Chapter 3 – Sexual Reproduction 6th Grade Science

Sexual Reproduction _______________________ results in two cells with the same DNA as the parent cell. ___________________ - reproduction by two parents. Living things that reproduce sexually have special cells called _________. The sex cells of the female parent are called ____________ The sex cells of the male parent are called ________________ Sex cells have only ______ as many ______________ as other cells in the organism’s body. Asexual Reproduction Sexual Reproduction Sex cells Egg Cells Sperm Half Chromosomes

Meiosis Meiosis one four half Male cells Female cells fertilization Sex cells form by a process called ____________ In meiosis, ________ cell divides into ________new cells. Each new cell has ________the number of chromosomes as the parent cell. During sexual reproduction, the __________ and the __________ join in a process called _______________ During fertilization, an _____________and a ____________ unite to form a ___________ called a ___________, A ____________is the first cell of a new organism. Since each sex cell has only half the usual number of chromosomes, the new organism receives a _______________. The zygote will divide by _____________ to form the many cells that make up the adult body of the organism. one four half Male cells Female cells fertilization Egg cell Sperm cell New cell zygote zygote Complete set mitosis

Meiosis

Parts of a Flower _______ - male part of a flower __________ - a grainy yellow powder is made in the stamen. A single flower may have many_________. ________ - female part of a flower. _______ often has a wide bottom an a narrow neck A single flower may have more than one ____. stamen pollen stamens pistil pistil pistil

Pollination / Parts of a flower

Flowering Plants adaptation fertilization pollen stamen pistil stamen A flower is an _______________ that allows a plant to reproduce sexually. In flowering plants, ________________ takes place within the flower. The male sex cells of flowering plants are in ____________—the powdery substance found on many flowers. Pollen is produced by the flower’s ________________ The female egg is produced at the bottom of the female part of the flower—the ____________. For a flowering plant to reproduce, pollen must get from a __________ to a ____________. This process is called _______________. adaptation fertilization pollen stamen pistil stamen pistil pollination

Fertilization in animals When animals reproduce sexually, they also must join a sperm cell and an egg cell. Fertilization can take place inside or outside the body of the ________________. Many animals that live in or near ___________ use fertilization that takes place ______________ the female’s body. This type of fertilization is called ____________________. During external fertilization, animals release ____________ and ___________ into the ___________. The sperm ____________ to the eggs, and __________________ takes place. Each time a sperm and egg unite, a ________________ forms and a new individual starts to develop. Females body water outside External fertilization sperm egg water swim fertilization zygote

Fertilization Animals like the ________________ that use external fertilization usually produce _________ numbers of sperm and eggs. But only a few of the fertilized eggs will ____________ to become adults. Many will die because of _____________________-severe weather, pollution or predators. External fertilization would be difficult for land animals because the sperm and eggs would ___________ too quickly. For most species of animals that live on land, fertilization takes place _____________ the female’s body. Stsghorn coral large survive Environmental conditions Dry out inside

Comparison Asexual Reproduction Can happen quickly Requires less energy • Needs just one parent cell • Produces offspring with DNA identical to parent Sexual Reproduction Is a slow process Requires more energy • Must have two parent cells Produces offspring with unique DNA

Advantages / Disadvantages