Free Practice Questions for Biology in General-studies

'Circadian rhythm' associated with body clock.

Important Points:

• Circadian rhythms are changes in physical, mental, and behavioural states.
• It operates on a 24-hour cycle.
• It is a natural process that reacts to light and darkness.
• It has an impact on all living things, including animals, plants, and bacteria.
• The study of circadian rhythms is known as chronobiology.
• Biological clocks are an organism's innate timing systems that regulate the cycle of circadian rhythms. 

Herbivores form the second trophic level in a food chain.

Important Points

• Those organisms which depend upon plants for their food and energy called herbivores.
• Examples cows, goats, deer, elephants are herbivores.
• The producers and  green plants forms  the first and lowest level .
• The herbivores, or plant eaters consumed the plants or their products and form the  second level . 
• At the third level, primary carnivores, or meat eaters, eat the herbivores; and at the fourth level, secondary carnivores eat the primary carnivores.

Vitamin B-12 is the only water soluble vitamin that can be stored in the liver for many years.

Important Points:

• Vitamin B-12 plays an essential role in red blood cell formation, nerve function ,cell metabolism and the production of DNA.
• The sources of vitamin B-12 included poultry, fish meat and dairy products. 
• Vitamin B-12 deficiency is treated by vitamin B-12 injections or nasal spray.

Onions produce the chemical irritant known as syn-propanethial-S-oxide, this stimulates the eyes lachrymal glands which release tears.

Important Points :

• Onions produce the chemical known as syn-propanethial-S-oxide. 
• It stimulates the eyes' lachrymal glands to release tears.
• When we cut an onion the lachrymatory-factor synthase is released into the air, this enzyme converts the amino acids sulfoxides of the onion into sulfenic acid.
• The  unstable sulfenic acid rearranges itself into syn-ropanethial-S-oxide.
• When Syn-propanethial-S-oxide gets into the air and comes in contact with our eyes. 
• The lachrymal glands become irritated and produces the tears.

Option Explanation :

There 13 vitamins are recognized as essential vitamins of March 2021.

Important Point: 

Vitamin is an organic molecule  ,it is necessary for body growth and development. 

It is a micronutrient and is primarily acquired through food .It cannot be synthesized within an organism.

There are many  types of vitamins and they are classified into water-soluble and fat-soluble vitamins.

Those vitamins which are dissolved in water called water soluble vitamins and those vitamins which dissolve in fat and oil are known as fat soluble vitamins.

Selenium is the trace mineral found in the human body.

Important Points:

• A chemical element whose concentration is very low is called trace element.
• There are some important essential trace elements of the human body included ,copper, selenium, zinc, chromium , cobalt , iodine, manganese, and molybdenum.
• Minerals are inorganic compound it is necessary for proper functioning of the human body.  

Anagen, catagen, telogen and exogen are the sequence of hair growth. 

Important Points:

• In theanagenphase, hair strands are formed after bulb regeneration. 
• The next phase of the hair growth cycle is called 'catagen'. 
• This is the transitional stage, which lasts 2-3 weeks. 
• This is followed by the telogen phase, where hair no longer grows but remains attached to the follicle. 
• This stage lasts for about 3-4 months. 
• After a period of exogenousrest, the follicles begin to grow. 
• When the follicle reaches its full length, new hair begins to grow. 

Anthocyanins pigment causes the red color in onions.

Important Points: 

• Anthocyanins are responsible for red, purple, and blue color.
•  In some fruits like berries, currants, and grapes,  have high anthocyanins content. 
• Anthocyanins are the pigments that color the fruit and flowers of many plants.
•  It is a type of flavonoid, formed by phenylpropanoid metabolism from phenylalanine.

Options Explanation:

Spider webs are made up of silk, a natural fiber made up of protein.

Important Points:

• A spider web also called cobweb is a structure formed  by a spider. 
• The silk is found in  liquid form when it inside the spider.

Option Explanation :

Collagen is a type of protein.

Important Points:

• It plays an essential role in the structure and function of bones,skin,cartilage and connective tissue of the body.
• Collagen is the important  protein for skin elasticity. 
• Collagen is produced by human body naturally. 
• The amino acids found in collagen protein are proline, glycine and hydroxyproline. 
• These amino acids are participated in the formation of 3 strands, which make up the triple-helix structure of collagen.

The upward and downward growth of shoots and roots, respectively, in response to the pull of gravity is called Geotropism.

Important Points:

• A tropic movement in response to gravity is called Geotropism ,It is also known as gravitropism.

