Biology For Class IX - Chapter No.9 - Transport - Questions and Answers

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CHAPTER 9
TRANSPORT
Questions and Answers

Q.1: Define transport system in living organism and its components. Write down its importance?
Ans: TRANSPORT SYSTEM:
Every organism requires number of substances for their survival and maintenance of healthy life. These substances or their raw materials are taken by organism from environment or may be from internal sources. If the distance between source and required organ is small enough, organism does not require any transport system but if the distance is too long then the organism require to develop a system called transport system.
It is define as:
"Substances required to transfer from one place to another place in an organism requires a system called transport system."

COMPONENTS OF TRANSPORT SYSTEM:
The transport system requires at least two component.

1. Transport of raw material from environment to organ where they required for metabolism.
2. Transport of metabolites from cell to organs where they require.

IMPORTANCE OF TRANSPORT SYSTEM:

• In Plants: Plants are autotrophs which synthesize organic bio-molecules from inorganic molecules. These inorganic molecules are transported from environment into plants, converted into bio-molecules. These bio molecules are also transported within the plant where they required.
• In Animals: Animals are heterotrophs which get organic molecules as food, digest them into digestive tract, diffuse into blood and transport to organs where required.

Q.2: Briefly describe the External and Internal structure of root? Draw labeled diagram of the Longitudinal section (L.S) and Transverse section (T.S) of root?
Ans: External Structure Of Root:

• Externally, root has a root tip which is the growing part of root covered by root cap.
• The remaining part of root is highly branched and each branch is heavily covered by root hairs.
• Each root hair is a fine tubular outgrowth of an epidermal cell. It grows between soil particles which remain in close contact with the soil solution surrounding them.

Internal Structure Of Root:
Internally, we can study the root by taking transverse section (T.S.) of root.
The T.S. of root shows that root is mainly consists of:

• Epidermis (Epiblema) the outer layer of cells, some of these cells have root hair.
• Cortex part of root lies between epidermis and endodermis, consist of number of cellular layers.
• Endodermis lies between cortex and vascular tissues.
• Vascular Bundles consists of xylem and phloem. It is surrounded by pericycle cells.
• Pith lies between the vascular tissues and in the center of root

Root as important organ for water and Mineral transport:
Water and mineral salts enter the plant through roots.

Q.3: Define passive and active transports in roots? OR Define transport processes found in roots of plants?
Ans: Transport System In Roots Of Plants:
The root absorb water and minerals from soil through root hairs. There are two processes of transport:
(a) Passive transport:
The uptake of water and mineral by osmosis and diffusion without using energy of ATP. It is due to concentration gradient i.e. always takes place from high to low quantity of substances.

(b) Active transport:
Movement of substances from low quantity to high quantity i.e. against the gradient and it requires energy of ATP. This movement is called active transport.

Q.4: Describe the uptake of water from soil through roots in plants ( by osmosis)?
Ans: Uptake of Water From Soil:
Cell Sap and Osmosis:
The root hair is long, thin and tubular structure. It increases the surface area which increases the rate of absorption of water and minerals. The cell membrane prevents the cell sap (a mixture of sugar, salts and amino acids in solution form) from leaking out. The cell sap has low tendency of water loss i.e. water potential, than the solution of soil which result in water movement from soil to root hair. This process of water movement from a solution of high water potential to a solution of low water potential is called Osmosis.

Ascent Of Sap
As a result of osmosis of water, the root hair become turgid and their cell-sap become dilute than that of adjacent cells so the water moves from root hair to their neighbour cells. In this way, water may pass from cell to cell and finally forced into xylem and ascend up to the aerial part of plant. This upward movement of water with mineral is called ascent of sap. other factor and forces are also involved in ascent of sap.

Low Quantity Of Solute In Soil:
For absorption of water by root, it is necessary that the solute quantity in soil solution should be low and solute quantity in sap should be comparatively high, otherwise the direction of water movement will be reversed and plant may die due to dehydration.

Q.5: Describe minerals transport in plants?
Ans: Mineral Transport:
Plant also require minerals i.e nitrates, sulphates, phosphates etc. These minerals are also taken up by root hair in two ways:
(a) By diffusion, when the concentration of certain ions in soil is higher than that in root hair cells i.e passive transport.
(b) By active transport, plant requires some substance even they found in soil in low quantity. The roots have to absorb these ions against a concentration gradient by using energy of ATP, which is active transport.

