CBSE Class 10 Biology, How do organisms reproduce

Class X Science
How do Organisms Reproduce
Asexual Reproduction in Plants
   Spore formation → eg. Bacteria, fungi
   Budding → eg. Fungi (yeast)
   Fragmentation → eg. Algae, fungi
   Vegetative propagation
(a)   Natural method
   By roots → eg. Sweet potato
   By stems → eg. Ginger, potato
   By leaves → eg. Bryophyllum
(b)   Artificial method
   Cutting → eg. Rose
   Layering → eg. Strawberry, lemon
   Grafting → eg. Mango, rose.
   Micropropagation → eg. Orchids, dahlia
Sexual Reproduction in Plants
   Flower is the reproductive organ.
   It has four whorls – Calyx, Corolla, Androecium, Gynoecuim.
   Calyx and corolla are accessory parts.
   Androecium - Male reproductive organ producing pollen grains.
   Gynoecium - Female reproductive organ having ovule (egg).
   Pollination – Transfer of pollens from anther to stigma for fertilization.
   Fertilization – Fusion of male and female gametes.
   Double fertilization (Triple fusion and syngamy) – unique events in the embryo sac of ovules.
Asexual Reproduction in Animals
   Fission
(a) Binary fission → eg. Amoeba
(b) Multiple fission → eg. Plasmodium
   Budding → eg. Hydra
   Regeneration → eg. Planaria, Hydra
Sexual Reproduction (Human)
   Human being is heterosexual.
   Reproductive system includes:
(a) Primary sex organs: Testes (males) and ovaries (females)
(b) Secondary sex organs: Genital ducts and glands (males) and fallopian tubes, uterus, vagina (females)
   Male sex hormone is testosterone and female sex hormones are progesterone and estrogen.
   Puberty is attained at the age of 13 – 14 years in males and 10 – 12 years in females.
   The zygote formed after fertilization develops into embryo which gets implanted in uterus.
   Placenta (a disc-like special tissue) develops between uterine wall and embryo for nourishment of the embryo.
   Gestation period in humans is 280 days.
Reproductive Health
   Birth control prevents unwanted pregnancies.
(a) Barrier methods
(b) Chemical methods
(c) Intrauterine contraceptive device
(d) Surgical method
   Sexually transmitted diseases (STD) are caused by bacteria, protozoa and viruses.
   AIDS is an incurable viral disease.