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Chapter Menu
Lesson 1:Sexual Reproduction and Meiosis
Lesson 2: Plant Reproduction
Lesson 3: Animal Reproduction
Lesson 4: Asexual Reproduction
Click on a hyperlink to view the corresponding lesson.
sexual reproduction
egg
sperm
fertilization
zygote
3.1 Sexual Reproduction and Meiosis
meiosis
diploid
haploid
What is sexual reproduction?
• Reproduction in organisms produces new offspring.
• Sexual reproduction is the production of an offspring that results when the genetic materials from two different cells combine.
3.1 Sexual Reproduction and Meiosis
What is sexual reproduction? (cont.)
• Half the genetic material in sexual reproduction is contained in:
– an egg cell
– a sperm cell
• In a process called fertilization, the sperm and egg cells fuse together forming a zygote.
3.1 Sexual Reproduction and Meiosis
What is sexual reproduction? (cont.)
Advantages of Sexual Reproduction
• Genetic variation
– Variety of genetic traits in a population of the same species
– Can help a species survive changes in environmental conditions
3.1 Sexual Reproduction and Meiosis
Advantages of Sexual Reproduction (cont.)
• Selective breeding
– Male and female organisms with certain preferred traits are selected to be the parents of offspring with those preferred traits
– Produces groups of organisms with similar traits
– Reduces genetic variation
3.1 Sexual Reproduction and Meiosis
Disadvantages of Sexual Reproduction• Getting egg and sperm together for fertilization can
be difficult
• Time is needed for organisms to grow and develop before they can reproduce
3.1 Sexual Reproduction and Meiosis
Why is meiosis important?• Meiosis is cell division that produces sperm or eggs
from certain reproductive cells in an organism.
– Meiosis ensures that a species’ offspring inherit the correct chromosome number.
– Without meiosis, the chromosome number would double with each generation.
3.1 Sexual Reproduction and Meiosis
Maintaining Diploid Cells• A diploid cell in an organism contains pairs of homologous chromosomes
that equal the chromosome number of that organism’s species.
– A diploid human cell has 23 pairs of homologous chromosomes.
– Homologous chromosomes are similar, but not identical.
3.1 Sexual Reproduction and Meiosis
Creating Haploid Cells• A haploid cell contains one chromosome from each
homologous pair.
3.1 Sexual Reproduction and Meiosis
Phases of Meiosis I
3.1 Sexual Reproduction and Meiosis
Prophase I—Nuclear membrane breaks apart and chromosomes condense.
Metaphase I—Sister chromatids line up along the center of the cell. Cytoskeleton fibers attach to sister chromatids.
Phases of Meiosis I (cont.)
3.1 Sexual Reproduction and Meiosis
Telophase I—Nuclear membrane forms around each set of sister chromatids and the cytoplasm divides, forming two daughter cells.
Anaphase I—Sister chromatids move to opposite ends of the cell.
Phases of Meiosis II
3.1 Sexual Reproduction and Meiosis
Metaphase II—Chromosomes line up along the center of the cell.
Prophase II—Nuclear membrane breaks apart.
Phases of Meiosis II (cont.)
3.1 Sexual Reproduction and Meiosis
Anaphase II—Sister chromatids of each chromosome begin to separate and move to opposite ends of the cells.
Telophase II—A nuclear membrane forms around each set of chromatids, and the cytoplasm divides.
Comparison of Meiosis and Mitosis
3.1 Sexual Reproduction and Meiosis
Lesson 1 Review
What is the new cell that forms from fertilization called?
A sperm
B egg
C haploid
D zygote
3.1 Sexual Reproduction and Meiosis
Lesson 1 Review
How many chromosomes from each homologous pair does a haploid cell contain?
A one
B two
C three
D four
3.1 Sexual Reproduction and Meiosis
Lesson 1 Review
How many daughter cells are produced in meiosis?
A one
B two
C three
D four
3.1 Sexual Reproduction and Meiosis
End of Lesson 1
spore
pollen grain
ovule
seed
angiosperm
stamen
anther
3.2 Plant Reproduction
filament
pistil
stigma
style
ovary
pollen tube
fruit
What is alternation of generations?
– One generation has primarily diploid cells, the other generation has only haploid cells.
– Organisms that alternate between diploid and haploid generations have an alternation of generations.
• Some organisms, including plants, have two life stages called generations.
3.2 Plant Reproduction
What is alternation of generations? (cont.)
3.2 Plant Reproduction
How do seedless plants reproduce?• Seedless plants, such as mosses and ferns, grow
from haploid spores, not seeds.
– Haploid spores that grow by mitosis and cell division into haploid plants.
– Fertilization results in a diploid zygote that grows by mitosis and cell division into the diploid generation.
– The diploid generation produces haploid spores by meiosis, and the cycle repeats.
3.2 Plant Reproduction
How do seed plants reproduce?• Most of the land plants that cover Earth grew from
seeds—called seed plants.
