10th Class Biology 6th Lesson Reproduction - The Generating System Textbook Questions and Answers

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Question 1.Why do fish and frog produce a huge number of eggs each year?


  • External fertilisation occurs in fish and frog
  • The female lays a vast number of eggs in water and male releases some millions of sperms on to them in water
  • Eggs may be carried to a long-distance by water currents or they may be eaten by predators
  • So fertilisation is a chance factor and controlled by nature
  • Fertilisation occurs externally hence it is inevitable to give rise to vast number of eggs by fish and frog
Question 2.Give examples and explain what is meant by external fertilisation?


  • Fusion of the male and female gametes is called fertilisation
  • The fertilized egg (ovum) is called zygote
  • If the fertilisation occurs outside the body of the female organism then it is called external fertilisation
  • External fertilisation is seen in fish, frog and earthworm, etc
Question 3.Write the differences between?
a) Grafting - Layering b) Stamen - Carpel.


  • Differences between Grafting and Layering
  • Grafting Layering
    1. Grafting is a technique of inserting a part of one plant into another plant in such a way that the two will unite and continue their growth 1. Stems that form roots while still attached to the parent plants are called layers. Propagating the plants in this method is known as layering
    2. Two plants of the same species are required for grafting 2. Only one plant is required for layering
    3. Grafting helps to pressure and perpetuate varieties that cannot reproduce by vegetative method 3. In layering we can propagate the plant varieties which are required by us
    5. The two plants stock and scion and joined together in such a way that two stems join and grow as a single plant 5. The common practice in layering is to injure the portion to be layered by notching, cutting, girdling
    6. Ex: Mango, apple, guava, etc 6. Ex: Jasmine, rose, grapevine, etc
  • Differences between Stamen and Carpel
  • Stamen Carpel
    1. Male reproductive organ of the flowering plant 1. Female reproductive organ of the flowering plant
    2. It has two parts - anther and filament 2. It has three parts - style, stigma and ovary
    3. Stamen produces pollen grains 3. Carpel produces ovule
    4. Pollen grain contains the male gamete 4. Ovule contains the female gamete ovum or egg
    Question 4.Describe the mode of fertilization in plants with a diagram?


    • Fertilisation is the process of fusion of male and female gametes
    • For the fusion of male and female gametes pollen grains have to reach the surface of the stigma. This is called pollination
    • Pollen grains received by the stigma germinate and give rise to pollen tubes. Only one pollen tube finally reaches the embryo-sac.
    • This tube will have two male nuclei, which migrate to the tip of the pollen tube at the time of fertilization
    • Usually the pollen tube enters the ovule through micropyle and discharges the two male gametes into its embryo-sac
    • One male nucleus (n) or (gamete) approaches the egg and fuses with it to form a diploid (2n) zygote. This is first fertilisation
    • The other male nucleus (n) or (gamete) reaches the secondary nucleus (2n) and fuses with it to form the endosperm nucleus which will be triploid. This is second fertilization in the embryo-sac
    • Thus double fertilisation occurs in embryo-sac which is unique in flowering plants
    Question 5.What are the different modes of asexual reproduction? Cite them with examples?

    Answer: Asexual reproduction takes place by six different methods. They are:

    • Fission
    • Budding
    • Spore formation
    • Regeneration
    • Fragmentation and
    • Vegetative propagation
    • Fission: Single-celled organisms split into two equal offsprings or more offsprings. Ex: Paramoecium, bacteria
    • Budding: A growth on the body as a bud grows to form identical copy of parent. Ex: Yeast
    • Spore formation : Spores are produced in the sporangium. Ex : Rhizopus, mucor, bacteria, ferns and mosses
    • Regeneration
    • Ability of organisms to give rise to new individual organisms from their body parts
    • That is if the individual is some how cut or broken up into many pieces, many of these pieces grow into separate individuals. Ex: Hydra and Planaria
    • Fragmentation
    • In multicellular organisms with relatively simple body organisation breaks up into smaller pieces upon maturation
    • These pieces of fragments grow into new individuals. Ex: Flatworms, Spirogyra, moulds, lichens
    • Parthenogenesis: In the process generally the female gametes or ova develop into zygote without fertilization
    • Ex : Bees, ants and wasps.
    • Vegetative propagation: When a vegetative part like stem, root and leaf can produce a new organism it is called vegetative propagation. It is of two types
    • Natural propagation: Bryophyllum Dahlia, Carrot, Radish
    • Artificial propagation
    • Layering: Eg: Nerium, Guava, Orange, Rose
    • Cutting: Eg: Rose, Hibiscus, Sugarcane
    • Grafting: Eg: Sapota, Guava, Mango, etc
    Question 6.In what ways does sexual reproduction differ from asexual one? State at least three reasons?
    (OR) What are the differences between sexual and asexual reproduction?


