they are only sparingly soluble whereas those of potassium and sodium are readily soluble due to low lattice energies.

Caesium has the lowest while lithium has the highest ionization enthalpy. Hence Cs can lose electrons very easily while lithium cannot.

Lithium, potassium, and cesium, are all alkali metals. But still, potassium and cesium are used in photoelectric cell and not Lithium because Li is smaller in size when compared to the other two.

On the other hand, cesium and potassium have low ionization energy. Therefore, they lose electrons easily. This property is utilized in photoelectric cells.

By using a stronger reducing agent, the oxides of metals gets reduced by the process called chemical reduction. Alkaline earth metals and alkali metals are strong among the reducing agents. No stronger reducing agent is available than them. Therefore alkaline earth metals and alkali cannot be obtained by chemical reduction of their oxides.

Insects- lepidopterans, coleopterans and depterans.

i. Palaeontology :

The scientific study of life of the geologic past involving the fossils of plants, animals and microbes is called Palaeontology.

ii. Fossils :

Fossils are the dead remains or traces of animals, plants, and other organisms from the remote past.

Correct Answer is: (B) Palaeontology 

Correct Answer is: (B) Ribosome 

Ribosomes are the organelles responsible for protein translation and are composed of ribosomal RNA (rRNA) and proteins. Some ribosome’s are found in the cytoplasm, a gel-like substance that organelles float in and some are found in the rough endoplasmic reticulum.

a–Promoter 

b–Terminator

Correct option is (c) Testes

The process of early mitotic division of the zygote to form a multicellular morula stage is called cleavage.

Correct option is (b) one

1. The layer zone pellucida is retained around the embryo and thus, there is no change in the overall size from zygote to morula. 

2. This layer is important because it prevents the implantation of the blastocyst at an abnormal site such as fallopian tube. 

3. Though the number of blastomeres increase, the size of morula remains almost same as that of ovum till it reaches the uterus by the end of the day 4.

Holoblastic, radial and indeterminate

1. Environmental sex determination is shown by lower organisms such as Bonellia viridis. 

2. In this animal the environmental factors decide the sex of an offspring. 

3. There is extreme sexual dimorphism in this worm. Female is about 10 cm long while male is tiny and parasitic in the reproductive parts of mature female. 

4. If larva is reared in vicinity of mature female then it becomes a male. By settling on the proboscis of mature female, larva becomes parasitic, enters the female’s mouth and then takes permanent shelter in the female uterus. Such males then produce gametes and fertilize the eggs. 

5. If larvae are drifted away from mature female or if they settle on the sea bottom, they develop into females. Thus determination of sex is due to environmental factors.

1. Holandric means entirely of male sex. Y-linked genes are called holandric genes because they are located on non-homologous region of Y chromosome. 

2. The Y-linked genes are inherited directly from male to male. 

3. These genes are never seen in females due to lack of Y chromosome in them. 

4. Hyper Mchosis and ichthyosis are examples of holandric genes. 

5. Hypertrichosis means excessive development of hair on pinna of ear. This character is transmitted directly from father to son.

6. Ichthyosis person with rough skin.

Correct option is (b) 1 : 2 : 1

1. German biologist, Henking in 1891, was studying spermatogenesis of the squash bug (Anasa tristis). 

2. He noted that 50% of sperms receive the unpaired chromosomes while other 50% sperms do not receive it. 

3. Henking gave a name to this structure as the X-body. He was unable to explain its role in sex determination. 

4. Further investigations by other scientists led to conclusion that the ‘Xbody’ of Henking was a chromosome and gave the name as X-Chromosome to X-body.

(1) Thalassemia is an autosomal-eeessive disorder. The synthesis of alpha ciiains are controlled by two genes, (HBA1 and HBA2) on chromosome 16. Beta chain synthesis is controlled by gene HBB located on chromosome 11. Two alpha chains and two beta chains together form four polypeptide chains that make heterotetrameric haemoglobin molecule. But when there is defective gene on either of chromosome 16 or 11, there is quantitative abnormality of polypeptide globin chain synthesis. This results into thalassemia. 

(2) Depending upon which chain is affected, thalassemia is classified as, alpha (α) thalassemia and beta (β) thalassemia. 

(3) The clinical symptoms of thalassemia are as follows:

• Pale yellow skin.
• Anaemia due to inability to synthesize haemoglobin. 
• Slow growth and development. 
• Variation in the shape and size of RBCs.

(4) Patients need regular blood transfusions to cope with the disorder.

Males can never be carriers. They have single X and other Y chromosome. In X linked inheritance, the genes are present on the nonhomologous region of X chromosome. Males do not have other X and hence if the genes are present on his X chromosome, they will not be suppressed in them. The Y chromosome does not have dominant gene to hide this expression as there is no homolorous region too. But in case of females, there are double X chromosomes and hence if X-linked gene is recessive, the other X can hide the expression of such X-linked gene.

Thus she becomes a carrier without showing any physical characters. She is physically normal and does not suffer from such Xlinked recessive disorder. Thus, Madhav will get his answer wrong due to incorrect concept.