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Tuesday, May 22, 2007

TRANSPORTATION, CIRCULATION & EXCRETION IN ORGANISMS - III : LONG ANSWERS

GIVE ANSWER IN DETAIL



*INDEX-TOPIC SEARCH


  1. Describe : Xylem.

    ANS :


    • Xylem is a tissue associated with the transport of water in higher plants.
    • Water absorbed through roots is transported to the stem, branches, leaves and flowers by xylem.
    • Tracheids and vessels (tracheae) are the main components of xylem.
    • TRACHEIDS :

      • Tracheids are present in pteridophytes, gymnosperms and some angiosperms.
      • They are long, thin and spindle-shaped cells.
      • They are dead as their nuclei are disintegrated.
      • There is deposition of lignin on the inner wall of the cells which provides mechanical support to tracheids.
      • The cells are arranged one above the other.
      • At the junction of two cells, the wall possesses pits through which water is conducted upwards.

    • VESSELS (TRACHEAE) :

      • They are present in angiospermic plants.
      • They are short, comparatively broad and blunt at both ends.
      • They are dead because the cytoplasm and nucleus disintegrate during the formation of vessels.
      • The cells are arranged one above the other.
      • The transverse wall between the cells disintegrates to form a continuous passage for rapid upward transportation of water.
      • Lignin deposition on the inner wall provides mechanical support.



  2. Describe : Transportation of Mineral Elements in Plants.

    ANS :


    • Plants absorb minerals (inorganic dissolved salts) by roots from the soil.
    • Absorption of minerals occurs simultaneously with the absorption of water but the process is independent. The minerals are in direct contact with the water film in between the soil particles.
    • Water enters roots through root hair along with minerals.
    • It then moves through root cortex and endodermis to reach the root xylem.
    • Then the water which contains minerals reaches to the leaf through inter-connected stem xylem.
    • The transportation of water and minerals from the roots to the leaves is known as ascent of sap.
    • Only about 5% of the absorbed water is used up in photosynthesis and other metabolic processes while remaining 95% is lost as vapour by the process of transpiration.


  3. Describe : Phloem.

    ANS :


    • Phloem is a tissue which translocates the carbohydrates and essential substances produced in leaves, and hormones synthesized at the shoot and root tips from their place of origin to the site where needed.
    • In pteridophytic and gymnospermic plants, the main component of phloem is the sieve cell.
    • In angiospermic plants the main components of phloem are sieve tube and companion cell.
    • Sieve cells are living as they possess cytoplasm and nucleus.
    • Sieve tube cell and companion cell are formed by the longitudinal division of a single cell.
    • Sieve tube cells are broad and their nuclei are disintegrated.
    • Companion cells are narrow and possess nucleus.
    • Companion cells are arranged laterally and longitudinally to the sieve tube cells and their nuclei regulate metabolic activities carried out in sieve tube cells.
    • The transverse walls (sieve plates) present between sieve tube cells are perforated. These pores are known as sieve pores. Due to the sieve pores the food can be translocated in both upward and downward directions.
    • The transverse wall between two sieve cells does not have pores hence the translocation of food is indirect.
    • Transport of food from leaves to other parts of the plant is called translocation.
    • Translocation of food is necessary to fulfil daily requirements of energy, to replace worn out cells and for plant growth.


  4. Write an explanatory note on blood.

    ANS :

    • Blood is a living, red coloured, liquid connective tissue which circulates constantly throughout the body.
    • The two main components of blood are : (1) Blood Plasma (2) Blood Corpuscles.
    • BLOOD PLASMA :

      • It is pale yellow, nonliving, intercellular matrix with basic properties.
      • It consists of 90% of water and 10% of various constituents like plasma proteins, nutrients, metabolic waste, enzymes, hormones, vitamins, etc.



    • BLOOD CORPUSCLES :

      • Three main types of blood corpuscles in blood plasma are : (1) erythrocytes or red blood corpuscles (2) leucocytes or white blood corpuscles (3) thrombocytes (blood platelets).
      • They are formed from the undifferentiated stem cells found in the bone marrow of long bones.
      • ERYTHROCYTES (RBC) :

        • They are round, biconcave and light red in colour.
        • They do not possess nucleus and mitochondria.
        • The cell membrane is thin and elastic.
        • The cytoplasm contains haemoglobin which is a conjugated protein containing iron. Iron gives red colour to haemoglobin.
        • Haemoglobin absorbs oxygen from the walls of the lungs and forms oxyhaemoglobin. It takes this oxygen to every cell of the body.
        • Similarly haemoglobin collects carbon dioxide from each cell and brings it to lungs.
        • Since haemoglobin transports respiratory gases, it is known as respiratory pigment.
        • Every day about 30 lakh (3 million) erythrocytes die and as much of them are formed in the bone marrow.
        • The average life span of an erythrocyte is of 120 days.

      • LEUCOCYTES (WBC) :

        • The leucocytes vary in size, shape, appearance of the nuclei and the cytoplasmic constituents.
        • They do not contain any respiratory pigment.
        • They destroy pathogenic microorganisms and harmful toxic substances.
        • As they can pass through very thin membranes of capillaries, they are capable of reaching any part of the body.
        • Thus leucocytes provide protection to the body.
        • Lymphocytes (a type of WBC) produce immunoglobulins.

      • BLOOD PLATELETS :


        • They are very small, spindle-shaped fragments of cells in blood plasma.
        • They do not have any nucleus.
        • Their cell membrane is very thin and sensitive.
        • They rupture when they come in contact with air and release chemicals which initiate the process of blood clotting.




  5. Describe : Clotting of Blood.

    ANS :

    • Blood vessels rupture when there is a wound. Blood oozes out from the wound. This blood comes in contact with air and the process of clotting starts. The process of clotting takes place in the following manner.
    • The blood platelets rupture at the point of injury.
    • The ruptured platelets release thromboplastin.
    • Thromboplastin converts prothrombin found in the plasma into thrombin. This requires calcium.
    • Thrombin converts liquid fibrinogen (in the plasma) into solid fibrin fibres. These fibres form a network at the point of injury.
    • The blood corpuscles entangled in this network form a solid layer which dries up and forms a solid clot which stops the flow of blood.
    • After some time, a viscous pale yellow liquid (serum) oozes out from the periphery of the clot.


  6. Explain : Blood Transfusion.

    ANS :

    • The transfer of blood from a healthy donor to a person in need is called blood transfusion.
    • Carl Landsteiner discovered that there are special antigens on the surface of erythrocytes and different antibodies in plasma.
    • If the antigen on the erythrocytes of the donor's blood and the antibody in the recipient's plasma are same, it causes clotting of the patient's blood and may lead to death.
    • There are two types of antigens 'A' and 'B' on the erythrocytes.
    • The corresponding antibodies which clump the blood are 'a' and 'b', respectively.
    • We have four different blood groups : A, B, AB and O.
    • Blood transfusion is possible between two persons having same blood group.
    • A person with 'O' group can donate blood to any person but can receive the blood of 'O' group only.
    • A person with 'AB' group can receive blood from any person but can donate blood only to a person with 'AB' group.
    • Rhesus factor (Rh) is also matched for blood transfusion.


  7. Describe : Structure and Working of Human Heart.

    ANS :


    STRUCTURE :

    • Human heart is located slightly on the left side in the space between two lungs.
    • It is conical and of the size of a closed fist.
    • It has four chambers. Two upper chambers are called atrium and the lower chambers are called ventricle.
    • Left atrium, right atrium, left ventricle and right ventricle are the four chambers based on their location in the heart.
    • The walls of the atria are thin whereas the walls of ventricles are thick.
    • All four chambers are separated from one another by partition called septa.
    • There is a bicuspid valve between left atrium and left ventricle whereas there is a tricuspid valve between right atrium and right ventricle.
    • These valves allow blood to flow from atrium to ventricle but do not allow it to flow from ventricle to atrium.
    • Heart is made of cardiac muscles.


    WORKING :

    • When all four chambers of the heart are in relaxed state (diastolic stage), deoxygenated blood from the organs enters the right atrium through the superior and inferior vena cava.
    • At the same time oxygenated blood from lungs enters the left atrium through the pulmonary vein.
    • When both the atria are filled with blood , they contract and deoxygenated blood from right atrium is poured into right ventricle through tricuspid valve. Similarly the oxygenated blood from the left atrium is poured into left ventricle through bicuspid valve.
    • When both ventricles are filled with blood, they contract (systolic stage) and deoxygenated blood from the right ventricle goes to lungs through pulmonary artery and oxygenated blood from the left ventricle is distributed to all the parts of the body (except lungs) through aorta.
    • Since the blood flows twice through the heart it is called double circulation.