    Sexual reproduction Asexual reproduction
    1. Two parents are required 1. One parent is needed
    2. Gametes are formed 2. Gametes are not formed
    3. Fertilization takes place 3. Fertilization does not take place
    4. Zygote is formed 4. Zygote is not formed
    5. New characters are formed 5. New characters are not formed but only through mutation
    6. Meiosis takes place 6. Meiosis does not take place
    7. Found in higher animals 7. Found in lower animals
    8. Support to evolution process 8. Supports evolution but not frequently
    9. Takes several months to complete 9. Takes very short period to complete
    Apart from the above differences Sexual and Asexual reproduction differs in the following ways:
  • The unit of reproduction in sexual reproduction is gamete whereas in asexual repro-duction it may be whole parent body or bud or a fragment or a single somatic cell
  • Sexual reproduction need more time to complete and it is less time in asexual reproduction
Question 7.How are sperm cells adapted for their function?


  • Sperm cell is adapted to its function by carrying genetic information to an egg
  • Its body consists of four parts
  • Head
  • Neck
  • Middle piece and
  • Tail
  • Sperm has a streamlined body that allows it to move quickly.
  • Nucleus is present in the head
  • Special structure on the head called acrosome helps in penetrating the ovum during fertilisation
  • The head of sperms also contain enzymes to breakdown and digest the zone on the egg through which it penetrates and fertilise it
  • Large number of mitochondria are present in the mid-region, so it is able to produce a lot of energy in order to operate tail
  • Its tail allows it to swim towards the egg for fertilisation
Question 8.The menstrual cycle prepares the uterus for a fertilised egg. How long is an average menstrual cycle from start to finish?


  • The cycle of changes that occur in the female reproductive system is called menstrual cycle
  • The average menstrual cycle from start to finish is 28 days long
Question 9.When the foetus is growing inside the uterus it needs nutrients? What provides these nutrients?


  • When the foetus is growing inside the uterus it needs nutrients for its growth and development
  • These nutrients are provided by the mothers blood through a special structure called placenta
  • Placenta is a tissue formed by the cells from the embryo and the mother
  • It is formed around 12 weeks of pregnancy and becomes an important structure for nourishment of the embryo
  • The foetus is connected to placenta in mothers body through umbilical cord
Question 10.Which type of substances are absorbed by foetus from the mother?


  • The digested food from the mother travel through the mothers blood stream and exchange to the blood stream of the foetus through the placenta
  • In addition to ingested food the mothers body continuously breakes down muscles, fat and bones
  • Releasing proteins, fat and calcium to the mothers blood that can be absorbed through the placenta to provide nutrients to the foetus
  • Some hormones also transfer to baby
Question 11.What is the job of Amniotic sac?


  • The amniotic sac is a bag of fluid inside a womens womb (uterus) where the embryo and foetus develops and grows
  • The cavity within the amnion becomes filled with fluid called amniotic fluid
  • The embryo or unborn baby floats and moves in the amniotic fluid
  • Amniotic sac and amniotic fluid give protection against minor mechanical injury
  • This fluid also provides a stable temperature and assists in maintaining a consistent body temperature for the unborn child
Question 12.What are the advantages of sexual reproduction?
(OR) What are uses of sexual reproduction?

Answer: Advantages of sexual reproduction:

  • Sexual reproduction promotes diversity of characters in the offsprings by providing genetic variation
  • It plays an important role in the origin of new species have different characters
  • This genetic variation leads to the continuous evolution of various species to form better and still better organisms
  • Sexual reproduction influences in diversity of characters in offsprings
  • It helps to maintain the continuty of organisms
  • It leads to new generation to tolerate adverse or diseased conditions
  • It helps the spreading of population to new areas
Question 13.How does reproduction help in providing stability to population of species?


  • The reproduction is directly linked to the stability of the population of species because it helps in replacing the lost or aging population with the new population and thus ensures the survival of the species
  • The process of reproduction ensure continuity of life on earth
  • In the absence of reproduction one particular species will disappear with time
  • Reproduction induces variations in the population which help the population to tide over adverse environmental conditions and adapt to changing environment
  • Reproduction also helps to generate copies of individuals which are suited to a particular environment
Question 14.Write the differences between mitosis and meiosis?

