Transcript Unit V Anatomy and Physiology

Unit V
Anatomy and Physiology
Learning Goal 5
Analyze patterns of growth,
development and reproduction in
plants, animals, and humans
Plant Reproduction
• Alternation of
Generations
Division of a plant life
cycle into a diploid,
spore-producing
generation and a
haploid, gameteproducing generation.
• Bryophytes (mosses
and liverworts)
Gametophyte is larger
than the sporophyte
which grows out of it.
• Ferns
Gametophyte is much
smaller than the
sporophyte and is
free-living for much of
its lifespan and
nourishes itself
through
photosynthesis.
• Angiosperms
Gametophytes are small
structures that are
retained inside the
sporophyte.
Female gametophytes
are embedded in floral
tissues.
Male gametophytes are
released into the
environment as pollen
grains.
•
Flower Structure
Flowers develop from the end of a
floral shoot called a receptacle.
Tissues of the receptacle differentiate
into four whorls:
The calyx is the outermost whorl and
is made up of leaflike sepals.
The corolla includes the petals.
The stamens in which male
gametophytes form. They consist of
filaments topped by anthers in which
pollen forms.
The innermost whorl is the carpel in
which female gametophytes form. It
consists of an ovary with one or more
ovules in which eggs develop and
fertilization takes place.
•
Flower Classifications
Complete flowers – contain all four
whorls.
Incomplete flowers – lack one or
more of the whorls.
Perfect flowers – have both kinds
of sexual parts.
Imperfect flowers – have stamens
or carpels but not both.
Monoecious - each plant has
some male flowers with only
stamens and some female flowers
with only carpels.
Dioecious – a given plant
produces flowers having only
stamens or only carpels.
• Pollination, Fertilization, and
Germination
Pollination – pollen makes
contact with the stigma of a
flower.
Fertilization – sperm from the
pollen grain moves down to
the ovary via a pollen tube
where it fuses with the egg to
create an embryo located
within a seed. Seeds are
protected in a fruit which is
mature ovary.
Germination – the seed
sprouts and develops into a
mature sporophyte.
• Asexual
Reproduction in
Flowering Plants
Fragmentation – cells in a
piece of the parent plant
dedifferentiate and regenerate
missing plant parts.
Apomixis – a diploid embryo
develops from an unfertilized
egg.
Cloning – Genetically identical
plants develop from the
underground stems of parent
plants.
Plant Development
• Plant Hormones
Auxins – stimulate plant growth by promoting cell elongation .
Gibberellins – promote lengthening of plant stems by stimulating
both cell division and cell elongation.
Cytokinins – play a major role in stimulating cell division in rapidly
dividing meristem tissues of root and shoot tips.
Ethylene – a gas given off by plants that plays a role in regulating
plant responses such as dormancy of seeds and buds, seedling
growth, stem elongation, fruit ripening, and separation of fruits,
leaves and flowers from the plant body.
Brassinosteroids – regulate the expression of genes associated
with a plant’s growth responses to light.
Abscisic Acid – inhibits growth in response to environmental cues
such as lack of water.
Jasmonates and Oligosaccharins – help protect plants against
pathogens and predators.
Animal Reproduction
Asexual Reproduction
Produces offspring with genes from only one individual.
One to many cells of a parent’s body develop directly
into a new individual.
Produces genetically identical offspring which can be an
advantage in stable environments. It is rapid and can
produce large numbers of offspring.
Occurs in many aquatic invertebrates and some
terrestrial annelids and insects. Rare among
vertebrates.
• Types of Asexual
Reproduction
Fission – the parent separates
into two or more offspring of
approximately equal size.
Budding – a new individual grow
and develops while attached to
the parent.
Fragmentation – pieces separate
from the parent’s body and
develop into new individuals.
Parthenogenesis – offspring
produced by the growth and
development of an egg without
fertilization.
• Sexual Reproduction
Offspring produced as a
result of the union
between sperm and egg
cells of two parents.
Main advantage is
generation of genetic
diversity among offspring
which is better in a
changing environment.
• Gametogenesis
Production of
gametes from germ
cells.
Germ cells divide by
meiosis to produced
haploid gametes.
• Spermatogenesis
Produces haploid
sperm cells by the
process of meiosis.
Spermatogonia
produced from male
germ cells divide into
four functioning
sperm cells.
• Oogenesis
Oogonia produced
from female germ
cells divide by
meiosis to produce
one functioning egg
cell and three
nonfunctioning polar
bodies.
• Fertilization
External – occurs in most
aquatic invertebrates, bony
fishes and amphibians. Sperm
and eggs are shed into the
surrounding water.
Internal – takes place in
invertebrates such as annelids,
some arthropods,and some
mollusks, and all terrestrial
vertebrates. Eggs must be
fertilized within the body of the
female.
• Development
Oviparous – Embryos
develop in an egg outside
the body of the female.
Ovoviviparous –
Embryos develop within
eggs inside the body of
the female, hatch, and
are born live.
Viviparous – Embryos
develop and are
nourished within the body
of the female.
•
Embryonic Development
Cleavage – first mitotic divisions
in the zygote that form a ball of
cells called a morula, followed by
a blastula, a ball of smaller and
smaller cells called blastomeres
Gastrulation – produces and
embryo with three distinct tissue
layers, the ectoderm, mesoderm,
and endoderm.
Organogenesis – the process by
which the ectoderm, mesoderm,
and endoderm develop into
organs.
Apoptosis – programmed cell
death that eliminates tissues no
longer required.