Reproduction Methods Quiz

PDF page 1497: Much of the information about the different reproductive systems of animals is not within the scope for AP . You likely studied human reproduction in a health course or previous biology course. Reproduction is necessary for the survival of a species, and animals have evolved various reproductive strategies. In a previous chapter we learned that asexual reproduction via mitosis produces genetically identical organisms (clones). We also previously explored how meiosis followed by sexual reproduction produces offspring that are genetically different from their parents. Whether or not the

PDF page 1497: material in this chapter is required or illustrative as part of your AP course, you should find the concepts interesting and relevant to your lives outside the classroom. Both asexual and sexual reproductive strategies have their advantages and disadvantages. Organisms that reproduce asexually—for example, bacteria and some eukaryotes—may be at a disadvantage in an unstable or unpredictable environment because, barring mutation, the identical offspring may not have sufficient genetic variation to survive in new or different conditions. On the other hand, the rapid rates of asexual reproduction may allow a speedy response to changing environmental conditions. Although sexual reproduction allows for greater genetic variation in offspring, organisms that reproduce sexually must maintain males and females in the population, which can limit the ability to colonize new habitats.

PDF page 1497: material in this chapter is required or illustrative as part of your AP course, you should find the concepts interesting and relevant to your lives outside the classroom. Both asexual and sexual reproductive strategies have their advantages and disadvantages. Organisms that reproduce asexually—for example, bacteria and some eukaryotes—may be at a disadvantage in an unstable or unpredictable environment because, barring mutation, the identical offspring may not have sufficient genetic variation to survive in new or different conditions. On the other hand, the rapid rates of asexual reproduction may allow a speedy response to changing environmental conditions. Although sexual reproduction allows for greater genetic variation in offspring, organisms that reproduce sexually must maintain males and females in the population, which can limit the ability to colonize new habitats.

PDF page 1498: Asexual reproduction occurs in prokaryotic microorganisms (bacteria) and in some eukaryotic single-celled and multicelled organisms. There are a number of ways that animals reproduce asexually. Fission Fission, also called binary fission, occurs in prokaryotic microorganisms and in some invertebrate, multi-celled organisms. After a period of growth, an organism splits into two separate organisms. Some unicellular eukaryotic organisms undergo binary fission by mitosis. In other organisms, part of the individual separates and forms a second individual. This process occurs, for example, in many asteroid echinoderms through splitting of the central disk. Some sea anemones and some coral polyps (Figure 34.2) also reproduce through fission.

PDF page 1498: Asexual reproduction occurs in prokaryotic microorganisms (bacteria) and in some eukaryotic single-celled and multicelled organisms. There are a number of ways that animals reproduce asexually. Fission Fission, also called binary fission, occurs in prokaryotic microorganisms and in some invertebrate, multi-celled organisms. After a period of growth, an organism splits into two separate organisms. Some unicellular eukaryotic organisms undergo binary fission by mitosis. In other organisms, part of the individual separates and forms a second individual. This process occurs, for example, in many asteroid echinoderms through splitting of the central disk. Some sea anemones and some coral polyps (Figure 34.2) also reproduce through fission.

PDF page 1498: Asexual reproduction occurs in prokaryotic microorganisms (bacteria) and in some eukaryotic single-celled and multicelled organisms. There are a number of ways that animals reproduce asexually. Fission Fission, also called binary fission, occurs in prokaryotic microorganisms and in some invertebrate, multi-celled organisms. After a period of growth, an organism splits into two separate organisms. Some unicellular eukaryotic organisms undergo binary fission by mitosis. In other organisms, part of the individual separates and forms a second individual. This process occurs, for example, in many asteroid echinoderms through splitting of the central disk. Some sea anemones and some coral polyps (Figure 34.2) also reproduce through fission.

PDF page 1498: Budding Budding is a form of asexual reproduction that results from the outgrowth of a part of a cell or body region leading to a separation from the original organism into two individuals. Budding occurs commonly in some invertebrate animals such as corals and hydras. In hydras, a bud forms that develops into an adult and breaks away from the main body, as illustrated in Figure 34.3, whereas in coral budding, the bud does not detach and multiplies as part of a new colony.

PDF page 1498: Budding Budding is a form of asexual reproduction that results from the outgrowth of a part of a cell or body region leading to a separation from the original organism into two individuals. Budding occurs commonly in some invertebrate animals such as corals and hydras. In hydras, a bud forms that develops into an adult and breaks away from the main body, as illustrated in Figure 34.3, whereas in coral budding, the bud does not detach and multiplies as part of a new colony.

PDF page 1498: Budding Budding is a form of asexual reproduction that results from the outgrowth of a part of a cell or body region leading to a separation from the original organism into two individuals. Budding occurs commonly in some invertebrate animals such as corals and hydras. In hydras, a bud forms that develops into an adult and breaks away from the main body, as illustrated in Figure 34.3, whereas in coral budding, the bud does not detach and multiplies as part of a new colony.

PDF page 1499: Fragmentation Fragmentation is the breaking of the body into two parts with subsequent regeneration. If the animal is capable of fragmentation, and the part is big enough, a separate individual will regrow. For example, in many sea stars, asexual reproduction is accomplished by fragmentation. Figure 34.4 illustrates a sea star for which an arm of the individual is broken off and regenerates a new sea star. Fisheries workers have been known to try to kill the sea stars eating their clam or oyster beds by cutting them in half and throwing them back into the ocean. Unfortunately for the workers, the two parts can each regenerate a new half, resulting in twice as many sea stars to prey upon the oysters and clams. Fragmentation also occurs in annelid worms, turbellarians, and poriferans.

PDF page 1499: Fragmentation Fragmentation is the breaking of the body into two parts with subsequent regeneration. If the animal is capable of fragmentation, and the part is big enough, a separate individual will regrow. For example, in many sea stars, asexual reproduction is accomplished by fragmentation. Figure 34.4 illustrates a sea star for which an arm of the individual is broken off and regenerates a new sea star. Fisheries workers have been known to try to kill the sea stars eating their clam or oyster beds by cutting them in half and throwing them back into the ocean. Unfortunately for the workers, the two parts can each regenerate a new half, resulting in twice as many sea stars to prey upon the oysters and clams. Fragmentation also occurs in annelid worms, turbellarians, and poriferans.

PDF page 1500: Note that in fragmentation, there is generally a noticeable difference in the size of the individuals, whereas in fission, two individuals of approximate size are formed. Parthenogenesis Parthenogenesis is a form of asexual reproduction where an egg develops into a complete individual without being fertilized. The resulting offspring can be either haploid or diploid, depending on the process and the species. Parthenogenesis occurs in invertebrates such as water flees, rotifers, aphids, stick insects, some ants, wasps, and bees. Bees and wasps use parthenogenesis to produce haploid males (called drones). If an egg is fertilized, it develops as a diploid female. Some vertebrate animals—such as certain reptiles, amphibians, and fish—also reproduce through parthenogenesis. Although more common in plants, parthenogenesis has been observed in animal species that were segregated by sex in terrestrial or marine zoos. Two female Komodo dragons, a hammerhead shark, and a blacktop shark have produced parthenogenic young when the females have been isolated from males.