Answer: Mitosis Meiosis 1. It occurs in somatic cells. 1. It occurs in germ cells. 2. Nucleus divides only once. 2. Nucleus divides twice. 3. Two daughter cells are formed. 3. Four daughter cells are formed. 4. Daughter cells are diploid. 4. Daughter cells are haploid. 5. It occurs more frequently. 5. It occurs less frequently. 6. Daughter cells form somatic organs. 6. Daughter cells form gametes. 7. There is only one prophase, one metaphase one anaphase and one telophase. 7. There are two of each phase and five sub-phases in prophase -1. 8. Number of chromosomes are not changed in the daughter cells. 8. Number of chromosomes are reduced to half. 9. Chromosome number doubles at the beginning of each cell division. 9. Chromosome number is not doubled. It doubles after the end of first meiotic division. 10. No crossing over in chromosomes. 10. Crossing over occurs chromosomes. 11. Equation division. 11. Reduction division.

Question 15.What happens to the wall of the uterus during menstruation? (OR) ?
What changes occur in the wall of the uterus during menstruation?


  • During the early stage of menstruation the cells in the wall of uterus increase in number by repeated mitotic divisions
  • The inner lining of uterus becomes thick and soft with lot of blood capillaries in it
  • These changes in the uterus are necessary because in case the ovum released by the ovary gets fertilised by the sperm, then the uterus has to keep this fertilised ovum for further development and supply it with food and oxygen etc
  • If fertilisation does not occur the additional growth of the uterus is detached and expelled along with some amount of blood
Question 16."All unicellular organisms undergo only mitotic cell division during favourable conditions" - Do you support this statement? Why?


  • Unicellular organisms undergo mitotic cell division not only during favourable conditions but also in unfavourable conditions. So I dont support the given statement
  • When the organism finds favourable conditions it deserves to perform division called Fission. Ex: Amoeba
  • Sometimes scarcity of food or to save it life, some organisms undergo mitotic cell division
  • Organisms like paramoecium undergo a type of sexual reproduction called conjugation during unfavourable conditions
Question 17.What would be the consequences if there is no meiosis in organisms that reproduce sexually?
(OR) What happens if Meiosis does not take place in reproductive cells?


  • If meiosis did not occur, a fusion of gametes would result in a doubling of the chromosomes for each successive reproduced generation
  • For example, in case of man egg cells and sperm cells like other cells must contain 46 chromosomes
  • This results in the formation of abnormalities in each generation
  • If meiosis did not occur, there is no genetic variation in the offsprings produced by random fusion of the gametes
  • New characters will not appear in the offsprings
  • The process of evolution will be stopped
Question 18.Vickys father wants to grow a single plant having two desirable characters colourful flowers and big fruits. What method will you suggest to him and why?


  • I will suggest the method of grafting to him
  • Grafting enables us to combine the most desirable characteristics of two plants into a single plant with colourful flowers and big fruits
  • By grafting method, a very young scion can be made to flower and produce fruits fast when it is grafted to the stock
  • Vickys father can grow one of the two plants as stock and second plant can be graft to some of its branches as scions
  • Then he can get the plant with both the desirable characters
Question 19.Uproot an onion plant and take a thin section of its root tip. Stain it and observe under the microscope. Draw as you see and identify the stages of the cell division?


Question 20.Visit a nearby village and collect information on how farmers grow sugarcane, flowering plants like chrysanthemum, primerose and vegetables like stem tubers, plump gourd (dondakaya), etc. Make a report and present in class?

Answer: Report on growing methods of various plants

Plant name Growing method
Sugarcane Stem bits with nodes called seed pieces or sets can be planted horizontally in the farrows
Chrysanthemum It propagates often by means of suckers (the basal shoot). But some farmers grow these using seeds or the transplanted nursery plants
Primerose These are generally grown using cuttings. Its root ball should be cut vertically making sure that each half has at least 2 plant stems
Potatoes These are the stem tubers. The nodes on the potato are called eyes which sprout out and grow into a new plant
Plumpgourd These have tubers just below the ground which on cutting and planting in soil can give rise to new plants
Question 21.Collect the information from school library or using internet what vegetative methods are followed in your district as well as in your state to propagate various plants of economic importance. Represent it with a graph?