  8. Write a note on blood vessels.

    ANS : There are three types of blood vessels : (1) Arteries (2) Veins (3) Blood capillaries.

    ARTERIES :

    • They carry blood from the heart to different organs of the body.
    • Their walls are thick and elastic.
    • They do not have valves.
    • After entering an organ, they branch into small arterioles.


    VEINS :

    • They carry blood from different organs to heart.
    • Their walls are thin and nonelastic.
    • They have valves.
    • After exiting an organ they unite to form vena cava.


    BLOOD CAPILLARIES :

    • Around the tissues, the arterioles break up into fine vessels called capillaries.
    • They are thin and narrow.
    • Capillaries unite to form small blood vessels called venules.
    • Venules unite to form veins.
    • Necessary substances diffuse from blood into the tissues through thin walls of the capillaries.


  9. Write a note on Lymphatic system.

    ANS :

    • The transparent fluid that oozes out in the surrounding intercellular space and the tissue cells from the blood flowing in the capillaries is called lymph.
    • It is a pale yellow liquid connective tissue containing lymphocytes.
    • It is in direct contact with the tissue cells and provides them the necessary substances.
    • The excretory substances formed in the tissue cells diffuse into the lymph.
    • After this exchange of essential substances and excretory substances the lymph reaches the lymph vessel.
    • The lymphatic system begins with lymph vessels.
    • The lymphatic system consists of lymphatic vessels, lymphatic capillaries, lymph nodes and lymph glands.
    • Lymph circulates from tissue cells to the heart.


  10. Explain : Excretion and Osmoregulation.

    ANS :
    EXCRETION :

    • During biochemical processes performed by body cells many unnecessary and toxic by-products are formed along with useful substances.
    • These unnecessary toxic substances are called excretory substances.
    • Excretion is the biological process involved in the removal of liquid excretory substances from the body.


    OSMOREGULATION :

    • The amount of water in the body may increase or decrease due to biological processes.
    • Osmoregulation is the process of maintaining the required amount of water and proper ionic balance in the body.
    • Excretion and osmoregulation occur simultaneously.
    • Methods of excretion, the type of excretory products and the amount of water required for excretion are correlated to the habitat of the organism, availability of water and necessity of osmoregulation.
    • Different animals have various structures for excretion and osmoregulation.
    • Amoeba has a contractile vacuole, sponges have osculum, hydra has oral opening, platyhelminthes have flame cells, earthworms have nephridia and human beings have kidneys.
    • Fresh water organisms get large amount of water easily. In order to remove this excess water they excrete ammonia which is soluble in water.
    • Marine and terrestrial animals possess mechanism to conserve water as they do not get fresh water easily. Their excretory system is capable of reabsorbing water and they excrete concentrated urine after a long interval. Urine mainly contains urea.
    • Desert animals convert the concentrated waste into crystals of uric acid as they cannot afford to lose water.
    • Birds do not have urinary bladder. They excrete waste in the form of uric acid.


  11. Describe excretion in earthworm.

    ANS :


    • The body of earthworm is divided into a series of segments separated internally by septa.
    • Excretory organs of the earthworm are called nephridia which are absent in first three segments.
    • Nephridia are coiled tubes.
    • There are three types of nephridia : (i) septal (ii) pharyngeal (iii) integumentary.
    • There are two types of excretion : (i) enteronephric (ii) exonephric.
    • In enteronephric excretion the excretory products are poured into alimentary canal through nephridia.
    • In exonephric excretion the excretory products are thrown out of the body through skin.
    • There is a funnel-like structure called nephrostome at the anterior end of the nephridium.
    • Its posterior end has an opening called nephridiopore.
    • The fluid carrying wastes enters nephrostome.
    • The cilia present in the tubule help the fluid to move through the nephridium.
    • During the process useful substances are reabsorbed by the cells lining the tubules.
    • These useful substances are then passed into the blood.
    • The remaining waste fluid is thrown out through nephridiopore.


  12. Describe excretion in human being.

    ANS :
    EXCRETORY SYSTEM :



    • Excretory organs consist of a pair of reddish brown bean-shaped kidneys, located in the abdomen.
    • From each kidney opens an excretory tube called ureter into the urinary bladder.
    • The bladder passes into a muscular tube called urethra.
    • Urethra opens out as small opening called urinary opening.
    • Kidney is divided into cortex and medulla.
    • Kidney consists of excretory units called nephrons.


    STRUCTURE OF A NEPHRON :


    • A kidney has very minute tubular and convoluted structures known as uriniferous tubules (nephrons).
    • A kidney has about 10 lac (one million) such units.
    • Each nephron has a double-walled cup-shaped structure called Bowman's Capsule at its beginning.
    • Bowman's capsule encloses a small group of capillaries called glomerulus.
    • The short region after Bowman's capsule is called the neck.
    • The tubule after the neck is narrow and coiled.
    • It consists of proximal convolution, Henle's loop and distal convolution.
    • The distal convolutions of many nephrons join a common collecting duct which leads to the renal pelvis.
    • Renal pelvis opens into the ureter.


    PROCESS OF FORMATION OF URINE :

    • Renal arteries bring blood containing the waste material to the kidney.
    • By ultrafiltration the blood is filtered out from blood capillaries into Bowman's capsule under pressure.
    • During the passage of this filtrate through tubular parts of nephron, useful products such as water, amino acids, minerals, ions, etc. are reabsorbed by blood capillaries surrounding the nephron.
    • The remaining fluid contains excretory substance called urine which passes into urinary bladder through ureter. When the bladder is filled with urine, it contracts and urine passes out of the body.


  13. Mention functions of blood.

    ANS :

    • Blood carries oxygen from lungs to other parts of the body.
    • It brings carbon dioxide from all parts of the body to lungs.
    • It carries digested food (nutrients) from alimentary canal to all parts (cells) of the body.
    • It carries hormones from different glands to the target area in the body.
    • It carries excretory waste products to throw them out through urine.
    • It regulates body temperature.
    • It fights pathogenic organisms through WBC and protects the body from various diseases.
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Thursday, May 17, 2007

TRANSPORTATION, CIRCULATION & EXCRETION IN ORGANISMS - II : BRIEF ANSWERS

ANSWER IN BRIEF



*INDEX-TOPIC SEARCH


  1. Describe : Ascent of sap.
    ANS:

    • Plants absorb water and minerals from the soil through root hairs.
    • Water along with minerals then moves through root cortex and endodermis to reach the root xylem.
    • From root xylem they enter the interconnected stem xylem which branches into leaves.
    • This transportation of water and minerals from the roots to the leaves is known as the ascent of sap.


  2. Explain : Rhesus factor.
    ANS:

    • Blood contains an antigen called Rh factor (Rhesus factor).
    • A person with Rh antigen in blood is called Rh +ve and one lacking it is called Rh -ve.
    • Incompatibility of Rh factor causes problems.
    • If an Rh +ve man marries an Rh -ve woman, the birth of the first child is normal. But mother's blood forms antibodies against Rh antigen.
    • If the second child is Rh +ve, the antibody in mother's blood reacts with the Rh antigen of the foetus and causes problems, sometimes leading to the death of the child.


  3. Describe excretion and osmoregulation in amoeba.
    ANS:


    • Amoeba is a fresh water unicellular organism.
    • It has a contractile vacuole for excretion and osmoregulation.
    • The waste produced in the cell enters contractile vacuole along with water.
    • The size of the contractile vacuole gradually increases and then it moves closer to the plasma membrane.
    • It bursts after touching the plasma membrane and releases the excretory substances into the surrounding water by diffusion.


  4. Give reason : An Rh(-ve) woman should not marry an Rh(+ve) man.
    ANS: [Refer to last two points mentioned in the answer about Rhesus factor].

  5. Distinguish between xylem and phloem.

    ANS:

  6. Distinguish between blood and lymph.

    ANS :

  7. Distinguish between artery and vein.

    ANS :
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Monday, May 07, 2007

TRANSPORTATION, CIRCULATION & EXCRETION IN ORGANISMS - I : MCQs & SHORT ANSWERS


*INDEX-TOPIC SEARCH

MULTIPLE-CHOICE QUESTIONS



SELECT THE CORRECT ALTERNATIVE:

  1. ______ is associated with the transport of water in plants.

