Download 3.2 Plant Reproduction

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Lesson 1: Sexual Reproduction
and Meiosis
Lesson 2: Plant Reproduction
Lesson 3: Animal Reproduction
Lesson 4: Asexual Reproduction
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3.1 Sexual Reproduction and Meiosis
sexual reproduction
meiosis
egg
diploid
sperm
haploid
fertilization
zygote
3.1 Sexual Reproduction and Meiosis
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.
What is sexual reproduction? (cont.)
3.1 Sexual Reproduction and Meiosis
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
• Selective breeding
(cont.)
– 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
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.
3.1 Sexual Reproduction and Meiosis
Phases of Meiosis I (cont.)
Anaphase I—Sister
chromatids move to
opposite ends of the
cell.
Telophase I—Nuclear
membrane forms
around each set of
sister chromatids and
the cytoplasm divides,
forming two daughter cells.
3.1 Sexual Reproduction and Meiosis
Phases of Meiosis II
Prophase II—
Nuclear membrane
breaks apart.
Metaphase II—
Chromosomes line
up along the center
of the cell.
3.1 Sexual Reproduction and Meiosis
Phases of Meiosis II (cont.)
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.
3.1 Sexual Reproduction and Meiosis
3.1 Sexual Reproduction and Meiosis
What is the new cell that forms
from fertilization called?
A sperm
B egg
C haploid
D zygote
3.1 Sexual Reproduction and Meiosis
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
How many daughter cells are
produced in meiosis?
A one
B two
C three
D four
3.2 Plant Reproduction
spore
filament
pollen grain
pistil
ovule
stigma
seed
style
angiosperm
ovary
stamen
pollen tube
anther
fruit
3.2 Plant Reproduction
What is alternation of generations?
• Some organisms, including plants, have
two life stages called 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.
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.
• Fruits and vegetables come from flowering
seed plants.
Seed Plants
3.2 Plant Reproduction
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.)
An Angiosperm’s Cycle
3.2 Plant Reproduction
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
What is the life cycle
of a simple plant?
3.2 Plant Reproduction
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
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
What is another name for a flowering
seed plant?
A zygote
B conifer
C gymnosperm
D angiosperm
3.3 Animal Reproduction
gonad
testes
ovary
metamorphosis
3.3 Animal Reproduction
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.
– Ovaries are female
gonads that
produce egg cells.
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.
• Examples
– Earthworms, spiders, insects, reptiles,
birds, and mammals
3.3 Animal Reproduction
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.
• Examples
– Jellyfishes, clams, sea urchins, sea
stars, many fish species, and
amphibians
3.3 Animal Reproduction
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
Where are sperm formed in
male animals?
A eggs
B ovaries
C testis
D glands
3.3 Animal Reproduction
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
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
3.4 Asexual Reproduction
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
What type of asexual reproduction
involves reproduction by cell
division only?
A fission
B budding
C regeneration
D cloning
3.4 Asexual Reproduction
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
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
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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
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
Where are pollen grains formed?
A anther
B ovule
C testes
D pollen tube
What are animal reproductive organs
called?
A zygotes
B gonads
C embryos
D buds
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 well
adapted to the same environmental
conditions
SCI 2.a
What type of organism can
reproduce asexually by
regeneration?
A human
B sea star
C bacterium
D yeast
SCI 2.a
What flower structure becomes fruit
surrounding the seed?
A stamen
B pollen tube
C ovary
D pistel
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
SCI 2.a
What type of seed plant does not
produce flowers?
A seedless plants
B gymnosperms
C angiosperms
D strawberry plants
SCI 2.a
How many times does division of the
nucleus and cytokinesis happen in
meiosis?
A one
B two
C three
D four
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