Case study ( 4 Marks )

Question 14 Marks

Read the following text carefully and answer the questions that follow:
A suspension is a heterogeneous mixture in which the solute particles do not dissolve but remain suspended throughout the bulk of the medium. Particles of a suspension are visible to the naked eye. The particles of a suspension scatter a beam of light passing through it and make its path visible. Due to the relatively smaller size of particles, as compared to that of a suspension, the mixture appears to be homogeneous. The scattering of a beam of light is called the Tyndall effect. The components of a colloidal solution are the dispersed phase and the dispersion medium. The solute-like component or the dispersed particles in a colloid form the dispersed phase, and the component in which the dispersed phase is suspended is known as the dispersing medium.

i.Differentiate between Dispersed phase and Dispersion medium?
ii. Differentiate between Homogeneous and Heterogeneous mixture?
iii. What is emulsion?
OR
Give an example of solid sol?

Answer

i. Dispersion medium is a continuous medium in which the dispersed phase is distributed throughout. Dispersed phase is the phase that is composed of particles that are distributed through another phase.
ii. Homogenous mixtures generally have a uniform composition throughout the mixture whereas Heterogeneous mixtures have composition which may vary from point to point. In Homogenous mixtures, the whole mixture is in the same phase whereas in Heterogeneous mixture, substances can be of two phases and layers may separate.
iii. An emulsion is a mixture of two or more liquids that are usually immiscible but under specific transforming processes will adopt a macroscopic homogeneous aspect and a microscopic heterogeneous one.
OR
Coloured gemstone.

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Question 24 Marks

Read the following text carefully and answer the questions that follow:
A farmer has grown wheat on his field consecutively two times but when the third time he grows wheat on the same field the quality of the wheat was not up to the desired level. To improve the quality of his crops he uses chemical fertilizer but the condition of the crop became worse. One of his friends told him to grow a different variety of crops after wheat so as to grow two or three crops in a year with good harvests and use biological manure in place of chemical fertilizers which he prepares by animal excreta and plant waste to get the good quality of crops. He also told him about the good storage of his grains to protect them from the biotic and abiotic losses as in agriculture storage losses are very high.
i. What are the bases on which the next crop is decided to grow in the same field also name the process?
ii. What is the advantage of using biological manure over chemical fertilizers?
iii. Is it possible for the farmer to grow two crops at the same time if yes what is the requirement?
OR
Enlist the biotic and abiotic losses?

Answer

i. The availability moisture and irrigation facilities decide the chose the crop to be cultivated after one harvest and the process knows as crop rotation.
ii. Biological manure help in improving soil structure, enriching the soil with nutrient also reduce the risk of water pollution which is a major problem with chemical fertilizers.
iii. Yes, it is possible to grow two crops simultaneously at the same but the two crops are chosen to grow should have a different nutrient requirement.
OR
Biotic losses caused by - insects, rodents, fungi, mites, and bacteria and abiotic losses are inappropriate moisture and temperature in place of quality.

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Question 34 Marks

Read the following text carefully and answer the questions that follow:
A few layers of cells beneath the epidermis are generally simple permanent tissue. Parenchyma is the most common simple permanent ulssue. Ir consists of relarively umpecialized cells with thin cell wells. They are living cells. Collenchyma allows bending of vartous parts of the plant-like tendrils and stems of climbers without breaking. Sclerenchyme tissue makes the plant hand and suff. We have seen the husk of a coconut. It is made of sclerenchymatous tissue. They are long and narrow as the walls are thickened dae to lignin. The tissue is present in stems, around vascular bundles, in the veins of leaves and in the hard covering of seeds and nuts.

i. The flexibility in plants is due to which tissue?
ii. Is aerenchyma provides mechanical support?
iii. Is apical and intercalary meristems permanent tissue?
OR
Menion the function of the tissue which is shown in the below diagram?

Answer

i. Collenchyma.
ii. No, aerenchyma helps aquatic plants to float.
iii. No, apical and intercalary meristems are not permanent tissue.
OR
Provides strength to the plant parts.

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Science Case study ( 4 Marks )

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