    1. Xylem
    2. Phloem
    3. Chloroplast
    4. Aerenchyma

  2. Tracheae are found in ______ plants.

    1. pteridophytes
    2. gymnosperms
    3. angiosperms
    4. all three

  3. The inner wall of the tracheids and tracheae shows deposition of ______.

    1. starch
    2. glucose
    3. lignin
    4. protein

  4. Which of the following is not a property of blood plasma ?

    1. It is pale yellow
    2. It is nonliving
    3. It is acidic
    4. It contains hormones

  5. Which of the following is not a blood corpuscle ?

    1. Leucocyte
    2. Erythrocyte
    3. Thrombocyte
    4. Nymphocyte

  6. Which of the following is true for human erythrocytes ?

    1. They are biconvex.
    2. They have nucleus.
    3. They contain haemoglobin.
    4. They do not have nucleus but possess mitochondria.

  7. ______ is a respiratory pigment.

    1. Haemoglobin
    2. Chlorophyll
    3. Mesophyll
    4. Adrinalin

  8. The lifespan of erythrocytes is about ______ days.

    1. 100
    2. 120
    3. 140
    4. 180

  9. Which of the following is false ?

    1. Erythrocytes are light red in colour.
    2. Haemoglobin is a respiratory pigment.
    3. Lymphocytes produce immunoglobulins.
    4. Thrombocytes destroy pathogens.

  10. ______ is a necessary mineral for clotting of blood.

    1. Calcium
    2. Potassium
    3. Iron
    4. Zinc

  11. ______ converts liquid fibrinogen into solid fibres of fibrin.

    1. Thromboplastin
    2. Oxyhaemoglobin
    3. Immunoproteins
    4. Thrombin

  12. There are ______ types of antigens on the erythrocytes.

    1. two
    2. three
    3. four
    4. five

  13. The blood group of a person is O and Rh (-ve). He can donate blood to...

    1. any person
    2. a person with group O
    3. A person with Rh (-ve)
    4. none

  14. Which of the following is true ?

    1. Heart purifies blood.
    2. Heart separates excretory products from blood.
    3. Heart circulates blood.
    4. Blood flows from heart to lungs.

  15. The relaxed state of yeart is called ______.

    1. Diastolic state
    2. Systolic state
    3. Thermostatic state
    4. Primary state.

  16. The structure for excretion and osmoregulation in sponges is ______.

    1. osculum
    2. contractile vacuole
    3. nephridia
    4. flame cell

  17. Urine mainly consists of ______.

    1. Uranium
    2. Urea
    3. CO2
    4. sugar

  18. Birds excrete wastes in the form of ______.

    1. urea
    2. proteins
    3. uric acid
    4. water

  19. Which structure is responsible for transportation of water in pteridophytes ?

    1. Tracheids
    2. Tracheae
    3. Sieve cells
    4. Sieve tubes

  20. Which structure has lignified cell wall ?

    1. Sieve tube
    2. Tracheids
    3. Trachea
    4. Sieve cells

  21. Which blood cells contain haemoglobin ?

    1. RBC
    2. WBC
    3. Platelets
    4. Lymphocytes

  22. Which blood cells produce immunoglobin ?

    1. Platelets
    2. Erythrocytes
    3. Lymphocytes
    4. Leucocytes

  23. Which chemical is released when blood cells rupture ?

    1. Prothrombin
    2. Fibrin
    3. Thrombin
    4. Thromboplastin

  24. Where are antigens for blood group located ?

    1. WBC
    2. RBC
    3. Platelets
    4. Blood plasma

  25. How many chambers are present in human heart ?

    1. 1
    2. 2
    3. 3
    4. 4

  26. Where is bicuspid valve found in human heart ?

    1. Between two atria
    2. Between left auricle and left ventricle
    3. Between two ventricles
    4. Between right auricle and right ventricle.

  27. Through which parts of the heart does oxygenated blood flow ?

    1. Both atria
    2. Left auricle and left ventricle
    3. Both ventricles
    4. Right auricle and right ventricle

  28. Where does deoxygenated blood get oxygenated ?

    1. Atrium
    2. Heart
    3. Lungs
    4. Kidneys

  29. Which type of blood flows through all arteries ?

    1. Impure
    2. Pure
    3. Toxic
    4. With nitrogenous waste

  30. What is the shape of human heart ?

    1. Round
    2. Bean shaped
    3. Conical
    4. Triangular

  31. Carboxy-haemoglobin is formed when haemoglobin reacts with...

    1. CO
    2. CO2
    3. O2
    4. CH4




SHORT QUESTIONS



ANSWER IN SHORT:

  1. Define : Transportation.

         ANS : The movement of different types of substances absorbed or synthesized in one part of the body to another part of the body is called transportation.

  2. Mention two main components of xylem responsible for the transportation of water.

         ANS : Tracheids and tracheae (vessels) are two main components of xylem responsible for the transportation of water.

  3. What are tracheids ?

         ANS : Tracheids are long, thin and spindle shaped cells of xylem of a plant.

  4. Why are tracheids dead cells ?

         ANS : Tracheids are dead cells because their nuclei are disintegrated.

  5. What is ascent of sap ?

         ANS : The transportation of water and minerals from the roots to the leaves is known as the ascent of sap.

  6. How much of the water absorbed by the plants is used up in photosynthesis and other metabolic processes ?

         ANS : Only about 5% of water absorbed by the plants is used up in photosynthesis and other metabolic processes.

  7. Define : Transpiration.

         ANS : The process by which water absorbed by plants through roots is lost (thrown out) in the form of vapours is called transpiration.

  8. Where are plant hormones synthesized ?

         ANS : Plant hormones are synthesized at the shoot and root tips.

  9. What is the function of phloem ?

         ANS : Phloem translocates carbohydrates, essential substances, plant hormones, etc. from their place of origin to the site where needed.

  10. In which plant is a sieve cell the main component of phloem ?

         ANS : In pteridophytes and gymnosperms sieve cell is the main component of phloem.

  11. In which plants are the sieve tube and companion cell the main components of phloem ?

         ANS : In angiospermic plants the sieve tube and companion cell are the main components of phloem.

  12. What regulates metabolic activities carried out in the sieve tube cells ?

         ANS : The nucleus of the companion cell regulates metabolic activities carried out in the sieve tube cells.

  13. Define : Sieve pores.

         ANS : The perforations in the transverse walls (sieve plates) present between sieve tube cells are called sieve pores.

  14. Define : Translocation.

         ANS : The transport of food from leaves to other parts of plants is called translocation.

  15. What is the need for translocation of food ?

         ANS : Translocation of food is necessary to fulfil the daily requirement of energy, to replace the worn out cells and for the growth of the plant.

  16. Define : Circulatory system.

         ANS : The system associated with the transport of various substances like nutrients, hormones, enzymes, respiratory gases, excretory products, etc. is called circulatory system.

  17. Mention two main components of blood.

         ANS : Blood plasma and blood corpuscles are the two main components of blood.

  18. Mention three main types of blood corpuscles.

         ANS : Erythrocytes (RBC), leucocytes (WBC) and thrombocytes (platelets) are three types of blood corpuscles.

  19. Why is haemoglobin called respiratory pigment ?

         ANS : Haemoglobin is called respiratory pigment because it transports respiratory gases (O2 and CO2) between lungs and organs.

  20. Where are erythrocytes formed ?

         ANS : Erythrocytes are formed in the bone marrow.

  21. Which type of WBC produce immunoglobulins ?

         ANS : Lymphocytes produce immunoglobulins.

  22. What is serum ?

         ANS : Serum is a viscous pale yellow liquid that oozes out from the periphery of a blood clot.

  23. Define : Blood transfusion.

         ANS : The transfer of blood from a healthy donor to a needy patient is called blood transfusion.

  24. Who discovered the presence of special antigens on the surface of erythrocytes ?

         ANS : Carl Landsteiner discovered the presence of special antigens on the surface of erythrocytes.

  25. Mention different blood groups in human beings.

         ANS : The blood groups present in human being are : A, B, AB and O.

  26. What happens during the diastolic state of heart ?

         ANS : During diastolic state of heart, deoxygenated blood from organs enters right atrium through the superior and inferior vena cava and oxygenated blood from lungs enters left atrium through pulmonary vein.

  27. Why is circulation of blood through heart called 'double circulation' ?

         ANS : The circulation of blood through heart is called 'double circulation' because deoxygenated blood from body organs passes twice through heart before it reaches the organs in oxygenated form.

  28. Define : Artery.

         ANS : The blood vessel which carries blood from heart to different organs of the body is called artery.

  29. Define : Vein.

         ANS : The blood vessel which carries blood from different organs to the heart is called vein.

  30. What is lymph ?

         ANS : The transparent fluid which oozes out in the surrounding intercellular space and the tissue cells from the blood flowing in the capillaries is called lymph.

  31. Which cells does lymph contain ?

         ANS : Lymph contains lymphocytes.