Answer: Vegetative methods followed in our district as well as in our state to propagate various plants of economic importance. I) Natural vegetative propagation: In this method of vegetative propagation, a part of the plant which may be stem, root-leaf or flower gets detached from the body of the mother plant

  • Vegetative propagation: Roots of radish, carrot, dahlia develop adventious buds which grow into leafy shoots
  • Vegetative propagation by stems: Stolons - Vallisneria, offsets - Eichhornia, Rhizome - Banana, Ginger Bulbs - Alliumcepa (Onion); Corn - Colacasia; Tuber - Potato
  • Vegetative propagation by leaves: Bryophyllum
  • Vegetative propagation by modified flowers (Bulbils): Agave
II) Artificial vegetative propagation: Certain flowering plants have the capacity to develop a part of their somatic body into a new independent plant. In artificial vegetative propagation such plants are identified and special techniques are applied to obtain new independent plant.
  • Cutting (Stems): Sugarcane, Roses, Hibiscus, Citrus plants
  • Cutting (Root): Lemon, Tamarind
  • Layering: Jasmine, Strawberry, Gooseberry
  • Grafting: Rubber, Apple, Pear, Citrus, Mango, Guava
  • Propagation by tissue culture technique: Lily, Rose, Magnolia, Fern, Banana for micropropagation, a small amount of tissue from a suitable part of the parent plant is excised and grown on a nutrient medium under aseptic conditions
  • Question 22.Make a flow chart to show the cell cycle and explain cell division describing different stages of mitosis?


    Different stages of mitotic cell division:
    Stage Description
    1) Prophase Chromatin condenses to form chromosomes. Chrormisomes split length ways to form chromatids, connected by centromeres. Nuclear membrane breaks down
    2) Metaphase Chromosomes move to spindle equator, centromeres attached to spindle fibres. Centromeres split, separating the chromatids
    3) Anaphase Spindle fibres attached to centromeres contract, pulling chromatids towards poles
    4) Telophase Chromatids elongate, become invisible. Nuclear membranes form round daughter nuclei. Nucleus divides into two and division of cytoplasm starts
    5) Cytokinesis Cytoplasm divides to form two daughter cells
    Question 23.Draw neat labelled diagrams of male and female reproductive systems of plant?


    Question 24.Observe the following part of flowering plant and prepare a note?

    Answer: The given diagram is the structure of ovule which is present in the ovary (carpel) of plant

    • An ovule is an egg shaped structure attached by a stalk (Funicle) to the inner side of the ovary
    • Depending upon the species of plant involved, an ovary may have one, two, several or even hundreds of ovules
    • At the centre of each ovule is a microscopic embryo sac filled with food and water
    • The embryo-sac is composed of gametophyte cells
    • The majority of flowering plants have an embryo sac consisting of seven cells and eight nuclei
    • They are one egg (female gamete), two synergids, one central cell (secondary nucleus) and three antipodals
    • Central cell contains two nuclei, they are called polar nuclei
    Question 25.Prepare a flow chart to explain the process of sexual reproduction in plants?


    Question 26.Draw a neat labelled diagram to explain plant fertilisation. Write few points on Pollen grain?


    Pollen grains:
    • Pollen grains develop in anther
    • Anther consists of spore-forming tissue. Some of the cells in the spore-forming tissue develop as pollen mother cells
    • Each pollen mother cell undergoes meiosis to form four daughter cells which develop into pollen grains
    • Pollen grains are haploid (n) and are otherwise known as microspores or male gametes
    • They contain only one set of chromosomes (n)
    • The study of pollen grain is called palynology
    • During pollination pollen grains are dispersed by wind and insects
    • Pollen grains are formed in large numbers. They are light in weight and are easily carried by wind currents
    Question 27.How will you appreciate cell division that helps in perpetuation of life?


    • Perpetuation means continuation of life
    • The perpetuation of life is based on the cell division
    • Both mitotic and meiotic divisions are very essential for perpetuation of life
    • In unicellular organisms, the mitotic cell divisions form the entire organisms
    • Mitotic division is essential for all types of asexual reproductions
    • In sexually reproducing organisms meiotic cell division helps in formation of gametes with haploid number of chromosomes which fuses to form diploid zygote during fertilization
    • Zygote further divides by mitosis again and grows into an embryo and then to offspring
    • Thus both mitotic and meiotic cell divisions play a key role in perpetuation of life. Without cell division, there is no perpetuation of life
    Question 28.What precautions will you take to keep away from various sexually transmitted?

    Answer: Precautions to be taken to keep away from various sexually transmitted diseases

    • Avoid sex with any one who has genital sores, a rash, discharge or other symptoms
    • The only time unprotected sex is a safe if the partners have sex only with each other
    • I use latex condoms every time 1 participate in sex. I use it for the entire sex act
    • I avoid sharing towels or under clothing
    • I wash genital organ before and after intercourse
    • I will get a vaccination for hepatitis B. This is a series of three shots
    • I will get tested for HIV for every six months
    • I will not drunk or take drugs. Under these conditions, I may fail to have safe sex
    • I consider that not having sex is the only way, sure way to prevent sexually transmitted diseases
    • Sexual act is supposed to be an act between husband and wife. Hence I will not participate in sex before marriage
    • When I grow up and get married, I will be upright and faithful to the life partner and will not behave immorally
    • Hence as a student I will concentrate on studies and create activities to achieve success in life
    Question 29.Conduct a seminar on child marriages and foeticide?

