GIVE ANSWER IN DETAIL
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INDEX-TOPIC SEARCH
- Describe fission as a method of reproduction.
ANS :Fission occurs in unicellular organisms. Binary fission and multiple fission are its two types.
BINARY FISSION :
- An organism produces two unicellular organisms identical to the parent cell through mitotic division.
- Amoeba, paramoecium, etc. reproduce by binary fission.
MULTIPLE FISSION :
- Under certain circumstances, the nucleus of a cell divides several times within the cell forming many nuclei.
- Each nucleus is then surrounded by cytoplasm to form a separate unit.
- All these newly formed cells then come out of the mother cell(parent cell) by breaking the wall and behave as a new organism.
- Plasmodium, amoeba, paramoecium, etc. exhibit such reproductive event.
- Describe budding as a method of reproduction.
ANS :
- Budding is observed in both unicellular and multicellular organisms.
- In unicellular organisms, some part of the body swells out at one point and developes into a 'bud' due to the formation of nucleus and cytoplasm within it. This bud then separates from the parent cell and behaves as an independent organism. Sometimes the buds form a chain before being separated. Example : yeast.
- In multicellular organisms like hydra, a part of its cylindrical body swells and develops into a bud. This bud then grows and separates from the mother's body to develop as an independent daughter animal.
- Describe spore formation as a method of reproduction.
ANS :
- Spore formation is the most common method of asexual reproduction in majority of bacteria and fungi.
- During spore formation, a structure called sporangium develops from fungal hypha which is a filamentous structure.
- The nucleus in sporangium divides several times and forms many nuclei.
- Each nucleus gets surrounded by cytoplasm and forms small unicellular structure called spore.
- When sporangium bursts, the spores spread into the surrounding environment and germinate into new hypha forming mycellium which behaves as new organism.
- Mucor and Rhizopus reproduce by this method.
- Describe regeneration as a method of reproduction.
ANS :
- Regeneration is the ability of an organism to reproduce the lost parts of its body.
- When some body part of an organism breaks suddenly, a new part similar to the lost (broken) part is created at the point of breaking after some time.
- All broken parts thus develop into new organisms.
- Hydra, planaria, sponge and starfish reproduce by regeneration.
- Some filamentous algae increase their number by this method. Algae filaments break frequently and each broken piece develops into independent algae. This is called fragmentation.
- Describe role of sex hormones in humans.
ANS :
- Once a male reaches puberty, testes start producing sex hormone testosterone. Similarly, in females, ovaries start producing sex hormones estrogen and progesterone.
- These hormones play an important role in the regulation of the processes of spermatogenesis (in male) and oogenesis (in female).
- Sex hormones are also responsible for the structural development, maintenance and functions of accessory sex organs.
- They induce secondary sexual characters at proper age.
- The secondary sexual characters in male include : growth of hair on face, chest and other body parts; change in voice, aggressive behaviour and mental agitation.
- Those in female include : changes in face and body, development of mammary glands, change in the pitch of voice, vigilant behaviour and sentimental approach.
- What is the difference between menstruation and menopause ?
ANS :When a woman (girl) attains puberty, her reproductive system becomes functional. As a result the ovary starts releasing ovum and this phenomenon is repeated after a definite period as a cycle. When an ovum is released the uterine wall gets ready for the implantation of fertilised ovum (zygote). If the ovum is not fertilised within certain period, it gets destroyed and the uterine wall disintegrates resulting in the breaking of blood vessels. The disintegrated tissue along with blood flows out through vagina. This flow of blood continues for about 3-5 days and is called menstruation.
Menstruation, as a part of sexual cycle, starts at the age of about 10-12 years and its commencement indicates that the reproductive system of the woman has become active. The reproductive system then remains active up to the age of about 45-50 years and then becomes non-functional. The sexual cycle stops and menstruation ceases. This is called menopause. Thus, menopause marks the end of reproductive period of a woman.
- Describe vegetative propagation in detail.
ANS :
- Development of a new plant from root, stem or leaf is called vegetative propagation.
- Some higher plants exhibit this method of reproduction.
- Examples : (i)Development of buds from the root of sweet potato.(ii)Development of buds on potato tuber.(iii)Development of buds on the margin of bryophyllum leaf.
- Besides natural method, artificial vegetative propagation is also used to increase production. Cutting, layering and grafting are commonly used methods of artificial vegetative propagation.
- Describe various methods of artificial vegetative propagation.
ANS :
- CUTTING :
- In this method, a piece of root, stem, leaf or sometimes a bud is sown in soil which develops into a new plant.
- The piece of the plant sown in the soil develops roots downwards in the soil and aerial organs in the external environment.