  32. What constitutes lymphatic system ?

         ANS : Lymphatic system consists of lymphatic vessels, lymphatic capillaries, lymph nodes and lymph glands.

  33. Define : Excretion.

         ANS : The biological process involved in the removal of liquid excretory substances from the body is called excretion.

  34. Define : Osmoregulation.

         ANS : The process of maintaining the required amount of water and proper ionic balance in the body is called osmoregulation.

  35. What is the structure for excretion and osmoregulation in amoeba known as ?

         ANS : The structure for excretion and osmoregulation in amoeba is known as contractile vacuole.

  36. What is the structure for excretion in earthworm known as ?

         ANS : The structure for excretion in earthworm is known as nephridia.

  37. What is the structure for excretion in platyhelminthes known as ?

         ANS : The structure for excretion in platyhelminthes is known as flame cells.

  38. What does hydra have for excretion and osmoregulation ?

         ANS : Hydra has oral opening for excretion and osmoregulation.

  39. Mention the types of nephridia in earthworm.

         ANS : The types of nephridia in earthworm are : (i) septal (ii) pharyngeal and (iii) integumentary.

  40. Which two types of excretion is shown by the earthworm ?

         ANS : Enteronephric excretion and exonephric excretion are the two types of excretion shown by the earthworm.

  41. What is enteronephric excretion ?

         ANS : In enteronephric excretion the excretory products are poured into the alimentary canal through nephridia.

  42. What is exonephric excretion ?

         ANS : In exonephric excretion the excretory products are thrown out of the body through the skin.

  43. Where are human kidneys located ?

         ANS : Human kidneys are located in the abdomen on the dorsal side.

  44. What is ultrafiltration ?

         ANS : The filtration of blood carrying waste material under pressure in glomerulus is known as ultrafiltration.

  45. What do desert animals do for osmoregulation ?

         ANS : Since desert animals cannot afford to lose water, they convert the concentrated waste into crystals of uric acid.

  46. Which substance provides mechanical support to the walls of xylem ?

         ANS : Lignin provides mechanical support to the walls of xylem.

  47. What is transported through sieve plate ?

         ANS : Food is transported through sieve plate.

  48. Mention the colour of blood and lymph.

         ANS : The colour of blood and lymph is red and pale yellow respectively.

  49. What is the shape of human erythrocytes ?

         ANS : Human erythrocytes are round, biconcave in shape.

  50. Which mineral is present on haemoglobin ?

         ANS : Iron is present in haemoglobin.

  51. Where are blood cells produced in our body ?

         ANS : Blood cells are produced in the bone marrow of long bones.

  52. Mention two functions of WBC.

         ANS : The two functions of WBC are : (i) They destroy pathogenic microorganisms. (ii) They destroy harmful substances.

  53. Give examples of enucleated blood cells.

         ANS : RBC (erythrocytes) and platelets are enucleated blood cells.

  54. State the function and location of stem cells.

         ANS : Stem cells are located in the bone marrow of long bones and they produce all types of blood corpuscles.

  55. Where is thromboplastin produced ?

         ANS : Thromboplastin is produced at the point of injury where blood vessels rupture.

  56. Which mineral is needed to convert prothrombin into thrombin ?

         ANS : Mineral calcium is needed to convert prothrombin into thrombin.

  57. What converts fibrinogen to fibrin ?

         ANS : Thrombin converts fibrinogen to fibrin.

  58. Where are blood antigens located ?

         ANS : Blood antigens are located on the surface of erythrocytes.

  59. Why does right atrium appear dark in colour ?

         ANS : Right atrium appears dark in colour because it has deoxygenated blood in it which is dark in colour.

  60. Why does left venticle appear red in colour ?

         ANS : Left ventricle appears red in colour because it has oxygenated blood in it which is red in colour.

  61. What type of valves are found in veins ?

         ANS : The valves in veins are of the type which allows blood to flow towards heart and stops it from flowing in opposite direction.

  62. Where is tricuspid valve present in human heart ?

         ANS : Tricuspid valve is present between right atrium and right ventricle of heart.

  63. To which part of the body does pulmonary artery supply blood ?

         ANS : Pulmonary artery supplies blood to lungs (from heart).

  64. What is the function of pulmonary vein ?

         ANS : Pulmonary vein collects blood from lungs and supplies it to the left atrium.

  65. Define : Conduction.

         ANS : The upward movement of water (absorbed by roots) through tracheids is called conduction.

  66. Define : Double circulation.

         ANS : The circulation of blood through heart is called double circulation because deoxygenated blood from body organs passes twice through heart before it reaches the organs in oxygenated form.

  67. What are blood capillaries ?

         ANS : Fine, thin-walled and narrow tubular branches of arterioles which reunite to form venules are called blood capillaries.

  68. Define : Companion cell.

         ANS : The cells arranged laterally and longitudinally to sieve tube cells in the phloem of angiospermic plants are called companion cells.

  69. Which organelle is absent in human RBC ?

         ANS : Nucleus and mitochondria are absent in RBC.

  70. State the location and function of stem cells.

         ANS :Stem cells are located in bone marrow of long bones and their function is of formation of all types of blood cells.
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Wednesday, April 18, 2007

NUTRITION AND RESPIRATION IN ORGANISMS - III : LONG ANSWERS

GIVE ANSWER IN DETAIL



*INDEX-TOPIC SEARCH


  1. Define nutrition, mention its types and describe each type with examples.

    ANS :

    • NUTRITION : The process of intake of nutrients and their utilisation in every living cell of the body is called nutrition.
    • TYPES OF NUTRITION : Based on the mode of obtaining food by the organisms, nutrition is classified into two main types-(i) Autotrophic nutrition (ii) Heterotrophic nutrition.
    • AUTOTROPHIC NUTRITION : Green plants and some bacteria prepare their own food from inorganic materials like carbon dioxide, water and minerals using pigment chlorophyll. These are called autotrophic organisms and their mode of nutrition is called autotrophic nutrition.
    • HETEROTROPHIC NUTRITION : Heterotrophic organisms are those which cannot synthesize their own food. These organisms obtain their food from plants and other animal sources. This type of nutrition is called heterotrophic nutrition. In this type of nutrition, the organic components of the food are digested into simple forms and then utilised by the organism. All animals, bacteria and examples of heterotrophic organisms.

      Heterotrophic nutrition is classified into three types : (i) Saprophytic nutrition (ii) Parasitic nutrition (iii) Holozoic nutrition.
    • SAPROPHYTIC NUTRITION : Organisms obtaining nutrients from dead and decaying organic matter are called saprophytes and their mode of nutrition is called saprophytic nutrition. Many species of bacteria and different types of fungi are saprophytes.
    • PARASITIC NUTRITION : If an organism depends on another living organism for nutrition, its mode of nutrition is called parasitic nutrition. Such organisms are called parasites and the organism from which they obtain nutrition is called host. The host organism is harmed by the parasite. Parasitic nutrition is observed in some bacteria, fungi, flowering plants like cuscuta and animal like ascaris.
    • HOLOZOIC NUTRITION : Holozoic nutrition involves intake of parts of plants or animals or an organism as a whole by the process of ingestion which is then digested and absorbed. Some examples are amoeba, frog, insects, human being, etc.


  2. Describe Photosynthesis in detail.

    ANS : Plants synthesize their own food by the process of photosynthesis. Photosynthesis is the process in which plants synthesize food from carbon dioxide and water with the help of sunlight and chlorophyll.



    Photosynthesis takes place in two phases : (1) Light Phase (2) Biosynthetic Phase.

    LIGHT PHASE : This phase is called light phase because the presence of light is necessary for it to occur.

    The chlorophyll molecule absorbs light energy in the form of photons, gets excited and emits electrons. These electrons travel through electron transport chain present in the chloroplast. During this ATP is synthesized from ADP and inorganic phosphate by photophosphorylation. This ATP is used as energy source in biosynthetic phase.

    During the light phase photolysis of water takes place.



    The H+ ions reduce NADP (Nicotinamide Adenine Dinucleotide Phosphate) into NADPH2.

    The oxygen released during photosynthesis comes from water and not from carbon dioxide.

    The whole process takes place in the grana of chloroplast.

    BIOSYNTHETIC PHASE : In this phase the ATP and NADPH2 formed during the light phase are used for the synthesis of carbohydrates from carbon dioxide. This process takes place in the stroma of the chloroplast.

    Calvin Cycle : It is called Calvin cycle as Calvin and Benson had discovered it.



    In this process, the carbon dioxide reacts with Ribulose biphosphate (RuBP) and enters the biosynthetic phase. In the end of the cycle carbohydrate is synthesised and RuBP is regenerated.