    Answer: child marriages can also be defined as "any marriage carried out under the age of 18 years and involves the girl who is physically, psychologically, mentally and physiologically immature"

    Causes of Child marriages :
    • Poverty in the families due to unemployment
    • Illiteracy among people
    • Ignorance of consequences of child marriages
    • Strong superstitions among people about child marriages
    • Religious and traditions are also responsible for occurance of child marriages
    Steps to prevent Child marriages:
    • By creating awareness among the people about the ill effects of child marriages
    • By educating the people especially in rural areas of backward districts
    • By providing employment opportunities to all the people
    • Performing live plays, skits and stage shows to create enlightenment among the rural illiterate women about the pathetic future of kids who are forced to get married
    • Foeticide is the illegal practice of killing a foetus. Female foeticide is prevalent in our country as a major social evil
    • Some kinds of complications in pregnancy can also demand surgical termination of pregnancy after 8 weeks of conception
    • This is where the abortion is legal and doctors may have to suggest for discontinuous of pregnancy for the sake of health of the mother. However the technique of surgical termination is misused by some people by getting rid of the unborn child
    • Abortion of foetus is an act of murder. God is the author of life and nobody should have right to take it
    Choose the correct answer.
    1. The part of the female reproductive system produces the eggs [ ] ?
    • Ovary
    • Epididymis
    • Cervix
    • Fallopian tube

    Answer: A

    2. The term that we use to describe a sperm cell fusing with an egg cell [ ] ?
    • Fragmentation
    • Fermentation
    • Fertilisation
    • Fusion

    Answer: C

    3. Which part of the male reproductive system produces (human) the sperm cells ? [ ] ?
    • Vas deference
    • Epididymis
    • Seminiferous tubules
    • Scrotum

    Answer: C

    4. How does the sperm break through the egg cell membrane? Choose the option you think is right. [ ] ?
    • Tears a hole in the membrane
    • Dissolves the membrane with chemicals
    • Bites through the membrane with teeth
    • Squeezes through gaps in the membrane

    Answer: B

    5. Why are egg cells larger than sperm cells? Choose the option you think is right. [ ] ?
    • Egg cells have more cells in them
    • Have food store to help growth after fertilisation
    • Have thicker cell membranes
    • Have larger nuclei


    6. Which of these things will affect the way a foetus grows? Choose the option you think is right. [ ] ?
    • Chemicals in cigarette smoke
    • Alcohol
    • Drugs
    • All of the above

    Answer: D

    7. Which of the following is the correct sequence of steps in the human life cycle? Choose the right option. [ ] ?
    • Babyhood, childhood, adolescence, adulthood
    • Childhood, babyhood, adulthood, adolescence
    • Adolescence, babyhood, adulthood, childhood
    • None of the above

    Answer: A

    10th Class Biology 6th Lesson Reproduction - The Generating System InText Questions and Answers

    10th Class Biology Textbook Page No. 117
    Question 1.How do you think bacteria were dividing to form curd?

    Answer: Curdling indicates that the increase in number of bacteria by fission

    10th Class Biology Textbook Page No. 118
    Question 2.How do you think this process (parthenogenesis) ?

    Answer: This process occurs by the development of female gamete or ovum directly develops into zygote without fertilisation

    Question 3.What about animals?


    • Normally the fertilized ovum (zygote) develops into a young one. But the unfertilized ovum also develops into a young one generally the male
    • The process of development of young ones from unfertilized ovum is called parthenogenesis
    • In this process sperms develop by mitotic division whereas ova develop by meiotic division
    • This strange kind of reproduction occurs in animals like bees and wasps
    Question 4.Is regeneration can also be known as a type of fragmentation? Do you agree? Why? Why not?


    • Yes. I agree that regeneration could be also called as a type of fragmentation. Because in both cases pieces or parts from the body of the organism can develop into a new individual
    • Fragmentation and regeneration occur in multicellular animals
    • Fragmentation occurs in organisms with relatively simple body organisation
    • Whereas regeneration occurs in organisms with fully differentiated body organisation
    Question 5.Which type of fission would produce larger colonies in less period of time. Why?

    Answer: Multiple fission would produce larger colonies in less period of time because more number of daughter cells are formed by multiple fission

    Question 6.Which mode of asexual reproduction provides maximum scope of choice of desirable characters?

