Blood Circulation  Part 1 (For Classes 7 and 10) 
Compiled By P K Verma

NCERT Chapter "Life Processes" Questions and Answers

Intracellular circulation occurs inside the cell through cyclosis.    It occurs in unicellular organism like Paramecium, Amoeba etc.😍

Extracellular circulation occurs outside the body cell, i.e., extracellular fluid that circulates in the body for transport of materials.😍

Water circulatory system is a system of circulation of water drawn from outside medium into body spaces for transport of respiratory gases, wastes and food articles, eg. sponges (water canal system), coelenterates (gastro­vascular system) and starfish (ambulacral system).😍

Blood vascular system is a system containing a special body fluid or blood, blood vessels and a pumping organ or heart for moving it.  Blood vascular system occurs in vertebrates and higher invertebrates (from annelids onwards).  😍

Blood vascular system may be open or closed.  In open circulatory system, blood flows partly through vessels and partly through haemocoelomic spaces. In a closed circulatory system, the blood vessels form a complete circuit in the body, carrying blood to and away from the organs.   Closed circulatory system occurs in annelids (earthworm), some molluscs (cephalopods), echinoderms and all vertebrates. 😍

The blood in open circulatory system is called haemolymph.   Open circulatory system is found in some molluscs  and in some arthropods.    In a closed circulatory system, the blood vessels  form a complete circuit in the body, carrying blood to and away from the organs.😀

Blood is a fluid connective tissues that circulates through the heart, arteries, capillaries and veins, carrying nutrients and oxygen to the body cells. Major elements of blood consists of cellular (RBC, WBC, platelets) and fluid (plasma) elements.😀

Plasma contains three major classes of plasma  proteins viz. serum albumin, serum globulins and   fibrinogen. They serve as a source of proteins for tissue cells. 😀

Albumin and globulins retain water in blood  plasma by their osmotic effects.  Plasma functions in (a) transport (b) body   immunity (c) prevention of blood loss (d) retention of fluid in blood (e) maintenance of blood pH (f) uniform distribution of heat all over the body,  and (g) conduction of heat to skin for dissipation.😀

Haemoglobin is the gas transporting protein  molecule that makes up 95% of a red blood cell.  Each red blood cell has about 270,000,000 iron­ rich haemoglobin molecules.😀

Optimum amount of haemoglobin in male is about  16 gm/100 ml blood and 13-14 gm/100 ml blood in female.😀

Process of RBC formation  is known  as   erythropoiesis (completed in 72 hours).   The ageing cells (RBC) swell up to a sphere­like shape and are engulfed by phagocytes, destroyed and their materials are released into the blood. The main sites of destruction are the liver and the spleen. The heme constituent of haemoglobin is eventually excreted as bilirubin.😀

Leucocytes are larger than red blood cells and  have a definite nucleus.  Leucocytes can be divided into two components- 

         granulocytes  (polymorphonuclear leucocytes)

  and agranulocytes  (mononuclear leucocytes).😀

Neutrophil,  eosinophil  and  basophil  are categorised as granulocytes. 😀

Neutrophils (constitute 60 -     70%) can be recognized by their segmented nuclei and the presence of abundant, small, pale staining granules in their cytoplasm.😀

Neutrophils are the most abundant and are  produced in red bone marrow.😀

Neutrophils are active in phagocytosis, play a role  in the healing of wounds and repairing worn out and damaged tissue; and prevent infections  from spreading to other tissues of the body.😀

Nongranular  leucocytes (or  mononuclear leucocytes) can be grouped into two classes - lymphocytes and monocytes.😀

Lymphocytes are produced in the spleen, tonsils  and lymph nodes and are the smallest of the white blood cells.  Lymphocytes  are  of  two  types -  B  and T lymphocyte.😀

Lymphocytes are involved in the synthesis and  distribution of antibodies in the blood. The B cells are responsible for humoral or antibody immunity and T cells are responsible for cellular immunity.😀

Serum is a pale yellow fluid that separates from the blood upon coagulation,when all cellular elements are removed.😀

Anticoagulants like heparin, sodium or potassium  oxalate are chemical substances which prevent blood clotting. The cation necessary for coagulation of blood is  calcium.😀

Platelet aggregation and fibrin formation both require the proteolytic enzyme thrombin. Platelets are the source of thromboplastin. Lymph, chiefly made of plasma and leucocytes  is an interstitial fluid, present between the cells of a tissue.😀

