Q. Explain reproduction.
Ans. Reproduction is the biological process by which new organisms are created from parent. Reproduction ensures the survival of a species from generation to generation. Types of reproduction….
- Asexual reproduction: Involves a single parent, with or without gamete formation. Offspring are genetically identical to the parent. Examples fission, fragmentation, regeneration, budding, spore formation, vegetative propagation.
- Sexual reproduction: Involves two parents of opposite sexes, with the fusion of male and female gametes. Sexual reproduction in flowering plants, reproduction in human.
Q. Explain fission.
Ans. A type of asexual reproduction in which an organism is broken down into two or more pieces to form new organism.
Types of fission: 1. Binary fission in amoeba Leishmania. 2. Multiple fission in plasmodium.
Binary Fission in Amoeba: Amoeba broken divides into two daughter cells after maturation. The division is at any plane.
Binary fission in Leishmania: Leishmania divides into two daughter cell. The division is in definite orientation.
Q. What is fragmentation? Is fragmentation possible in all multi cellular organism?
Ans. Spirogyra on maturation divides into many fragments (pieces) and each fragments develop into new spirogyra. Fragmentation is not possible in all milti cellular organism as all multicellular organism are not a random collection of cells like in spirogyra. Cell organise to form tissue , tissues form organ, organ form organ system and organ system form organism.
Q. Define regeneration. Why it is not considered a type of reproduction?
Ans. Organism like planaria and hydra when cut into pieces, each piece grow into new individual this is called regeneration. These organisms are made up of regenerative cells. Regeneration is not considered a type of reproduction because reproduction is self sustaining process and it should not depend on other organism. Regeneration depends on cut by other organism.
Q. What is budding.
Ans. It is found in yeast and hydra. Buds develop as out growth. On maturation it detach from the parent and become new individual.
Q. Explain spore formation.
Ans. It is found in Rhyzopus (bread mould). Filament (tube ) like structure called hyphae and blob like structure in which spores are present are called sporangia. When there is favourable condition for Rhyzopus sporangia breaks and spores start growing and form new Rhyzopus.
Q. Define vegetative propagation. Write it’s benefits.
Ans. Growing plants by their vegetative parts like stem, roots, leaf etc is called vegetative propagation. Examples. Sugarcane ( by stem), bryophylum ( by leaf), rose ( by stem)
Benefits:
- Genetically similar plants can be grown
- Less time will be taken, growing faster
- a method of growing plants which lost capacity to produce seed.
- More than one vegetative parts like leaf, root, stem etc can be used to grow.
Q. List reproductive parts of flower.
Ans. Male reproductive parts: also called stamen. It consists of filament and anther. Anther contain pollen grain which carry male gamete.
Female reproductive parts: It is also called pistil or carpel. It consists of stigma, style and ovary.
Q. List examples of unisexual and bisexual plants.
Ans.
Unisexual flower: flower which carry only one type of gametes i.e either male or female gamete. Example. Papaya and water melon.
Bisexual flower: flower which contains both male and female gametes are called bisexual flower. Example hibiscus and mustard.
Q. Define pollination.
Ans. Transfer of pollen grain from anther to stigma is called pollination. Types 1. Self pollination 2. Cross pollination. Colourful petals of flowers attract pollination agents like butterfly and insects
Self pollination: transfer of pollen grain from anther to stigma of same flower. It cause less variation. It is possible in bisexual flower.
Cross Pollination: transfer of pollen grain from anther to stigma of different flower. It cause more variation. It is possible in both Unisexual and bisexual flower.
Q. What happens after pollination?
Ans. After pollination germination of pollen grain into pollen tube , fertilisation and formation of seed happen.
Pollen tube: When pollen grain falls on suitable stigma. It starts germinating and a pollen tube develops which connect Stigma to ovule in the ovary.
Fertilisation: Through pollen tube male gamete reach into the ovule where fertilisation takes place. Zygote is formed after fertilisation which grows into embryo and finally into seed. Ovule turns into seed coat. Ovary changes into fruit. Petals, sepals fall off.
Q. Define germination of seed.
Ans. Seed or embryo contain future plant which develops into seedling under appropriate condition is called germination. Part of seed that grow to form shoot is called plumule and future root is called radicle. Cotyledon provide food to germinating seed so called seed leaf.
SEXUAL REPRODUCTION IN HUMAN
Q. Write function of human male reproductive systems.
Ans.
- Testes: It produces male gamete of male called sperm. Testes located outside the body in the scrotum as it requires lesser temperature than body temperature to produce sperm .
- Vas defence: It is a tube which carry sperm from testes. It is important male reproductive system.
- Prostate and seminal glands: These glands produce fluide like semen which nourish sperm and facilitate easy flow.
Q. Write function of female reproductive system.
Ans.
- Ovary: a pair of ovary in female release female gametes called ovum or egg cells.
- Fallopian tube/ovuduct: It tube like structure which connect ovary and uterus of female. Fertilisation of sperm and ovum and formation of zygote takes place in fallopian tube.
- Uterus: It is bag like structure where nourishment of embryo and baby takes place in the uterus. A disc like structure connects baby to uterus wall called placenta. Embryo and baby get nourished from mother’s blood through placenta.
Q. Define menstrual cycle.
Ans. To receive embryo wall of uterus develop a new setup in which numerous blood vessels and muscle created. When uterus do not receive embryo to nourish. These extra wall along with blood start breaking which come out as discharge. This take a week to complete and the cycle happen about every 4th week. Menstrual cycle represent good reproductive health. The start of menstrual cycle during puberty is called menarche and when menstrual cycle stops , that stage is called menopause. Reproductive age in female is from menarche to menopause.
Q. Write sequence of birth of baby in human.
Ans.
- Fertilisation in fallopian tube and formation of zygote. Movement if zygote (one cell) towards uterus.
- development of zygote into embryo which implant with uterus wall by placenta
- embryo develops into foetus which develops into baby
- birth of baby.
Q. Explain contraceptive method/ device.
Ans. Method which prevents unwanted pregnancy is called called method of contraception. These can be divided as:
- Physical Barrier: Condom (used by male) and diaphragm ( used by female) . This method is considered one of the best method of contraception as it can prevent unwanted pregnancy as well as STDs.
- Surgical Method: a. Vascotomy- vas deference in male is blocked b. Tubectomy – fallopian tube in female is blocked c. IUCD( intra uterine contraceptive device)- copperT like device prevent embryo to settle on uterus.
- Anti pregnancy pills: these are effective but have many side effects.