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9th Notes Chapter 9 Transport Mardan board
Short Questions
Q.1) Why does an RBC lack cellular organelle?
Answer:
A matured mammalian RBCs lacks all organelles because:
- They are specialized cells containing 95% hemoglobin in the cytoplasm. Hemoglobin carries oxygen in the blood.
- RBCs lack nucleus which allows the cell to have a unique biconcave shape that helps in the diffusion of gases at the site of tissues.
- RBCs lack cellular organelles, in order to accommodate maximum space for hemoglobin.
- This helps the RBCs to move easily through the thin capillaries.
Q.2) Is the rate of transpiration higher on a sunny day or a rainy day? Why?
Answer:
The rate of transpiration is higher on a sunny day because light directly controls the opening and closing of stomata. On a sunny day, the light is strong, the stomata open up and rate of transpiration become high. Whereas on a rainy day, stomata get close and transpiration stops.
Q.3) What would happen to transpiration stream if the air is injected in xylem vessel?
Answer:
Transpiration of water from the leaves creates a pulling force in the leaves. This pulling force is called transpiration pull. The transpiration pull occurs when mesophyll cells of leaves lose water vapours, more water enters in them from the xylem vessels of stem and root. There is an unbroken column of water in xylem vessels. If the air is injected in xylem vessel, the chain of water molecule breaks and it does not move up through these tubes. As a result, transpiration pull will interrupt and transpiration stops.
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Q.4) What is translocation of food in plants?
Answer:
Translocation is the transport of food in plants. Phloem tissue is responsible for the translocation of food among different parts of the plant body. The translocation of food in plants was explained by Ernst Munch in 1930. He explains translocation through "the theory of pressure flow". According to this theory, the dissolved food flows from a source to a sink. The source includes photosynthetic tissues (e.g. mesophyll of leaves) and storage organs (e.g. roots). Sink includes the sites of food utilization (e.g. growing tips of roots and stems) and storage tissues.
Q.5) What is transpiration pull? Describe the importance of transpiration in the life of the plant.
Answer:
Transpiration pull:
Loss of water in the form of vapors from the aerial parts of the plant is called transpiration. Transpiration of water from the leaves creates a pulling force in the leaves. This pulling force is called transpiration pull.
Importance of transpiration:
- Transpiration helps in absorption of water and its conduction to different parts of the plants.
- It helps in receiving water and inorganic salts. So, transpiration indirectly helps in maintaining water and salt balance in the plant body.
- Water is necessary for plants but only a small amount of water is used by the plant. The excessive water is removed from the plant by means of transpiration.
- A suction force is created due to transpiration. In case of tall plants, suction force helps to keep the plant body upright.
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Q.6) How does the pressure-flow theory explain the movement of sugars though phloem vessels of a plant?
Answer:
Pressure-flow theory:
The translocation of food in plants was explained by Ernst Munch (a German biologist) in 1930. He called his explanation "the theory of Pressure Flow". According to this theory, the dissolved food flows from a source to a sink.
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Source:
The source includes photosynthetic tissues (e.g. mesophyll of leaves) and storage tissues (e.g. roots).
Sink:
Sink includes the sites of food utilization (e.g. growing tips of roots and stems) and the storage tissues.
The following are the steps of translocation of food in plants.
- At the source site, food (sucrose) enters the sieve tubes of phloem by active transport. Companion cells of phloem provide ATP energy for this transport.
- Due to higher solute concentration in sieve tubes than the nearby xylem tissue, water flows into sieve tubes by osmosis.
- Due to the movement of water, the turgor pressure of sieve tubes increases and the solution of food flows towards the sink.
- At the sink, food is actively removed from sieve tubes. Water also moves from the sieve tubes by osmosis.
- In this way, the turgor pressure in sieve tubes falls down, causing a flow of mass from the higher pressure at the source to the lower pressure at the sink.
Q.7) Describe the composition of human blood. What are the main functions of blood cells?
Answer:
Blood:
Blood is a specialized body fluid (a connective tissue) that is composed of a liquid called blood plasma and blood cells. It is a red fluid which circulates through blood vessels (arteries, veins, and capillaries) and heart.
Composition of Blood:
The human blood is composed of:
1) Blood plasma
2) Blood cells and cells like bodies
1) Blood plasma:
If blood is taken in a test tube and allowed to stand for a few minutes, a yellow colored liquid is separated from the cells and cell-like bodies. Cellular components settle down and the pale yellow liquid remains at the top. This yellow colored material is called plasma. It constitutes about 55% by volume of blood. It contains 90% water and 10% dissolved substances. Out of these substances, about 7% are different types of proteins generally called plasma proteins.
0.9% of plasma is made up of inorganic salts, while 2% consists of food materials, hormones, waste products, etc.
Functions of blood plasma:
Plasma performs various functions:
- Plasma keeps all the tissues moist.
- Plasma of the blood transports nutrients, water, salts, hormones, and waste materials.
- Plasma helps in the regulation of body temperature.
