Perpetuation of Life PDF

Lesson 04 Perpetuation of Life MS. KYLA AQUINO Lesson 04 Reproduction Ensures the continuity of species. Sexual Reproduction - Two parents contribute genetic informatio...

Lesson 04 Perpetuation of Life MS. KYLA AQUINO Lesson 04 Reproduction Ensures the continuity of species. Sexual Reproduction - Two parents contribute genetic information to produce unique offspring. Parents produce reproductive cells-called Gametes. Lesson 04 Reproduction Ensures the continuity of species. Asexual Reproduction - Involves a single parent which results to offspring identical to one another and to the parent. Lesson 04 A male gamete is called a spermatozoon or sperm cell A female gamete is called an ova or egg cell Lesson 04 Gametes are haploid cells. They contain only half number of chromosomes found in other cells of organisms. Lesson 04 Two gametes unite through the process of fertilization. The produced fertilized cell is termed as zygote. Zygote is a diploid cell, it has twice the number of chromosomes one copy from each gamete. Lesson 04 Types of Fertilization Lesson 04 Internal Fertilization May occur by the male directly depositing sperm in the female during mating May also occur by the male depositing the sperm in the environment, which a female picks up to deposit in he reproductive tract. Lesson 04 External Fertilization It is the fusion of gametes outside the female body. Usually occurs in aquatic environments. In most species of frogs, fertilization is external. The male frog grabs the female's back and fertilizes the eggs as the female frog releases them. Spawning - process where one or several females release their eggs and the male/s release sperm in the same area, at the same time. Nearly all fish spawn, as well as crabs and shrimp, oysters, squid, and sea urchins and sea cucumbers. Frogs and corals also spawn Lesson 04 Types of Sexual Reproduction Lesson 04 Ovuliparity External fertilization Ovuliparity is observed in a wide range of animals, from reptiles and birds to some species of fish and insects. Lesson 04 Oviparity Animals lay shelled eggs, and are hatched outside the body Internal fertilization External development All birds are oviparous, as are most fish, reptiles, and insects. Lesson 04 Viviparity Animals give birth to live youngs Internal fertilization Internal development Majority of mammals are viviparous. Monotremes are the only mammals that lay eggs (platypus & echidna)  Types of Viviparty Lesson 04 Histotrophic Hemotrophic Viviparity Viviparity  Types of Viviparty Lesson 04 The fetus develops in the womb but finds nutrients from other tissues. An example of this are marsupials, which are born incredibly quickly after spending little time within the womb and very underdeveloped. They then climb into the mother’s pouch and continue their Histotrophic development within its Viviparity security.  Types of Viviparty Lesson 04 With histotrophic viviparity, there are two other ways embryos find nutrients. Oophagy - The embryo survives by consuming eggs produced by the mothers’ ovaries whilst still in the womb (seen in some shark species). Adelphophagy - Also known as intrauterine cannibalism, multiple embryos produced but only the largest or strongest survive by consuming the Histotrophic weaker, less developed ones Viviparity (seen in some shark species such as the Great White).  Types of Viviparty Lesson 04 The fetus develops inside a uterus and is connected via an umbilical cord to a placenta which provides nutrients. This is a method of reproduction seen in most mammals including humans. Hemotrophic Viviparity Lesson 04 Ovoviviparity Animals hatch eggs inside of their bodies, but give birth to live youngs Internal fertilization Internal development Seahorses and some sharks are ovoviviparous. Lesson 04 Hermaphrodite Organisms having both male and female reproductive organs. Sequential Hermaphrodite - Individual capable to change sex at some point of its life, meaning it can produce both egg and sperm over the course of its lifetime (but not at the same time) Lesson 04 Hermaphrodite Organisms having both male and female reproductive organs. Simultaneous Hermaphrodite - Individual that has both male and female reproductive organs, and produces both types of gametes Lesson 04 Methods of Asexual Reproduction Binary Fission Fragmentation Budding Lesson 04 Parthenogenesis “virgin birth” Occurs when a female can produce an embryo without fertilizing an egg with sperm. Ants, bees, wasps, and Komodo dragons are some of the few animals that can reproduce through parthenogenesis. Lesson 04 Parthenogenesis “virgin birth” Some wasps, crustaceans, and lizards reproduce only through parthenogenesis and are called obligate parthenogens. A larger number of species experience spontaneous parthenogenesis. Spontaneous parthenogens typically reproduce sexually, but may have occasional cycles that produce developmentally ready eggs. Lesson 04 Parthenogenesis “virgin birth” Scientists have learned spontaneous parthenogenesis may be a heritable trait, meaning females that suddenly experience parthenogenesis might be more likely to have daughters that can do the same. Zebra Shark