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Sunday, July 29, 2007

REPRODUCTION IN ORGANISMS - I : MCQs & SHORT ANSWERS


*INDEX-TOPIC SEARCH

MULTIPLE-CHOICE QUESTIONS



SELECT THE CORRECT ALTERNATIVE:

  1. Which of the following is not a unicellular organism ?

    1. Amoeba
    2. Paramoecium
    3. Hydra
    4. Yeast

  2. Which of the following shows budding ?

    1. Yeast
    2. Amoeba
    3. Paramoecium
    4. Plasmodium

  3. Which of the following shows multiple fission ?

    1. Hydra
    2. Yeast
    3. Spirogyra
    4. Plasmodium

  4. Which is the most common method of reproduction in majority of fungi and bacteria ?

    1. Binary fission
    2. Multiple fission
    3. Budding
    4. Spore formation

  5. Which of the following shows spore formation ?

    1. Amoeba
    2. Mucor
    3. Plasmodium
    4. Paramoecium

  6. Regeneration is observed in ______.

    1. Amoeba
    2. Planaria
    3. Spirogyra
    4. Yeast

  7. Which of the following does not show regeneration ?

    1. Mucor
    2. Planaria
    3. Sponges
    4. Starfish

  8. Which of the following is not an artificial method of vegetative propagation ?

    1. Cutting
    2. Layering
    3. Grafting
    4. Hybridization

  9. Testes produce ______ hormone.

    1. Estrogen
    2. Testosterone
    3. Progesterone
    4. Both estrogen and testosterone

  10. Which of the following is not produced in the ovary ?

    1. Ovum
    2. Estrogen
    3. Progesterone
    4. Testosterone

  11. The main reproductive organ of human male is ______.

    1. a pair of testes
    2. vas deferens
    3. urethra
    4. penis

  12. The main female reproductive organ is ______.

    1. Fallopian tubes
    2. uterus
    3. vagina
    4. a pair of ovaries

  13. The first phase of the sexual cycle in human female is called ______.

    1. ovulation
    2. implantation
    3. menstruation
    4. follicle phase

  14. Menstrual flow(menstruation) lasts for about ______ days.

    1. 2 - 3
    2. 3 - 5
    3. 5 - 7
    4. 14

  15. In a normal healthy woman, menstruation occurs every ______ days.

    1. 14
    2. 28 - 32
    3. 21 - 24
    4. 270

  16. What marks the beginning of the reproductive life of a woman ?

    1. ovulation
    2. menopause
    3. menarche
    4. fertilisation

  17. What is formed after fertilisation ?

    1. A sperm
    2. An ovum
    3. A zygote
    4. A gamete

  18. Where does fertilisation take place ?

    1. vagina
    2. cervix
    3. Fallopian tube
    4. uterus

  19. What should be the normal weight of a fully matured foetus (child at birth)?

    1. 2.5 - 3.0 pounds
    2. 2.5 - 3.0 kg
    3. 3.0 - 3.5 pounds
    4. 3.0 - 3.5 kg

  20. ______ prevents ovulation.

    1. Testosterone
    2. Progesterone
    3. Estrogen
    4. Contraception

  21. Which of the following shows budding ?

    1. Hydra
    2. Amoeba
    3. Paramoecium
    4. Spirogyra

  22. Several new individuals are produced.

    1. Binary fission
    2. Multiple fission
    3. Both binary fission and multiple fission
    4. Fertilisation

  23. In grafting the plant rooted in the soil is called ______.

    1. stock
    2. sucker
    3. scion
    4. rhizome

  24. Which of the following plants shows vegetative propagation ?

    1. Wheat
    2. Radish
    3. Sunflower
    4. Bryophyllum

  25. Testes in human male are located in ______.

    1. abdominal cavity
    2. vas deferens
    3. scrotum
    4. penis

  26. In the process of sexual reproduction ______.

    1. only males are needed
    2. both male and female are needed
    3. only females are needed
    4. only mitosis is involved

  27. The process of release of an egg from the ovary is called ______.

    1. reproduction
    2. ovulation
    3. menstruation
    4. fertilisation

  28. ______ takes place in a woman after 45 - 50 years.

    1. Menstruation
    2. Ovulation
    3. Menopause
    4. Lactation

  29. The period taken for one complete menstrual cycle is ______.

    1. 31 days
    2. 32 - 35 days
    3. 28 - 32 days
    4. 22 - 25 days

  30. The development of foetus inside the uterus till birth is called ______.

    1. gestation
    2. parturition
    3. lactation
    4. fertilization

  31. The unicellular fungus which shows bud formation is ______.

    1. mucor
    2. yeast
    3. amoeba
    4. none of these

  32. The animal which shows regeneration is ______.

    1. amoeba
    2. paramoecium
    3. hydra
    4. rhizopus

  33. The method by which desired characters of two plants can be combined is ______.

    1. cutting
    2. layering
    3. budding
    4. grafting

  34. The disease caused by treponema palidium is ______.

    1. AIDS
    2. syphillis
    3. gonorrhoea
    4. hepatitis

  35. Yeast reproduces by...

    1. budding
    2. fission
    3. regeneration
    4. spore formation

  36. A chain of buds is formed in...

    1. hydra
    2. yeast
    3. mucor
    4. plasmodium

  37. Vegetative propagation is observed in...

    1. yeast
    2. hydra
    3. mucor
    4. bryophyllum

  38. ______ is useful where seeds have long dormancy period and poor germination capacity.