- Small amount of oxygen are also carried by plasma. Most of the CO2 is carried by plasma.
- Plasma proteins e.g. albumins maintain the osmotic pressure of blood.
- Important plasma proteins called antibodies defend the body against pathogens.
- Another plasma protein fibrinogen is responsible for blood-clotting.
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2) Blood cells and cell-like bodies:
These include red blood cells (erythrocytes), white blood cells (leukocytes) and cell-like bodies i.e. platelets (thrombocytes).
a) Red Blood Cells (Erythrocytes):
These are the most numerous blood cells. The function of RBCs is to transport oxygen and small amounts of CO2.
b) White Blood Cells (Leukocytes):
WBCs function as the main agents in the body’s defense system. Its' main functions are:
- They are part of the immune system and defend our body against diseases.
- They circulated and are transported to an area where infection has developed.
- Some WBCs kill pathogens (bacteria, virus etc) by engulfing them.
- Some of them also produce inflammation at the site of infection. While some of the WBCs make antibodies against pathogens.
c) Platelets (Thrombocytes):
Functions of platelets:
- Platelets help in blood clotting. The clot serves as a temporary seal at the damaged area. They release a substance which converts plasma protein fibrinogen into threads of insoluble fibrin.
- These threads make a mesh in which platelets and other blood cells are entangled to make a clot and stop the blood flow from the wound.
Q.8) How are different blood groups formed. What is their practical implication in blood transfusion?
Answer:
Blood groups:
Blood Group Systems Blood group is determined by the type of antigen present on the surface of the RBCs. An antigen is a substance that stimulates the production of antibodies. Antigens that are normally present in the body provoke no response. However, when foreign antigens enter the body, the WBCs respond by producing antibodies against them.
Blood transfusion in ABO system:
Before a blood transfusion, it is checked that both the donor and the recipient have the same blood groups. If a person with blood group A receives blood group B, the anti-B antibodies present in recipient's blood will at once recognize the antigen B present on RBCs of donated blood. The antibodies of the recipient will react with the B antigens on the donated RBCs and the blood will coagulate. The coagulated blood blocks the flow of blood through blood vessels. The same is true for a person with blood group B transfused with blood group A. Anti-A antibody present in recipient's blood will coagulate with RBCs having antigen-A of donated blood. A person with blood group AB accepts all types of blood. A person with blood group O can only be given the blood group O because blood group O has anti-A as well as anti-B antibodies.
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Rh blood group system:
Rh+ve blood group can be transfused to Rh+ve recipient because both have Rh antigen. Similarly, Rh-ve blood group can be given to Rh-ve donors. If an Rh-ve Person receives Rh+ve blood, he will get Rh antigens. His blood will produce anti-Rh antibodies against Rh antigens and it will result in coagulation. But a Rh+ve person can receive Rh-ve blood. People who have AB+ve blood group are universal recipients. They can receive A, B, AB or O blood because they do not have antibodies A or B. People who have O-ve blood group are universal donors. They can donate blood to people who have A, B, AB or O blood because they do not have A or B antigens.
Recipient’s blood groupDonor’s blood groupAA and OBB and OABA, B, AB and ORh+Rh+, Rh-Rh- Rh- only
Q.9) If we don't take water the whole day in the month of June, what would be the effect on the volume of plasma in blood?
Answer:
Plasma contains 90% water and 10% dissolved substance. In the month of June, the temperature is very high and dehydration occurs quickly. The amount of water in our body decreases, as a result, the normal functions of blood will be disturbed.
Q.10) Write any four differences between xylem and phloem?
Answer:
XylemPhloemXylem helps in the conduction of water in plants.Phloem helps in the transport of food in plants.Xylem consists of two types of cells i.e. vessels and tracheids.Phloem consists of sieve tube cells and companion cells.Moves substances up the stem using passive transport that does not require energy consumptionMoves substances up and down the stem using active transport that does require energy consumption.Xylem occupies the center of vascular bundlesPhloem occupies the outer side of the vascular bundle.
Long Questions
Q.1) Draw the internal structure of a human heart and show the blood circulation with the help of arrows.
Q.2) Discuss the function of major arteries and veins.
Answer:
Function of major arteries:
- Aorta is the largest artery of the body which arises from left ventricles. Many arteries arise from the aorta.
- The first arteries branching from the aorta are coronary arteries. These arteries supply the oxygenated blood and food to the heart itself.
- Aorta then forms an arch which, before descending down, gives off three branches which supply blood to head, shoulders and arms.
- After it, aorta descends down along with vertebral column. Here, it is called dorsal aorta. It gives off many arteries. For example, coeliac artery supplies blood to stomach and spleen, mesenteric arteries to duodenum, pancreas, intestine, and rectum.
- Similarly, hepatic artery supplies blood to liver and pair of renal arteries to kidneys.
- The aorta then divides to form right and left iliac arteries which supply blood to right and left legs.
- Pulmonary artery originates from right ventricle and carries deoxygenated blood to lungs.