Q.6: Define transpiration? Draw a labeled diagram to the show process of transpiration?
Ans: TRANSPIRATION:
Plants absorb water continuously from soil. Some of its quantity utilized in photosynthesis and other metabolic functions while the rest is retained in cell to maintain turgidity of cell. Some water is removed in the form of vapours.
"The loss of internal water of plant in the form of vapours from aerial part of plant is called transpiration. It mainly takes place through special pores guarded by specialized guard cells called stomata (sing: stoma)."

Q.7: Explain the process of transpiration in plant by bell jar experiment?
Ans: Evidences of transpiration:
Experiment:

• Take a potted plant and wrap a polythene bag around pot not around the plant to make sure that water is not coming from soil of pot and surface of pot.
• Place the pot on the glass plate and cover it with dry bell jar.
• Take another jar without plant for control setup.
• Put these two jars side by side in an area where light fall on it for two hours.

Observation:
You will observe water droplets at the bell jar which has plant while other jar remains dry.

Conclusion:
Water vapours evaporate hence transpiration occurs in plants.

Q.8: How many types of leafs are there on the basis of stomatal distribution?
Ans: Relation of transpiration with leaf surface:
Plants have three types of leaves on the basis of stomatal distribution.
(i) Bifacial Leaves:
Leaves that have stomata at lower epidermis called bifacial leaves e.g. leaves of mango plant.

(ii) Monofacial Leaves:
Leaves that have stomata at both surfaces (upper and lower epidermis) called monofacial leaves e.g leaves of maze plant.

(iii) Epistomatal Leaves:
Leaves that have stomata at upper epidermis only e.g. leaves of water lily.

Q.9: Prove to find that transpiration mainly take place through stomata perform simple experiment.
Ans: Requirement:
Few leaves, petroleum jelly or wax, scale etc.

Procedure:

• Take three leaves of pepal or mango tree where stomata are mainly present at lower surface of leaves.
• The leaves should be of equal size.
• Treat leaves as follows:
  * Leaf 1- cover the upper epidermis surface with petroleum jelly or any wax.
  * Leaf 2- cover lower surface with same.
  * Leaf 3- cover both surfaces with same.
• Weigh each leaf before and after covering.
• Hang these leaves near window in sunlight.
• After few hours note the conditions and weigh again.
• Leaf which loss more weight transpire efficiently.

Observation:
It will be observed that the leaf 1 transpire more efficiently because it has stomata at lower epidermis.

Conclusion:
The experiment shows that most of the water vapour is lost from the surface where stomata are present.

Q.10: Why surface area of leaf is important for transpiration?
Ans: Surface area of leaf is also an important factor for the rate of transpiration, because the larger size leaves have high number of stomata which increases the rate of transpiration.

Q.11: Why do the leaves of desert plants modify as spine?
Ans: The desert plants require to save their water so they have smaller size leaves or their leaves become spines to reduce number of stomata as well as rate of transpiration.

Q.12: What are stomata? Describe its structure and working?
Ans: STOMATA:
Stomata are the pores usually found in the leaf epidermis.

Structure Of Stomata:
Stomata is surrounded by two kidney shaped guard cells, these cells contain chloroplast while other epidermal cells do not. The guard cells control the opening and closing of stomata. The inner wall of guard cells is thick and inelastic whereas the outer wall is thin, elastic and permeable.

Opening/Closing Mechanism Or Working Of Stomata:
The changes in the turgidity of guard cells controls the opening and closing of stomata. Stomata open when the guard cell become turgid and close when the guard cells become flacid. The turgidity of guard cell is regulated by concentration of solutes present in it which mainly depends upon the rate of photosynthesis.

Function Of Stomata:
Opening and closing of stomata is one of the important factor to control rate of transpiration. The stomata remain open during the sunny day, as a result rate of transpiration increases. But at night they are closed, hence transpiration also stops.

Q.13: Define Transpiration pull and transpiration stream?
Ans: TRANSPIRATION PULL:
Transpiration maintains low concentration of water and high concentration of solutes in cell i.e. high solute potential. The high solute potential of leaf cells attract more water and draw more water from xylem. This continuous withdrawal of water from xylem develops deficit of water in xylem which develops a pull or tension called transpiration pull.

TRANSPIRATION STREAM:
As a result of this transpiration pull and water attraction for other water molecule i.e cohesion of water, water is pulled upward in the xylem vessels through a continuous column called transpiration stream, which helps in ascent of sap.