    The process of photosynthesis is affected by light, temperature, water and carbon dioxide.

  3. Explain the factors that affect Photosynthesis.

    ANS : The factors that affect photosynthesis are : (1) light (2) temperature (3) water (4) carbon dioxide.

    LIGHT : Intensity and quality of light affect photosynthesis. Chlorophyll absorbs mostly red and orange regions of visible spectrum. The rate of photosynthesis is more in red and orange light. Rate of photosynthesis increases at low intensity of light and decreases at high intensity.

    TEMPERATURE : Photosynthesis takes place in the presence of enzymes. At low temperatures the activity of enzymes is low and the rate of photosynthesis is low. As the temperature increases, the enzymes get activated and the process of photosynthesis accelerates. But at very high temperatures the enzymes become denatured and the rate of photosynthesis decreases.



    WATER : The rate of photosynthesis decreases under water-deficient conditions as the stomata remain closed to reduce transpiration. This stops gaseous exchange and hence the photosynthesis as carbon dioxide is not available.

    CARBON DIOXIDE : The rate of photosynthesis increases with the increase in the concentration of carbon dioxide up to a certain level. Beyond that level it may have inhibitory effect on the rate of photosynthesis.

  4. Explain : Nutrition in Amoeba.

    ANS : The mode of nutrition in amoeba is holozoic. The process of obtaining food is called phagocytosis. Amoeba feeds on microscopic organisms floating on water. The nutrition involves processes like ingestion, digestion, assimilation and egestion.

    Process : Amoeba forms pseudopodia to take food. When the tips of

    pseudopodia touch each other, the membrane at that point dissolves and the food is encaptured along with lysosomes into food vacuole. Digestive enzymes present in the lysosome digest the food. The digested food diffuses into the cytoplasm and utilized by the cell. This is called assimilation. The undigested food left in the food vacuole is thrown out of the body. This is called egestion.

  5. Describe Nutrition in grasshopper (locust).

    ANS : Grasshopper is a herbivorous insect feeding on leaves of plants. The alimentary canal of the grasshopper is divided into three parts : (1) foregut (2) midgut (3) hindgut.



    Foregut : It starts from mouth and extends up to gizzard. It consists of a short pharynx, narrow oesophagus and crop. The gizzard has a muscular wall and its lumen is lined with cuticle which forms six chitinous teeth. A pair of salivary glands along the crop opens into the cavity of the mouth through ducts.

    Midgut : It is the region between gizzard and hindgut. At its anterior end there are fingerlike projections called hepatic caecae which open into the midgut and secrete digestive enzymes.

    Hindgut : It is the region between the midgut and anus. It consists of three parts. An anterior ileum, a middle colon and a posterior rectum. The rectum opens outside through the anus. The junction of midgut and hindgut has many yellow threadlike minute tubules called Malphighian tubules which work as excretory organs.

    PROCESS OF DIGESTION :Grasshopper holds the food with fore legs and ingests it inside the mouth where the food mixes with saliva. The saliva lubricates and makes the food soft. Its digestive enzyme digests starch. The food then passes to the crop via oesophagus where it is stored temporarily. Then it passes into the gizzard where it is ground by chitinous teeth and then passes into the midgut. Here the food is digested by enzymes secreted by hepatic caecae. The digested food is absorbed and the indigested food passes into the hindgut from where it is egested out through the anus.

  6. Write an explanatory note on Human Digestive System.

    ANS : Human digestive system consists of alimentary canal and accessory digestive glands. Alimentary canal consists of mouth, buccal cavity, pharynx, oesophagus, stomach, small intestine, colon, rectum and anus. Accessory digestive glands are salivary glands, liver and pancreas. They secrete digestive juices.



    The alimentary canal begins with mouth which is located at the anterior end between two lips. The mouth opens into the buccal cavity which lies between the upper and lower jaws.

    The muscular tongue at the floor of the buccal cavity helps in digestion of food.

    The upper and lower jaws have four kinds of teeth. (1) Incisors for cutting (2) Cannines for tearing (3) Premolars and (4) Molars for chewing and grinding.

    The posterior region of buccal cavity is called pharynx which opens into the oesophagus. The oesophagus opens into the stomach which is situated on the left side of the abdomen. The inner wall of the stomach secretes gastric juices. The stomach opens into the duodenum through pyloric valve which is guided by sphincter muscle.

    The proximal region of small intestine is called duodenum. It is U-shaped and receives the secretion of liver and pancreas through a common bile duct. The middle region of small intestine is called jejunum and the distal region is called ileum.

    Ileum is about 7 m long. The inner wall of the small intestine has long fingerlike projections called villi. These increase the surface area for absorption. The small intestine opens into the large intestine. There is a projection called vermiform appendix at the junction of two intestines.

    The large intestine opens into the rectum which, in turn, opens out by anus. The anus is guarded by sphincter muscles.

  7. Explain the exchange of gases in plants.

    ANS :
    EXCHANGE OF GASES IN ROOT AND STEM :



    • Oxygen is present between soil particles.
    • Roots take up oxygen by the process of diffusion through the root hairs of piliferous layer.
    • This oxygen then passes into other root cells.
    • Carbon dioxide from the root cells moves out into the soil through the similar route.
    • Root hairs are not present in all parts of the root.
    • The parts devoid of root hair have a layer of dead cells having tiny openings called lenticels. In woody plants the bark has lenticels.
    • Gaseous exchange occurs between the soil and inner living cells through lenticels.

    EXCHANGE OF GASES IN LEAVES :



    • There are numerous tiny apertures called stomata on the leaf surface.
    • During respiration the atmospheric oxygen diffuses into the stomata and then into the leaf cells.
    • Stomata opens and releases carbon dioxide into atmosphere when the concentration of carbon dioxide increases in the cells.


  8. Write Important Points on Respiration in Animals.

    ANS :

    • Different animals have different respiratory organs.
    • Amoeba and paramoecium exchange gases through body wall.
    • Fish respire through gills.
    • Frog, lizard, birds and man have lungs for respiration.
    • Frogs respire through skin and lungs.
    • Atmospheric oxygen diffuses through their moist skin into the blood capillaries.
    • Carbon dioxide from the blood diffuses out into the atmosphere through skin.
    • Similar process occurs during the exchange of gases in lungs.
    • The exchange process occurs according to the Law of Partial Pressures of gases.
    • Insects like locust, housefly, cockroach, etc. possess trachea for respiration.
    • The tracheal system reaches every part of the body.
    • Air enters the tracheal system through spiracles situated on the lateral sides of the body.
    • Oxygen reaches each and every cell through trachea.
    • Carbon dioxide released by the cells moves out to the atmosphere through spiracles.

    [Last 5 points describe respiration in insects.]

  9. Describe Respiration In Human Being.

    ANS :
    HUMAN RESPIRATORY SYSTEM :

    • The human respiratory system is well-developed.
    • It consists of nostrils, nasal cavity, pharynx, larynx, trachea, bronchi and lungs.
    • Nostrils are the opening of nasal cavity.
    • The oxygen-rich air enters nasal cavity through the nostrils.
    • The deoxygenated air (containing CO2) is expelled out through nostrils.
    • The mucus in nasal cavity keeps it moist so that dust particles and microbes in the air are trapped there and do not enter lungs.
    • Nasal cavity also warms and moistens the air.
    • Air enters pharynx through nasal cavity and then into trachea (wind pipe) through a slit called glottis.
    • Glottis is protected by a cartilaginous flap called epiglottis.
    • As glottis is covered by epiglottis during the swallowing of food, the food does not enter the wind pipe.
    • Trachea is a wide tubular structure supported by C-shaped cartilaginous rigs.
    • Trachea divides into two bronchi which lead into the lungs.
    • There is a pair of lungs situated in thoracic cavity.
    • The lungs are covered by two membranes called pleura.
    • Brochi branch into many bronchioles in the lungs. Each bronchiole terminates in a sac called alveolar sac.
    • The walls of the alveoli are thin and covered by blood capillaries.


    MECHANISM OF BREATHING :

    • Intake of air into lungs is called inhalation.
    • When the diaphragm and the muscles attached to the ribs contract, the volume in the thoracic cavity increases, the air pressure decreases and the oxygen-rich air from the atmosphere enters the lungs through nostrils.
    • Alveolar sacs are filled with oxygen-rich air and exchange of gases occurs.
    • When the diaphragm relaxes the volume of the thoracic cavity decreases, the pressure increases and the air containing carbon dioxide is expelled out of lungs through nostrils.
    • This is called exhalation.
    • The process of inhalation and exhalation is collectively called breathing.


