CBSE Questions for Class 11 Medical Biology Body Fluids And Circulation Quiz 8 - MCQExams.com

Both vena cava passes the deoxygenated blood to the right atrium. Blood from right atrium enters right ventricle and pulmonary arteries carry deoxygenated blood from right ventricle to lungs for oxygenation. Two pulmonary veins come from each lung and pass O$$_2$$-rich blood to left atrium. Blood enters left ventricle from the left atrium. The left ventricle pumps blood into the aorta which in turn branches and delivers blood to the major body regions and organs. So, the correct sequence is C.

Both venae cavae (7) pass the deoxygenated blood to the right atrium. Blood from the right atrium (1) enters right ventricle (2) and pulmonary arteries (6) carry deoxygenated blood from right ventricle to lungs for oxygenation. Two pulmonary veins (8) come from each lung and pass oxygenated blood to left atrium (3). The left ventricle (4) pumps blood into the aorta (5) which in turn branches and delivers blood to the major body regions and organs. So, the correct answer is option A.

• The diagram shows the different types of blood cells.
• The label A refers to eosinophils. The nucleus of these cells is bilobed. They are involved in allergic and inflammatory reactions.
• The label B refers to monocytes. They have a kidney-shaped nucleus.
• The label C refers to neutrophils. They have a multilobed nucleus. the monocytes and neutrophils are involved in phagocytosis. The label D refers to lymphocyte. They have a large circular nucleus. They form the immune T cells and B cells. 

• Blood clotting occurs following an injury or trauma. This is a mechanism to prevent excessive loss of blood from the body. 
• A clot is formed mainly of a network of threads, called fibrin. 
• An injury stimulates the platelets in the blood to release certain factors, which activate the mechanism of coagulation. 
• Platelets are a source of thromboplastin. Thromboplastin converts prothrombin, which is a plasma protein that is formed in the liver, into the enzyme thrombin. 
• In turn, thrombin converts fibrinogen into fibrin. Fibrin is insoluble and forms the threads that bind the clot.
• Thus, the correct answer is option B.

• The primary function of white blood cells, or leukocytes, is to fight infection. A high white blood cell count usually indicates: An increased production of white blood cells to fight an infection.
  
• When Rahul is having fever he may be be having some infection inside his body which is causing fever. During any infection the count of WBC increases to fight the infection.
• So, the correct answer is 'WBC'.

• Sinus arrhythmia is a normal phenomenon in which heart rate increases during inspiration and decreases during expiration.
• This is due to reflex changes in vagal nerves. It is most commonly seen in children and young adults. 
• It is interpreted using ECG. It is cyclic changes that occur in heart rate during normal breathing.

• All mammals possess enucleated red blood cells whereas red blood cells of birds, reptiles, amphibians and fish all possess their nuclei. 
• Humans and camels belong to class Mammalia while frog is a amphibian.

• The Red blood cells or erythrocytes do not contain lysosomes, mitochondria, nucleus etc.
  
• The absence of cellular organelles help them to accommodate maximum space for haemoglobin and helps in carrying more oxygen.
• It also gives a distinctive bi-concave shape to these cells and also helps in diffusion.
• So, the correct answer is 'Erythrocyte'.

a) The actual nerve cell is the neuron. It is like the conducting cell which transmits impulses and the structural unit of the nervous system.

b) The nephron is the microscopic structural and functional unit of the kidney.

c) Islet of Langerhans Known as the insulin-producing tissue. These are the groups of specialized cells in the pancreas to secrete hormones.

d) Blood is considered a connective tissue because it has a matrix. Like the other connective tissues, blood is having mesodermal in origin. Also, it connects the body systems, transports oxygen, and nutrients to all the parts of the body, with the removal of the waste products. So Blood is the connective tissue.

Thus, the correct answer is [d].