Question Discussion & Solution

The correct answer is Virus protection.

Functions of operating system are:

• Therefore, Virus Protection is not the function of OS. It is a function of Firewall and Antivirus.

The correct answer is a Female egg cell.

The female egg cell is the largest cell in the human body. The nerve cell is the longest cell in the body.

• The egg cell or ovum is the largest cell in the human body.
• It has a diameter of about 0.1 mm.
• A nerve cell is the longest cell in the human body.
• Muscle cells are the primary cells responsible for the movement of the body. There are three types of muscle cells found in our body, namely ;
  • Skeletal muscle or voluntary muscle.
  • Smooth muscle or involuntary muscle.
  • Cardiac muscle.

Mistake Points

• The smallest cell is Mycoplasma (PPLO-Pleuro pneumonia-like organisms).
• It is about 10 micrometres in size.
• The largest cell is an egg cell of ostrich.
• The longest cell is the nerve cell.
• The largest cell in the human body is the female ovum.
• The smallest cell in the human body is the male gametes, that is, sperm.

The correct answer is Both 2 and 3.

Key Points

• Both mitochondria and chloroplasts  possess their own genetic material thus, they are called as semi-autonomous organelles.
• The mitochondrial DNA and plastid DNA possess genes which produce the proteins necessary for the functioning of mitochondria and chloroplasts  respectively.

• Mitochondria (sing.: mitochondrion), unless specifically stained, are not easily visible under the microscope.
• The number of mitochondria per cell is variable depending on the physiological activity of the cells.
• In terms of shape and size also, a considerable degree of variability is observed.
• Typically it is sausage-shaped or cylindrical having a diameter of 0.2-1.0µm (average 0.5µm) and length 1.0-4.1µm.
• Each mitochondrion is a double membrane-bound structure with the outer membrane and the inner membrane dividing its lumen distinctly into two aqueous compartments, i.e. the outer compartment and the inner compartment.

The correct answer is Silicon.

• An integrated circuit, or IC, is a small chip that can function as an amplifier, oscillator, timer, microprocessor, or even computer memory.
• An IC is a small wafer, usually made of silicon, that can hold anywhere from hundreds to millions of transistors, resistors, and capacitors.
• An integrated circuit or monolithic integrated circuit (also referred to as an IC, a chip, or a microchip) is a set of electronic circuits on one small flat piece (or "chip") of semiconductor material that is normally silicon.

Key Points

• Silicon is a highly pure, easy to use, and cheap semiconductor, perfect for the now huge computer chip industry.
• Silicon is used because it can be used as either an insulator (doesn't allow electricity to flow) or a semiconductor (allows a little flow of electricity).

Important Points

The advantages of ICs :

• Extremely small in size.
• Low power consumption.
• Reliability.
• Reduced cost.
• Very small weight.
• Easy replacement. 

Eureka:

• Constantan is a Nickel-Copper alloy also known as Eureka.
• It usually consists of 55% copper and 45% nickel.
• Its main feature is the low thermal variation of its resistivity, which is constant over a wide range of temperatures
• Constantan is a Nickel-Copper-based alloy wire that has a high resistivity and is mainly used for thermocouples and electrical resistance heating.
• It has a constant resistivity over a wide range of temperatures.
   

Composition:

• Ni = 45 %
• Cu = 55 %
   

Properties of Eureka:

• Resistivity - 490 µΩ -cm
• Melting point: 1300 ⁰C
• Specific gravity: 8.9 gm /cm³
• Negligible temperature Coefficient
• Easily ductile
• Resistant to atmospheric corrosion
• Can be easily soldered and moulded
   

Application:

• It is used for the measurement of temperature.
• It is used for the formation of thermocouple, along with the wires of other metals such as copper, iron, and chromium.
• It is especially used for resistance purposes since its resistance does not change much with the change in its temperature. It is used for DC current shunts.