    EXCHANGE OF GASES IN TISSUES :

    • Respiratory gases are exchanged between the blood and the tissues.
    • Oxygen is utilised in the tissues and carbon dioxide is released.
    • The blood coming from lungs to the tissues has higher concentration of oxygen and lower concentration of carbon dioxide.
    • The difference in concentration induces exchange of gases between tissue and blood capillaries.


    The end result of respiration process is that the oxidation of simple food molecules like glucose in mitochondria releases energy which is stored in ATP.

  10. Distinguish between autotrophic nutrition and heterotrophic nutrition.

    ANS :


  11. Distinguish between photosynthesis and respiration.

    ANS:
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Tuesday, April 17, 2007

NUTRITION AND RESPIRATION IN ORGANISMS - II : BRIEF ANSWERS

ANSWER IN BRIEF



*INDEX-TOPIC SEARCH


  1. Describe Aerobic respiration.

    ANS: The respiration that takes place in the presence of oxygen is called aerobic respiration. Majority of the organisms show aerobic respiration.

    During aerobic respiration glucose is completely broken down into carbon dioxide and water and the energy that is released is stored in ATP.

    Since the process takes place in the cell it is called Cellular respiration or Internal respiration.


  2. Describe Anaerobic respiration.

    ANS: Anaerobic respiration takes place in the absence of oxygen. It is seen in micro-organisms like bacteria, yeast, fungi, endoparasites and in muscle cells.

    In plants, carbon dioxide and ethanol are formed as end products.



    Lactic acid is formed as end product in muscle cells.
  3. How does the respiration in plants differ from that in animals ?

    ANS: The respiration in plants differs from that in animals in the following ways :

    • All parts of a plant like root, stem and leaf perform respiration individually.
    • There is little transport of gases from one part of plant to another.
    • The rate of respiration in plants is much slower than that in animals.

  4. Distinguish between aerobic and anaerobic respiration.

    ANS:

  5. What is photolysis? Give reaction.

    ANS:Photolysis is the process of breaking a molecule with the help of light. For example, photolysis of water during light phase of photosynthesis:

    H2O ---> 2H+ + 1/2 O2 + 2e-

  6. Distinguish between breathing and (cellular) respiration.

    ANS:
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Friday, April 13, 2007

NUTRITION AND RESPIRATION IN ORGANISMS - I : MCQs & SHORT ANSWERS


*INDEX-TOPIC SEARCH

MULTIPLE-CHOICE QUESTIONS



SELECT THE CORRECT ALTERNATIVE:



  1. The autotrophic organisms contain ______ pigment.

    1. methylene blue
    2. chlorophyll
    3. phenolphthalin
    4. carbon black

  2. Oxygen released during photosynthesis comes from ______.

    1. water
    2. carbon dioxide
    3. chloroplast
    4. sunlight

  3. Rate of photosynthesis is more in ______ and ______ light.

    1. red, green
    2. red, orange
    3. yellow, orange
    4. green, orange

  4. The process of obtaining food in amoeba is called ______.

    1. pyrolysis
    2. phosphorylation
    3. phagocytosis
    4. phenocytosis

  5. The cavity between the upper and the lower jaws is called ______ cavity.

    1. thoracic
    2. nasal
    3. hepatic
    4. buccal

  6. The length of ileum is about ______ m.

    1. 5
    2. 6
    3. 7
    4. 8

  7. The energy released during cellular respiration is stored in ______.

    1. ATP
    2. glucose
    3. lungs
    4. ileum

  8. The layer of dead cells having tiny openings on the roots is called ______.

    1. root nodule
    2. stomata
    3. chlorenchyma
    4. lenticels

  9. Fish respire through ______.

    1. Gills
    2. spiracles
    3. lungs
    4. skin

  10. In insects the air enters the tracheal system through openings called ______.

    1. spiracles
    2. nostrils
    3. lungs
    4. bronchi

  11. Lungs are situated in ______.

    1. buccal cavity
    2. nasal cavity
    3. thoracic cavity
    4. stomach

  12. Oxidation of glucose takes place in ______.

    1. lungs
    2. heart
    3. mitochondria
    4. chloroplast

  13. The lungs are covered by two membranes called ______.

    1. glottis
    2. pleura
    3. epiglottis
    4. epidermis

  14. The process which releases energy from nutrients is called ______.

    1. respiration
    2. photosynthesis
    3. nutrition
    4. absorption

  15. Which organism shows parasitic mode of nutrition ?

    1. Cascuta
    2. Plasmodium
    3. ascaris
    4. All three

  16. During photosynthesis electrons are released from ______.

    1. Electron Transport System
    2. Chloroplast
    3. Light
    4. All three

  17. During which phase of photosynthesis ATP is used as an energy source ?

    1. Light phase
    2. Light synthetic phase
    3. Biosynthetic phase
    4. Grana phase

  18. During biosynthetic phase carbon dioxide combines with ______.

    1. RuBP
    2. starch
    3. glucose
    4. PGA

  19. Cockroach shows ______ mode of nutrition.

    1. herbivorous
    2. carnivorous
    3. omnivorous
    4. grazing

  20. Gizzard is found in the digestive system of ______.

    1. man
    2. amoeba
    3. locust
    4. earthworm

  21. The function of incisors is ______.

    1. cutting
    2. tearing
    3. grinding
    4. chewing
















SHORT QUESTIONS



ANSWER IN SHORT:



  1. Define : Nutrition.

         ANS : The process of intake of nutrients and their utilization in every living cell of the body is called nutrition.
  2. What is the aim of the nutrition ?

         ANS : The aim of nutrition is to provide energy to the body and help in biosynthesis of body constituents.
  3. Mention two main modes of nutrition.

         ANS : Autotrophic nutrition and heterotrophic nutrition are two main modes of nutrition.
  4. From what do autotrophic organisms synthesize glucose and other molecules ?

         ANS : Autotrophic organisms synthesize glucose and other molecules from inorganic molecules like carbon dioxide, water and some minerals using solar energy.
  5. What do we mean by autotrophic organisms ?

         ANS : Those organisms which can synthesize their own food by using carbon dioxide, water and solar energy are called autotrophic organisms.
  6. What do we mean by heterotrophic organisms ?

         ANS : Those organisms which cannot prepare their own food and are dependent on other organisms for nutrition are called heterotrophic organisms.
  7. Mention different types of heterotrophic nutrition.

         ANS : The types of heterotrophic nutrition are : saprophytic nutrition, parasitic nutrition and holozoic nutrition.
  8. How is energy derived during heterotrophic nutrition ?

         ANS : Energy is derived from the intake and digestion of organic nutrients obtained from plant and animal origin.
  9. Define : Saprophytic nutrition.

         ANS : The mode of nutrition in which an organism obtains nutrients from dead and decaying organic matter is called saprophytic nutrition.
  10. Define : Saprophyte

         ANS : An organism which obtains nutrition from dead and decaying matter is called a saprophyte.
  11. Define : Parasitic nutrition.

         ANS : [TEXT BOOK DEFINITION] If an organism depends on another living organism for nutrition, then this mode of nutrition is called parasitic nutrition.

    [PROPER DEFINITION] If an organism obtains nutrition from other organism and in turn harms the latter, the mode of nutrition is called parasitic nutrition.
  12. What is the organism providing food to a parasite called ?

         ANS : The organism providing food to a parasite is called 'host'.
  13. Define : Holozoic nutrition.

         ANS : The nutrition obtained by the intake of parts of plants or animals or an organism as a whole by the process of ingestion which is then digested and nutrients are absorbed is called holozoic nutrition.
  14. By which process do green plants synthesize food ?

         ANS : Green plants synthesize food by photosynthesis.
  15. What does photosynthesis mean ?

         ANS : Photosynthesis means synthesis of food with the help of light energy.
  16. Define : Photosynthesis.

         ANS : Photosynthesis is a process in which plants (and some micro-organisms) synthesize food from environmental carbon dioxide and water using sunlight and chlorophyll.
  17. Write the chemical equation for photosynthesis.

         ANS :



  18. Mention the two phases of photosynthesis.

         ANS : The two phases of photosynthesis are (i) Light phase (ii) Biosynthetic phase.
  19. In which form do the chlorophyll molecules absorb light energy ?

         ANS : Chlorophyll molecules absorb light energy in the form of photons.
  20. What is photophosphorylation ?

         ANS : The synthesis of ATP from ADP and inorganic phosphate during the light phase of photosynthesis is called photophosphorylation.
  21. Write the equation for photolysis of water during photosynthesis.

         ANS :



  22. What is the full form of NADP ?

         ANS : The full form of NADP is Nicotinamide Adenine Dinucleotide Phosphate.
  23. Where does the light phase of photosynthesis take place in the chloroplast ?