If the formation rate of lymph exceeds the rate of  its return to blood then oedema occurs.  Blood groups are the special characteristic of blood  in human and related primates due to the presence of genetically controlled antigens and antibodies.😀

Antigens are relatively large proteins molecules  that provide the biological signative of an individuals blood type.😀

Within blood there are substances called antibodies  which distinguish particular antigen from others and causing bursting or agglutination of the red blood cells when alien antigen are found.😀

More than 20 different blood group systems are recognized in medicine. Of these, the best known are the ABO system and the Rh system.😀

The antigens of ABO systems are A, B and H. The H antigen is the precursor to the A and B antigens.😀 

What is the Positive and Negative sign attached to blood Group like A+  or  A-?

That shows the presence or absence of Rhesus (Rh) factor. Rh factor is an antigen (a type of protein that is inherited) on the surface of red blood cells. For example if your blood group is A+, it means your blood group is A with the presence of Rh factor. Majority of people are Rh positive. It is an issue when a Rh negative pregnant mother having a Rh positive baby. The body might not recognise the Rh factor presented in the baby and treat that as a foreign particle in the body. Hence, the antibodies in the mother would attack the baby’s blood cells. Therefore, pregnant ladies are always given a blood group test.


NCERT Questions With Answers 

Chapter :- Life Process

Question 1:

Why is diffusion insufficient to meet the oxygen requirements of multi-cellular organisms like humans?

Answer

Multicellular organisms such as humans possess complex body designs. They have specialised cells and tissues for performing various necessary functions of the body such as intake of food and oxygen. Unlike unicellular organisms, multicellular cells are not in direct contact with the outside environment. Therefore, diffusion cannot meet their oxygen requirements.

Question 2:

What criteria do we use to decide whether something is alive? Answer

Any visible movement such as walking, breathing, or growing is generally used to decide whether something is alive or not. However, a living organism can also have movements, which are not visible to the naked eye. Therefore, the presence of life processes is a fundamental criterion that can be used to decide whether something is alive or not.

Question 3:

What are outside raw materials used for by an organism? Answer

An organism uses outside raw materials mostly in the form of food and oxygen. The raw materials required by an organism can be quite varied depending on the complexity of the organism and its environment.

Question 4:

What processes would you consider essential for maintaining life? Answer

Life processes such as nutrition, respiration, transportation, excretion, etc. are essential for maintaining life.

Question 1:

What are the differences between autotrophic nutrition and heterotrophic nutrition? Answer

	Autotrophic nutrition		Heterotrophic nutrition
(i)	Food is synthesised from simple inorganic raw materials such as CO2 and water.	(i)	Food is obtained directly or indirectly from autotrophs. This food is broken down with the help of enzymes.
(ii)	Presence of green pigment (chlorophyll) is necessary.	(ii)	No pigment is required in this type of nutrition.
(iii)	Food is generally prepared during day time.	(iii)	Food can be prepared at all times.
(iv)	All green plants and some bacteria have this type of nutrition.	(iv)	All animals and fungi have this type of nutrition.

Question 2:

Where do plants get each of the raw materials required for photosynthesis? Answer

The following raw materials are required for photosynthesis:

•  The raw material CO₂ enters from the atmosphere through stomata.

•  Water is absorbed from the soil by the plant roots.

•  Sunlight, an important component to manufacture food, is absorbed by the chlorophyll and other green parts of the plants.

Question 3:

What is the role of the acid in our stomach? Answer

The hydrochloric acid present in our stomach dissolves bits of food and creates an acidic medium. In this acidic medium, enzyme pepsinogen is converted to pepsin, which is a protein-digesting enzyme.

Question 4:

What is the function of digestive enzymes? Answer

Digestive enzymes such as amylase, lipase, pepsin, trypsin, etc. help in the breaking down of complex food particles into simple ones. These simple particles can be easily absorbed by the blood and thus transported to all the cells of the body.

Question 5:

How is the small intestine designed to absorb digested food? Answer

The small intestine has millions of tiny finger-like projections called villi. These villi increase the surface area for more efficient food absorption. Within these villi, many blood vessels are present that absorb the digested food and carry it to the blood stream. From the blood stream, the absorbed food is delivered to each and every cell of the body.

