BPSC Practice Test- 2 - BPSC (Bihar) MCQ

• Rust is an iron oxide, a usually reddish-brown oxide formed by the reaction of iron and oxygen in the catalytic presence of water or air moisture.

• Chemical formula of rust is Fe₂O₃.xH₂O

According to the given information:
A, U, and O are the vowels.
While D is a consonant.
So, D is not similar to the other alphabets.

• In an electrochemical cell, the flow of current is opposite to that of the flow of electrons.
• Since the electron is moving from anode to cathode through an external circuit, therefore, current flows from cathode to anode.

OPTIONS EXPLANATION

• Dry cells – They are used in transistors and clocks. They are also known as Leclanche cell.

• Mercury cells – They are used in low current devices like hearing aids, watches, etc

• Fuel cells - The cell was used for providing electrical power in the Apollo space programme.

When nettle sting person, it injects an acidic liquid (methanoic acid) into the skin. Rubbing with mild base like baking soda solution on the stung area of the skin gives relief.

OPTIONS EXPLANATION

• Hydrochloric acid and sulphuric acid – These are examples of mineral acids.

• Citric acid – It is and example of organic acid and it is present in citrus fruits like oranges.

• Gastric juice is made up of digestive enzymes, hydrochloric acid and other substances that are important for absorbing nutrients

• Since hydrochloric acid is present in gastric juice, it gives large amount of H+ ions.

• This is because hydrochloric acid is a strong acid.

OPTIONS EXPLANATION

• Sodium hydroxide solution – It gives highest amount of OH- ions. It is also known as caustic soda.

• Milk of magnesia – is a mild base, gives less amount of OH- ions.

• Lemon juice – It is rich of citric acid. It gives less number of OH- ions.

• This is because citric acid is an organic acid and all organic acids are weak acids.

• Photometer is used to measure the intensity of light produced by an unknown source in terms of a standard source.

• It can be defined as an instrument that measures visible light.

• It is an instrument that measures the strength of electromagnetic radiation in the range from ultraviolet to infrared and including the visible spectrum.

• Most photometers convert light into an electric current using a photoresistor, photodiode, or photomultiplier.

Ammeter

• Ammeter, instrument for measuring either direct or alternating electric current, in amperes.

• An ammeter can measure a wide range of current values because at high values only a small portion of the current is directed through the meter mechanism; a shunt in parallel with the meter carries the major portion.

Anemometer-

• An anemometer is a device used for measuring wind speed and direction.

• It is also a common weather station instrument.

Dynamometer-

• A device for measuring force, moment of force (torque), or power.

• A dynamometer can also be used to determine the torque and power required to operate a driven machine such as a pump. In that case, a motoring or driving dynamometer is used.

Scalar-

• Physical Quantities which have only magnitude and no direction are called scalar quantities.
• example: Mass, Time, Volume, Temperature, etc.

Vector

• Physical Quantities which have both magnitude and direction are called vector quantities.
• example: Force, Velocity, Momentum, etc.

• Relative density is a dimensionless physical quantity.
• Relative density is defined as the ratio of the density of a given substance and the density of water.
• Relative density is equal to the ratio of density of substance to density of water.
• Since both have the same dimensions, thus their ratio is dimensionless.

Centrifugal force

• Centrifugal Force is force which acts on a rotating body when viewed from the rotating frame of reference.
• It acts in a direction away from the centre of rotation of the body.
• The origin of centrifugal force is due to the property of inertia.

Centripetal force

Centripetal force is the force that attracts any object to its center when it moves in any circular path, then it depends on three things-

• Velocity of the object moving in the circular path.
• Distance of the object from the center of the path.
• Mass of the object

Options explanation

• Root cap- The root cap is a type of tissue at the tip of a plant root. It is also called calyptra

• Root apex, is a small region at the tip of a root in which all cells are capable of repeated division and from which all primary root tissues are derived

• Root hairs are found only in the zone of maturation, also called the zone of differentiation

• Meristematic zone- The apical meristem, also known as the “growing tip,” is an undifferentiated meristematic tissue found in the buds and growing tips of roots in plants.

Related points

Root System

• The root is a underground part of a plant. Root with their branches is collectively called a root system.

• In Dicotyledons, elongation of radicle forms the primary roots which bears lateral roots of several orders called secondary roots, tertiary roots, etc.