Q.14: Describe importance or significance of transpiration and also write down disadvantage of excessive transpiration?
Ans: SIGNIFICANCE OR IMPORTANCE OF TRANSPIRATION:

1. Help In Ascent Of Sap: By active transpiration, a suction force or a transpiration pull is created which helps in the ascent of sap.
2. Help in Absorption: Transpiration also increases the rate of absorption because the loss at one end increases demand on other end.
3. Remove Excess Of Water: Transpiration gets rid of the excess amount of water from plant.
4. Prevent Overheating: Transpiration helps in maintaining the temperature of plant for its metabolism and survival because evaporation causes cooling.
5. Help In Stomatal Mechanism: Opening and closing of stomata is also regulated by transpiration, which indirectly influences upon the rate of photosynthesis and respiration.

Disadvantage Of Excessive Transpiration:
Excessive loss of water from aerial parts which results in wilting and dehydration and ultimately may lead to death of plant in extreme conditions.
Although transpiration is considered as necessary element for plant due to its advantages but on the other hand, transpiration is also considered as an evil for plant because million of plants die every year due to excessive transpiration.

Q.15: Describe the factors which affects the rate of transpiration?
Ans: Factors affecting the rate of transpiration:
The rate of transpiration is also affected by some of the following environmental factors.

1. Temperature:
   Rate of evaporation of water from cell surface increases with increase in temperature.
   
   
2. Humidity:
   Transpiration takes place only when concentration of the vapours must be low outside than inside, so dry atmosphere is also the condition for transpiration. The rate of transpiration decrease with the increase in water vapours in atmosphere i.e. humidity.
   
   
3. Wind:
   The increase in wind velocity increases the rate of transpiration. The wind decreases the water vapours around plant and makes the atmosphere dry.
   
   
4. Atmospheric Pressure:
   Low atmospheric pressure increases the rate of transpiration through reduction in the density of air.

Q.16: Describe transport of water and food in stem of plants?
Ans: TRANSPORT OF WATER AND FOOD IN STEM:
Flowering plants have a system of vessels for transport of water, minerals and food. These vessels are called transport or vascular tissues.
There are two types of transport tissues in plants.

1. Xylem (Wood):
2. Phloem (Bast):

1. Xylem (Wood):
In flowering plants xylem is made up of four type of tissues but the main tissues are the xylem vessels.
A xylem vessel:

• It is a long, hollow, tubular structure from root to leaf. It is made up of many dead cells arranged vertically.
• The walls of these vessels become strong by the deposition of chemical substance called lignin.
• Dead cells of xylem vessels arranged vertically have empty space inside called lumen, without protoplasm and end walls.

Function Of Xylem:

• Water and mineral transportation:
  Xylem vessels reduces the resistance of water flowing through the xylem. It gives faster passage to sap, as a result transpiration pull is created in leaf.
• Provides Mechanical Support:
  The thick, rigid and lignified walls of vessels also provides mechanical support which strengthen the wall.

2. Phloem (Bast):
Phloem is also made up of four type of tissues but mainly consist of:

• Sieve tubes and
• Companion cells

The Sieve Tubes:

• Sieve tube elements of phloem is made up of columns of elongated and thin walled living cells.
• The transverse walls separating the cells have lots of minute pores.
• The cross walls look like a sieve and therefore called sieve plates.
• A mature sieve tube cell has only a thin layer of cytoplasm inside the cell. This cytoplasm is connected to cells above and below through sieve plates.
• Each sieve tube cell has lost its central vacuole, nucleus and most organelles.

Companion Cells:

• Each sieve tube cell has a companion cell beside it, which carries out the metabolic processes need to keep the sieve tube cells alive.
• Each companion cell is a narrow, thin walled cell with many mitochondria, cytoplasm and a nucleus.
• Companion cells provide nutrients and help the sieve tube cells to transport manufactured food.

Function Of Phloem:
Conduction of food by phloem:

• Phloem conducts manufactured food (sucrose) from part of plant where it is synthesized in high quantity to other parts of plant where it is required.
• In contrast to sieve tube cell, the companion cells have many mitochondria to provide energy needed for the companion cells to load sugar from mesophyll cell to sieve tube cells by active transport. 
• The perforations of sieve plates allow rapid flow of manufactured food substance through the sieve tube.
• Phloem also conducts other substances such as vitamins, hormones etc.

