REPRODUCTION

What is reproduction? It is the biological process by which new individual organisms are produced. It ensures the perpetuation of the species. PROGENITORS DESCENDANTS

TYPES OF REPRODUCTION Asexual: It requires only one parent. It produces new identical descendents. Fungi, algae, protozoa, some plants and animals, bacteria Sexual: It requires two parents: male and female. The descendents have a combination of genetic material from both parents. Multicellular organisms.

Asexual reproduction in animals It is common in unicellular organisms. Types: Gemmation: (budding), a bud on parent’s body Fragmentation: a new organism grow from a parent body

SEXUAL REPRODUCTION It requies two members of the opposite sex: MALE (♂) AND FEMALE (♀). Reproductive organs: gonads: Testicles (♂),and ovaires (♀) Reproductive cells: gametes: Spermatozoon (spermatozoa) and ovm (ova)

HUMAN GAMETES

Unisexual and hermaphrodites Unisexual organisms : Each individual has only one tupe of gonad. Hermaphrodite organisms: each individual has both gonads. Some animals can reproduce both sexually and asexually: Jelly fish (polyp and medusa phase)

Jelly fish cycle

FERTILISATION It is the union of an ovum and a spermatozoon. They form a zygote. Types: External: The union of gametes occurs outside the female’s body. Aquatic animals, amphibians and some insects. Internal: The fusion of the gametes occurs inside the body of the female or hermaphrodite. It involves copulation. Terrestrial animals and some fish.

EMBRYONIC DEVELOPMENT It incluides the processes from the formation of the zygote to the birth of the new individual. The zygote undergoes many changes and becomes a multicellular organism called embryo. Depending on where embryonic development takes place: VIVIPAROUS OVIPAROUS OVOVIVIPAROUS

VIVIPAROUS The embryo develops inside of the female body where it recieves nourishment and protection. It grows in the uterus feed by the placenta through the umbilical cord. It ends with birth. Typical from mammals with pacenta, fish, reptiles and amphibians with placenta –like stuctures.

HUMAN PLACENTA

OVIPAROUS The embryo develops inside an egg, normally outside the female’s body. Most parents incubate the egg. It finishes when the egg hatches. Typical of birds, reptiles and fish.

EGG

OVOVIVIPAROUS The embryo develops inside an egg which remains inside the female’s body until it hatches. Typical of some sharks, snakes and lizards.

ASEXUAL REPRODUCTION IN PLANTS It occurs when plants form new individuals from the cells of a single parent. Types: Spore formation: The nucleus of a parent cell divides into a number of daughter cells called spores. Spores become new individuals. Vegetative reproduction: Plant create new individuals from a particular organ.

VEGETATIVE REPRODUCTION Bulbs: undergroud stems: onions and tulips. Stem tubers: underground stems with buds. Potatoes Stolons: aerial stems with roots when they touch the ground and produce new stems. Strawberries Fragmentation - spread and establishment of ramet by various plant parts, such as excised leaves or stems  

SEXUAL REPRODUCTION IN PLANTS It is typical of plants with seeds. Production of gametes. Pollination Fertilisation Formation of embryos and seeds.

FORMATION OF GAMETES: THE FLOWER Flower structure: Calyx: green sepals. Protection Corolla: coloured petals. To attract insects. Stamen: male organ. Filament and anthers containig pollen. Pistil: female organ. Carpels containing ovaries, style and stigma.

THE FLOWER

FERTILISATION AND SEEDS The pollen grains land on the pistil. The pollen tubes reach the ovary . Both nucleus fuse and form the zygote. It grows into an embryo. The ripened ovule becomes a seed that contains the embryo and food stored in the endosperm. It slowly becomes a fruit.

SEED GERMINATION The embryo develops into a new plant. The embryo can contain one or two leaves with food called cotyledons.

GERMINATION

TYPES OF SEEDS

SUMMARY FLOWER POLLEN OVULE fertilisation EMBRYO formation of seeds germination FRUIT NEW PLANT