• Taproot - The taproot is mainly found in dicotyledonous plants. It develops from the radicle of the germinating seed, along with its primary roots and branches. Example- Mustard seeds, mangoes, grams and banyan.

• Fibrous root- In monocotyledons, primary root is replaced by large number of roots at its base of stem to constitute the. This root develops from thin, moderately branching roots or primary roots, growing from the stem. Example- ferns and in all monocotyledonous plants.

• Adventitious root - The roots that arise from other parts of plant beside radicle are called adventitious roots. Example- Grass, Banyan tree, Maize, etc.

Related points

• Osmosis is the spontaneous net movement or diffusion of solvent molecules through a selectively permeable membrane from a region of high water potential to a region of low water potential
• Osmotic pressure
• If a membrane is present, water will flow to the area with the highest concentration of solute. Osmotic pressure is the pressure created by water moving across a membrane due to osmosis. The more water moves across the membrane, the higher the osmotic pressure.

How Is Osmotic Pressure Calculated?

• Osmotic pressure is affected by concentration and temperature.
• The concentration of solute and temperature each affect the amount of pressure created by the movement of water across a membrane. Higher concentrations and higher temperatures increase osmotic pressure.
• Osmosis is also impacted by how the solute behaves in water, which is where Van't Hoff's factor comes in. Basically, the Van't Hoff's factor of a solute is determined by whether or not a solute stays together or breaks apart in water. Some solutes break apart and form ions, or charged atoms, in water. As shown here, table salt, NaCl, will form sodium (Na+) and Chlorine (Cl-) ions in water. The Van't Hoff's factor of NaCl is two because it breaks into two ions.
• When placed in water, some molecules such as sucrose stay together and do not form ions. Since sucrose does not break into ions, it has a Van't Hoff's factor of 1.

Related points

• A vitamin is an organic molecule that is an essential micronutrient which an organism needs in small quantities for the proper functioning of its metabolism.
• Based on the solubility, Vitamins have been classified into two different groups:
• Fat-soluble vitamin
• Fat-soluble vitamins are stored in the fat cells and as the name suggests, these vitamins require fat in order to be absorbed. Vitamin A, D, E, and K are fat-soluble vitamins.
• Water-soluble vitamin
• Water-soluble vitamins are not stored in our body as their excess gets excreted through the urine. Therefore, these vitamins need to be replenished constantly. Vitamin B and C are water-soluble vitamins.

Other points

Options explanation

The liver is a large, meaty organ that sits on the right side of the belly. Weighing about 3 pounds, the liver is reddish-brown in color and feels rubbery to the touch.

• Normally you can't feel the liver, because it's protected by the rib cage. The liver has two large sections, called the right and the left lobes.

Mitosis and meiosis

• Most of the time when people refer to “cell division,” they mean mitosis, the process of making new body cells. Meiosis is the type of cell division that creates egg and sperm cells. Mitosis is a fundamental process for life.

• A germ cell is any biological cell that gives rise to the gametes of an organism that reproduces sexually. In many animals, the germ cells originate in the primitive streak and migrate via the gut of an embryo to the developing gonads.

Confusing points

• Lymphocytes Are Required for Adaptive Immunity

• There are about 2 × 1012 lymphocytes in the human body, making the immune system comparable in cell mass to the liver or brain. Despite their abundance, their central role in adaptive immunity was not demonstrated until the late 1950s.

• The crucial experiments were performed in mice and rats that were heavily irradiated to kill most of their white blood cells, including lymphocytes. This treatment makes the animals unable to mount adaptive immune responses.

• Then, by transferring various types of cells into the animals it was possible to determine which cells reversed the deficiency. Only lymphocytes restored the adaptive immune responses of irradiated animals, indicating that lymphocytes are required for these responses

Important facts

• In addition to serving as a drainage network, the lymphatic system helps protect the body against infection by producing white blood cells called lymphocytes, which help rid the body of disease-causing microorganisms.

• The organs and tissues of the lymphatic system are the major sites of production, differentiation, and proliferation of two types of lymphocytes—the T lymphocytes and B lymphocytes, also called T cells and B cells, respectively.

• Although lymphocytes are distributed throughout the body, it is within the lymphatic system that they are most likely to encounter foreign microorganisms.