– There are flowerless seed plants and flowering seed plants.
– The haploid generation is within diploid tissue.
– Separate diploid male and diploid female reproductive structures produce haploid sperm and haploid eggs.
3.2 Plant Reproduction
The Role of Pollen Grains• A pollen grain forms from tissue in a male
reproductive structure of a seed plant.
• Pollination occurs when pollen grains land on a female reproductive structure of a plant of the same species.
3.2 Plant Reproduction
The Role of Ovules and Seeds• The female reproductive structure of a seed plant
contains one or more ovules.
• After fertilization, a seed develops from the ovule.
3.2 Plant Reproduction
Flowerless Seed Plant Reproduction• In flowerless seed plants—gymnosperms— the seeds
are not surrounded by a fruit.
– Cones are the male and female reproductive structures of conifers.
– Male cones produce pollen grains.
– Female cones produce eggs.
– Seeds form as part of the female cone.
3.2 Plant Reproduction
Flowering Seed Plant Reproduction• Flowering seed plants—angiosperms—include most
of the plants you see.
3.2 Plant Reproduction
Seed Plants
• Fruits and vegetables come from flowering seed plants.
Reproduction and the Flower• A typical flower has male and female reproductive
organs surrounded by petals.
• The stamen is the male reproductive organ.
• Pollen grains form at the tip of the stamen, in the anther.
• The filament is a long stalk that supports the anther and connects it to the base of the flower.
3.2 Plant Reproduction
Reproduction and the Flower (cont.)
• The female reproductive organ of a flower is the pistil.
• Pollen can land at the tip of the pistil on the stigma, which is at the top of a long tube called the style.
• At the base of the style is an ovary containing one or more ovules which eventually will contain a haploid egg.
3.2 Plant Reproduction
Reproduction and the Flower (cont.)
3.2 Plant Reproduction
An Angiosperm’s Cycle 3.2 Plant Reproduction
Fruit and Seed Dispersal• Fruits and seed are important sources of food for
people and animals.
• Fruits and seeds can be dispersed by:
– Air currents
– Animals
– Water
– Gravity
3.2 Plant Reproduction
What is the life cycle of a simple plant?
Lesson 2 Review
In alternation of generations, the haploid structures of the diploid generation produces daughter cells called what?
A zygotes
B spores
C pollen
D seeds
3.2 Plant Reproduction
Lesson 2 Review
What is an immature diploid plant that develops from the zygote of a seed plant called?
A embryo
B seed
C fruit
D stigma
3.2 Plant Reproduction
Lesson 2 Review
What is another name for a flowering seed plant?
A zygote
B conifer
C gymnosperm
D angiosperm
3.2 Plant Reproduction
End of Lesson 2
gonad
testes
ovary
metamorphosis
3.3 Animal Reproduction
– Ovaries are female gonads that produce egg cells.
Animal Reproductive Organs• Gonads are specialized organs that produce sperm or
eggs.
– Testes are male gonads that contain a network of coiled tubes in which sperm cells form.
3.3 Animal Reproduction
Internal Fertilization• Internal fertilization happens inside the body of an
organism.
– Internal fertilization ensures that an embryo is protected and nourished until it leaves the female’s body.
3.3 Animal Reproduction
• Examples
– Earthworms, spiders, insects, reptiles, birds, and mammals
External Fertilization• External fertilization occurs in the environment,
outside of an animal’s body.
– Most animals that reproduce using external fertilization do not care for the eggs or young.
3.3 Animal Reproduction
• Examples
– Jellyfishes, clams, sea urchins, sea stars, many fish species, and amphibians
External Embryo Development• Animals whose embryos develop outside the mother are usually protected inside
an egg.
3.3 Animal Reproduction
Metamorphosis• A developmental process in which the form of the body
changes as an animal grows from egg to adult
3.3 Animal Reproduction
Internal Development• The embryos of some animals, including most
mammals, develop inside the mother.
– A tissue or organ transfers nourishment from the mother to the embryo.
– Other embryos—some snakes, insects, and fishes—develop in an egg with a yolk inside the mother.
3.3 Animal Reproduction
Gestation• Gestation is the length of time between fertilization
and the birth of an animal.
• Gestation varies by species and usually relates to the size of the animal at birth—smaller animals have shorter gestation.
3.3 Animal Reproduction
Lesson 3 Review
Where are sperm formed in male animals?
A eggs
B ovaries
C testis
D glands
3.3 Animal Reproduction
Lesson 3 Review
How is the embryo in an egg nourished?
A the outer covering
B an organ transfers nourishment from the mother
C fluid produced in glands near the testes
D the yolk
3.3 Animal Reproduction
Lesson 3 Review
What is the developmental process in which the form of the body changes as an animal grows from egg to adult?