- this method is useful for large scale production which is greatly economical and profitable.
- Example : sugarcane, grapes, rose, phalsa.
- LAYERING :
- In this method, a branch of stem of a plant is bent towards the soil in such a way that some part of the branch remains inside the soil and its tip remains outside.
- The part covered by the soil develops roots.
- When this part is detached from the parent plant, it grows independently into a new daughter plant.
- Example : Lemon, guaua, hibiscus, jasmine and bougainvillaea.
- In plants like strawberry and raspberry, sometimes a branch comes into contact of the soil naturally and develops as a daughter plant after producing roots.
- GRAFTING :
- Grafting is a method in which two parts of different plants are joined together in such a way that they unite to grow as one plant.
- A part of an adult (mature) plant is tied up with a unit of soft plant to get early flowering in the soft plant.
- The portion of the plant having roots on which grafting is performed is called 'stock'.
- The portion of the plant which is grafted on the other plant is called 'scion'.
- By this method, desirable characteristics of different plants can be combined.
- This method is very useful for plants whose seeds have long dormancy period and poor germination capacity.
- Example : On the stock of lemon, a scion of lemon or orange can be grafted. This method is widely used to increase the production of mango.
- Describe reproductive system in human male.
ANS :
- A pair of testes is the main reproductive organ in human male.
- Vas deferens and penis are the accessory reproductive organs.
- Seminal vesicle, prostate gland and bulbourethral gland are the accessory reproductive glands.
- The two testes lie in a muscular sac called scrotum outside the abdominal cavity in the region between legs.
- The temperature in the scrotum is 3°C lower than that of the body. This temperature is suitable for the process of spermatogenesis.
- The sperms produced in the testes are transported through vas deferens to the penis.
- Sperms mix with the semen which is formed by the secretions of reproductive glands.
- Semen provides movement to sperms so that they can reach the egg cell(ovum).
- In male, urine and sperms get released through the same path called urinogenital path.
- Describe reproductive system in human female.
ANS :
- The main reproductive organ in human female is a pair of ovaries located in the abdominal cavity.
- The reproductive system includes ovaries, fallopian tube (oviduct), uterus, cervix, vagina and vaginal opening.
- Accessory reproductive organs include labia major, labia minor and clitoris.
- Ovaries possess many ovarian follicles which become mature at puberty stage and form graffian follicle. Graffian follicle form the structure of ovum.
- Generally, one ovarian follicle becomes active alternately and forms one ovum.
- The free end of the oviduct towards ovary is fimbricated and funnel shaped. It is known as oviductal funnel.
- The oviducts on both sides join in the middle to form inverted triangular shaped muscular sac called uterus. The mouth of uterus opens into vagina through narrow cervix.
- Vagina opens outside the body through vaginal opening.
- There is a separate urinary opening above the vaginal opening. Thus, in female, the urinary passage and genital passage are separate from each other.
- Describe sexual cycle in human female.
ANS :
- The sexual cycle in female starts at puberty stage when the development of ovum starts in ovary from ovarian follicle.
- When the ovum develops (matures) up to a definite stage it is released by rupturing of ovarian follicle. This is called ovulation.
- During first 13 days of cycle, development of ovum occurs and ovulation takes place on the 14th day. After ovulation, the ovum enters oviduct through oviductal funnel.
- Simultaneously, the walls of uterus get ready for the implantation of embryo.
- If fertilisation occurs, the implantation of embryo on the walls of uterus takes place and the process of supply of nutrition to embryo starts.
- If fertilisation does not occur, the walls of uterus that got prepared for implantation in the form of blood-filled tissues start disintegrating.
- This results in the breakdown of blood vessels and the broken uterine wall tissues come out through vagina along with blood. This is known as Menstruation.
- Menstruation may last for 3-5 days during which abdominal pain is experienced.
- Then the cycle is repeated. Generally menstruation cycle is repeated every 28-32 days.
- The secretion of sex hormones at puberty stage is responsible for the commencement of menstrual cycle. With this the female attains the ability of conception.
- The sexual cycle generally remains functional up to the age of 45-50 years. Then gradually the sexual cycle stops due to hormonal changes and menopause starts indicating the loss of the ability of conception.
- Describe fertilisation and embryo development in humans.
ANS :
- During the sexual cycle of a female ovulation occurs on the 14th day and the ovum enters the fallopian tube.
- If copulation occurs during the period when the ovum is present in the oviduct, sperms released in semen try to reach the ovum with the help of the fluid substances present in semen.
- If one of the sperms can reach the egg(ovum) in the oviduct, then fertilisation takes place.
- If fertilisation occurs, then the walls of uterus start further developments.