Q.17: Define translocation. Also describe mechanism of translocation by bulk flow or Munch theory?
Ans: TRANSLOCATION:
In higher plant, only the green parts specially leaves can manufacture food and it must be supplied to other non green parts like root, stem and flower for consumption and storage. The movement of organic materials (food) takes place through phloem. Along with food, phloem also conducts other substances such as vitamins, hormones etc. The movement of prepared food from leaves to different parts of plant through phloem elements (sieve-tubes) is called translocation.

MECHANISM OF TRANSLOCATION:
It is an established fact that translocation of solutes take place through phloem but it is still debatable. Several hypothesis and theories have been proposed to explain the mechanism of translocation. Among them bulk-flow or Munch hypothesis is the most convincing.

MUNCH THEORY (OR BULK FLOW THEORY):
According to this hypothesis,
"Solutes are translocated through the sieve tubes which flow in bulk from the supply end i.e source (leaves) to the consumption end i.e sink (root) under a turgor pressure gradient. "

As a result of photosynthesis, the supply ends (leaves) have a large amount of organic solutes, which causes tremendous increase in suction pressure of leaf cells (Mesophyll cells) and they draw water from the xylem of the leaf. As a consequence their turgor pressure is increased. The turgor pressure in the cells of stem and root is comparatively low and hence, the soluble organic solutes begin to flow in mass from mesophyll through sieve-tubes down to the cells of stem and root under the gradient of turgor pressure. These solutes are either consumed or stored in insoluble form. The excess water is released back into the xylem vessels.

Q.18: Describe transport system in animals?
Ans: Transport System In Unicellular Animals:
Cytoplasm of unicellular animals remains very much close to plasma membrane which remains in contact with environment. In these animals oxygen can diffuse through the body surface and reach easily to energy producing organelles. Similarly, the waste products can rapidly move from the body by simple diffusion.

Transport System In Multicellular Animals:
In multi-cellular organisms like mammals including man, many cells are situated away from environment. Only simple diffusion is not enough to supply O₂ (oxygen) to these cells and to get rid of wastes from there. It needs proper transport system to carry substances from one part of the body to another. Such system involved in the transport of various substances within the body of an animal is called Circulatory System. The circulatory system transports gases like O₂, CO₂ etc. nutrients, wastes, hormones and defense proteins.

Q.19: What is circulatory system? How many types of circulatory system are in animals? Name and define them with examples?
Ans: CIRCULATORY SYSTEM:
The system involved in the transport of various substances within the body of an animal is called Circulatory System. The circulatory system transports gases like O₂, CO₂ etc. nutrients, wastes, hormones and defense proteins.

TYPES OF CIRCULATORY SYSTEM:
There are two types of Blood Circulatory Systems found in animals:

1. Open circulatory system
2. Closed circulatory system

(i) Open circulatory system:
In this type of Circulatory System blood flows through the spaces among tissue so it directly comes in contact with tissues. It remains filled in the open tissue spaces called Sinuses. After exchange of materials with tissues, blood enters the pumping organs or heart which pumps it into blood vessels. These vessels again drain out blood into sinuses so it remains in Circulation.
Example: This type of circulatory system found in arthropods and molluscs.

(ii) Closed circulatory system:
This type of system allows blood to flow inside the closed tubular blood vessels and never comes out in direct contact with tissues.
Example: Human and Most vertebrates and some invertebrates such as, Annelid like earthworm, have a closed circulatory system.

Q.20: Which type of circulatory system is found in man? Write the names of the components of the circulatory system of man? Also draw neat and labelled diagram of closed circulatory system in man
Ans: Transport System OR Circulatory System In Man:
In man, closed type of circulatory system is found, which consists of following components.

1. Blood: A fluid with cells and other dissolved substances.
2. Heart: A pumping, pulsatile organ.
3. Blood vessels: Tubes i.e. Arteries, veins and capillaries.

This is much more efficient and rapid system of transport.

Closed Circulatory System In Man

Q.21: What is blood? Describe the composition of blood and explain its functional importance. OR What is blood? Write down its components. Also give their functions.
Ans: BLOOD:
Blood is a special type of tissue, found in the form of fluid which circulates in the body. It transports substances in the body of an organism.