A metamorphosis
B gestation
C fertilization
D internal development
3.3 Animal Reproduction
End of Lesson 3
asexual reproduction
fission
budding
regeneration
cloning
3.4 Asexual Reproduction
Asexual Reproduction• The production of offspring by one parent without a
sperm and an egg joining
• Results in offspring that are genetically identical to the parent organism
3.4 Asexual Reproduction
Advantages of Asexual Reproduction• No time or energy expended finding
a mate.
• Less time to produce offspring
• Parent and offspring are genetically identical—equally well-adapted to the same environmental conditions.
3.4 Asexual Reproduction
Disadvantages of Asexual Reproduction
• Lack of genetic variation.
• Harmful mutations in the cells of an organism will be passed to offspring
3.4 Asexual Reproduction
Types of Asexual Reproduction• Prokaryotes reproduce asexually by cell division
that does not involve mitosis.
• Eukaryotes reproduce asexually by mitosis and cell division.
3.4 Asexual Reproduction
Fission• Bacteria reproduce by a process called fission which
produces two genetically identical cells very rapidly.
3.4 Asexual Reproduction
Mitotic Cell Division• Some single-celled eukaryotes reproduce by mitotic cell
division—mitosis followed by cell division.
– Produces two identical cells.
– Each cell is an organism.
3.4 Asexual Reproduction
Budding• Asexual reproduction in which a new organism
forms on the parent organism
• The new organism—a bud—forms by mitosis and cell division, and eventually separates from the parent
• Example
– Some single-cell (yeast) and multicellular eukaryotes (hydra)
3.4 Asexual Reproduction
Plant Cuttings• If you cut a green stem from a houseplant and put it in
water, roots and leaves can grow, producing a new plant.
• Some plants propagate themselves asexually.
• Examples
– Strawberry plants and kalanchoe plants
3.4 Asexual Reproduction
Animal Regeneration• Some animals have cells that can change into
other cell types.
• Regeneration is asexual reproduction that produces new animals from pieces of an animal’s body.
• Regeneration is sometimes used to describe growth that replaces a missing part of an animal.
3.4 Asexual Reproduction
What is cloning?• Cloning refers to a method of asexual reproduction
developed by scientists and performed in laboratories.
• Cloning produces identical individuals from a cell or cells taken from a multicellular organism.
3.4 Asexual Reproduction
Plant Cloning
3.4 Asexual Reproduction
Animal Cloning• The first animal to be successfully cloned was a sheep
named Dolly, in 1996
3.4 Asexual Reproduction
Lesson 4 Review
What type of asexual reproduction involves reproduction by cell division only?
A fission
B budding
C regeneration
D cloning
3.4 Asexual Reproduction
Lesson 4 Review
What type of asexual reproduction involves a new organism forming on the parent organism?
A mitotic cell division
B cloning
C regeneration
D budding
3.4 Asexual Reproduction
Lesson 4 Review
What type of asexual reproduction involves producing a new animal from pieces of an animal’s body?
A plant cuttings
B cloning
C regeneration
D budding
3.4 Asexual Reproduction
End of Lesson 4
Chapter Assessment
California Standards Practice
Concepts in Motion
Image Bank
Science Online
Chapter Resources Menu
Click on a hyperlink to view the corresponding feature.
What is the name for the process of a sperm cell and an egg cell fusing together?
A sexual reproduction
B fertilization
C meiosis
D pollination
Chapter Assessment 1
What is one advantage of sexual reproduction?
A produces many offspring
B offspring are genetically identical
C offspring have more genetic variation
D can produce offspring quickly
Chapter Assessment 2
Where are pollen grains formed?
A anther
B ovule
C testes
D pollen tube
Chapter Assessment 3
What are animal reproductive organs called?
A zygotes
B gonads
C embryos
D buds
Chapter Assessment 4
What is not an advantage of asexual reproduction?
A organism does not have to spend time and energy finding a mate
B can produce a number of offspring faster than with sexual reproduction
C offspring have more genetic variation
D parent and offspring are equally welladapted to the same environmental conditions
Chapter Assessment 5
What type of organism can reproduce asexually by regeneration?
A human
B sea star
C bacterium
D yeast
CA Standards Practice 1
SCI 2.a
What flower structure becomes fruit surrounding the seed?
A stamen
B pollen tube
C ovary
D pistel
CA Standards Practice 2
SCI 2.a
What term describes the development of a ladybug larva to an adult ladybug?
A alternation of generations
B asexual reproduction
C metamorphosis
D mitotic cell division
CA Standards Practice 3
SCI 2.a
What type of seed plant does not produce flowers?
A seedless plants
B gymnosperms
C angiosperms
D strawberry plants
CA Standards Practice 4
SCI 2.a
How many times does division of the nucleus and cytokinesis happen in meiosis?
A one
B two
C three
D four
CA Standards Practice 5
SCI 2.a
Concepts in Motion 1
Concepts in Motion 2
Image Bank
End of Resources