Biology 30 Reading Notes
Section 16.4
Pages 573-580
Name:______
Reproductive Strategies
Asexual reproduction is a reproductive process in which a parent organism produces genetically identical offspring.
Sexual reproduction involves the production of gametes by meiosis, followed by fertilization between genetically distinct parental gametes to produce genetically distinct offspring.
Reproduction in Prokaryotes
______, such as bacteria, have a ______, circular chromosome and no nucleus. They reproduce ______by ______the DNA and then distributing ______complete copy of the DNA into each of two ______cells. There are ______spindle fibres or centrioles, as in ______cells, that divide the nucleus by ______, nor is there a nuclear ______.
Conjugation is the ______of genetic material from one cell to another by ______contact through a bridging structure (______). This results in a single cell with new ______material. Neither ______, nor ______formationoccurs.
In ______reproduction, ______gametes that contain half the genetic material of the ______organism are formed by meiosis. Gametes unite in the process of ______and form a new ______organism that is______unique.
Asexual Reproduction
Budding is a form of ______reproduction in which a ______but miniature version of the parent grows out from the parents’ body. The new organism then ______to become on ______organism.
Plants can reproduce asexually via ______reproduction. In this process, a ______plant develops at the end of a ______, stem, or ______of the ______plant.
Another form of asexual reproduction is called ______. During this process a new plant develops from a ______(portion) of a parent plant, such as a ______leaf, tuber, or a cutting from the parent plant.
Both of these methods above result in a new plant that is genetically ______to its parent.
______is considered to be a form of asexual reproduction because the egg is ______fertilized by the male gamete. As such, it is the ______source of genetic material for the creation of an embryo. The resulting offspring is genetically ______to the parent.
A ______is a structure that contains genetic material and ______surrounded by a protective ______or wall. The wall protects the contents until conditions are ______, at which point the spore wall opens and the______begins to develop.
Because spores tend to be very ______, they are readily dispersed in ______and by the _____. Spores may be ______or ______, and not all spores are the product of ______reproduction. Whilesome organisms produce spores by ______, others produce spores by ______.
Alternation of Generations
The life cycle of plants consists of a ______generation and a ______generation that alternate. This is called the ______of generations.
Strictly speaking, the term “alternation of generations” refers to this alternation of diploid and haploid generations. This reproductivestrategy is found only in ______.
The ______generation of a plant is called the ______(spore-making body). Through the process of ______, the sporophyte produces one of more ______spores. These spores develop without fertilization. Each haploid spore grows into a plant body called the ______(gamete-making body). Gametophytes ______male and female gametes, which fuse at fertilization and develop into another ______. The cycle then repeats.
Three important features of these life cycles should be recognized, including:
one generation in the life cycle is ______and one is ______
the______organism produces spores via ______, which are haploid, that divide via ______to form a ______gametophyte
the haploid gametophyte divides via ______to produce haploid gametes, and undergoes ______to form a ______zygote, which divides mitotically to form a ______sporophyte organism.
Some animal life cycles, however, alternate between ______-reproducing and ______-reproducing phases in a process called the “alternation of ______cycles.”
Advantages and disadvantages of reproductive strategies
Sexual reproduction provides populations with a means of ______to a ______environment (some offspring, for example, may have a greater ability to resist ______or toxins in the environment or to take ______of newfood sources); ______among siblings may be ______if they are genetically ______; and pairing of homologous chromosomes and ______offer opportunities to replace or repair damaged chromosomes.
However, sexual reproduction requires the presence of a ______organism,may take more ______and ______than asexualreproduction, and offspring must often fend for ______in the environment after birth.
Asexual reproduction is often ______and requires ______energy than sexual reproduction; ______require the presence of a second parent organism; and because the daughter organism does not fully separate from the parentuntil it is capable of ______survival, asexual reproduction may increase chances of survival in some cases.
However, asexual reproduction ______allow for genetic variation (offspring are genetic ______of the ______).