COMPONENTS OF BLOOD:
It consists of two parts:

1. Plasma
2. Corpuscles

i) Plasma:

• Plasma is the fluid part of blood and constitutes about 55% by volume of whole blood. It is pale yellowish liquid.
• About 90% of plasma is water in which complex mixture of various substances are dissolved.
• There are dissolved mineral salts like bicarbonates, sulphates, chlorides and phosphates of sodium (Na) and potassium (K). All these are found in the form of ions.
• Salts of calcium are also present in blood for clotting of blood.
• Soluble proteins are also present in plasma i.e. Serum albumin, Serum globulin, fibrinogen and prothrombin. The last two play important part in clotting of blood.
• Antibodies are also present in plasma, which are involved in fighting diseases.
• Plasma contains digested food substances such as glucose, amino acids, fatty acids and vitamins.
• It also contains excretory products such as Urea, Uric acid and creatinine. Carbondioxide (CO₂) is also present as bicarbonate ions.
• It also contains hormones.

Function:

• It provides medium for exchange of materials between the body cells and the blood.

ii) Corpuscles:
In man, 45%of the blood consists of blood cells. The blood cells are of the following types:

1. Erythrocytes OR Red Blood Cells (RBCs)
2. Leucocytes OR White Blood Cells (WBCs)
3. Platelets

a) Erythrocytes OR Red Blood Cells (RBCs):

• In mammals, RBCs are disc like circular, bi-concave cells in shape.
• They are 0.007-0.008 mm in diameter in size. RBCs are non-nucleated, and do not have mitochondria, endoplasmic reticulum and Golgi bodies.
• 1mm³(1 drop) of blood contains approximately 5 million RBCs.
• They also contain respiratory pigments i.e. haemoglobin. Haemoglobins are red pigment protein containing iron. The red color of the blood is due to the haemoglobin of RBcs.
• RBCs are produced in bone marrow and destructed in spleen and liver. There life is 120 days on average.

Function:

• Haemoglobin of RBCs:
  * Transports O₂ from lungs to body cell.
  * Transports CO₂ from body cell to lungs.
• When haemoglobin are bronken down:
  * Iron released (stored in liver)
  * Bile pigments (excreted in GUT)

b) Leucocytes OR White Blood Cells (WBCs):

• Leucocytes or WBCs are colourless, irregular in shape, nucleated and lager sized cell than R.B.Cs.
• 1 mm³ contains approximately 7000 WBCs.
• They are of several types basis on the shape of the nucleus.

Function:

• Leucocytes or WBCs are commonly known as the "Police of the Body". They protect the body by killing germs that enter the body.
• There are several types of White blood cells which perform different functions.

Types Of Leucocytes OR White Blood Cells (WBCs):

c) Platelets:

• Platelets are the fragments of cells which are formed from large precursor cells in the bone marrow.
• On injury, exposure to the air stimulate the platelets at cut end to produce an enzyme in blood. This enzyme causes the soluble plasma protein fibrinogen to form insoluble fiber of another protein fibrin which forms a network of fibers around wound.

Function:

• It protects blood to flow, that is called clot, which prevents bleeding and stops the entry of pathogen.

Blood Components In Tabular Form

Q.22: Write a note on blood disorders? OR write down the symptoms and causes of blood Leukemia and Thalassemia.
Ans: BLOOD DISORDERS:
(a) Leukemia:
It is a type of cancer that affects the blood, bone marrow and lymphatic system. In this type of blood cancer, number of W.B.Cs increases and R.B.Cs decreases.
Symptoms:

• Fever or chill
• Persistent fatigue, weakness
• Frequent or severe infections
• Loss of weight without try
• Swollen lymph node
• Enlarge liver or spleen
• Easy bleeding or bruising
• Recurrent nose bleeding
• Ting red spots on skin
• Sweating at night
• Bone pain or tenderness

Causes:
Leukemia is caused by a cancerous mutation (change in their gene DNA), in bone marrow or lymphatic tissue cells. It can be result of:

• Genetic disorder
• Exposure to certain chemicals
• Smoking
• Family history

(b) Thalassemia:
It is the name of a group of inherited conditions that affect the blood haemoglobin. Persons having thalassemia do not produce or produce little amount of haemoglobin, which is used by red blood cells to carry oxygen around the body.

Symptoms:
Person having problems of thalassemia having following symptoms.

• A pale and restless appearance
• Poor appetite
• Slowed growth and delayed puberty
• Dark urine An enlarged spleen
• liver or heart Jaundice

Causes:
It is a genetic problem due to mutations in the gene of haemoglobin.

