Question Discussion & Solution

Here the pattern is,

CONCEPT:

• Plane mirror: This mirror is straight without any inward or outward curve.
  • It forms a virtual image and upright image which is of size as same as the object.
  • The bathroom mirrors are an example.
• Concave mirror: The mirrors curved inside on the reflecting side are called concave mirrors.
  • These mirrors produce a real, inverted, and magnified image of the object.
  • These are used in reflecting telescopes, shaving mirrors, and ophthalmoscope.

• Convex mirror: It is an outward curved mirror that produces a diminished image.
  • Convex mirrors either diverge a parallel beam of light into all directions or gather light from all directions and produce a parallel beam out of it.

EXPLANATION:

• Following are the reasons as to why a convex mirror is used as a rearview mirror in the vehicle

• The image formed by the convex mirror is virtual and erect in contrast to that of the real but inverted image of the concave mirror.
• It gathers light from all directions and aligns it as a parallel beam so that it provides a wider view to the viewer. That's why the convex mirror is used as a rear-view mirror in vehicles. So option 2 is correct.

The correct answer is Element.

Key Points

• An electric room heater or an electric heater used for cooking contains a coil of wire.
• The coil of wire used in electric heaters is called a heating element.
• The heating coil of the electric room heater transfers the electric energy into heat energy.
• The elements become red hot and give out heat after connecting to the electric supply.
• The amount of heat produced in a wire depends on its material used, length, and thickness.
• The coil of the electric heater is made up of nichrome.
• Nichrome consists of 80% nickel, 20% chromium.

Additional Information

• The filament is usually made of very thin tungsten wire.
  • In an incandescent bulb, an electric current is passed through a metal filament.
• A cell is a single unit device that converts chemical energy into electric energy.
  • It produces electricity capable to run smaller appliances.
• A battery usually consists of a group of cells.

Mistake Points

• A filament is a fine resistance wire the purpose of which is to emit white light. 
• An element is a resistive wire the sole purpose of which is to produce heat.

Concept:

The nucleus of the Cell

• The cell is the basic building block of all living beings. 
• The nucleus is the special structure located generally at the center of the cell. 
• The nuclear membrane separates the cytoplasm from the nucleus. 
• The nucleus contains a central part called nucleolus and chromosomes. 
• Chromosomes and nucleolus coexist in the nucleus. Chromosomes are not present in the nucleolus.

Chromosomes and Genes

• Chromosomes carry genes and help in the inheritance or transfer of characters from the parents to their children. 
• The chromosomes can be seen only when the cell divides.
• The credit for the discovery of chromosomes goes to Strasburger as he first described the chromosome structure seen in the nucleus during cell division.
• Usually, chromosomes are rod-shaped, elongated, or dot-like in shape with sizes varying from 0.5 to 32 micrometer.
• In humans, 23pairs of chromosomes are found i.e. 46 in numbers.

Conclusion:

• Chromosomes are present in the nucleus of the cell. So, all the given options are wrong. 
• The correct option is None of these.

Additional Information

• The cell membrane is also known as the plasma membrane. 
  • It is a porous structure that allows the exit and entry of certain materials according to its requirement. 
  • This is the major function of the cell membrane. 
• The cytoplasm is between the cell and the nucleus.
  • Cell organelles like mitochondria, Golgi bodies, ribosomes, etc. are present in the cytoplasm. 
  • Mitochondria is called the powerhouse of cells and is responsible for cellular respiration. 
  • vacuole is open space between cell which is used for storing food. 
• Plastids are double-membrane organelles found in the plant cell. They contain pigments that help the plant in photosynthesis.

The correct answer is Plotter.

• The plotter is an output device producing continuous lines of different colours.

​Key Points

• Plotter
  • ​The plotter is used to draw Continuous lines.
  • A plotter is a printer that reads commands from a computer to make line drawings on paper with one or more automated pens.
  • The plotter can draw continuous point-to-point lines directly from vector graphics files or commands.
• There are a number of different types of plotters:
  • A drum plotter
    • Draws on paper wrapped around a drum which turns to produce one direction of the plot, while the pens move to provide the other direction.
  • A flatbed plotter
    • It draws on paper placed on a flat surface.
  • An electrostatic plotter
    • It is used to draw on negatively charged paper with positively charged toner.

Additional Information

• Daisy wheel printing 
  • It is an impact printing technology invented in 1970 by Dr. Andrew Gabor.
  • Used for high-quality text printing.
• Chain Printer
  • An early line printer that used type slugs linked together in a chain as its printing mechanism.
  • The chain spins horizontally around a set of hammers.
  • When the desired character is in front of the selected print column, the corresponding hammer hits the paper into the ribbon and onto the character in the chain.