Enlarged view of a villus

Question 1:

What advantage over an aquatic organism does a terrestrial organism have with regard to obtaining oxygen for respiration?

Answer

Terrestrial organisms take up oxygen from the atmosphere whereas aquatic animals need to utilize oxygen present in the water. Air contains more O₂ as compared to water. Since the content of O₂ in air is high, the terrestrial animals do not have to breathe faster to get more oxygen. Therefore, unlike aquatic animals, terrestrial animals do not have to show various adaptations for better gaseous exchange.

Question 2:

What are the different ways in which glucose is oxidized to provide energy in various organisms? Answer

Glucose is first broken down in the cell cytoplasm into a three carbon molecule called pyruvate. Pyruvate is further broken down by different ways to provide energy.

The breakdown of glucose by different pathways can be illustrated as follows.

In yeast and human muscle cells, the breakdown of pyruvate occurs in the absence of oxygen whereas in mitochondria, the breakdown of pyruvate occurs in the presence of oxygen.

Question 3:

How is oxygen and carbon dioxide transported in human beings? Answer

Haemoglobin transports oxygen molecule to all the body cells for cellular respiration. The haemoglobin pigment present in the blood gets attached to four O₂ molecules that are obtained from breathing. It thus forms oxyhaemoglobin and the blood becomes oxygenated. This oxygenated blood is then distributed to all the body cells by the heart. After giving away O₂ to the body cells, blood takes away CO₂ which is the end product of cellular respiration. Now the blood becomes de-oxygenated.

Since haemoglobin pigment has less affinity for CO₂, CO₂ is mainly transported in the dissolved form. This de-oxygenated blood gives CO₂ to lung alveoli and takes O₂ in return.

Transportation of O₂ and CO₂ in blood

Question 4:

How are the lungs designed in human beings to maximize the area for exchange of gases? Answer

The exchange of gases takes place between the blood of the capillaries that surround the alveoli and the gases present in the alveoli. Thus, alveoli are the site for exchange of gases. The lungs get filled up with air during the process of inhalation as ribs are lifted up and diaphragm is flattened.

The air that is rushed inside the lungs fills the numerous alveoli present in the lungs.

Each lung contains 300-350 million alveoli. These numerous alveoli increase the surface area for gaseous exchange making the process of respiration more efficient.

Question 1:

What are the components of the transport system in human beings? What are the functions of these components?

Answer

The main components of the transport system in human beings are the heart, blood, and blood vessels.

·       Heart pumps oxygenated blood throughout the body. It receives deoxygenated blood from

the various body parts and sends this impure blood to the lungs for oxygenation.

·       Being a fluid connective tissue, blood helps in the transport of oxygen, nutrients, CO₂, and nitrogenous wastes.

·       The blood vessels (arteries, veins, and capillaries) carry blood either away from the heart to various organs or from various organs back to the heart.

Question 2:

Why is it necessary to separate oxygenated and deoxygenated blood in mammals and birds? Answer

Warm-blooded animals such as birds and mammals maintain a constant body temperature by cooling themselves when they are in a hotter environment and by warming their bodies when they are in a cooler environment. Hence, these animals require more oxygen (O₂) for more cellular respiration so that they can produce more energy to maintain their body temperature.

Thus, it is necessary for them to separate oxygenated and de-oxygenated blood, so that their circulatory system is more efficient and can maintain their constant body temperature.

Question 3:

What are the components of the transport system in highly organised plants? Answer

In highly organised plants, there are two different types of conducting tissues − xylem and phloem. Xylem conducts water and minerals obtained from the soil (via roots) to the rest of the plant. Phloem transports food materials from the leaves to different parts of the plant body.

Question 4:

How are water and minerals transported in plants? Answer

The components of xylem tissue (tracheids and vessels) of roots, stems, and leaves are interconnected to form a continuous system of water-conducting channels that reaches all parts of the plant. Transpiration creates a suction pressure, as a result of which water is forced into the xylem cells of the roots. Then there is a steady movement of water from the root xylem to all the plant parts through the interconnected water-conducting channels.

Components of xylem tissue

Question 5:

How is food transported in plants? Answer

Phloem transports food materials from the leaves to different parts of the plant body. The transportation of food in phloem is achieved by utilizing energy from ATP. As a result of this, the osmotic pressure in the tissue increases causing water to move into it. This pressure moves the material in the phloem to the tissues which have less pressure. This is helpful in moving materials according to the needs of the plant. For example, the food material, such as sucrose, is transported into the phloem tissue using ATP energy.