Thalassemia Majors:
It occurs when a child inherits two mutated genes, one from each parent. Children born with this disorder usually develop the symptoms of severe anemia within the first year of life. They lack the ability to produce normal, haemoglobin and feel chronic fatigue.
Thalassemia Minors:
Thalassemia minor have occurred when a child inherit it from one of the parent. Persons have mild anemia and slight lowering of haemoglobin level in the blood. It resembles with mild iron deficiency anemia. People with this disorder do not have any symptoms.

Q.23: Describe the external and internal structure of human heart and draw labeled diagram also. Also write down the working of heart.
Ans: External Structure Of Human Heart:

• Heart is the major organ of Circulatory system. It is a muscular pump which keeps the blood circulating throughout the body.
• Location: It is located in the thorax slightly at the left side.
• Pericardium: It is enclosed in a fibrous bag like protective cover called Pericardium. It is conical in shape externally.
• Pericardial fluid: The space between pericardium and heart is pericardial cavity which is filled with a fluid called pericardial fluid. This fluid reduces friction and Pericardium protects the heart, prevent it from over extension.

Internal Structure Of Human Heart:
Internally, it consists of four chambers:

1. The upper two are thin walled called atria (sing: artrium). They divide into:
   i. Right Auricle
   ii. Left Auricles
2. the lower two are thick walled called ventricles. They divide into:
   iii. Right Ventricles
   iv. Left Ventricles

Auricles OR Atria (sing: artrium):

• The upper two are thin walled chambers called auricles atria.
• Atria are completely separated from each other by a septum called inter-atrial septum.
• Each atrium is connected (opened) with its ventricle by an auriculo-ventricular aperture.
• The right atrium receives deoxygenated blood from all parts of the body through superior and inferior vena cava.
  * The right atrium and right ventricle are connected by Tricuspid Valve.
• Similarly, left atrium received oxygenated blood from lungs through pulmonary veins.
  * The left atrium and left ventricle are connected by bicuspid valve
•  These valves prevent the backward flow of blood from the ventricles to the atria.

Function Of Atria:
The function of atria is to stretch to receive blood as it returns to the heart and then contract with enough force to push the blood through the atrioventricular valves into the ventricles. This requires a lower pressure than that developed in the ventricles, so the walls of the atria are much thinner and more elastic than those of the ventricles.

Ventricles:

• The lower two are thick walled chambers called ventricles.
•  The two ventricles are separated from each other by a muscular partition called inter-ventricle septum.
• Two main blood vessels (Aorta & Pulmonary arch) are arising from ventricles to carry blood from heart to all parts of the body.
• The blood from the right ventricle is pumped through pulmonary arch to the lungs for oxygenation
• While the blood from the left ventricle is pumped through a systemic aorta to all the parts of the body.
• The pulmonary arch and systemic aorta, both are guarded by semi-lunar valves to prevent backward flow of blood.
• There is a difference in thickness of muscle wall of the left ventricle as compared to right ventricle.

Function Of Ventricle:
The left ventricle is much thicker and narrow in space. This is related to their functions. The right ventricle only pumps blood to the lungs while the left ventricle pumps blood to all other parts of the body. The resistance to blood flow through the body capillary networks is for higher than that through the lung capillaries so, a high pressure is developed in the systemic circulation, it requires a thicker muscle wall and narrow space.

Q.24: Explain the mechanism of circulation in man? OR Explain double circuit circulation in man? OR explain working of human heart? Draw labelled diagram to show circulation of blood in human body?
Ans: DOUBLE CIRCUIT CIRCULATION SYSTEM IN MAN:
The circulation of blood in human body is called double circuit system because it circulates blood in two separate circuits and enter twice in heart during complete circulation. These two circuits are:

1. Pulmonary Circuit; from heart to lungs and back from lungs to heart.
2. Systemic Circuit; from heart to different organs and from organs back to heart.

1. Pulmonary circuit:
It transports blood from right ventricle to lungs through pulmonary arteries and flow back to heart in left atrium through pulmonary veins.

• Pulmonary Arteries: The deoxygenated blood from all over the body except lungs received in right atrium and then collected into right ventricle, upon contraction of ventricle this deoxygenated blood enters into pulmonary arch which supply this blood to the lungs, where blood gives up its CO₂ and receives O₂ from air at capillary level.
• Pulmonary veins: The deoxygenated blood now becomes oxygenated which flow back to the left atrium through pulmonary veins. This oxygenated blood now circulates through the body by Systemic Circulation.