- The embryo(fertilised egg) reaches the walls of the uterus and gets implanted on the wall.
- An umbilical cord develops from the embryo to the uterine wall and supplies nutrition to the embryo from mother's body.
- For the protection of the developing embryo, a structure (amnion) filled with amniotic fluid develops.
- The birth of the child takes place, usually, after 40 weeks or 280 days. (this is the time for the development of the embryo into a mature baby).
- Duration from zygote formation till birth of the child is called embryo developing time.
- When the development of the embryo is complete, a new born child comes out of the mother's body by breaking the amnion. This event is known as delivery.
- The calculation of embryo development time starts from the first day of last menstrual cycle.
- The normal weight of the foetus(at the time of birth) should be about 3-3.5 kg.
- Write an explanatory note on population control.
ANS :
- Growth of population is one of the biggest problems in the world. The population of India has crossed 1 billion mark and it needs serious attention . Also, frequent delivery can be dangerous to both the mother and the child as it results in ill health and the birth of a weak baby.
- Keeping the growth rate of population limited by using some scientific devices is called population control.
- Types of such devices include : (i) Birth-control tools (ii) Chemical devices (iii) Surgical devices.
- Birth-control tools :
- A condom used by males prevents the entry of semen into vagina during copulation.
- A copper-T or a loop used by a female prevents implantation in uterus.
- Chemical devices include birth-control pills containing hormones which prevent implantation.
- Surgical methods :
- In males, the vas deferens is cut and tied up to prevent the transport of sperms. The method is called Vasectomy.
- In females, the oviduct is cut and tied up to prevent the transport of ovum. The method is called Tubectomy.
- A doctor must be consulted before following any method of population control to avoid side effects.
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- Write a note on sexually transmitted diseases (STDs).
ANS :
- Sexually transmitted diseases are infectious and some times they prove fatal.
- The diseases occurring due to unsafe sexual intercourse are called Sexually Transmitted Diseases(STDs).
- Such diseases are caused by virus, bacteria, fungi and protozoans.
- Syphillis is caused by Treponema Palidium.
- Gonorrhoea is caused by Neissena Gonorrhoea.
- Symptoms of STDs :
- Inflammation of the passage of urine.
- Lesions on the skin of urinary tract and vagina.
- Itching sensation in penis or vagina.
- Lesions on genital passage.
- STDs are curable by proper treatment, so a doctor must be consulted immediately without hesitation when any of the symptoms of STDs become visible.
- AIDS can prove fatal. Research work is in progress to find out medicines to cure AIDS.
- WHO has given several guidences to prevent the spread of STDs and to protect human race.
- In India, NACO (National AIDS Control Organisation) and other NGOs (Non-Government Organisations) are functioning to create awareness about STDs.
- Individual Care :
- One should keep awareness about the cleanliness of the reproductive organs.
- There must be limit in developing friendship with opposite sex.
- Use of birth-control tools during intercourse can prevent such diseases.
- The best one is to learn to keep control on sexual desires.
- Morality must be imposed as religious practice.
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ANS :
ANSWER IN BRIEF
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INDEX-TOPIC SEARCH
- What is reproduction ? Mention its importance.
ANS:
The process by which organisms produce new organisms similar to them is known as reproduction.
The importance of reproduction is :
- It maintains the existence of each species.
- It transfers hereditary characteristics to the next generation.
- It brings concomitant changes in evolutionary events.
- What is asexual reproduction ? Mention its types(methods).
ANS:The process of reproduction in which any somatic part of the body of a single organism develops into a new organism is called asexual reproduction.
Its types are :
- fission
- budding
- spore formation
- regeneration
- vegetative propagation
- What is vegetative propagation ? Mention its different methods.
ANS:Development of a new plant from the root, stem or leaf is called vegetative propagation.
The different methods of vegetative propagation are :
- Write a note on fission as a method of reproduction.
ANS:
- Fission occurs in unicellular organisms.
- It is a method of asexual reproduction.
- Binary fission and multiple fission are its two types.
- Amoeba, paramoecium,plasmodium,etc. reproduce by fission.
- Explain : Binary fission.
ANS:
- It is a method of asexual reproduction occurring in unicellular organism.
- An organism produces two unicellular organisms identical to the parent cell through mitotic division.
- Amoeba, paramoecium,etc. reproduce by binary fission.
- Write a note on puberty.
ANS:
- Puberty is the stage in the life of a human being when the reproductive organs show gradual change in structure and they become functional.
- A boy attains puberty at the age of 13-14 years whereas a girl attains it at the age of 10-12 years.
- During puberty,testes in male start producing sperms and sex hormone testosterone.