         ANS : The light phase of photosynthesis takes place in the grana of chloroplast.
  24. What is formed during the light phase of photosynthesis ?

         ANS : ATP and NADPH2 are formed during the light phase of photosynthesis.
  25. What happens during the biosynthetic phase of photosynthesis ?

         ANS : Carbohydrates are formed from carbon dioxide using ATP and NADPH2 during biosynthetic phase.
  26. Where does the biosynthetic phase take place ?

         ANS : Biosynthetic phase takes place in the stroma of the chloroplast.
  27. Who discovered the biosynthetic phase of photosynthesis ?

         ANS : Calvin and Benson discovered the biosynthetic phase of photosynthesis.
  28. How does carbon dioxide enter the biosynthetic phase ?

         ANS : Carbon dioxide reacts with Ribulose biphosphate (RuBP) and enters the biosynthetic phase.
  29. Mention the factors affecting photosynthesis.

         ANS : The factors affecting photosynthesis are : (i) light (ii) water (iii) temperature (iv) carbon dioxide.
  30. What part of visible light is mostly absorbed by chlorophyll ?

         ANS : Mostly red and orange region of visible light is absorbed by chlorophyll.
  31. How does the intensity of light affect the rate of photosynthesis ?

         ANS : The rate of photosynthesis increases at low intensity and decreases at high intensity.
  32. Why does the low temperature inhibit photosynthesis ?

         ANS : Low temperature inhibits the rate of photosynthesis because at low temperatures the activity of the enzymes is lowered.
  33. Why does the rate of photosynthesis decrease at very high temperatures ?

         ANS : The rate of photosynthesis decreases at very high temperatures because at those temperatures the enzymes are denatured.
  34. How are animals classified according to their food habit ?

         ANS : Animals are classified as herbivores, carnivores and omnivores according to their food habit.
  35. On what does amoeba feed ?

         ANS : Amoeba feeds on microscopic plants and animals floating on water.
  36. Mention the processes involved in the nutrition in amoeba.

         ANS : The processes involved in the nutrition in amoeba are : ingestion, digestion, assimilation and egestion.
  37. In which parts is the alimentary canal of a grasshopper divided ?

         ANS : The alimentary canal of a grasshopper is divided into three parts : (i) foregut (ii) midgut (iii) hindgut.
  38. What forms the foregut of a grasshopper ?

         ANS : The foregut of a grasshopper starts from the mouth, followed by a short pharynx, a short and narrow oesophagus, crop and extends upto gizzard.
  39. Which parts does the hindgut of a grasshopper consist of ?

         ANS : The hindgut of a grasshopper consists of three parts : (i) an anterior ileum (ii) a middle colon (iii) a posterior rectum.
  40. What are Malphighian tubules ?

         ANS : The yellow thread-like minute tubules in the hindgut of a grasshopper are called Malphighian tubules.
  41. What do hepatic caecae do ?

         ANS : Hepatic caecae secrete digestive enzymes.
  42. What does the alimentary canal in human digestive system consist of ?

         ANS : The alimentary canal in human digestive system consists of mouth, buccal cavity, pharynx, oesophagus, stomach, small intestine, large intestine, rectum and anus.
  43. Mention the accessory digestive glands of human digestive system.

         ANS : Salivary glands, liver and pancreas are the accessory digestive glands of human digestive system.
  44. Mention the types of teeth.

         ANS : The types of teeth are : (i) incisors (ii) canines (iii) premolars (iv) molars.
  45. What is the posterior region of buccal cavity called ?

         ANS : The posterior region of buccal cavity is called pharynx.
  46. Through which valve does the stomach open into duodenum ?

         ANS : The stomach opens into duodenum through pyloric valve.
  47. What does the small intestine consist of ?

         ANS : The small intestine consists of (i) duodenum (ii) jejunum (iii) ileum.
  48. What is the function of villi in small intestine ?

         ANS : The function of villi is to increase the surface area for absorption in small intestine.
  49. Where is the vermiform appendix located ?

         ANS : The vermiform appendix is located at the junction of the small intestine and the large intestine.
  50. Define : Inspiration.

         ANS : The intake of oxygenated air into lungs is called inspiration.
  51. Define : Expiration.

         ANS : The removal of deoxygenated air containing carbon dioxide from the lungs is called expiration.
  52. Define : Breathing.

         ANS : The alternate process of inspiration and expiration together is called breathing.
  53. Define : Respiration.

         ANS : Respiration is the process involving inspiration and expiration during which every cell of the body receives oxygen and utilises it for oxidation of glucose to release energy.
  54. Define : Aerobic respiration.

         ANS : The respiration that takes place in the presence of oxygen is called aerobic respiration.
  55. Why is aerobic respiration also called cellular (internal) respiration ?

         ANS : Aerobic respiration is also called cellular (internal) respiration because it takes place within the cell.
  56. Write the chemical equation for aerobic respiration.

         ANS :


  57. Define : Anaerobic respiration.

         ANS : Respiration which takes place in the absence of oxygen is called anaerobic respiration.
  58. Which organisms exhibit anaerobic respiration ?

         ANS : Micro-organisms like bacteria, yeast, fungi and endoparasites exhibit anaerobic respiration.
  59. Mention end products of anaerobic respiration.

         ANS : The end products of anaerobic respiration are carbon dioxide and ethanol in plants and lactic acid in the muscles of animals.
  60. Write the chemical equation for anaerobic respiration in plants.

         ANS :


  61. Write the chemical equation for anaerobic respiration in muscles.

         ANS :[SA-61]
  62. Through what does the gaseous exchange occur between the soil and the inner living cells of plants ?

         ANS : The gaseous exchange occurs between the soil and the inner living cells of plants through lenticels.
  63. Through what does the gaseous exchange occur in animals like amoeba/paramoecium ?

         ANS : The gaseous exchange occurs through body wall in amoeba/paramoecium.
  64. Gaseous exchange occurs through ______ in earthworm.

         ANS : the skin
  65. Through what does the frog respire ?

         ANS : The frog respires through skin and lungs.
  66. What is the respiratory organ of insects like locust, housefly and cockroach ?

         ANS : Trachea is the respiratory organ of insects like locust, housefly and cockroach.
  67. Through what does the air enter tracheal system in insects ?

         ANS : The air enters tracheal system through openings called spiracles in insects.
  68. What type of respiratory surface should be for rapid and efficient gaseous exchange ?

         ANS : The respiratory surface should be thin, moist, richly supplied with blood capillaries and in direct contact with the atmosphere for rapid and efficient gaseous exchange.
  69. What does the human respiratory system consists of ?

         ANS : Human respiratory system consists of nostrils, nasal cavity, pharynx, larynx, trachea, bronchi and lungs.
  70. What is glottis ?

         ANS : Glottis is a slit through which pharynx leads to trachea.
  71. Why does the food not enter the windpipe ?

         ANS : The food (during swallowing) does not enter the windpipe because the glottis is covered by a cartilaginous flap of skin called epiglottis.
  72. Name the salivary glands of human digestive system.

         ANS : (1) Submendibular salivary gland (2) Sublingual salivary gland
  73. What is the function of canines?

         ANS : The function of canines is'tearing' the food particles.
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Saturday, April 07, 2007

ORGANIC COMPOUNDS -III : LONG ANSWERS

GIVE ANSWER IN DETAIL



*INDEX-TOPIC SEARCH


  1. Explain : Alcohol group giving common name, IUPAC name and chemical formula of first five compounds.
    ANS :

    • The functional group of an alcohol is -OH.
    • The general formula of alcohols is CnH2n + 1OH where CnH2n + 1 is alkyl group (also written as R) and n=1,2,3,...
    • The suffix "-ane" of an alkane is replaced by "-anol" to give name to the corresponding alcohol. For example : CH4 is methane and CH3OH is methanol.
    • The first five alcohol compounds and their formulas are as follows :




  2. Describe preparation of ethyl alcohol.
    ANS : Ethyl alcohol can be prepared by two methods.

    1. Fermentation of carbohydrates
    2. Hydration of ethene


    FERMENTATION OF CARBOHYDRATES :

    Slow breaking down of carbon compounds in presence of enzymes and in absence of oxygen into simpler compounds is called fermentation.

    The sugar (carbohydrates) present in sugarcane, juices of fruits, etc. is first broken down to simple sugars like glucose and fructose by enzyme invertase.



    Glucose (and fructose) is converted to ethanol by the enzyme zymase.[Yeast contains both invertase and zymase].



    HYDRATION OF ETHENE : Ethene reacts with water in presence of concentrated sulphuric acid to form ethyl alcohol.