    1. Cutting
    2. Layering
    3. Grafting
    4. Regeneration

  39. ______ is a very useful method for developing garden.

    1. Cutting
    2. Layering
    3. Grafting
    4. Budding

  40. The stage at which there is a gradual change in structure of reproductive organs in human male and female is called...

    1. spermatogenesis
    2. oogenesis
    3. menarche
    4. puberty

  41. The temperature in the scrotum is about ______ deg C lower than the body temperature.

    1. 2
    2. 3
    3. 5
    4. 6

  42. Which of the following is not a part of reproductive system in human male ?

    1. Testis
    2. Seminal vesicle
    3. Clitoris
    4. vas deferens

  43. Which of the following is not a part of reproductive system in human female ?

    1. Ovary
    2. Cervix
    3. Vagina
    4. vas deferens

  44. The sexual cycle in human female starts at...

    1. birth
    2. the age of 45
    3. the age of 28
    4. puberty stage

  45. Ovulation occurs on the ______ day of the sexual cycle.

    1. 14th
    2. 20th
    3. 28th
    4. any

  46. The sexual cycle in human female remains active(functional), generally, up to the age of...

    1. 30 years
    2. 35-40 years
    3. 45-50 years
    4. 55-60 years

  47. The 14th day of sexual cycle in human female is important because on that day...

    1. ovulation occurs
    2. she becomes pregnant
    3. menstrual flow starts
    4. she gives birth to a child

  48. ______ fertilises an ovum in a female's body.

    1. Blood
    2. Testosterone
    3. A sperm
    4. Seminal fluid

  49. The nutritional requirements of an embryo are maintained through...

    1. ovarian follicle
    2. oviduct
    3. mouth
    4. umbilical cord

  50. In humans, generally, the birth takes place after ______ of embryo development.

    1. 14 weeks
    2. 28 weeks
    3. 40 weeks
    4. 280 weeks

  51. The calculation of embryo development (age of embryo) starts from...

    1. the first day of last menstrual cycle
    2. the first day of first menstrual cycle
    3. the last day of first menstrual cycle
    4. the last day of last menstrual cycle

  52. Which of the following is a chemical device of birth control ?

    1. Copper-T
    2. Condum
    3. Birth-control pills
    4. Loop

  53. Where are the testes of human male located ?

    1. In abdominal cavity
    2. In vas deferens
    3. In scrotum
    4. In penis

  54. The process of release of egg from ovary is called...

    1. reproduction
    2. ovulation
    3. menstruation
    4. menopause

  55. The period after 45-50 years in woman is known as...

    1. menstruation
    2. gestation
    3. menopause
    4. lactation

  56. How many days are there in one menstrual cycle ?

    1. 31
    2. 32-35
    3. 28-32
    4. 22-40

  57. The period from the formation of embryo to birth is known as...

    1. gestation
    2. parturition
    3. lactation
    4. fertilisation

  58. Every organism produces another identical organism. This event is known as...

    1. growth
    2. reproduction
    3. alteration of generation
    4. regeneration

  59. The method by which the desired characters of two plants can be combined is...

    1. cutting
    2. layering
    3. budding
    4. grafting

  60. During embryo development, the embryo is protected by...

    1. amnion
    2. placenta
    3. umbilical cord
    4. oviduct







ANSWERS TO MCQs:

(1) C (2) A (3) D (4) D (5) B (6) B (7) A (8) D (9) B (10) D (11) A (12) D (13) D (14) B (15) B (16) C (17) C (18) C (19) D (20) B (21) A (22) B (23) A (24) D (25) C (26) B (27) B (28) C (29) C (30) A (31) B (32) C (33) D (34) B

SHORT QUESTIONS



ANSWER IN SHORT:

  1. What is reproduction ?

         ANS : The process by which the organisms produce new organisms similar to them is known as reproduction.

  2. Why is reproduction essential ?

         ANS : Reproduction is essential for the perpetuation of species and thereby life.

  3. Mention the types of reproduction.

         ANS : Asexual reproduction and sexual reproduction are the two types of reproduction.

  4. What is asexual reproduction ?

         ANS : Asexual reproduction is the method of reproduction involving only a single individual (organism),i.e. only one organism is needed for reproduction.