- Similarly, ovaries in female start producing ovum and sex hormones estrogen and progesterone.
- Mention accessory reproductive glands and their function in human male.
ANS:Seminal vesicle,prostate gland and bulbourethral gland are the accessory reproductive glands in human male. The secretions of these glands form semen which provides movement to sperms so that they can reach the egg cell easily.
- Mention the requirements of fertilisation of an ovum.
ANS:
- Ovulation must have occurred and hence the ovum must be present in the oviduct.
- Copulation must occur before the ovum gets destroyed.
- A sperm must reach the ovum to fertilise it.
- Why is population control needed ?
ANS:Population control is needed to control population growth which is the biggest problem in the world. Also, frequent deliveries can be dangerous for the health of a female and they can result in the birth of a weak(unhealthy) child.
- Mention symptoms of STDs (Sexually Transmitted Diseases).
ANS:
- Inflammation of urinary tract and hence pain at the time of passing urine.
- Lesions on skin of the urinary tract.
- Itching sensation in penis or vagina.
- Lesions on genital passage.
- What individual care should one take to prevent STDs ?
ANS:
- One should keep awareness about the cleanliness of reproductive organs.
- There must be limit in developing friendship with opposite sex.
- One should use birth-control tools during intercourse to prevent such diseases.
- One should learn to keep control on sexual desires.
- Morality must be imposed as a religious practice.
- Distinguish between menarche and menopause.
ANS:
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ANS:
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INDEX-TOPIC SEARCHMULTIPLE-CHOICE QUESTIONS
SELECT THE CORRECT ALTERNATIVE:
- Which of the following is not a unicellular organism ?
- Amoeba
- Paramoecium
- Hydra
- Yeast
- Which of the following shows budding ?
- Yeast
- Amoeba
- Paramoecium
- Plasmodium
- Which of the following shows multiple fission ?
- Hydra
- Yeast
- Spirogyra
- Plasmodium
- Which is the most common method of reproduction in majority of fungi and bacteria ?
- Binary fission
- Multiple fission
- Budding
- Spore formation
- Which of the following shows spore formation ?
- Amoeba
- Mucor
- Plasmodium
- Paramoecium
- Regeneration is observed in ______.
- Amoeba
- Planaria
- Spirogyra
- Yeast
- Which of the following does not show regeneration ?
- Mucor
- Planaria
- Sponges
- Starfish
- Which of the following is not an artificial method of vegetative propagation ?
- Cutting
- Layering
- Grafting
- Hybridization
- Testes produce ______ hormone.
- Estrogen
- Testosterone
- Progesterone
- Both estrogen and testosterone
- Which of the following is not produced in the ovary ?
- Ovum
- Estrogen
- Progesterone
- Testosterone
- The main reproductive organ of human male is ______.
- a pair of testes
- vas deferens
- urethra
- penis
- The main female reproductive organ is ______.
- Fallopian tubes
- uterus
- vagina
- a pair of ovaries
- The first phase of the sexual cycle in human female is called ______.
- ovulation
- implantation
- menstruation
- follicle phase
- Menstrual flow(menstruation) lasts for about ______ days.
- 2 - 3
- 3 - 5
- 5 - 7
- 14
- In a normal healthy woman, menstruation occurs every ______ days.
- 14
- 28 - 32
- 21 - 24
- 270
- What marks the beginning of the reproductive life of a woman ?
- ovulation
- menopause
- menarche
- fertilisation
- What is formed after fertilisation ?
- A sperm
- An ovum
- A zygote
- A gamete
- Where does fertilisation take place ?
- vagina
- cervix
- Fallopian tube
- uterus
- What should be the normal weight of a fully matured foetus (child at birth)?
- 2.5 - 3.0 pounds
- 2.5 - 3.0 kg
- 3.0 - 3.5 pounds
- 3.0 - 3.5 kg
- ______ prevents ovulation.
- Testosterone
- Progesterone
- Estrogen
- Contraception
- Which of the following shows budding ?
- Hydra
- Amoeba
- Paramoecium
- Spirogyra
- Several new individuals are produced.
- Binary fission
- Multiple fission
- Both binary fission and multiple fission
- Fertilisation
- In grafting the plant rooted in the soil is called ______.
- stock
- sucker
- scion
- rhizome
- Which of the following plants shows vegetative propagation ?
- Wheat
- Radish
- Sunflower
- Bryophyllum
- Testes in human male are located in ______.
- abdominal cavity
- vas deferens
- scrotum
- penis
- In the process of sexual reproduction ______.
- only males are needed
- both male and female are needed
- only females are needed
- only mitosis is involved
- The process of release of an egg from the ovary is called ______.