2. Systemic circuit:
Circulation of oxygenated blood from left ventricle through systemic aorta to all organs of body and back to heart by superior and inferior vena cava as deoxygenated blood is called systemic circulation or circuit.
Systemic Aorta: Upon contraction the left ventricle forces oxygenated blood into systemic aorta, the largest artery of our body. Initially, the aorta gives off three branches which supply blood to head, arms and shoulders. This aorta then descends down and gives off many branches which supply blood to their respective organs e.g.

• A branch which supplies blood to liver called Hepatic artery,
• Another branch called renal artery supplies blood to the kidney and
• Coronary artery to heart etc.

Q.25: Define heart beat and describe its phases?
Ans: HEART BEAT:
The pumping of blood by the rhythmic pulsation of heart throughout the body is called heartbeat.
PHASES OF HEART BEAT:
It is a two phase pumping action of blood that takes less than a second.

The First Phase:
When blood is collected in the left and right atria, the heart receives an electrical signal that causes the atria to contract. This contraction pushes blood into the right and left ventricles through tricuspid and bicuspid valves respectively.

The Second Phase:
The Second Phase of pumping blood begins when the ventricles are full of blood. The electrical signals travel along a pathway of cells to the ventricles, this causes ventricles to contract.

• The relaxation of heart muscle and allowing the chambers to fill with blood, this phase of heartbeat is called diastole.
• The contraction of heart muscle and pumping the blood from the chambers into the arteries named as systole.

Q.26: Define heart rate? Also describe the effect of slow and fast heart rate?
Ane: HEART RATE:
The number of heartbeats in a minute i.e. the heart rate can be measured by the beating of heart. On average, a healthy heart beats 72 times in a minute. The normal range of heart rate is 60 – 100 beats in a minute. It is necessary to keep the heart rate within the normal range. The slow or fast heart rate may cause severe heart diseases. The heart rate may vary from person to person.

The Effect Of Slow Heart Rate:
The decreasing heart rate is a result of slow heartbeat, which leads to a condition called bradycardia. In this condition, the heart rate is too slow (or below 60 beats per minute) due to very slow heartbeat. This slow heart rate reduces amount of blood and oxygen to vital organs of body,
Symptoms Of Bradycardia:
It causes shortness of breath, dropping of blood pressure, extreme fatigue etc.

The Effect Of Fast Heart Rate:
On the other hand, when a heart beats very fast (more than 100 beats per minute), this condition is called tachycardia. Due to this rapid heart rate, the function of heart becomes very hard. It means that the heart does not have enough time to fill with blood and enough blood is pumped forward.
Symptoms Of Tachcardia:
Chest pain, dizziness and fainting are the symptoms of tachycardia.
Causes Of Tachycardia:
The tachycardia is caused by the fever, dehydration, excessive caffeine or a reaction to medication.
The main causes can be:

• Sudden cardiac arrest
• Heart failure
• Weaken heart muscle
• Lung diseases

Q.27: Define pulse rate?
Ans: Contrary to the heart rate, the pulse rate is exactly equal to the heartbeat. If the heartbeat is faster so as the pulse rate and if the heartbeat is slower, the pulse rate will be slower too. Taking a pulse is therefore a direct measure of heart rate.

Q.28: Define blood vessels and their types?
Ans: Blood vessels:
The way large buildings have the corridors, similarly blood vessels run through all of the tissues of body, while some blood vessels are as wide as your thumb, most of them are much finer than a human hair.
Types Of Blood Vessels:
There are three types of blood vessels, which are;

1. Arteries
2. Veins and
3. Capillaries

(i) Arteries:
Blood vessels carry oxygenated blood (except pulmonary artery) away from the heart.
Funtion of Arteries:

• Pulmonary arteries: Right ventricle of heart pumps blood into the pulmonary artery that goes to the lungs.
• Aorta: Left ventricle of heart pumps blood into the aorta (largest artery in body). Every organ receives blood from arteries that branch off the aorta.

Structure Of Arteries: The first branch called the coronary artery, carry blood to the walls of heart itself.
Other branches carry blood to the brain, intestine and other organs.
Arteries wall consist of three layers,

• The inner most layer, which is made up of epithelial tissues.
• The middle layer consists mostly of smooth muscle and elastic fibers.
• The outer wall is made up of flexible connective tissue.

Because of layered structure arteries have both strength and flexibility.

(ii) Veins:
Blood vessels carry deoxygenated blood (except pulmonary vein) from body towards the heart.
Structure Of Veins: The walls of veins, like those of arteries have three layers, with muscle in the middle layer. However, the walls of vein are generally thinner than those of arteries. They have large lumen.
Blood pressure in the veins is much lower than the blood pressure in the arteries. Semilunar valves in the veins prevent backflow of blood. Flow of blood along the veins is assisted by the action of skeletal muscles on the veins.