  5. Mention different types of asexual reproduction.

         ANS : (i) Fission (ii) Budding (iii) Spore Formation (iv) Regeneration (v) Vegetative propagation, etc are types of asexual reproduction.

  6. Mention two types of reproduction by fission.

         ANS : Binary fission and multiple fission are the two types of fission.

  7. What is binary fission ?

         ANS :When two independent adult organisms are formed after the division of the nucleus and the cytoplasm of one (mother) cell into two (daughter) cells, the process of reproduction is called binary fission.

  8. Give examples of organisms showing binary fission.

         ANS : Amoeba and paramoecium show binary fission.

  9. What is multiple fission ?

         ANS :When the nucleus of one (mother) cell divides several times into many (daughter) nuclei, each forming an individual organism, the process is called multiple fission.

  10. Give examples of organisms showing multiple fission.

         ANS : Plasmodium and amoeba show multiple fission.

  11. What is budding ?

         ANS : Budding is a process of reproduction in which a small protuberance (bud) appearing on an adult cell gradually grows bigger and then behaves as an independent organism after being detached from the (mother) cell.

  12. Give examples of organisms showing budding.

         ANS : Yeast and hydra show budding.

  13. What is the similarity between hydra and yeast ?

         ANS : both hydra and yeast exhibit budding as the method of reproduction.

  14. Mention some organisms showing spore formation.

         ANS : Mucor, rhizopus and penicillium show spore formation.

  15. What is sporangium ?

         ANS : Sporangium is a structure developing from fungal hypha and it contains a nucleus (spore) which divides several times forming a large number of spores which develop into new hyphae after falling on the ground.

  16. What is regeneration ?

         ANS : The ability of an organism to replace the lost parts of its body is called regeneration.

  17. What is fragmentation ?

         ANS : When an organism breaks into two or more pieces after being mature and then each piece grows as an individual organism, the process is known as fragmentation.

  18. Give examples of organisms showing fragmentation.

         ANS : Oscillatoria and spirogyra show fragmentation.

  19. What is vegetative propagation ?

         ANS : Vegetative propagation is a method of reproduction in which a new plant developes from a part of a root, stem or leaf.

  20. Give examples of plants showing vegetative propagation.

         ANS : Potato, sweet potato, bryophyllum, etc. show vegetative propagation.

  21. Mention names of artificial methods of vegetative propagation.

         ANS : Cutting, layering, grafting etc are artificial methods of vegetative propagation.

  22. Give examples of some plants in which cutting is used as a method of vegetative propagation.

         ANS : Cutting is used as a method of vegetative propagatin for sugarcane, grapes, rose, phalsa, etc.

  23. Give examples of some plants in which layering is used as a method of vegetative propagation.

         ANS : layering is used as a method of vegetative propagation for lemon. guaua, hibiscus, jasmine, bougainvillaea, etc.

  24. What is grafting ?

         ANS : Grafting is a method of vegetative propagation in which two parts of two different plants are joined together in a specific manner so that they unite to grow as one plant.

  25. What is 'scion' ?

         ANS : The portion of the plant which is grafted on other plant is called scion.

  26. What is 'stock' ?

         ANS : The plant on which grafting is performed is called stock.

  27. In what circumstances is grafting a better method ?

         ANS : Grafting is a better method for plants where seeds are having long dormancy period and poor germination capacity.

  28. At which stage of life the reproductive system of human being becomes functional ? (write one word).

         ANS : Puberty.

  29. Mention the age of puberty in male and female human beings.

         ANS : The age of puberty in human male is about 13-14 years and that in human female is about 10-12 years.

  30. Mention the names of human gonads.

         ANS : Testis (testes) in male and ovary in female are human gonads.

  31. Name the sex hormone of human male.

         ANS : Testosteron is the sex hormone of human male.

  32. Which hormones are produced in ovary of human female ?

         ANS : Estrogen and progesteron are produced in the ovary of human female.

  33. Which are the two processes referred to as gametogenesis ?

         ANS : Spermatogenesis and oogenesis are referred to as gametogenesis.

  34. Mention the optimal temperature for spermatogenesis.

         ANS : A temperature 3 °C lower than the body temperature is optimal for spermatogenesis.

  35. What is urinogenital path ?

         ANS : Urinogenital path is the common opening through which both urine and the sperms are released.

  36. What is ovulation ?

         ANS : The release of an ovum from the ovary by rupturing the ovarian follicle is called ovulation.

  37. What is menstrual cycle ?

         ANS : The cycle of events taking place in the ovaries and uterus every 28 days and marked by the flow of blood is called menstrual Cycle.

  38. What is menarche ?

         ANS : The commencement of menstruation at puberty in a woman is called menarche.

  39. What is menopause ?

         ANS : Menopause is the stage in a woman's life when menstrual flow and other related events stop.

  40. What is fertilisation ?

         ANS : The union of the male and female gametes resolting in the formation of zygote is called fertilisation.