- reproduction
- ovulation
- menstruation
- fertilisation
- ______ takes place in a woman after 45 - 50 years.
- Menstruation
- Ovulation
- Menopause
- Lactation
- The period taken for one complete menstrual cycle is ______.
- 31 days
- 32 - 35 days
- 28 - 32 days
- 22 - 25 days
- The development of foetus inside the uterus till birth is called ______.
- gestation
- parturition
- lactation
- fertilization
- The unicellular fungus which shows bud formation is ______.
- mucor
- yeast
- amoeba
- none of these
- The animal which shows regeneration is ______.
- amoeba
- paramoecium
- hydra
- rhizopus
- The method by which desired characters of two plants can be combined is ______.
- cutting
- layering
- budding
- grafting
- The disease caused by treponema palidium is ______.
- AIDS
- syphillis
- gonorrhoea
- hepatitis
- Yeast reproduces by...
- budding
- fission
- regeneration
- spore formation
- A chain of buds is formed in...
- hydra
- yeast
- mucor
- plasmodium
- Vegetative propagation is observed in...
- yeast
- hydra
- mucor
- bryophyllum
- ______ is useful where seeds have long dormancy period and poor germination capacity.
- Cutting
- Layering
- Grafting
- Regeneration
- ______ is a very useful method for developing garden.
- Cutting
- Layering
- Grafting
- Budding
- The stage at which there is a gradual change in structure of reproductive organs in human male and female is called...
- spermatogenesis
- oogenesis
- menarche
- puberty
- The temperature in the scrotum is about ______ deg C lower than the body temperature.
- 2
- 3
- 5
- 6
- Which of the following is not a part of reproductive system in human male ?
- Testis
- Seminal vesicle
- Clitoris
- vas deferens
- Which of the following is not a part of reproductive system in human female ?
- Ovary
- Cervix
- Vagina
- vas deferens
- The sexual cycle in human female starts at...
- birth
- the age of 45
- the age of 28
- puberty stage
- Ovulation occurs on the ______ day of the sexual cycle.
- 14th
- 20th
- 28th
- any
- The sexual cycle in human female remains active(functional), generally, up to the age of...
- 30 years
- 35-40 years
- 45-50 years
- 55-60 years
- The 14th day of sexual cycle in human female is important because on that day...
- ovulation occurs
- she becomes pregnant
- menstrual flow starts
- she gives birth to a child
- ______ fertilises an ovum in a female's body.
- Blood
- Testosterone
- A sperm
- Seminal fluid
- The nutritional requirements of an embryo are maintained through...
- ovarian follicle
- oviduct
- mouth
- umbilical cord
- In humans, generally, the birth takes place after ______ of embryo development.
- 14 weeks
- 28 weeks
- 40 weeks
- 280 weeks
- The calculation of embryo development (age of embryo) starts from...
- the first day of last menstrual cycle
- the first day of first menstrual cycle
- the last day of first menstrual cycle
- the last day of last menstrual cycle
- Which of the following is a chemical device of birth control ?
- Copper-T
- Condum
- Birth-control pills
- Loop
- Where are the testes of human male located ?
- In abdominal cavity
- In vas deferens
- In scrotum
- In penis
- The process of release of egg from ovary is called...
- reproduction
- ovulation
- menstruation
- menopause
- The period after 45-50 years in woman is known as...
- menstruation
- gestation
- menopause
- lactation
- How many days are there in one menstrual cycle ?
- 31
- 32-35
- 28-32
- 22-40
- The period from the formation of embryo to birth is known as...
- gestation
- parturition
- lactation
- fertilisation
- Every organism produces another identical organism. This event is known as...
- growth
- reproduction
- alteration of generation
- regeneration
- The method by which the desired characters of two plants can be combined is...
- cutting
- layering
- budding
- grafting
- During embryo development, the embryo is protected by...
- amnion
- placenta
- umbilical cord
- 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:
- What is reproduction ?
ANS : The process by which the organisms produce new organisms similar to them is known as reproduction.
- Why is reproduction essential ?
ANS : Reproduction is essential for the perpetuation of species and thereby life.
- Mention the types of reproduction.
ANS : Asexual reproduction and sexual reproduction are the two types of reproduction.
- 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.
- 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.
- Mention two types of reproduction by fission.
ANS : Binary fission and multiple fission are the two types of fission.
- 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.
- Give examples of organisms showing binary fission.
ANS : Amoeba and paramoecium show binary fission.
- 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.
- Give examples of organisms showing multiple fission.
ANS : Plasmodium and amoeba show multiple fission.
- 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.
- Give examples of organisms showing budding.