Geotropism is a 2 types:

• Positive geotropism happens when root of plant grows downward with the force of gravity.
• Negative geotropism happens when roots grows in the opposite direction of gravity.

When a host is exposed to antigens, which may be in the form of living or dead microbes or other proteins, antibodies are produced in the host body. This type of immunity is called Active immunity.

Important Points:

Acquired Immunity-

• Acquired immunity develops when a person's immune system reacts to a pathogenic organism or microorganism and it also occurs when a person receives antibodies from another source.

Adaptive Immunity-

• Adaptive immunity occurs in response to being infected with or immunized against a microorganism or foreign organism.
• This immunity in the body creates an immune response, which can prevent future infection with the microorganism.

Passive Immunity

• Passive immunity occurs when a person receives antibodies to a disease, rather than making them through their own immune system.
• A newborn baby receives passive immunity from the mother through the placenta.

• Detritivores in the soil break down detritus into smaller particles, This process is called Fragmentation .

Important Points :

• Decomposition is the first step in the process of decomposition of dead and decaying matter or detritus in an ecosystem.

  During the decomposition process, small invertebrate animals called detritivores, such as crickets, earthworms and termites, feed on the detritus and then break down the organic matter into smaller pieces.

• Detritivores are also called decomposers.

Option Explanation :

Leaching :

• In the process of leaching, water-soluble inorganic nutrients go down into the soil horizon and get precipitated as unavailable salts.

Catabolism :

• Bacterial and fungal enzymes degrade detritus into simpler inorganic substances. This process is called as catabolism.

Mineralization :

• Mineralization is  process of the conversion of organic matter to mineral nutrients, which are normally absorbed by plants, The humus is further degraded by some microbes and release of inorganic nutrients occur by the process known as mineralization.

Earthworms are beneficial residents of the soil. Earthworms break down dead and decaying organic material into humus soil, by this process they support plant growth. 

Important Points:

• They help in the aeration of the soil and improve drainage. 
• They breathe through their skin.  
• In earthworms, five “hearts” are found that pump blood through their bodies.

Oats not fall under the category of oilseeds.

Important Points:

• Crops which are mainly grown for the extraction of oil comes under the category of oilseeds crops.
• Some important  oilseed crops are sunflower, soybean, groundnut, brassica, sesame, canola, coconut, oil palm, rapeseed, peanuts.
• Seed oils are vegetable oils obtained from the seeds.

A healthy individual has $12-16$ grams of haemoglobin in every 100 $\mathrm{ml}$ of blood.

Important Points:

• Hemoglobin is a red coloured iron containing pigment present in the RBCs. 
• It consists of four polypeptide (globin) chains 2 alpha and 2 beta chains. 
• Hemoglobin acts as the respiratory carrier. 
• It has a high affinity for O₂ and combines with it to form oxyhemoglobin. 
• One hemoglobin molecule can carry four oxygen molecules (O₂). 
• Condition with less number of RBCs or less amount of hemoglobin or both is called as anaemia.

Crocodiles have four heart chambers.

Important Points- 

• There are two atria and two ventricles where oxygenated and deoxygenated blood is separated. 
• In animals the oxygenated and deoxygenated blood received by the left and right atria respectively goes to the ventricles of the same side. 
• The ventricles pump it out without any mixing, i.e. two separate circulatory pathways are present in these animals, these animals have a double circulation. 
• Amphibians and reptiles (except crocodiles) have a 3-chambered heart. 
• The heart of fishes is 2 chambered.

The sinoatrial node is located in the heart.

Important Points:

• The heart is made of cardiac muscles. 
• The walls of ventricles are more thicker than that of the atria. 
• Nodal tissue is a specialised cardiac musculature distributed in the heart.
• The sino-atrial node (SAN) is present in the right upper corner of the right atrium.
• The atrio-ventricular node (AVN) is seen in the lower left corner of the right atrium close to the atrio-ventricular septum .
• Sinu-atrial node initiates and regularizes the heartbeat, it is also called the pacemaker.

Renal arteries carries blood from the heart to the kidneys.

Important Points:

• Renal arteries are major blood channels that carry oxygen-rich blood from the heart to the kidneys. 

  Renal is another word for kidney. There are two renal arteries. 

  The right renal artery supplies blood to the right kidney, while the left artery supplies blood to the left kidney. 

  They are an essential part of the circulatory system. 

  Each renal artery enters the kidney through the renal hilum.

AB+ blood groups is called the 'Universal Receiver

Important Points:

• In the Blood group system, blood group O- is a universal donor.
• Blood group AB+ is a universal recipient. 
• The A, B and O blood groups were discovered by Karl Landsteiner.

Options Explanation: