Free Practice Questions for Biology in General-studies

Hemoglobin is a red colored iron-rich pigment present in RBCs.

Important Points-

• Hemoglobin is the oxygen-carrying protein found in all RBCs.

  It takes oxygen from the lungs and releases oxygen only where the body needs it.

• Blood is composed of blood corpuscles (45%) and blood plasma (55%).
• Blood is the main circulating fluid in the body. It helps in the transport of various substances.

Bone Marrow is responsible for the red blood cells.

Important Points:

• Erythrocytes, also known as red blood cells (RBC), are the most abundant of all blood cells. 
• In adults, RBCs are formed in the red bone marrow. 
• RBCs in most mammals lack a nucleus and are biconcave in shape. 
• They are red due to the presence of hemoglobin, a pigment that acts as an oxygen carrier. 
• RBCs have an average lifespan of 120 days before being destroyed in the spleen (graveyard of RBCs).

Blood clot is formed because of the presence of certain cells presence in blood called platelets .

Important Points:

• Platelets, also known as thrombocytes, are cell fragments produced by megakaryocytes (special bone marrow cells). 

  Normally, blood contains 1,500,00-3,500,00 platelets mm-3. 

  They are little, oval-shaped cell fragments that lack a nucleus. 

  Thrombocytopenia occurs when the number of thrombocytes is lower than usual. 

  Internal bleeding (haemorrhage) is caused by this disorder.

Arteries carry oxygenated blood from the heart to other parts of the body.

Important Points:

• Arteries are vessels that transport oxygenated blood from the heart to all parts of the body. With the exception of the pulmonary arteries, which transport deoxygenated blood.
• Arterioles have thick elastic walls because blood flow is fast and under high pressure.

Options Explanation:

Bombay blood group is also known as hh blood group.

Important Points:

• This is a very uncommon blood phenotype.

  Dr. Y.M. Bhinde made the discovery in 1952 in Mumbai.

  This H antigen is not produced by the HH or Bombay blood groups, and neither do the A or B antigens.

  They only carry the 'H' antibody, which no other blood group has, hence blood transfusions with other blood groups are not possible for Bombay blood.

Blood Groups (Antigens and Antibodies)

Pulmonary veins carries oxygenated blood from the lungs to the heart.

Important Points:

• Pulmonary veins are the blood vessels that are responsible for carrying the oxygenated blood from lungs to the heart.
• The pulmonary arteries are the blood vessels that are responsible for carrying the deoxygenated blood from the heart to the lungs. 
• The renal arteries are large blood vessels that carry blood from heart to kidneys. 
• Vena Cava refers to the large vein which delivers oxygen-poor or deoxygenated blood from the upper and lower halves of the body into the right side of the heart. The aorta is the main artery that carries blood away from your heart to the rest of your body.

Oxygen-rich blood from the lungs enters the thin-walled upper chamber of the heart on the left side, the left atrium.

Importent Points:

• When it is collecting blood, the left atrium relaxes.
• It then contracts while the next chamber, the left ventricle, relaxes, allowing blood to move into it.
• When the left ventricle of the muscle contracts in its turn, blood is pumped out to the body.
• De-oxygenated blood moves from the body into the upper chamber, the right atrium, as it relaxes.
• Because it's relaxing. As the right atrium contracts, the corresponding lower chamber, the right ventricle, dilates.
• It pumps blood into the right ventricle, which in turn pumps it to the lungs for oxygenation.

Fishes have only two chambers.

Important Points:

• The blood is pumped to the gills and here it is oxygenated.
• It passes straight to the rest of the body.
• Blood goes through the heart only once in the fish during one cycle of passage through the body.
• Sparrows, monkeys, and human beings have four chambered heart.

Options Explanation:

Crocodiles are classified as reptiles despite having a four-chambered heart because they have dry, non-glandular skin, epidermal scales are also present.

Important Points:

• Kingcobra - It has a three chambered heart.
• Chameleon - The chameleon's heart has three chambers: two atria and one ventricle.
• Tortoise - It has a three chambered heart.

White blood cells fight against germs that enter the human body.

Important Points : 

• Leucocytes are also known as white blood cells (WBC) as they are colorless due to the lack of hemoglobin. They are nucleated and are relatively lesser in number which averages 6000-8000 mm^–3 of blood. Leucocytes are generally short-lived. A decrease in the number of WBCs is called leucopenia. An uncontrolled increase in the number of WBCs is a type of blood cancer called leukaemia. 

Option Explanation : 

 Erythrocytes (RBC) -

• They are globular, dicotyledonous, and nucleated (in camels and llamas they are nucleated).
• The life span of a red blood cell is about 120 days.
• They are red in color due to the presence of a pigment called hemoglobin, which acts as an oxygen carrier.

Thrombocytes (platelets):

• Their life span is of 7 days.
• They release platelet releasing factors that help in blood clotting.
• They are very small, oval-shaped cell fragments without a nucleus.

Hemoglobin

• Hemoglobin is a red colored iron-rich pigment present in RBCs.
• Each hemoglobin molecule can contain up to four O₂ molecules.

SSC CPO 15/03/2019 (Morning)

IMPORTANT FACTS

Blood-

• Blood is composed of blood corpuscles (45%) and blood plasma (55%).
• Blood is the main circulating fluid in the body. It helps in the transport of various substances.
• Blood is also known as life stream of the body because blood is essential nutrients to all parts of the body and thus giving life to the body.

Erythrocytes (RBC):

• They are circular, biconcave and enucleated (in camel and llama they are nucleated). 
• The lifespan of a red blood cell is around 120 days.
• They are red in color due to the presence of a pigment called haemoglobin, which acts as an oxygen carrier. 
• The process of disintegration of RBC occurs in the liver.
• If a fall in number of RBC occurs, the condition is called anaemia.
• The formation of RBCs takes place in the red bone marrow in the adults.
• Erythrocytopenia - Decrease in number of RBCs is called as erythrocytopenia. 
• Erythropoiesis – The process of formation of RBCs is called erythropoiesis.

Leucocytes (WBC):

• Leucocytes are also known as white blood cells (WBC) as they are colourless due to the lack of haemoglobin.
• They are nucleated and are relatively lesser in number which averages 6000-8000 mm^–3 of blood.
• Leucocytes are generally short lived. 
• Decrease in number of WBCs is called leucopenia. 
• Uncontrolled increase in number of WBCs is a type of blood cancer called leukemia. 

Persons with ‘AB’ group can accept blood from persons with AB as well as the other groups of blood. Therefore, such persons are called ‘Universal Recipients’.

Important Points:

• Person with blood group ‘O’ blood can donate blood to persons with any other blood group. 
• ‘O’ group individuals are called ‘universal donors’.

SSC CHSL 11/07/2019 (Evening)

IMPORTANT FACTS

Blood vessels- 

• There are three main types of blood vessels in the human circulatory system viz, arteries, veins and capillaries.

Veins :

• Veins are the vessels that carry carbon dioxide-rich blood from all parts of the body back to the heart. 
• The veins have thin walls. They have larger lumen than arteries.
• There are valves present in veins that allow blood to flow only towards the heart.
• Except pulmonary vein which carries oxygenated blood (oxygen-rich blood) from the lungs to the heart.

Arteries-

• Arteries carry oxygen-rich blood from the heart to all parts of the body. 
• They are usually situated at a depth inside the body.
• They have narrow lumen.
• Since the blood flow is rapid and at a high pressure, the arteries have thick elastic walls.

Capillaries-

• Capillary walls are only one cell thick, allowing exchange of gases, nutrients, and wastes.
• Capillaries, the smallest and most numerous of the blood vessels, form the connection between the vessels that carry blood away from the heart (arteries) and the vessels that return blood to the heart (veins). 

The septum is not a valve of the heart.

Important Points:

• The heart is a muscular organ .
• The organ Pumps blood through the blood vessels of the circulatory system.
• In humans, birds and mammals, the heart is divided into four chambers.
• The tricuspid valve protects the opening between the right atrium and the right ventricle. It is made up of three muscular flaps, or cusps.
• A bicuspid valve, also called a mitral valve, guards the opening between the left atrium and the left ventricle. 

Carbon monoxide is reduces the oxygen carrying capacity of the blood.

Important Points:

• Carbon monoxide is a colourless, odorless gas that is highly toxic to living beings because of its ability to block the supply of oxygen to the organs and tissues of living beings.

  It is produced as a result of incomplete combustion of carbon.

  It binds to hemoglobin to form carboxyhemoglobin, which is about 300 times more stable than the oxygen-hemoglobin complex.

  In the blood, when the concentration of carboxyhemoglobin reaches about 3-4 percent, the oxygen-carrying capacity of the blood becomes very low.

  Lack of oxygen results in headache, weak vision, nervousness and cardiac disorders.

White blood cells are called the soldiers of the body.

Important Points:

• White blood cells are components of the immune system.
• White blood cells are also called leukocytes. 
• They are colorless due to a lack of hemoglobin. 
• A decrease in the number of WBCs is called leucopenia. 
• A type of blood cancer known as leukemia is characterized by an uncontrolled increase in the number of WBCs.

Epithelial tissue is a protective tissue in the body of animals.

Important Points:

• Epithelia cover most of the organs and cavities within the body. 
• It also forms a barrier to keep different body systems apart. 
• The skin, the lining of the mouth, the lining of blood vessels, the alveoli of the lungs, and the tubules of the kidneys are all made of epithelial tissue. 
• The cells of epithelial tissue are closely packed and form a continuous layer.  

Option Explanation:

SSC MTS 11/10/21(Morning)

IMPORTANT FACTS

Retina

• Retina contains three layers of neural cells – from inside to outside – ganglion cells, bipolar cells and photoreceptor cells. 
• Retina present at the posterior portion of the eyeball.
• There are two types of photoreceptor cells - rods and cones. 
• These cells contain the light-sensitive proteins called the photopigments. 

Iris

• It has a small circular opening called the pupil.
• It has a rich supply of blood vessels and contains muscles.
• The color of the iris is responsible for the color of the eye e.g., brown, black, blue, or green. 
• The iris adjusts the size of the pupil and regulates the amount of light that enters the eye.

Vitreous humor

• The space between the lens and the retina is called the vitreous chamber.
• It is filled with a transparent gel called thevitreous humor.

Crystalline lens-

• The eye ball contains a transparent crystalline lens which is held in place by ligaments attached to the ciliary body.
• It focuses the light reflected by objects on the retina.
• A crystallin is a water-soluble structural protein found in the lens.

Aqueous humor

• The space between the cornea and the lens is called the aqueous chamber and contains a thin watery fluid called aqueous humor.

There is a small circular opening in the iris called the pupil.

Important Points-

• The color of the iris is responsible for the color of the eye, such as brown, black, blue or green.
• The iris adjusts the size of the pupil and controls the amount of light entering the eye.
• The wall of the human eyeball is made up of three layers – the cornea, the choroid and the retina.
• The outer layer is made up of the cornea and the sclera. Inside the sclera is the middle layer, which is called the choroid.
• The retina, the innermost layer, contains two types of photoreceptor cells, namely rods and cones.

SSC MTS 06/10/21 (Afternoon)

IMPORTANT FACTS

• The eyeball is approximately spherical in shape with a diameter of about 2.3 cm.