(iii) Capillaries:
Microscopic blood vessels are found in the cells of tissues.
Structure  Of Capillaries:
They have walls made up of single layer of flattened cells called endothelium. Capillary walls are partially permeable that enable substances diffuse readily through it. They are originated from arterioles and branches repeatedly to provide large surface area for the exchange of substances between the blood and the tissue cells.

Q.29: Describe the main arteries of the body?
Ans: Main Arteries Of The Body:
There are two main arteries in human circulatory system.
1. The pulmonary artery:
which originates from the right ventricle carries deoxygenated blood towards the lungs.

2. Aorta:
which originates from the left ventricle carries oxygenated blood towards the body. Aorta terminates into arteries of the head, neck and arms. Aortic arch curls backward to the left side of the heart and continues downwards as the dorsal aorta, which distributes blood to regions of the body below the heart. For example, it supplies blood (oxygenated) through:

• Hepatic artery to the liver
• Renal artery to kidney and
• Femoral artery to lower limb

Q.30: Describe the main vein of human body?
Ans: Main Veins Of Human Body:
Blood returned to the heart by the main veins as follows:
Pulmonary veins bring oxygenated blood from the lungs to the left atrium of the heart.
Vena Cava:

• Inferior vena cava runs upwards parallel to the dorsal aorta and brings deoxygenated blood from the lower body. Among these are:
  * Renal vein bringing blood from kidneys
  * Hepatic vein bringing blood from the liver and
  * Femoral veins bring blood from lower limb to the right atrium.
• Superior vena cava brings deoxygenated blood from the head, neck and arms to right atrium.

Q.31: Who explained pulmonary and systematic circulation? OR Write down the contribution of Ibn-al-nafees and William Harvey in biology?
Ans: Contribution Of Ibn-al-nafees OR Discovery Of Pulmonary Circulation:
Ibn-al-nafees was the first Arab Physician to explain pulmonary circulation. He believed that all the blood that reached the left ventricle passed through the lungs.

Contribution Of William Harvey OR Discovery Of Systematic Circulation:
William Harvey was an English Physician to explain systemic circulation in detail. He believed that blood being pumped to the brain and body by the heart.

Q.32: Describe cardiovascular disorder (CVD)?
Ans: Cardiovascular disorders (CVD):
Cardiovascular disorders related to cardiovascular system i.e. heart and blood vessels. In recent days CVD becomes leading cause of death around the world.
Types Of CVD:
Atherosclerosis (ATH):
Most common among cardiovascular disease is atherosclerosis (ATH). ATH is a disorder in which bad fats (i.e. low density lipoprotein or LDL and cholesterol) get deposited in blood vessels internal layer. Accumulation of fats leads to gradual narrowing of lumen of blood vessel. Narrow lumen leads to gradual compromise of blood supply to target organs, and leads to myocardial infarction and stroke.

Arteriosclerosis:
It is a process in which arteries loss their elasticity due to some pathological process (e.g. ATH) or simply by aging. Loss of elasticity leads to high blood pressure which may eventually be able to lead to vascular hemorrhage.

Causes of myocardial infarction:
Causes of myocardial infarction can be divided in to non-modifiable factors (which we cannot change) and modifiable factors (which we can change).

Non-modifiable factors	Modifiable factors
Sex (More in males)	Stationary life (no exercise)
Age ( More in old age)	Smoking
Race (More in blacks)	Stress
Family history	Heavy alcohol consumption
-	High fat diet

Q.33: What is vascular surgery?
Ans: Vascular surgery:
Vascular surgery is a prominent field of surgery in which vessels i.e. arteries, veins and lymphatic vessels are managed by vascular surgeons. Field gained very prominence when surgery involves bypass surgeries of heart, angioplasty, and fistula formation in cases of renal failure.

Q.34: What are leading causes of death in Pakistan?
Ans: Leading causes of death in Pakistan:
In 2018 cardiovascular disorders (ischemic heart diseases) and stroke (paralysis which is due to damage of brain tissue) becomes major cause of deaths in the world. Stationary life style, poor socioeconomic status, unavailability of state of the art facilities of health, unavailability of doctors in rural areas, lack of health and dietary awareness, etc. all contributed to increase incidence of cardiovascular disorders in our country.