ANS : Yeast and hydra show budding.
- What is the similarity between hydra and yeast ?
ANS : both hydra and yeast exhibit budding as the method of reproduction.
- Mention some organisms showing spore formation.
ANS : Mucor, rhizopus and penicillium show spore formation.
- 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.
- What is regeneration ?
ANS : The ability of an organism to replace the lost parts of its body is called regeneration.
- 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.
- Give examples of organisms showing fragmentation.
ANS : Oscillatoria and spirogyra show fragmentation.
- 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.
- Give examples of plants showing vegetative propagation.
ANS : Potato, sweet potato, bryophyllum, etc. show vegetative propagation.
- Mention names of artificial methods of vegetative propagation.
ANS : Cutting, layering, grafting etc are artificial methods of vegetative propagation.
- 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.
- 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.
- 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.
- What is 'scion' ?
ANS : The portion of the plant which is grafted on other plant is called scion.
- What is 'stock' ?
ANS : The plant on which grafting is performed is called stock.
- 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.
- At which stage of life the reproductive system of human being becomes functional ? (write one word).
ANS : Puberty.
- 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.
- Mention the names of human gonads.
ANS : Testis (testes) in male and ovary in female are human gonads.
- Name the sex hormone of human male.
ANS : Testosteron is the sex hormone of human male.
- Which hormones are produced in ovary of human female ?
ANS : Estrogen and progesteron are produced in the ovary of human female.
- Which are the two processes referred to as gametogenesis ?
ANS : Spermatogenesis and oogenesis are referred to as gametogenesis.
- Mention the optimal temperature for spermatogenesis.
ANS : A temperature 3 °C lower than the body temperature is optimal for spermatogenesis.
- What is urinogenital path ?
ANS : Urinogenital path is the common opening through which both urine and the sperms are released.
- What is ovulation ?
ANS : The release of an ovum from the ovary by rupturing the ovarian follicle is called ovulation.
- 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.
- What is menarche ?
ANS : The commencement of menstruation at puberty in a woman is called menarche.
- What is menopause ?
ANS : Menopause is the stage in a woman's life when menstrual flow and other related events stop.
- What is fertilisation ?
ANS : The union of the male and female gametes resolting in the formation of zygote is called fertilisation.
- Mention the type of fertilisation taking place in humans.
ANS : Internal fertilisation takes place in humans.
- Mention the term used for male gamete.
ANS : Sperm.
- What indicates that the fertilisation has taken place ?
ANS : The absence of menstrual flow at its regular interval indicates that the fertilisation has occured.
- What is implantation ?
ANS : The close attachment of the embryo with the walls of uterus is called implantation.
- 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.
- What is the function of amniotic fluid ?
ANS : The function of amniotic fluid is to protect the foetus against temperature changes and mechanical shocks.
- What is gestation ?
ANS : The development of the foetus inside the uterus till birth is called gestation.
- 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.
- What is parturition ?
ANS : The birth of a fully developed foetus after the completion of gestation period is called parturition.
- What is family planning ?
ANS : Family planning is the adoption of various new techniques which prevent fertilisation or pregnancy.
- 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.
- 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).
- Mention two natural methods of contraception.
ANS : (i)Zero (Rhythm) method (ii) Coitus interruptus.
- What is the full form of IUCD ?
ANS : The full form of IUCD is IntraUterine Contraceptive Device.
- What is a contraceptive ?
ANS : A device or a substance that prevents fertilisation during intercourse is called a contraceptive.
- What is contraception ?
ANS : Contraception is a method of prevention of fertilisation of ovum (pregnancy).
- What is vasectomy ?
ANS : Vasectomy is the process of surgical removal of a small portion of vas deferens of a male to prevent fertilisation.
- What is tubectomy ?
ANS : Tubectomy is the process of surgically cutting and tying the Fallopian tube of a female to prevent fertilisation.
- What is the full form of WHO ?
ANS : The full form of WHO is World Health Organisation.
- 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.
- 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).
- What is gonorrhoea ?
ANS : Gonorrhoea is the inflammation of urinogenital tract causing burning sensation during urination.
- Which organism causes gonorrhoea ? (Write the name only).
ANS : Neissena gonorrhoea.
- What is syphillis ?
ANS : Syphillis is an STD in which there are lesions in the mucuos membrane urinogenital tract and ulcers on genitalia.
- Which organism causes syphillis ?
ANS : Treponema palidium causes syphillis.
- What is the full form of AIDS ?
ANS : The full form of AIDS is Acquired
Immuno-Deficiency Syndrome.
- Which virus causes AIDS ?
ANS : HIV or Human Immuno-deficiency Virus causes AIDS.
