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:
The practice of keeping or rearing, coring, and management of honey bee on a large scale for obtaining honey and wax is called apiculture. The place where bees are raised is called an apiary. Bee-keeping requires low investment and generates additional income, hence it is done by farmers along with agriculture.
Following ate the Honey bee varieties that are used for bee-keeping as follows:

Indigenous varieties	Exotic varieties
Apis cerana indica (Indian bee)	Apis mellifera (Italian bee)
Apis dorsata (Rock bee), Apis florae (Little bee)	Apis adamsoni (South African bee)

i. Why bee keeping should be done in good pasturage?
ii. Does honey bee help in pollination? Which type of flowers attracts the honey bee?
iii. Mention the products obtained from the honey bee.
OR
Why cambium is called lateral meristem?
OR
What is the best season to start beehive?

Answer

i. Bees need quality nectar to produce honey. A good pasturage consists of plenty of flowers that can be used by bees to get quality nectar. This increase the quality as well as the quantity of the bees. If bees are confined to only a single variety of flowers for nectar honey quality will have a similar taste and consistency. Most farmers make honey obtained from single nectar.
ii . Yes, honey bee helps in pollination. The bright-coloured flowers attract the honey bee.
iii. Besides honey, other products of bee-keeping are bee wax, bee venom, propolis, and royal jelly.
OR
The cambium is called the lateral meristem because it increases the girth of the axis.
OR
Spring season is best to start a beehive.

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Question 34 Marks

Read the following text carefully and answer the questions that follow:
The tissue is a group of cells having similar origin, structure\& function. Study of tissues is called Histology. In unicellular organism (Amoeba) single cell performs all basic functions, whereas in multi-cellular organisms (Plants and Animals) shows division of labour as Plant tissue \& Animal tissues. Plant tissues are two types:

Meristematic tissue: The meristems are the tissues having the power of cell division. It is found on that region of the plant which grows.
Following are the types of Meristems:
The Apical meristems- It is present at the growing tip of the stem and roots and increases the length.
The lateral meristems- It present at the lateral side of stem and root (cambium) and increases the girth.
The intercalary meristems- It present at internodes or base of the leaves and increases the length between the nodes.
i. Which tissue help in the secondary growth of the plant?
ii. In what region of the plant does intercalary meristematic growth occur?
iil. Where does meristematic tissue mostly found in a plant?

Answer

i. Cambium tissue help in the secondary growth of the plant.
ii. Between mature tissue segments, intercalary meristematic growth occurs.
iii. Meristematic tissues are mostly found at the apices of root and shoot.

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Science Case study ( 4 Marks )

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