Function of major veins:
- The deoxygenated blood is poured into the right atrium through two major veins superior vena cava and inferior vena cava.
- Superior vena cava is formed by the union of many pairs of veins from head, shoulders, and arms.
- The inferior vena cava is made of many veins from parts of the lower region. For example, two femoral veins from legs empty into inferior vena cava.
- Renal veins carry blood from the kidneys.
- The hepatic portal vein carries blood from the alimentary canal to the liver. From the liver, a hepatic vein carries blood to the inferior vena cava.
- From heart walls, deoxygenated blood returns to the right atrium through coronary veins.
- Pulmonary veins originate from lungs and bring oxygenated blood to the left atrium.
Q.3) Discuss transpiration and its importance for plants.
Answer:
Transpiration:
"Loss of water in the form of vapors from the aerial parts of the plant is called transpiration".
Transpiration occurs mainly through the special openings present in leaf epidermis. These openings are called stomata (Singular: stoma). In leaves, water is present in the xylem tissues. This water moves to the cell walls of mesophyll cells. From the moist walls of mesophyll cells, water evaporates into the air spaces of the leaf. These water vapors then move towards the stomata and pass into the outside air.
Importance of transpiration:
1) Stomatal Control of Transpiration:
Transpiration occurs through stomata which allows the water vapors to transpire into the environment. When there is sufficient water, stomata remain open allowing transpiration to take place. Each stoma is lined by two bean-shaped cells called guard cells. Guard cells are the only epidermal cells which contain chloroplasts. Stomata open and close when the turgor pressure of guard cells changes. Stoma opens when guard cells are turgid, while it closes when guard cells become flaccid. Transpiration helps the plants to get rid of excess water and salts.
2) Photosynthesis:
Transpiration provides water to the plant body. Water is a crucial component for carrying out the process of photosynthesis.
3) Cooling effect:
Transpiration involves the evaporation of water. The cells in the leaves are exposed to direct sunlight which causes evaporation. Transpiration prevents overheating of plant cells.
4) Exchange of gases:
Due to transpiration, the mesophyll cells always remains moist. these help plant in gaseous exchange especially the absorption of carbon dioxide which is necessary for the process of photosynthesis.
5) Movement of minerals:
Transpiration from the leaves causes pulling force on the water in xylem tissue of stem and roots. this pulling force causes the water to rise up in the xylem tissue, which contains dissolved mineral salts which are used to produce a variety of substances such as proteins in the plant.
Q.4) Describe the structure of blood and its importance.
Answer:
Blood:
Blood is a specialized body fluid (a connective tissue) that is composed of a liquid called blood plasma and blood cells. It is a red fluid which circulates through blood vessels (arteries, veins, and capillaries) and heart.
Components of Blood and their functions:
The two components of blood are:
1) Blood plasma
2) Blood cells and cells like bodies
1) Blood plasma:
If blood is taken in a test tube and allowed to stand for a few minutes, a yellow coloured liquid is separated from the cells and cell-like bodies. Cellular components settle down and the pale yellow liquid remains at the top. This yellow coloured material is called plasma. It constitutes about 55% by volume of blood. It contains 90% water and 10% dissolved substances. Out of these substances, about 7% are different types of proteins generally called plasma proteins.
0.9% of plasma is made up of inorganic salts, while 2% consists of food materials, hormones, waste products, etc. Plasma performs various functions:
- Plasma keeps all the tissues moist.
- Plasma of the blood transports nutrients, water, salts, hormones, and waste materials.
- Plasma helps in the regulation of body temperature.
- The small amount of oxygen is also carried by plasma. Most of the CO2 is carried by plasma.
- Plasma proteins e.g. albumin's maintain the osmotic pressure of blood.
- Important plasma proteins called antibodies defend the body against pathogens.
- Another plasma protein fibrinogen is responsible for blood-clotting.
2) Blood cells and cell-like bodies:
These include red blood cells (erythrocytes), white blood cells (leukocytes) and cell-like bodies i.e. platelets (thrombocytes).
a) Red Blood Cells (Erythrocytes):
These are the most numerous blood cells. A cubic millimeter of blood contains 5 to 5.5 million of RBCs in males, and 4 to 4.5 million in females. When RBCs are formed, they have nucleus. In mammals, when a red blood cell matures, its nucleus is lost. After the loss of nucleus, RBC enters blood. About 95% of the cytoplasm of RBCs is filled with hemoglobin, which transports O2 and small amounts of CO2. The remaining 5% consists of enzymes, salts and other proteins. RBCs are biconcave and have an elastic cell membrane. In the embryonic and fetal life, they are formed in liver and spleen. In adults, they are formed in the red bone marrow of short and flat bones, such as sternum, ribs, and vertebrae. An average life span of RBC is about four months (120 days) after which it breaks down in liver and spleen by phagocytosis.
b) White Blood Cells (Leukocytes):
These are colorless because they do not contain pigments. They are not confined to blood vessels and also migrate out into tissue fluid. One cubic millimeter of blood contains 7000 to 8000 WBCs.
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