  3. Describe chemical properties of ethyl alcohol.
    ANS :




  4. Explain : Aldehyde group giving common name, IUPAC name and chemical formula of first four compounds.
    ANS : Aldehydes are compounds with -CHO as their functional group.

    The IUPAC name of an aldehyde is given by replacing "-ane" of the parent hydrocarbon to "-anal". Thus methane (CH4) becomes methanal (HCHO) and ethane (C2H6) becomes ethanal (CH3CHO).

    The common name, IUPAC name and chemical formula of first four aldehyde compounds are as follows :




  5. Describe preparation, properties and uses of formaldehyde.
    ANS :

    PREPARATION : Formaldehyde can be prepared by heating methanol to 600 - 700°C in presence of silver oxide as a catalyst. Methanol is oxidised to methanal (formaldehyde).



    PHYSICAL PROPERTIES :

    • Formaldehyde is a colourless gas.
    • Its boiling point is 20°C.
    • It is miscible with water.


    CHEMICAL PROPERTIES :

       Oxidation : Methanal is oxidised to methanoic acid (formic acid) in presence of oxidising agents like Tollen's reagent, Fehling's reagent, potassium permanganate solution or potassium dichromate solution.


    {Note : Tollen's reagent contains silver ammonium ion [Ag(NH3)2]+ }

       Reduction : In presence of catalyst palladium [Pd], hydrogen reduces methanal to methanol.



       Addition of HCN : Addition of hydrogen cyanide to methanal gives methanal cyanohydrin.



    USES :

    • Formalin (30 - 35 % solution of formaldehyde) is used to preserve biological specimens because it makes proteins insoluble in water.
    • For the manufacture of polymers like phenol-formaldehyde.


  6. Write an introductory note on carbonyl compounds.
    ANS :

    • The functional group >C=O is known as carbonyl group.
    • Aldehydes and ketones are carbonyl compounds.
    • When carbonyl group is attached to at least one hydrogen [i.e.it is attached to either two hydrogen atoms or one hydrogen atom and one alkyl group], an aldehyde compound is obtained.
    • When carbonyl group is attached to two alkyl groups, a ketone is obtained.



    • The name of an aldehyde is given by replacing "-ane" from the parent hydrocarbon by "-anal". Example : methane → methanal.
    • The name of a ketone is given by replacing "-ane" from the parent hydrocarbon by "-anone". Example : propane → propanone.


  7. Describe preparation, properties and uses of propanone (acetone).
    ANS :

    PREPARATION : Acetone is prepared by 'Fischer and Tropsch' process. When ethene, obtained from the cracking of petroleum, and water gas are mixed and passed over cobalt oxide catalyst at 180°C and 150 atm pressure, propanone is obtained.



    PHYSICAL PROPERTIES :

    • Acetone is a colourless, volatile liquid.
    • It has a pleasant odour.
    • It is miscible with water.
    • Its boiling point is 56°C.


    CHEMICAL PROPERTIES :

       Reduction : Propanone reacts with hydrogen in presence of catalysts like sodium boron hydride (NaBH4) or lithium aluminium hydride (LiAlH4) to yield 2-propanol.



       Oxidation : Propanone is oxidised to ethanoic acid by alkaline potassium permanganate.



       Addition Reaction With HCN : Acetone reacts with hydrogen cyanide to give acetone cyanohydrin.



    USES :

    • As a nail-polish remover.
    • In making models, air-plane glue, lacquers, paints, etc.
    • In leather industry and in artificial fibres.
    • As a solvent in laboratory.


  8. What are organic acids ? Explain giving example.
    ANS :

    • Organic compounds having -COOH (carboxylic acid) as funcional group are called organic (carboxylic) acids.
    • Their general formula is CnH2n + 1COOH where n = 0, 1, 2, 3,...
    • The suffix "-ane" of parent alkane is replaced by "-anoic" to give the name to an organic acid.
    • Following table gives common name, chemical name and formula of some organic acids. [Table : 12.4 to be posted- LA-15].


  9. Describe preparation, properties and uses of acetic acid (ethanoic acid).
    ANS :

    PREPARATION :

       Fermentation : Acetic acid is manufactured by the fermentation of ethyl alcohol with the help of bacteria (acetobacter). Acetic acid obtained by this process is very less and is called 'Vinegar'.



       Chemical Synthesis : The reaction of methanol with carbon monoxide in the presence of catalyst iodine-rhodium (I2-Rh) gives acetic acid.



    PHYSICAL PROPERTIES :

    • Acetic acid is a colourless liquid.
    • It has pungent smell.
    • It is miscible with water.
    • Its boiling point is 118°C.


    CHEMICAL PROPERTIES :

       Reaction With Metals : Acetic acid reacts with metals such as sodium(Na), potassium(K) or magnesium(Mg) and liberates hydrogen.



       Neutralisation : Acetic acid reacts with an alkali (NaOH or KOH) to form respective salt of acetic acid and water.



       Esterification : Acetic acid reacts with alcohols in presence of concentrated sulphuric acid to form ester.



       Decarboxylation : When acetic acid is heated with soda lime (CaO + NaOH) it loses (-COO) part forming methane.



    USES :

    • As vinegar, acetic acid is used as a preservative and taste-enhancer in food (like pickle).
    • As a laboratory reagent.
    • As a solvent.
    • For the preparation of white lead and lead acetate.


  10. Write a note on 'rubber'.
    ANS :

    • Rubber is an addition polymer.
    • Natural rubber is obtained from the latex of rubber trees.
    • Natural rubber consists of a long chain of isoprene (monomer) units.



    • Elasticity of natural rubber is low and is less strong.
    • Synthetic rubber (neoprene) is obtained by addition polymerization of chloroprene (monomer).
    • Vulcanisation of Rubber :

      • Natural rubber becomes brittle below 10°C and melts above 60°C.
      • Thus, natural rubber is less elastic and less strong.
      • To make natural rubber more elastic and tough, it is mixed with sulphur powder and heated to 100 to 140°C.
      • This forms strong links of sulphur between isoprene units.
      • This process is called vulcanisation of rubber.
      • Vulcanised rubber is used for making rubber bends, tubes and tyres of vehicles.



  11. Describe preparation of polyester and mention its uses.
    ANS : Polyester is prepared by reacting two compounds, one having two carboxylic groups and the other having two hydroxyl groups. This forms a long chain of esters called polyester.



       Uses : Polyester fibres are used in textiles industry along with cotton fibres.

  12. Describe preparation of polyamides (nylon) and mention its uses.
    ANS : Polyamides are prepared by reacting two compounds, one having two carboxylic groups and the other having two amide groups. This forms a long chain of amides called polyamides.



       Uses :

    1. As these fibres are strong and waterproof, they are used in making clothes and raincoats.
    2. In making fishing nets and in tyres.


  13. Describe the cleansing action of soaps and detergents.
    ANS :

    • The cleansing actions of soap and detergent are similar.
    • Both the soap and detergent have two parts in their molecular structure.
    • The hydrocarbon chain forms nonpolar tail which has no attraction for water but is attracted towards dirt or stains.
    • The head (negative part) consists of -COONa or SO3Na group which is polar as it has attraction towards water molecules.
    • When soap (detergent) solution is applied on the surface having dirt or stain, its nonpolar part is attracted by nonpolar dirt or stain. the polar part remains in water. This type of arrangement around dirt particles is called 'micelle'.
    • As hydrocarbon part remains attached to dirt or stain and the polar part remains in water, dirt is removed from the surface making it clean and water becomes dirty.


  14. Distinguish between natural rubber and vulcanised rubber.

    ANS :


  15. Write a note on fermentation.

    ANS :
    Fermentation :Fermentation is a slow process of breaking down of carbon compounds in the presence of enzymes and in the absence of oxygen.
    Fermentation is used in the manufacture of ethyl alcohol(ethanol) from sugar(carbohydrates). The sugar present in sugarcane, fruit-juices, etc., is first broken down to simple sugars like glucose and fructose by enzyme invertase.

    invertase
    C12H22O11 + H2O → C6H12O6 + C6H12O6
    Sugar or molasses           glucose       fructose


    Simple sugars (glucose and fructose) are converted to ethanol by the enzyme zymase.

    zymase
    C6H12O6          → 2C2H5OH + 2CO2
    glucose             ethanol


    Yeast is used in this process because it contains both enzymes invertase and zymase.

    [NOTE : The text book defines fermentation as a process taking place in absence of oxygen. While describing the preparation of acetic acid from ethanol, it has been mentioned that Vinegar (ethanoic acid) is formed by oxidation of ethanol in air by acetobactor enzyme through fermentation process. This is an example of one of several controversial issues found in the text book.]
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