Case study ( 4 Marks )

Question 14 Marks

Read the following text carefully and answer the questions that follow:
Mixtures are constituted by more than one kind of pure form of matter. Sodium chloride is itself a pure substance matter. The solution is a homogeneous mixture of two or more substances. Lemonade, soda water etc. are all examples of solutions. Alloys are mixtures of two or more metals or a metal and a non-metal and cannot be separated into their components by physical methods. A solution has a solvent and a solute as its components. The component of the solution that dissolves the other component in it (usually the component present in a larger amount) is called the solvent. The component of the solution that is dissolved in the solvent (usually present in lesser quantity) is called the solute.

i. In a water-sugar solution: Identify solute and solvent?
ii. What is the size of the particles of a solution?
iii. What is pure substance?
OR
What do you mean by Alloy?

Answer

i. Water is solvent and sugar is solute.
ii. 1 nm in diameter
iii. Pure substances are substances that are made up of only one kind of particle and have a fixed or constant structure.
OR
The meaning of the term 'alloy' is a substance formed from the combination of two or more metals. Alloys can also be formed from combinations of metals and other elements. ex-steel.

View full question & answer→

Question 24 Marks

Read the following text carefully and answer the questions that follow:
A bee colony consists of a single queen and a large number of worker bees. Drones are present in the early stages but do not occur later on. All the functions of the colony are performed by worker bees. They build the hive, collect food, feed themselves as well as the queen, store food and protect the hive. Genetically, a worker bee does not differ from a queen bee and can even become a laying worker bee, but in most species will produce only male (drone) offspring.
i. Why are drones absent in the mature bee colony?
ii. When and how are drones produced?
iii. What is bee bread?
OR
Why worker bees are females but they do not lay eggs?

Answer

i. They take part in nuptial flight after which they but not allowed to enter the colony.
ii. During new colony formation and from unfertilized eggs.
iii. Bees produce food substances for worker bees and larvae in the form of bee bread.
OR
Colony behavior, egg laying and ovary development in worker honey bees is prevented by queen pheromones and open brood pheromone. However, in the absence of these regulating pheromones, workers may develop ovaries which will enable them to lay their own eggs.

View full question & answer→

Question 34 Marks

Read the following text carefully and answer the questions that follow:
The process of taking up a permanent shape, size, and a function is called differentiation. Differentiation leads to the development of various types of permanent tissues. A few layers of cells beneath the epidermis are generally simple permanent tissue. another type of permanent tissue is complex tissue. Complex tissues are made of more than one type of cells. All these cells coordinate to perform a common function. Xylem and phloem are examples of such complex tissues. Xylem consists of tracheids, vessels, xylem parenchyma and xylem fibres. Phloem is made up of five types of cells: sieve cells, sieve tubes, companion cells, phloem fibres and the phloem parenchyma.
i. Identify the type of cell in the given figure

ii. Which part of desert plants reduces the loss of water?
iii. What is the dead element present in the phloem?
OR
Is cardiac muscle A involuntary muscle?

Answer

i. Tracheids
ii. Cuticles reduce the loss of water.
iii. Phloem fibres
OR
Yes, the muscles whose functioning cannot be controlled are called involuntary muscles.

View full question & answer→

Science Case study ( 4 Marks )

Test yourself on this topic