fertilization

Examples of fertilization in the following topics:

• External and Internal Fertilization

  • After the sperm reaches the egg, fertilization can then take place.
  • External fertilization in an aquatic environment protects the eggs from drying out.
  • Internal fertilization has the advantage of protecting the fertilized egg from dehydration on land.
  • Internal fertilization also enhances the fertilization of eggs by a specific male.
  • The anemone fish utilizes a form of external fertilization.

• Double Fertilization in Plants

  • Angiosperms undergo two fertilization events where a zygote and endosperm are both formed.
  • Together, these two fertilization events in angiosperms are known as double fertilization .
  • After fertilization is complete, no other sperm can enter.
  • After fertilization, embryonic development begins.
  • This is called a double fertilization.

• Fertilization

  • In fertilization, the sperm binds to the egg, allowing their membranes to fuse and the sperm to transfer its nucleus into the egg.
  • Fertilization is the process in which gametes (an egg and sperm) fuse to form a zygote.
  • The egg and sperm are haploid, which means they each contain one set of chromosomes; upon fertilization, they will combine their genetic material to form a zygote that is diploid, having two sets of chromosomes.
  • To ensure that no more than one sperm fertilizes the egg, once the acrosomal reactions take place at one location of the egg membrane, the egg releases proteins in other locations to prevent other sperm from fusing with the egg.
  • (a) Fertilization is the process in which sperm and egg fuse to form a zygote.

• Infertility

  • Other factors that affect fertility include toxins (such as cadmium), tobacco smoking, marijuana use, gonadal injuries, and aging.
  • Eggs are obtained from the woman after extensive hormonal treatments that prepare mature eggs for fertilization and prepare the uterus for implantation of the fertilized egg.
  • If fertilization is not accomplished by simple IVF, a procedure known as intracytoplasmic sperm injection (ICSI) can be used to inject the sperm into an egg .
  • IVF procedures produce a surplus of fertilized eggs and embryos that can be frozen and stored for future use; the procedures can also result in multiple births.
  • A sperm is inserted into an egg for fertilization during intracytoplasmic sperm injection (ICSI).

• Life Cycle of a Conifer

  • Conifers are monoecious plants that produce both male and female cones, each making the necessary gametes used for fertilization.
  • At fertilization, one of the sperm cells will finally unite its haploid nucleus with the haploid nucleus of an egg cell.
  • Upon fertilization, the diploid egg will give rise to the embryo, which is enclosed in a seed coat of tissue from the parent plant.
  • Fertilization and seed development is a long process in pine trees: it may take up to two years after pollination.
  • Pollen from male cones moves up into upper branches where it fertilizes female cones.

• The Biological Species Concept

  • A species is defined as a group of individuals that, in nature, are able to mate and produce viable, fertile offspring.
  • A species is a group of individual organisms that interbreed and produce fertile, viable offspring.
  • According to this definition, one species is distinguished from another when, in nature, it is not possible for matings between individuals from each species to produce fertile offspring.
  • If humans were to artificially intervene and fertilize the egg of a bald eagle with the sperm of an African fish eagle and a chick did hatch, that offspring, called a hybrid (a cross between two species), would probably be infertile: unable to successfully reproduce after it reached maturity.

• Contraception and Birth Control

  • Strictly speaking, contraception aims to prevent the sperm and egg from joining, while birth control can refer to methods used to prevent a fertilized egg from developing into a fetus.
  • Barrier methods such as condoms, cervical caps, and diaphragms serve to block sperm from entering the uterus, thereby preventing fertilization.
  • IUDs are inserted into the uterus where they establish an inflammatory condition that prevents fertilized eggs from implanting into the uterine wall .
  • These changes give a general indication of when intercourse is more or less likely to result in fertilization.
  • This inflammation prevents a fertilized egg from implanting in the uterine wall.

• Angsiosperm Fruit

  • A fertilized, fully grown, and ripened ovary containing a seed forms what we know as fruit, important seed dispersal agents for plants.
  • In botany, a fertilized, fully-grown, and ripened ovary is a fruit.

• Methods of Reproducing

  • During sexual reproduction, the male gamete (sperm) may be placed inside the female's body for internal fertilization, or the sperm and eggs may be released into the environment for external fertilization.
  • Following a mating dance, the female seahorse lays eggs in the male seahorse's abdominal brood pouch where they are fertilized.
  • Female seahorses produce eggs for reproduction that are then fertilized by the male.

• The Phosphorus Cycle

  • Excess phosphorus and nitrogen that enters these ecosystems from fertilizer runoff and from sewage causes excessive growth of microorganisms and depletes the dissolved oxygen, which leads to the death of many ecosystem fauna, such as shellfish and finfish.
  • One of the worst dead zones is off the coast of the United States in the Gulf of Mexico, where fertilizer runoff from the Mississippi River basin has created a dead zone of over 8,463 square miles.
  • Phosphate and nitrate runoff from fertilizers also negatively affect several lake and bay ecosystems, including the Chesapeake Bay in the eastern United States, which was one of the first ecosystems to have identified dead zones.
  • Dead zones occur when phosphorus and nitrogen from fertilizers cause excessive growth of microorganisms, which depletes oxygen, killing flora and fauna.