  41. Mention the type of fertilisation taking place in humans.

         ANS : Internal fertilisation takes place in humans.

  42. Mention the term used for male gamete.

         ANS : Sperm.

  43. What indicates that the fertilisation has taken place ?

         ANS : The absence of menstrual flow at its regular interval indicates that the fertilisation has occured.

  44. What is implantation ?

         ANS : The close attachment of the embryo with the walls of uterus is called implantation.

  45. What is placenta ?

         ANS : A special tissue between the uterus wall and the embryo (foetus) that fulfils the nutritional, respiratory and excretory needs of the foetus from mother's body is called placenta.

  46. What is the function of amniotic fluid ?

         ANS : The function of amniotic fluid is to protect the foetus against temperature changes and mechanical shocks.

  47. What is gestation ?

         ANS : The development of the foetus inside the uterus till birth is called gestation.

  48. What is the average duration of pregnancy (gestation period) in human beings ?

         ANS : The average duration of pregnancy in human beings is about 280 days or 40 weeks.

  49. What is parturition ?

         ANS : The birth of a fully developed foetus after the completion of gestation period is called parturition.

  50. What is family planning ?

         ANS : Family planning is the adoption of various new techniques which prevent fertilisation or pregnancy.

  51. What is Zero (Rhythm) method ?

         ANS : Zero or Rhythm method is a natural method of contraception in which sexual intercourse is avoided 3 days before ovulation and 1 day after ovulation.

  52. What is 'coitus interruptus' ?

         ANS : Coitus interruptus is a natural method of contraception in which the penis is withdrawn from vagina before ejeculation (of semen).

  53. Mention two natural methods of contraception.

         ANS : (i)Zero (Rhythm) method (ii) Coitus interruptus.

  54. What is the full form of IUCD ?

         ANS : The full form of IUCD is IntraUterine Contraceptive Device.

  55. What is a contraceptive ?

         ANS : A device or a substance that prevents fertilisation during intercourse is called a contraceptive.

  56. What is contraception ?

         ANS : Contraception is a method of prevention of fertilisation of ovum (pregnancy).

  57. What is vasectomy ?

         ANS : Vasectomy is the process of surgical removal of a small portion of vas deferens of a male to prevent fertilisation.

  58. What is tubectomy ?

         ANS : Tubectomy is the process of surgically cutting and tying the Fallopian tube of a female to prevent fertilisation.

  59. What is the full form of WHO ?

         ANS : The full form of WHO is World Health Organisation.

  60. Define 'health' according to WHO.

         ANS : According to WHO, health is a state of complete physical, mental and social well being and not merely the absence of disease.

  61. What are STDs ?

         ANS : The infectious diseases which are spread from an infected person to a healthy person by sexual contact are called Sexually Transmitted Diseases (STDs).

  62. What is gonorrhoea ?

         ANS : Gonorrhoea is the inflammation of urinogenital tract causing burning sensation during urination.

  63. Which organism causes gonorrhoea ? (Write the name only).

         ANS : Neissena gonorrhoea.

  64. What is syphillis ?

         ANS : Syphillis is an STD in which there are lesions in the mucuos membrane urinogenital tract and ulcers on genitalia.

  65. Which organism causes syphillis ?

         ANS : Treponema palidium causes syphillis.

  66. What is the full form of AIDS ?

         ANS : The full form of AIDS is Acquired
    Immuno-Deficiency Syndrome.

  67. Which virus causes AIDS ?

         ANS : HIV or Human Immuno-deficiency Virus causes AIDS.

  68. Name two animals that can regenerate their lost body parts.

         ANS : Planaria and starfish.

  69. Which two sex hormones are produced by ovary in human female ?

         ANS : Progesterone and estrogen are produced by ovary in human female.

  70. Name main sex organs in humans.

         ANS : Apair of testes in male and a pair of ovary in female are the main sex organs in humans.

  71. What is an ovary ?

         ANS : An ovary is the main sex organ in human female which exists in pair and releases an every month to the fallopian tube.

  72. Give the location and function of placenta.

         ANS : Placenta is located between the wall of the uterus and the foetus and its function is to fulfil the nutritional, respiratory, developmental and excretory needs of the foetus by connecting the foetus to mother's body.

  73. What is population control ?

         ANS : The prevention of unwanted births by applying proper techniques so that the population does not increase rapidly is called population control.

  74. When does a girl attain puberty ?

         ANS : A girl attains puberty at the age of about 10-12 years.

  75. What do you mean by reproductive health ?

         ANS : Reproductive health means capacity to reproduce without getting diseases like AIDS, gonorrhoea, syphillis, etc. which are contagious and transmitted sexually.

  76. What is the full form of NACO ?

         ANS : The full form of NACO is National AIDS Control Organisation.