    Answer: Parthenogenesis provides maximum scope of choice of desirable characters

    10th Class Biology Textbook Page No. 120
    Question 7.What are the characters that would you like to select?

    Answer: The characters that I would like to select are plant with large number of fruits which are big in size and taste sweet with less or no seeds

    Question 8.What mode of propagation would help you to produce the plants with selected characters?

    Answer: Mode of propagation that would help me to produce the plants with selected characters is grafting

    Question 9.Whether they reproduce by budding or fission or fragmentation, organisms are copies of their parents. Is it true? Why ?


    • Yes, it is true that organisms reproduced by budding or fission or fragmentation are copies of their parents
    • Because budding or fission or fragments are not the methods of sexual reproduction
    • No gametes were formed or fused in these methods
    • Exchange of chromosomes or crossing over do not take place. Hence the offsprings produced are similar to their parents
    10th Class Biology Textbook Page No. 122
    Question 10.Do you find any similarities between rhizopus and fern spores and sporangia?


    • Both rhizopus and fern reproduce asexually through spores
    • In both the spores are microscopic, unicellular bodies produced in the sporangia
    Question 11.What about mushrooms, how do they grow? Discuss in your class?

    Answer: Fungi grow from the fragmentation of hypae. They also form buds which are bulged from out side of cells which detaches after division of the nucleus. A special reproducĀ¬tive sac called sporangium produces asexual spores which are released outside. FunĀ¬gal sexual reproduction includes plasmogamy, Karyogamy and gametangia

    10th Class Biology Textbook Page No. 123
    Question 12.Think why testis are located outside the abdominal cavity?

    Answer: The testis are located outside the abdominal cavity because the temperature required for proper functioning of spermatogenesis is generally 2 to 3 degrees less than the body temperature

    10th Class Biology Textbook Page No. 127
    Question 13.What function do you think is served by petals and sepals?
    • Calyx consists of sepals give protection to the flower particularly in bud condition
    • Corolla consists of bright coloured petals and are useful in attracting insects for pollination
    Question 14.Draw the diagram of the flower that you collect and label the parts shown and write their functions?

    Answer: Functions of flower parts

    • Calyx: Consists of sepals - protects flower in bud conditions
    • Corolla: Consists of coloured petals - helps in pollination
    • Androecium: Consists of stamens - produce male gametes pollen grains
    • Gynoecium: Female reproductive part - produce ovules inside the ovary. Stigma receives pollen grain
    10th Class Biology Textbook Page No. 128
    Question 15.How does the male reproductive cell fertilise the female reproductive cell in flowers of such plants (pea plants) ?


    • In self pollinated plants anthers are usually present above the stigma
    • Pollen from the anthers drop on the stigma
    • A process that takes place as the flowers close for the night
    • And sometimes occurs before they are completely developed and ready to open
    • At the time of pollination slightest movement of the flowers petals stimulate the stamen to dislodge its pollen and transfer it to the near by stigma in pea plant
    • Pollination usually occurs before the flower is fully open
    10th Class Biology Textbook Page No. 129
    Question 16.How many nuclei are present in the pollen grain?

    Answer: Pollen grain has two nuclei. One is called a tube cell and the another is generative cell

    10th Class Biology Textbook Page No. 131
    Question 17.Which floral part may be seen in a fruit?

    Answer: Sometimes calyx may remain with fruit

    Question 18.How cotyledons are useful for the plant?


    • The cotyledons digest and absorb the endosperm
    • They make the stored food available for the growth of the epicotyl and hypocotyl
    • The cotyledons of some flowering plants, digest, absorb, and store the foods from the endosperm as the ovule is maturing into a seed. Eg: beans
    • As a consequence, the cotyledons become greatly enlarged because of stored food and the endosperm disappears more or less completely
    10th Class Biology Textbook Page No. 137
    Question 19.What differences do you find in mitosis and meiosis? Write in a tabular form?


    Mitosis Meiosis
    1. It occurs in somatic cells 1. It occurs in germ cells
    2. Nucleus divides only once 2. Nucleus divides twice
    3. Two daughter cells are formed 3. Four daughter cells are formed
    4. Daughter cells are diploid 4. Daughter cells are haploid
    5. It occurs more frequently 5. It occurs less frequently
    6. Daughter cells form somatic organs 6. Daughter cells form gametes
    7. There is only one prophase, one metaphase one anaphase and one telophase 7. There are two of each phase and five sub-phases in prophase -1
    8. Number of chromosomes are not changed in the daughter cells 8. Number of chromosomes are reduced to half
    9. Chromosome number doubles at the beginning of each cell division 9. Chromosome number is not doubled. It doubles after the end of first meiotic division
    10. No crossing over in chromosomes 10. Crossing over occurs chromosomes
    11. Equation division 11. Reduction division
    Question 20.What would happen if the gametes do not have half the chromosome number as the skin parent?