- Name two animals that can regenerate their lost body parts.
ANS : Planaria and starfish.
- Which two sex hormones are produced by ovary in human female ?
ANS : Progesterone and estrogen are produced by ovary in human female.
- 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.
- 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.
- 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.
- 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.
- When does a girl attain puberty ?
ANS : A girl attains puberty at the age of about 10-12 years.
- 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.
- What is the full form of NACO ?
ANS : The full form of NACO is National AIDS Control Organisation.
ANS :
ANSWER AS ASKED
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INDEX-TOPIC SEARCH
- 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.
- 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 :
- The leaves of Mimosa (touch-me-not) are sensitive to touch. They droop when touched.
- All insectivorous plants bend down or curl up when touched by insects.
- 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.
- Distinguish between tropic movement and nastic movement.
ANS :
- 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.
- 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.
- 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.
- 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.
- 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'.
- 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.
- 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.
- 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.
- Mention different endocrine glands, hormones secreted by them and the functions of these hormones.
ANS:
- 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.
*
INDEX-TOPIC SEARCHMULTIPLE-CHOICE QUESTIONS
SELECT THE CORRECT ALTERNATIVE:
- ______ is the complimentary system of nervous system.
- Circulatory system
- Endocrine system
- Lymphatic system
- Skeletal system
- Plant hormones are called ______.
- hypohormones
- metahormones
- phytohormones
- cytohormones
- The leaves of mimosa are sensitive to ______.
- light
- touch
- heat
- smell
- A sunflower plant bends towards the sun. It is ______ response.
- Thigmonastic
- seismonastic
- thermonastic
- photonastic
- All multicellular organisms, except ______, have well-developed nervous system.
- porifera
- mammals
- arthropoda
- insecta
- Nerve mass in invertebrates is called ______.
- brain
- neuron
- ganglion
- pelvis
- Hormones are secreted by ______.
- endocrine glands
- blood
- midbrain
- liver
- The space between meninges is filled with ______.
- lymph
- blood plasma
- cerebrospinal fluid
- ACTH
- ______ is not the part of hindbrain.
- cerebellum
- pons
- medulla oblongata
- cerebrum
- ______ protects spinal cord.
- Cranium
- Vertebral column
- Skull
- Ribs
- ______ pairs of spinal nerves arise from spinal cord.
- 21
- 31
- 32
- 42
- Which of the following organs is not controlled by autonomous nervous system ?
- Heart
- Uterus
- Glands
- Eyes
- The effects of sympathetic and parasympathetic nervous systems are ______.
- complimentary
- contradictory
- complimentary and contradictory
- none of above.
- Endocrine glands ______.
- secrete plasma
- secrete nutrients
- secrete hormones
- secrete antibodies
- Acetylcholine ______.
- increases the speed of conduction of impulses
- decreases the speed of conduction of impulses
- quickens the effect of growth hormones
- controls pituitary gland
- ______ is called the master gland.
- Pineal
- Pituitary
- Thyroid
- Thymus
- ______ hormone regulates ionic balance.
- Vasopressin
- Thyroxin
- Glucagon
- Testosterone
- ______ is the hormone responsible for development of female characteristics.
- Adrenalin
- Testosterone
- Thyroxin
- Progesterone
- ______ is responsible for lowering glucose level in blood.
- Glucagon
- Oxytocin
- Insulin
- Adrenalin
- ______ is responsible for increasing glucose level in blood.
- Glucagon
- Oxytocin
- Insulin
- Adrenalin
- Prolactin regulates ______.
- blood pressure
- heartbeat
- mammary glands
- glucose metabolism
- Nerve net is found in ______.
- sponges
- hydra
- earthworm
- cockroach
- Which multicellular organism lacks the nervous system ?
- Hydra
- Locust
- Sponges
- Tapeworm
- Which hormone functions as a growth promotor ?
- Auxin
- Ethylene
- Abscisic acid
- Both B and C
- Which of the following shows thigmonastic response ?
- Sun flower
- Insectivorous plants
- Lotus
- Bryophyllum
- Which two organs are connected by pons with the help of transverse band of nerves ?
- Nerves of brain and spinal cord
- Both the cerebral hemispheres
- Cerebellum and central nervous system
- 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:
- What is a stimulus ?
ANS : Any environmental factor that affects a living organism by showing changes is called a stimulus.
- 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.
- What does the nervous system do ?
ANS : The nervous system controls and coordinates various activities in the body of an organism.
- Mention some factors (stimuli) to which plants respond.
ANS : Light, touch, water, gravitational force, insects, chemicals, etc are some stimuli to which plants respond.