  77.      ANS :
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Monday, June 25, 2007

CONTROL AND COORDINATION IN LIVING ORGANISMS - II : BRIEF AND LONG ANSWERS

ANSWER AS ASKED



*INDEX-TOPIC SEARCH


  1. Explain : Tropism

    ANS:

    • The movement of curvature of plants in the direction of stimuli is known as tropism.
    • Phototropism : When illuminated by a unidirectional light, the response of a growing plant by bending towards that light is called phototropism.


    • Geotropism : The downward movement of the roots of the plants, for fixation and absorption, as a response to the gravitational force is called geotropism.
    • Chemotropism : The movement of a plant or its part as a response to certain chemicals is called chemotropism. For example, germination of pollen grains and development of pollen tubes as a response to the chemicals secreted by the surface of the stigma.


  2. Explain : Explain : Nastic movement

    ANS:

    • The response by some plants to the external stimuli without any directional movement of growth or curvature towards that external stimuli is called nastic movement.
    • Examples :

      1. The leaves of Mimosa (touch-me-not) are sensitive to touch. They droop when touched.
      2. All insectivorous plants bend down or curl up when touched by insects.
      3. A sunflower plant bends towards the sun.

    • Of the above examples, (i) and (ii) are examples of thigmonastic response and (iii) is an example of photonastic response.


  3. Distinguish between tropic movement and nastic movement.

    ANS :


  4. Explain : Photoperiodism.

    ANS:

    • Photoperiodism is the phenomenon in which the duration of light decides the flowering and germination in plants.
    • Plants are (i) Long-day plant and (ii) Short-day plant on the basis of the duration of light received by them.
    • Day natural plants do not respond to photoperiodism.
    • Plants respond to photoperiodic stimulus by a specialised pigment present in them called phytochrome.


  5. Explain : Coordination in animals.

    ANS:

    • All multicellular organisms, except porifera, have well-developed nervous system.
    • Hydra and other cnidarians possess nerve cells which form a nerve net in the body.


    • In invertebrates, the nerve net condenses into nerve mass called 'ganglion'.
    • Insects have a bilobed nerve mass (brain), nerve cord and nerve ganglia.



    • Higher organisms possess sensory organs (receptors) related to light, hearing, taste, touch and smell.
    • Receptors receive the stimulus and pass on the message to the brain through sensory neuron.
    • The brain transmits information to the effector organ (generally muscles and glands) through motor neuron.
    • The brain acts as the center for the analysis of information.
    • Motor neurons stimulate the muscles of the organ to respond.
    • Hormones also play an important role in control and coordination in animals.
    • In vertebrates there is a successive development of nervous system.
    • The nervous system of human beings is highly developed.
    • Hormones secreted by endocrine glands control various biochemical and mechanical activities carried out in the organisms. This is chemical control.


  6. Write an explanatory note on HUMAN BRAIN.

    ANS:



    • Human brain is the main coordinating center for all the activities of the human body.
    • It is protected by a bony box in the skull called cranium and three membranes called meninges.
    • There is a fluid called cerebrospinal fluid in the space between these membranes.
    • Cerebrospinal fluid acts as a cushion and protects the brain from mechanical shocks.
    • The brain is divided into three regions : (i) fore-brain (ii) mid-brain and (iii) hind-brain.
    • FORE-BRAIN consists of cerebrum and olfactory lobes.

      • Cerebrum is the most complex and specialised part of the brain.
      • It consists of two cerebral hemispheres.
      • It has sensory area to receive impulse from the sense organs and motor area to send impulse to muscles and effector organs.
      • Cerebrum has four regions having different centers of activity : (i) frontal lobe (ii) parietal lobe (iii) temporal lobe (iv) occipital lobe.


      • The frontal lobe possesses centres for voluntary muscular activities.
      • Parietal lobe possesses the centres for temperature control, smell and touch.
      • Temporal lobe possesses the centres for auditory and olfactory reception.
      • Occipital lobe possesses the centres for visual reception.

    • MID-BRAIN is a part of the brain stem and possesses the regions for visual reception, auditory reception and touch.
    • HIND-BRAIN consists of cerebellum, pons and medulla oblongata.

      • Cerebellum is situated on the posterior side of the fore-brain and it controls the rhythmic movement of muscles, body balance and posture.
      • Pons connects various parts of the central nervous system and cerebellum by the transverse bands of nerves.
      • Pons takes part in the regulation of respiration and helps in the movement of head as per audio-visual perception in coordination with medulla oblongata and spinal cord.
      • Medulla oblongata possesses the centres to regulate heartbeats, breathing, blood-pressure, sneezing, coughing, vomiting, swallowing, hiccups, etc.



  7. Write in brief about Spinal cord.

    ANS:

    • Spinal cord is a cylindrical structure.
    • It is the posterior extension of of medulla oblongata.
    • The vertebral column and meninges protect the spinal cord.
    • There are 31 pairs of spinal nerves arising from the spinal cord.
    • These nerves connect various organs of the body to the brain.
    • They help in the conduction of impulses from brain to organs and from organs to brain.
    • They also perform reflex action.


