TYPES OF FERTILISATION
EXTERNAL FERTILISATION-In external fertilisation the fusion of male and female gametes
takes place outside the body of the female.
Eg-frogs , fish etc.
INTERNAL FERTILISATION-In internal fertilisation the fusion of male gamete with the
female gamete takes place inside the body of the female.
Eg-cats , dogs etc.
Sexual reproduction is a process that creates a new organism by combining the genetic material of two
organisms. It occurs both in eukaryotes and prokaryotes: in multicellular eukaryote organisms, an
individual is created anew; in prokaryotes, the initial cell has additional or transformed genetic material. In a
process called genetic recombination, genetic material (DNA) originating from two different individuals
(parents) join up so that homologous sequences are aligned with each other, and this is followed by exchange of
genetic information. After the new recombinant chromosome is formed, it is passed on to progeny.
Sexual reproduction is the primary method of reproduction for the vast majority of macroscopic organisms,
including almost all animals and plants. The evolution of sexual reproduction is a major puzzle. The first
fossilized evidence of sexual reproduction in organisms such as eukaryotes is in the Steinem period, about 1 to
1.2 billion years ago. There are two main processes during sexual reproduction in eukaryotes: meiosis,
involving the halving of the number of chromosomes; and fertilization, involving the fusion of two gametes and
the restoration of the original number of chromosomes. During meiosis, the chromosomes of each pair usually
cross over to achieve homologous recombination
PARTS OF MALE REPRODUCTIVE SYSTEM
TESTES-There is a pair of testes which lie outside the body within the scrotum.They
produce a million of sperms.
VAS DEFERENS-Vas deferens are 2 in no.this duct connects each testes to the urethra.It
carries sperms to the urethra along with the secretion of reproductive glands .
URETHRA-The 2 vas deferens open into the urethra and pass through penis.
PENIS-Urethra leads to a muscular organ called penis.It is used to deliver semen into the
vagina of the female during mating.
SPERMS-Sperms are produced in millions by the testes.They are very small in size
PARTS OF FEMALE REPRODUCTIVE SYSTEM
OVARIES-There are 2 ovaries which are situated in the abdominal cavity.Each ovary
produces one mature ovum every month.
OVIDUCT-It joins the uterus with the ovary .It carries the ovum into the uterus.
UTERUS-The developmemt of the baby takes place inside it.The lower narrow part of the
uterus is called cervix.
VAGINA-The vagina receives the penis during sexual intercourse.The sperms are
discharged into the vagina.
DEVELOPMENT OF EMBRYO
During development cells and tissues undergo changes in pattern and form that employ a wider range of physical
mechanisms than at any other time in an organism's life. This book demonstrates how physics can be used to
analyze these biological phenomena. Written to be accessible to both biologists and physicists, major stages and
components of the biological development process are introduced and then analyzed from the viewpoint of
physics. The presentation of physical models requires no mathematics beyond basic calculus.
Demonstration of the power of a physics-based approach to the life sciences, accessible to both biologists and
Extensively illustrated in full-colour throughout
Describes more than two dozen physical models of developmental biological processes