    • Daughter cells formed in meiosis are gametes
    • These gametes have half of the chromosomes in number as the parent
    • If the gametes do not have half of the chromosomes in number as the parent, when they fuse, they form zygote with double the number of chromosomes when compared to parent cell
    • If it continues, cells in the offspring will have thousands of chromosomes within few generations
    • If the chromosome number increases in a species it leads to the formation of abnormalities
    Question 21.How would it affect the progeny formed by sexual reproduction?

    Answer: If the progeny have thousands of chromosomes in them, it results in formation of abnormalities in each generation.

    Question 22.Why did the government of India fixed the legal marriage age of boys (21 years) and girls (18 years) ?


    • Government of India fixed legal marriage age of boys as 21 years, and girls as 18 years
    • This is because teenage mothers are not prepared mentally or physically for motherhood
    • Early marriage and motherhood cause health problems for the mother and child
    • It may also cause mental agony, as teenage mother is not ready for responsibilities of motherhood
    Question 23.Do you feel that it is a social responsibility to control birth after having one or two children?


    • Yes, it is a social responsibility of every individual to control birth after having one or two children
    • If we dont control birth after having one or two children, population will grow rapidly
    • If the population increases we will not be able to provide all the facilities such as education, medicine, employment etc., to all the people
    • It shows impact on the economic conditions of the family and the society
    • The quality of life will decrease
    Question 24.What do you understand by the term Healthy Society?


    • If all the people in a society are in the state of complete physical, mental and social well being, then the society is said to be healthy society
    • To be in a healthy society, every one in the society should take care of their own personal hygiene and cleanliness of the surroundings
    • Avoiding child marriages, unprotected sex and creating awareness among the people regarding adverse effects of these are very essential to form a healthy society
    Question 25.Will you encourage child marriage? Why?


    • No. I will never encourage child marriage
    • This is because, the sexual act always has potential to lead to pregnancy
    • In case of child marriage, the age of girls is less than 18 years and so they are not prepared mentally or physically for motherhood
    • If they got pregnancy the health of them and their child will be affected
    Question 26.How does HIV is transmitted?

    Answer: Hiv is transmitted by unsafe sexual contacts, using infected devices,infected blood transfusion, from an infected mother to child, etc

    10th Class Biology Textbook Page No. 138
    Question 27.Social discrimination against AIDS patients is also a social evil. Can you support this? Why?


    • Yes, I will support this statement
    • The persons suffering from HIV/AIDS are shown lot of social discrimination in the society
    • This happens even with their own family members
    • This is due to lack of awarness among public about spreading of disease, illiteracy misconception about AIDS
    • If everyone knows how it will not spread they will treat HIV + ves with love and effection
    • HIV +ves are patients. It will spread through sexual contact, blood transfusion, mother to child and not with other modes
    • Hence they can live with us without any discrimination they need our love and family support
    • If anybody shows discrimination, it is definitely a social evil
    10th Class Biology Textbook Page No. 140
    Question 28.Do you think you have moral right to kill a foetus?

    Answer: No, I dont think that we have moral right to kill a foetus. It is our social responsibility to protect the foetus

    Question 29.Why doctors are prohibited to do sex determination through ultrasound scanping for pregnant women?

    Answer: Knowing the sex of foetus inside mothers womb is a severe crime as per the acfmade by government. Ultrasound tests are mend to know the growing condition of the foetus and also to see whether it is suffering with severe ailments. By knowing the sex of the foetus, if it is female, people are ready for aborting it. This leads to reduction in male female ratio in the country. Thats why doctors are prohibited to do sex determination through ultrasound scanning for pregnant women

    10th Class Biology 5th Lesson Reproduction - The Generating System Activities Activity - 1
    Formation of bacterial colony in milk?