  8. Explain : Reflex action

    ANS:



    • An unconscious and involuntary response of effectors to the stimulus is called reflex action.
    • Due to reflex action we suddenly withdraw our leg when we step on a very hot or pricking object.
    • Similarly, our response towards very hot or very cold water is sudden and involuntary.
    • The reflex action is performed by the spinal cord when the brain is busy or at rest.
    • In reflex action, a message from the receptors is relayed by sensory nerves to the spinal cord and the spinal cord sends response via motor nerve to the effector organ.
    • This entire pathway is called 'REFLEX ARC'.


  9. Write a note on Autonomous nervous system.

    ANS:

    • The system which is responsible for the intervention in the activities of the organs located in the body cavity without the awareness of brain is called autonomous nervous system.
    • This system controls heart, blood vessels, glands, uterus and coelomic organs.
    • Autonomous nervous system is of two types : (i) sympathetic (ii) parasympathetic.
    • The involuntary actions of the body are controlled and regulated by the coordination of these two systems.
    • The effects of sympathetic and parasympathetic nervous systems are complimentory and contradictory.
    • For example : If the sympathetic system increases the heartbeats abnormally, the parasympathetic system decreases it and brings it back to normal.


  10. Mention characteristics of hormones.

    ANS:

    • They are specific chemical messengers.
    • Generally the origin and the target area of hormones are different.
    • They are directly poured into the blood (from the gland) and carried by blood circulation.
    • The effect of a hormone is either rapid or slow (i.e. it may increase or decrease the speed of some process). For example, acetylcholine increases the speed of the conduction of impulses whereas decreases (slows down) the effect of sex hormones.


  11. Write a note on endocrine glands.

    ANS:

    • Endocrine glands play an important role in coordination (in animals).
    • These are ductless glands and secrete hormones which are specific chemical messengers.
    • The main endocrine glands are hypothalamus, pituitary,, pineal, thyroid, parathyroid, pancreas, adrenal, testis and ovary.
    • Pituitary gland is called the master gland as it regulates the secretion of hormones by other endocrine glands.
    • The function of the pituitary gland is controlled by the secretion of hypothalamus.


  12. Mention different endocrine glands, hormones secreted by them and the functions of these hormones.

    ANS:



  13. How is brain protected ?

    ANS : The brain is surrounded by cranium, a bony box in the skull and three membranes called meninges. In the space between these membranes there is a fluid called cerebrospinal fluid. This fluid protects the brain against mechanical shocks. Thus brain is protected.
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Saturday, June 16, 2007

CONTROL AND COORDINATION IN LIVING ORGANISMS - I : MCQs AND SHORT ANSWERS


*INDEX-TOPIC SEARCH

MULTIPLE-CHOICE QUESTIONS



SELECT THE CORRECT ALTERNATIVE:

  1. ______ is the complimentary system of nervous system.

    1. Circulatory system
    2. Endocrine system
    3. Lymphatic system
    4. Skeletal system

  2. Plant hormones are called ______.

    1. hypohormones
    2. metahormones
    3. phytohormones
    4. cytohormones

  3. The leaves of mimosa are sensitive to ______.

    1. light
    2. touch
    3. heat
    4. smell

  4. A sunflower plant bends towards the sun. It is ______ response.

    1. Thigmonastic
    2. seismonastic
    3. thermonastic
    4. photonastic

  5. All multicellular organisms, except ______, have well-developed nervous system.

    1. porifera
    2. mammals
    3. arthropoda
    4. insecta

  6. Nerve mass in invertebrates is called ______.

    1. brain
    2. neuron
    3. ganglion
    4. pelvis

  7. Hormones are secreted by ______.

    1. endocrine glands
    2. blood
    3. midbrain
    4. liver

  8. The space between meninges is filled with ______.

    1. lymph
    2. blood plasma
    3. cerebrospinal fluid
    4. ACTH

  9. ______ is not the part of hindbrain.

    1. cerebellum
    2. pons
    3. medulla oblongata
    4. cerebrum

  10. ______ protects spinal cord.

    1. Cranium
    2. Vertebral column
    3. Skull
    4. Ribs

  11. ______ pairs of spinal nerves arise from spinal cord.

    1. 21
    2. 31
    3. 32
    4. 42

  12. Which of the following organs is not controlled by autonomous nervous system ?

    1. Heart
    2. Uterus
    3. Glands
    4. Eyes

  13. The effects of sympathetic and parasympathetic nervous systems are ______.

    1. complimentary
    2. contradictory
    3. complimentary and contradictory
    4. none of above.

  14. Endocrine glands ______.

    1. secrete plasma
    2. secrete nutrients
    3. secrete hormones
    4. secrete antibodies

  15. Acetylcholine ______.

    1. increases the speed of conduction of impulses
    2. decreases the speed of conduction of impulses
    3. quickens the effect of growth hormones
    4. controls pituitary gland

  16. ______ is called the master gland.