Components of phloem tissue

Question 1:

Describe the structure and functioning of nephrons. Answer 

Nephrons are the basic filtering units of kidneys. Each kidney possesses large number of nephrons, approximately 1-1.5 million. The main components of the nephron are glomerulus, Bowman’s capsule, and a long renal tubule.

Functioning of a nephron:

·       The blood enters the kidney through the renal artery, which branches into many capillaries

associated with glomerulus.

·       The water and solute are transferred to the nephron at Bowman’s capsule.

·       In the proximal tubule, some substances such as amino acids, glucose, and salts are selectively reabsorbed and unwanted molecules are added in the urine.

·       The filtrate then moves down into the loop of Henle, where more water is absorbed.

·       From here, the filtrate moves upwards into the distal tubule and finally to the collecting duct. Collecting duct collects urine from many nephrons.

·       The urine formed in each kidney enters a long tube called ureter. From ureter, it gets transported to the urinary bladder and then into the urethra.

Question 2:

What are the methods used by plants to get rid of excretory products? Answer

Plants can get rid of excess of water by transpiration. Waste materials may be stored in the cell vacuoles or as gum and resin, especially in old xylem. It is also stored in the leaves that later fall off.

Question 3:

How is the amount of urine produced regulated? Answer

The amount of urine produced depends on the amount of excess water and dissolved wastes present in the body. Some other factors such as habitat of an organism and hormone such as Anti- diuretic hormone (ADH) also regulates the amount of urine produced.

Question 1:

The kidneys in human beings are a part of the system for

(a)  nutrition.

(b)  respiration.

(c)  excretion.

(d)  transportation.

Answer

(c) In human beings, the kidneys are a part of the system for excretion.

Question 2:

The xylem in plants are responsible for

(a)  transport of water.

(b)  transport of food.

(c)  transport of amino acids.

(d)  transport of oxygen.

Answer

(a) In a plant, the xylem is responsible for transport of water.

Question 3:

The autotrophic mode of nutrition requires

(a)  carbon dioxide and water.

(b)  chlorophyll.

(c)  sunlight.

(d)  all of the above.

Answer

(d) The autotrophic mode of nutrition requires carbon dioxide, water, chlorophyll and sunlight.

Question 4:

The breakdown of pyruvate to give carbon dioxide, water and energy takes place in

(a)  cytoplasm.

(b)  mitochondria.

(c)  chloroplast.

(d)  nucleus.

Answer

(b)  The breakdown of pyruvate to give carbon dioxide, water and energy takes place in mitochondria.

Question 5:

How are fats digested in our bodies? Where does this process take place?

Answer

Fats are present in the form of large globules in the small intestine. The small intestine gets the secretions in the form of bile juice and pancreatic juice respectively from the liver and the pancreas. The bile salts (from the liver) break down the large fat globules into smaller globules so that the pancreatic enzymes can easily act on them. This is referred to as emulsification of fats. It takes place in the small intestine.

Question 6:

What is the role of saliva in the digestion of food? Answer

Saliva is secreted by the salivary glands, located under the tongue. It moistens the food for easy swallowing. It contains a digestive enzyme called salivary amylase, which breaks down starch into sugar.

Question 7:

What are the necessary conditions for autotrophic nutrition and what are its by-products? Answer

Autotrophic nutrition takes place through the process of photosynthesis. Carbon dioxide, water, chlorophyll pigment, and sunlight are the necessary conditions required for autotrophic nutrition. Carbohydrates (food) and O₂ are the by-products of photosynthesis.

Question 8:

What are the differences between aerobic and anaerobic respiration? Name some organisms that use the anaerobic mode of respiration.

Answer

	Aerobic respiration		Anaerobic respiration
1.	It occurs in the presence of O2.	1.	It occurs in the absence of O2.
2.	It involves the exchange of gases between the organism and the outside environment.	2.	Exchange of gases is absent.
3.	It occurs in cytoplasm and mitochondria.	3.	It occurs only in cytoplasm.
4.	It always releases CO2 and H2O.	4.	End products vary.
5.	It yields 36 ATPs.	5.	It yields only 2 ATPs.