    • Take a tea spoon full of curd and mix it thoroughly with around tea spoon full of (half of the glass) luke warm milk in a bowl
    • Take another tea spoon full of curd and mix it with 30 tea spoon full of cold milk in another bowl
    • Cover both the bowls and note the initial time
    • Keep observing every hour to see whether curd has formed
    • Curdling indicates that the increase in number of bacteria
    • Note the time taken for formation of curd in both the bowls
    • Does it take the same time to form curd in both the bowls? Answer: No. Formation of curd in the bowl containing luke warm milk takes nearly 5 - 6 hours. In the second bowl in which cold milk is present no curdling took place
    • What does the time taken to form nearly 30 times the size of the bacterial colony indicate
    • Answer: Time taken to form nearly 30 times the size of the bacterial colony indicates how fast bacteria are growing
    Activity - 2
    Examine Rhizopus or common mould under Microscope?
    (OR) Write the materials required and the procedure followed by you to observe Rhizopus in the lab. (OR) Write the procedure which you follow to observe bread-mould Sporangium m your laboratory. What precautions do you take during the activity? (OR) Suneetha wanted to observe Rhizopus on the piece of bread, (i) Suggest the apparatus needed. (ii) Write the procedure to be followed.

    Answer: Aim: To grow and examine rhizopus or common mould. Materials required: Bread, plastic bag, plain glass slide, cover slip, water, eye dropper, disposable gloves, compound microscope

    Procedure to grow mould:
    • Take a soft bread and leave it in the open for about an hour so it is exposed to contaminants in the air
    • Place the bread in a plastic bag, sprinkle water over it, so it is damp and seal the bag living some air inside
    • Check on the piece of bread every few days and add more water if it is becoming dried out
    • We can find whitish thread like growth with masses of black, gray and green fine dotted structures, the black dotted structure is that of bread mould
    • A good sample of mould may take up to two weeks to form
    • Using this mould make a slide and observe under the microscope
    • Procedure to make a slide:
    • Place a drop of water in the centre of the slide, using an eye dropper if you have one, or the tip of a clean finger
    • Using a tooth pick, scrape some of the mould off, and place it on the drop of water
    • Take the coverslip and set it at an angle to the slide so that one edge of it touches the water drop
    • Then carefully lower it over the drop, so that the coverslip covers the specimen without trapping air bubbles underneath
    • Use the corner of a tissue paper or blotting paper to blot up any excess water at the edges of the coverslip
    • View the slide with a compound microscope, starting with a low objective
  • The common bread mould plant consists of fine thread like projections called hyphae and thin stems having knob like structures called sporangia
  • Each sporangium contains hundreds of minute spores
  • Precautions:
  • This should not be done by those with allergies to mould or with severe asthma
  • Avoid opening the plastic bag as much as you can
  • If you touch the bread, be sure to thoroughly wash your hands afterwards
  • Activity - 3
    Observation of pollen grain?
    • Take a slide and put a few drops of water on it
    • Take any flower like hibiscus, tridax, marigold, etc. Tap the anther over the drop of water
    • We will see small dot like structures in water. These are pollen grains
    • Take permanent slide of pollen grain from your lab
    • Also see a permanent slide of pollen grain from our lab
    • Observe under a microscope. We will make a drawing of what we observe and compare with the given diagram
    Observation: Pollen grain germinates only on stigma. Pollen grain consists of two to three cel Is surrounded by a protective wall in Angiosperms. In gymnosperms the pollen grain consists of several living cells. Activity - 4
    Seed germination?


    • Soak a few groundnut or bengal gram (chana) seeds overnight
    • Drain the excess water and cover the seeds with wet cloth. Leave them for a day
    • Keep sprinkling water at regular intervals so that they do not dry up
    • Open the seeds carefully and observe the parts
    Observation: The seed is germinated i.e., the seed embryo is developed into seedling plumule which grows into plant. Activity - 5
    Observe different stages of mitotic cell division. (OR) Describe various stages of mitosis with the help of neat diagrams?


    • Take permanent slides which shows different stages of mitotic cell division from your lab kit
    • Observe carefully under microscope
    • Draw diagrams what you observe, and compare your observations with the following chart
    1. 1. 1. 1.
    Stage Description
    1. ProphaseChromosomes contract, spiral and become visible even in light microscope and nucleoli become smaller (material to chromosomes). 2. Chromosomes split lengthwise to form chromatids, connected by centromeres. 3. Nuclear membrane disappears. 4. Centrosome, containing rod-like centrioles, divides and forms ends of spindle (probably animal cells only). (Note : No pairing of chromosomes as in meiosis)
    2. MetaphaseChromosomes move to spindle equator, spindle fibres attached to centromeres
    3. AnaphaseCentromeres split, separating the chromatids. 2. Spindle fibres attached to centromeres contract, pulling chromatids towards poles
    4. TelophaseChromatids elongate, become invisible, (replication at this stage to become chromosomes). 2. Nuclear membranes form round daughter nuclei. 3. Cell membrane pinches in to form daughter cells (animals) or new cell wall material becomes laid down across spindle equator (plants). 4. Nucleus divides into two and division of cytoplasm starts

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