    1. Pineal
    2. Pituitary
    3. Thyroid
    4. Thymus

  17. ______ hormone regulates ionic balance.

    1. Vasopressin
    2. Thyroxin
    3. Glucagon
    4. Testosterone

  18. ______ is the hormone responsible for development of female characteristics.

    1. Adrenalin
    2. Testosterone
    3. Thyroxin
    4. Progesterone

  19. ______ is responsible for lowering glucose level in blood.

    1. Glucagon
    2. Oxytocin
    3. Insulin
    4. Adrenalin

  20. ______ is responsible for increasing glucose level in blood.

    1. Glucagon
    2. Oxytocin
    3. Insulin
    4. Adrenalin

  21. Prolactin regulates ______.

    1. blood pressure
    2. heartbeat
    3. mammary glands
    4. glucose metabolism

  22. Nerve net is found in ______.

    1. sponges
    2. hydra
    3. earthworm
    4. cockroach

  23. Which multicellular organism lacks the nervous system ?

    1. Hydra
    2. Locust
    3. Sponges
    4. Tapeworm

  24. Which hormone functions as a growth promotor ?

    1. Auxin
    2. Ethylene
    3. Abscisic acid
    4. Both B and C

  25. Which of the following shows thigmonastic response ?

    1. Sun flower
    2. Insectivorous plants
    3. Lotus
    4. Bryophyllum

  26. Which two organs are connected by pons with the help of transverse band of nerves ?

    1. Nerves of brain and spinal cord
    2. Both the cerebral hemispheres
    3. Cerebellum and central nervous system
    4. Sympathetic and parasympathetic






ANSWERS TO MCQs:

(1) B (2) C (3) B (4) D (5) A (6) C (7) A (8) C (9) D (10) B (11) B (12) D (13) C (14) C (15) A (16) B (17) A (18) D (19) C (20) A (21) C (22) B (23) C (24) A (25) B (26) C

SHORT QUESTIONS



ANSWER IN SHORT:

  1. What is a stimulus ?

         ANS : Any environmental factor that affects a living organism by showing changes is called a stimulus.

  2. What is the structural and functional unit of the nervous system in multicellular organisms ?

         ANS : Neuron is the structural and functional unit of the nervous system in multicellular organisms.

  3. What does the nervous system do ?

         ANS : The nervous system controls and coordinates various activities in the body of an organism.

  4. Mention some factors (stimuli) to which plants respond.

         ANS : Light, touch, water, gravitational force, insects, chemicals, etc are some stimuli to which plants respond.

  5. Mention some plant hormones.

         ANS : Auxin, gibberellin, cytokinin, abscisic acid, ethylene, etc are some plant hormones.

  6. Mention growth hormones of plants.

         ANS : Auxin, gibberellin and cytokinin are growth hormones of plants.

  7. Which hormones in plants are responsible for ripening of fruits and shedding of leaves ?

         ANS : Abscisic acid and ethylene are responsible for ripening of fruits and shedding of leaves.

  8. Which plant hormones retard growth ?

         ANS : Abscisic acid and ethylene retard growth.

  9. What is tropism ?

         ANS : The movement of curvature of plants in the direction of stimulus is known as tropism.

  10. What is phototropism ?

         ANS : The bending of a growing plant towards unidirectional light as a response to the illumination is called phototropism.

  11. What is geotropism ?

         ANS : Geotropism is a growth response of a plant to the force of gravitation (gravity) in which the roots show the downward movement.

  12. What is hydrotropism ?

         ANS : Hydrotropism is a growth response of a plant towards water shown by the growth of roots towards water.

  13. What is chemotropism ?

         ANS : Chemotropism is a growth response (movement) of a plant towards certain chemicals.

  14. Give an example of chemotropism.

         ANS : The germination of pollen grains and the development of pollen tube as a response to the chemicals secreted by the stigmatic surface is an example of chemotropism.

  15. Define : Nastic movement.

         ANS : A response of a plant to an external stimulus independent of its direction is called nastic movement.

  16. What is thigmonastic response ?

         ANS : The bending down or curling up of insectivorous plants, when touched by insects, is called thigmonastic movement.

  17. What is photoperiodism ?

         ANS : Photoperiodism is the response of some plants to the duration of light which mainly affects the flowering and germination in plants.

  18. Which specialised pigment is responsible for the photoperiodic response by plants ?

         ANS : Phytochrome is responsible for the photoperiodic response by plants.

  19. Which organisms possess nerve net ?

         ANS : Hydra and other cnidarians possess nerve net.

  20. What does the nervous system of insects consist of ?

         ANS : The nervous system of insects consists of a bilobed nerve mass (brain), nerve cord and nerve ganglia.