Anaerobic respiration occurs in the roots of some waterlogged plants, some parasitic worms, animal muscles, and some micro-organisms such as yeasts.

Question 9:

How are the alveoli designed to maximise the exchange of gases? Answer

The alveoli are the small balloon-like structures present in the lungs. The walls of the alveoli consist of extensive network of blood vessels. Each lung contains 300−350 million alveoli, making it a total of approximately 700 million in both the lungs. The alveolar surface when spread out covers about 80 m² area. This large surface area makes the gaseous exchange more efficient.

Alveoli and capillaries

 Question 10:

What would be the consequences of a deficiency of haemoglobin in our bodies? Answer

Haemoglobin is the respiratory pigment that transports oxygen to the body cells for cellular respiration. Therefore, deficiency of haemoglobin in blood can affect the oxygen supplying capacity of blood. This can lead to deficiency of oxygen in the body cells. It can also lead to a disease called anaemia.

Question 11:

Describe double circulation in human beings. Why is it necessary? Answer

The human heart is divided into four chambers − the right atrium, the right ventricle, the left atrium, and the left ventricle.

Flow of blood in the heart:

·       The heart has superior and inferior vena cava, which carries de-oxygenated blood from the upper and lower regions of the body respectively and supplies this de-oxygenated blood to the right atrium of the heart.

Flow of blood in the human heart

·       The right atrium then contracts and passes the de-oxygenated blood to the right ventricle, through an auriculo-ventricular aperture.

·       Then the right ventricle contracts and passes the de-oxygenated blood into the two pulmonary arteries, which pumps it to the lungs where the blood becomes oxygenated. From the lungs, the pulmonary veins transport the oxygenated blood to the left atrium of the heart.

·       Then the left atrium contracts and through the auriculo-ventricular aperture, the

oxygenated blood enters the left ventricle.

·       The blood passes to aorta from the left ventricle. The aorta gives rise to many arteries that distribute the oxygenated blood to all the regions of the body.

Schematic diagram of blood circulation in humans

Therefore, the blood goes twice through the heart. This is known as double circulation.

Importance of double circulation:

The separation of oxygenated and de-oxygenated blood allows a more efficient supply of oxygen to the body cells. This efficient system of oxygen supply is very useful in warm-blooded animals such as human beings.

As we know, warm-blooded animals have to maintain a constant body temperature by cooling themselves when they are in a hotter environment and by warming their bodies when they are in a cooler environment. Hence, they require more O₂ for more respiration so that they can produce more energy to maintain their body temperature. Thus, the circulatory system of humans is more efficient because of the double circulatory heart.

Question 12:

Transport of materials in xylem Transport of materials in phloem (i) Xylem tissue helps in the transport of water and minerals. (i) Phloem tissue helps in the transport of food. (ii) Water is transported upwards from roots to all other plant parts. (ii) Food is transported in both upward and downward directions.

What are the differences between the transport of materials in xylem and phloem? Answer

(iii)

Transport in xylem occurs with the help of simple physical forces such as transpiration pull.

(iii)

Transport of food in phloem requires energy in the form of ATP.

Question 13:

Compare the functioning of alveoli in the lungs and nephrons in the kidneys with respect to their structure and functioning.

Answer

Alveoli

Nephron

Structure (i)  Alveoli are tiny balloon-like structures present inside the lungs. (ii)  The walls of the alveoli are one cell thick and it contains an extensive network of blood capillaries. Function (i)  The exchange of O2 and CO2 takes place between the blood of the capillaries that surround the alveoli and the gases present in the alveoli. (ii)  Alveoli are the site of gaseous exchange.

Structure (i)  Nephrons are tubular structures present inside the kidneys. (ii)  Nephrons are made of glomerulus, bowman’s capsule, and a long renal tube. It also contains a cluster of thin- walled capillaries. Function (i) The blood enters the kidneys through the renal artery which branches into many capillaries in the glomerulus. The water and solute are transferred to the nephron at Bowman’s capsule. Then the filtrate moves through the proximal tubule and then down into the loop of henle. From henle’s loop, filtrate passes into the distal tubule and then to the collecting duct. The collecting duct collects the urine from many nephrons and passes it to the ureter. During the flow of filtrate, some substances such as glucose, amino acids, and water are selectively re- absorbed.  (ii) Nephrons are the basic filtration unit.