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Life Science: 7th Grade: Chapter 3

___ ___ combines genetic material from two different parent cells. Sexual reproduction
Sexual reproduction creates ___ ___, which helps populations survive changing environmental conditions and disease. genetic variation
The major disadvantages of sexual reproduction are the need to get ___ and ___ together, and the time needed for organisms to reach an age when they can reproduce. egg, sperm
___ is cell division that produces sperm or egg cells in sexually reproducing organisms. Meiosis
Meiosis ensures that a species’ offspring inherit the correct number of ___. chromosomes
Meiosis produces ___ sperm and egg cells, which combine to form a diploid zygote. haploid
Prophase I: Nuclear membranes break apart and pairs of replicated ___ line upclose to each other. chromosomes
Metaphase I: Pairs of chromosomes line up along the middle of the cell, and fibers attach to each pair of ___ ___. sister chromatids
Anaphase I: Sister chromatids move to ___ ends of the cell. opposite
Telophase I: Nuclear membranes form and ___ divides, producing two cells. cytoplasm
Prophase II: Chromosomes do not ___ before nuclear membrane breaks apart. replicate
Metaphase II: ___ line up along the center of the cell. Chromosomes
Anaphase II: Sister ___ separate, moving to opposite ends of the cell. chromatids
Telophase II: Nuclear ___ reform and the cytoplasm divides. membranes
Meiosis results in ___ haploid nuclei from one diploid nucleus. four
Meiosis I produces two ___ different cells. genetically
Meiosis II produces two ___ haploid cells from each cell produced in meiosis I. identical
Organisms such as plants that alternate between diploid and haploid stages have alternation of ___. generations
In seedless plants, the ___ generation lives on its own. haploid
In seed plants, the haploid generation lives within ___ tissue. diploid
Seedless plants, such as moss and ferns, grow from haploid ___, not seeds. spores
Spores grow by mitosis and cell division to form ___ plants. haploid
___ results in a diploid zygote that grows by mitosis and cell division into the tiny diploid generation. Fertilization
Sperm cells form inside a hard, protective structure called a ___ ___. pollen grain
Egg cells form inside a female reproductive structure called an ___. ovary
In ___, pollen grains from the male structure reach the female structure. pollination
When sperm enters the ___, fertilization occurs, and a seed develops. ovule
A seed consists of an ___, food supply, and protective covering. embryo
Male cones produce pollen grains and female cones produce ___. eggs
Seeds form as part of the ___ cone female
The flower’s male reproductive organ is the ___; the female organ is the pistil. stamen
Pollen grains form in the ___ at the stamen’s tip. anther
The ___ is a long stalk that connects the anther to the base of the flower. filament
The pollen grains land on the pistil’s ___, which is at the top of a long tube called the style. stigma
A ___ ___ grows from the pollen grain into the stigma, down the style, to the ovary, where fertilization occurs. pollen tube
Each ovule and its embryo will become a ___. seed
The ___ of the plant protects the seed and helps with seed dispersal. fruit
Separate male and female organisms have reproductive organs called ___. gonads
Male gonads called ___ produce sperm testes
Female gonads called ___ produce eggs. ovaries
___ ___ takes place inside the body of an organism. Internal fertilization
Males deposit ___ in or near the female’s reproductive system. sperm
Animals that use ___ ___ usually protect their eggs during development. internal fertilization
___ ___ takes place outside the organism’s body. External fertilization
During external fertilization, the female usually releases ___ into water when the male releases sperm. eggs
Most animals that use external fertilization do not ___ their eggs or care for theiryoung. protect
Embryo development in most animals occurs ___ the mother, in an egg surrounded by aprotective covering. outside
In ___, an animal goes through several stages of development. metamorphosis
Embryos that develop inside the mother get nourishment in ___ different ways. two
Some develop inside an egg with a ___ within the mother’s body, until they hatch and leave the mother’s body. yolk
Others, including those of most ___, get nourishment directly from the mother. mammals
___ ___ produces offspring from a single parent that is identical to the parent organism. Asexual reproduction
Asexual reproduction takes less time and energy than sexual reproduction, and organisms well-adapted to the environment always produce well-adapted ___. offspring
Lack of genetic variation makes populations more susceptible to disease, changes in theenvironment, and harmful ___. mutations
Bacteria, which have no nucleus, reproduce by ___, or producing two identical cells. fission
Some single-celled eukaryotes reproduce by ___, followed by cell division. mitosis
Yeast reproduces by ___, in which a new organism forms on the parent. budding
Many plants can reproduce from ___, in addition to reproducing sexually. cuttings
___ produces a new organism from part of an animal’s body. Regeneration can also mean regrowth of a missing animal part. Regeneration
Scientists can ___ plants to produce identical plants with desirable genetic traits. clone
Animals can be cloned in the laboratory, but they are often not as ___. healthy
Created by: jnosik