  21. What is the function of receptors in nervous system ?

         ANS : Receptors receive the stimuli and pass the message to the brain with the help of sensory neuron.

  22. What is sensory neuron ?

         ANS : Sensory neuron is a nerve cell which receives the stimuli from receptor and passes the message to the brain.

  23. What is motor neuron ?

         ANS : Motor neuron is a nerve cell which receives information from brain, transmits it to effector organ and stimulates it to respond.

  24. Through what do hormones reach the target organ ?

         ANS : Hormones reach the target organ through blood.

  25. What protects brain in human beings ?

         ANS : A bony box in the skull called cranium and three membranes called meninges protect the brain in human beings.

  26. What is the function of cerebrospinal fluid ?

         ANS : Cerebrospinal fluid acts as a cushion and protects the brain from mechanical shocks.

  27. Mention three regions of brain.

         ANS : The three regions of brain are : forebrain, midbrain and hindbrain.

  28. What does forebrain consist of ?

         ANS : Forebrain consists of cerebrum and olfactory lobes.

  29. Mention the regions of cerebrum.

         ANS : The regions of cerebrum are : frontal lobe, parietal lobe, temporal lobe and occipital lobe.

  30. Mention the centres located in frontal lobe region.

         ANS : Frontal lobe possesses the centres for voluntary muscular activities.

  31. Mention the centres located in parietal lobe region.

         ANS : Parietal lobe possesses the centres for temperature control, smell and touch.

  32. Mention the centres located in temporal lobe region.

         ANS : Temporal lobe possesses the centres for auditory and olfactory reception.

  33. Mention the centres located in occipital lobe region.

         ANS : Occipital lobe possesses the centre for visual reception.

  34. Mention the regions of the midbrain.

         ANS : The midbrain has the regions for visual reception, auditory reception and touch.

  35. Mention the parts of brainstem.

         ANS : Brainstem consists of midbrain, pons and medulla oblongata.

  36. What does hindbrain consist of ?

         ANS : Hindbrain consists of cerebellum, pons and medulla oblongata.

  37. What is the function of cerebellum ?

         ANS : Cerebellum controls the rythmic movement of muscles, body balance and posture.

  38. Mention the centres possessed by medulla oblongata.

         ANS : Medulla oblongata possesses the centres to regulate heartbeat, breathing, blood pressure, sneezing, vomiting, coughing, swallowing, hiccups, etc.

  39. What is reflex action ?

         ANS : Reflex action is an unconscious and involuntary response of effectors to a stimulus.

  40. What is reflex arc ?

         ANS : Reflex arc is the pathway through which a message from receptors is relayed by sensory nerves to the spinal cord which sends to effectors for response via motor nerve.

  41. Which organ performs reflex action ? When ?

         ANS : The spinal cord performs reflex action when the brain is busy or at rest.

  42. What is meant by autonomous nervous system ?

         ANS : The system responsible for the control of organs located in the body cavity without the awareness of the brain is called autonomous nervous system.

  43. Mention the organs controlled by the autonomous nervous system.

         ANS : Heart, blood vessels, glands, uterus, coelomic organs, etc are controlled by the autonomous nervous system.

  44. Mention two types of autonomous nervous system.

         ANS : Sympathetic nervous system and parasympathetic nervous system are the two types of autonomous nervous system.

  45. Write the names of important glands.

         ANS : Hypothalamus, pituitary, pineal, thyroid, parathyroid, thymus, pancreas, adrenal, testis, ovary, etc are important glands.

  46. Which gland is called the master gland ?

         ANS : Pituitary gland is called the master gland.

  47. Why is pituitary gland called the master gland ?

         ANS : Pituitary gland is called the master gland because it regulates the secretion of hormones by other glands.

  48. What controls the functioning of pituitary gland ?

         ANS : The secretion of hypothalamus controls the functioning of pituitary gland.

  49. What is the function of trophic hormones ?

         ANS : Trophic hormones regulate the secretion from other endocrine glands.

  50. Which hormone controls male characteristics ?

         ANS : Testosterone controls the male characteristics.

  51. What is the function of parathyroid hormone ?

         ANS : Parathyroid hormone regulates the level of calcium and phosphate in blood.

  52. Name growth inhibitors in plants.

         ANS : Abscisic acid and ethylene are growth inhibitors in plants.

  53. Which structure protects brain ?

         ANS : The structure consisting of cranium and three membranes called meninges having CSF (cerebrospinal fluid) in between them protects brain.

  54. How are ganglia formed ?

         ANS : Ganglia are formed by the condensation of nerve nets at some junction in the body of insects.

  55. Explain the importance of cerebrospinal fluid.

         ANS :Cerebrospinal fluid between the meninges of brain act as a cushion and protect the brain against mechanical shock.

  56. What is the role of phytochrome in plants ?

         ANS :Phytochrome is a specialized pigment present in plants which plays an important role in control and coordination of plants with environmental stimuli.
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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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