- Mention some plant hormones.
ANS : Auxin, gibberellin, cytokinin, abscisic acid, ethylene, etc are some plant hormones.
- Mention growth hormones of plants.
ANS : Auxin, gibberellin and cytokinin are growth hormones of plants.
- 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.
- Which plant hormones retard growth ?
ANS : Abscisic acid and ethylene retard growth.
- What is tropism ?
ANS : The movement of curvature of plants in the direction of stimulus is known as tropism.
- What is phototropism ?
ANS : The bending of a growing plant towards unidirectional light as a response to the illumination is called phototropism.
- 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.
- What is hydrotropism ?
ANS : Hydrotropism is a growth response of a plant towards water shown by the growth of roots towards water.
- What is chemotropism ?
ANS : Chemotropism is a growth response (movement) of a plant towards certain chemicals.
- 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.
- Define : Nastic movement.
ANS : A response of a plant to an external stimulus independent of its direction is called nastic movement.
- What is thigmonastic response ?
ANS : The bending down or curling up of insectivorous plants, when touched by insects, is called thigmonastic movement.
- 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.
- Which specialised pigment is responsible for the photoperiodic response by plants ?
ANS : Phytochrome is responsible for the photoperiodic response by plants.
- Which organisms possess nerve net ?
ANS : Hydra and other cnidarians possess nerve net.
- 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.
- 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.
- What is sensory neuron ?
ANS : Sensory neuron is a nerve cell which receives the stimuli from receptor and passes the message to the brain.
- 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.
- Through what do hormones reach the target organ ?
ANS : Hormones reach the target organ through blood.
- 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.
- What is the function of cerebrospinal fluid ?
ANS : Cerebrospinal fluid acts as a cushion and protects the brain from mechanical shocks.
- Mention three regions of brain.
ANS : The three regions of brain are : forebrain, midbrain and hindbrain.
- What does forebrain consist of ?
ANS : Forebrain consists of cerebrum and olfactory lobes.
- Mention the regions of cerebrum.
ANS : The regions of cerebrum are : frontal lobe, parietal lobe, temporal lobe and occipital lobe.
- Mention the centres located in frontal lobe region.
ANS : Frontal lobe possesses the centres for voluntary muscular activities.
- Mention the centres located in parietal lobe region.
ANS : Parietal lobe possesses the centres for temperature control, smell and touch.
- Mention the centres located in temporal lobe region.
ANS : Temporal lobe possesses the centres for auditory and olfactory reception.
- Mention the centres located in occipital lobe region.
ANS : Occipital lobe possesses the centre for visual reception.
- Mention the regions of the midbrain.
ANS : The midbrain has the regions for visual reception, auditory reception and touch.
- Mention the parts of brainstem.
ANS : Brainstem consists of midbrain, pons and medulla oblongata.
- What does hindbrain consist of ?
ANS : Hindbrain consists of cerebellum, pons and medulla oblongata.
- What is the function of cerebellum ?
ANS : Cerebellum controls the rythmic movement of muscles, body balance and posture.
- 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.
- What is reflex action ?
ANS : Reflex action is an unconscious and involuntary response of effectors to a stimulus.
- 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.
- Which organ performs reflex action ? When ?
ANS : The spinal cord performs reflex action when the brain is busy or at rest.
- 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.
- 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.
- Mention two types of autonomous nervous system.
ANS : Sympathetic nervous system and parasympathetic nervous system are the two types of autonomous nervous system.
- Write the names of important glands.
ANS : Hypothalamus, pituitary, pineal, thyroid, parathyroid, thymus, pancreas, adrenal, testis, ovary, etc are important glands.
- Which gland is called the master gland ?
ANS : Pituitary gland is called the master gland.
- 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.
- What controls the functioning of pituitary gland ?
ANS : The secretion of hypothalamus controls the functioning of pituitary gland.
- What is the function of trophic hormones ?
ANS : Trophic hormones regulate the secretion from other endocrine glands.
- Which hormone controls male characteristics ?
ANS : Testosterone controls the male characteristics.
- What is the function of parathyroid hormone ?
ANS : Parathyroid hormone regulates the level of calcium and phosphate in blood.
- Name growth inhibitors in plants.
ANS : Abscisic acid and ethylene are growth inhibitors in plants.
- Which structure protects brain ?
ANS : The structure consisting of cranium and three membranes called meninges having CSF (cerebrospinal fluid) in between them protects brain.
- How are ganglia formed ?
ANS : Ganglia are formed by the condensation of nerve nets at some junction in the body of insects.
- 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.
- 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.
GIVE ANSWER IN DETAIL
*
INDEX-TOPIC SEARCH
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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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