Reproduction of Plants and Animals

• Reproduction, is the biological or natural process by which new individual organisms, called offspring, are produced from a single parent or from two parents.
• Two modes of procreation in plants and in animals: 1 asexual and sexual
• two ways that plants can propagate asexually: spore formation and vegetative reproduction
• Spore formation is a method of asexual reproduction which occurs in non-flowering plants
• Vegetative reproduction is a mode of procreation that occurs through the vegetative or body parts of a plant such as stems, leaves, and roots.
• spore is a reproductive cell which is capable of developing into a new individual plant without combining with another reproductive cell
• Vegetative reproduction

  Plants that grow in this method are exact copies of their parents as they are bred from a single plant
• Sexual reproduction in plants occurs in gymnosperms (cone-bearing) plants and in angiosperms (flowering) plants
• sexual reproduction - This mode of breeding requires the union of a male and a female gamete to produce a zygote (baby) called seeds.
• in angiosperms, the flowers act as a sex organ. Stamen is the male reproductive part while the pistil is the female reproductive part.
• Stamen has anther which contains pollen grains or male gametes
• A pistil has stigma, style, and ovary, the ovary consists of ovules.
• The female gamete called ovum (ova – plural) lives in the ovule.
• Flowers having both reproductive parts are bisexual while the flower with only one of the reproductive parts is unisexual.
• In gymnosperms, the cone is the female reproductive part and the pollen is the male reproductive part.
• two types of cones; the male cone called the pollen cone and the female cone (larger) is the seed cone.
• two steps in plants sexual reproduction: pollination and fertilization
• Pollination - is the transfer of pollen grains from the plant’s male reproductive structure to the female reproductive part.
• two ways plants pollinate: self-pollination or autogamy and cross- pollination or allogamy.
• self-pollination or autogamy and cross- pollination or allogamy.
• When the transfer of pollen grains occurs within the same plant, the process is called self-pollination. However, when it happens between two different plants of the same species, it is referred to as cross-pollination.
• Plant fertilization is the union of the female gamete or ovum and the male gamete produced in the pollen tube by the pollen grain.
• Fission - is an instance in which an animal appears to split itself into two or more parts and regenerate or grow the missing parts – resulting to two or more new organisms.
• Budding - results from the outgrowth of a part of the body leading to a separation of the “bud” from the original organism and the formation of two individuals, one smaller than the other.
• Fission - This asexual method of reproduction occurs in some invertebrate animals like sea anemone, planaria (turbellarian flatworms) and sea cucumbers.
• Budding - occurs commonly in some invertebrate animals such as hydras and corals. In hydras, a bud forms that develops into an adult and breaks away from the main body
• Fragmentation - occurs when a part of an individual animal breaks off. If the animal is capable of fragmentation, the process will be followed by regeneration, resulting to a separate individual growing from each of the broken part.
• fragmentation - Animals such as annelids (round worms) and echinoderms such as starfishes and sea stars are able to reproduce though this process.
• Parthenogenesis - results when an egg develops into an individual without being fertilized
• Sexual procreation requires two types of specialized cells called sex cells.
• The union of male and female gametes in animals is referred to as fertilization.
• fertilization is also known as conception, impregnation, insemination or syngamy
• The result of this mode of reproduction is a genetically unique organism which carries one half of the total number of chromosomes from its mother and another half from the father. Sexual Reproduction
• External Fertilization - occurs when the sperm fertilizes the egg cell outside the body of the female animal
• Most external fertilization happens during the process of spawning. It means that one or several females release their eggs and the male or males release sperm in the same area, at the same time.
• In internal fertilization the male introduces the sperm cells into the female’s body and the union of male and female gametes occurs inside the body of the female animal.
• This method of syngamy results to higher survival rate of offspring since the developing embryo is isolated within the female’s body. It is protected from dehydration, predators and harsh conditions on the outside environment. internal fertilization
• Oviparity - Oviparous animals lay eggs. Embryos develop within eggs outside the body of the mother. Birds, turtles, lizards, some snakes are examples of this type of organisms.
• Ovoviviparity - Ovoviviparous animals develop within eggs which remain inside the mother’s body up until they hatch or are about to hatch. This occurs in some bony fish such as the guppy (Lebistes reticulatus), some sharks, some lizards, some snakes, and some invertebrate animals like cockroaches.
• Viviparity - In viviparous animals, the young develop within the female. It receives nourishment from the mother’s blood through a placenta. The offspring develops inside the female’s body and is born alive. This occurs in most mammals, some cartilaginous fish, and a few reptiles.