Sexual Reproduction Notes


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Angler Fish-

Angler Fish Reproduction


Fertilization: the fusion of DNA from two sex cells called a __________ (a sperm or egg cell) creates the first single cell of new life.

  • The first cell of life is called a ____________.
  • If the sperm and egg are produced by the same individual it is called a _________________.

ex. earthworms

  • Sometimes the sex of an organisms can change AFTER they are born.

ex. ___________


Internal Fertilization vs. External Fertilization

External Fertilization: Sperm is deposited near eggs in water and __________ to fertilize the egg. Embryo develops ______________.

Common in __________ and amphibians


    1. ________ eggs and sperm are released
    2. water is required (also keeps egg from drying out)
    3. nutrients come from ________
    4. little parental care
    5. ________ survival rate

Internal Fertilization: Meeting of the sperm and egg occurs __________ the female species. Embryo can develop internally OR externally (shelled egg is ____________).

Common in reptiles, mammals and __________

    Oviparous organisms, including most insects, reptiles and all birds lay eggs that continue to develop after being laid, and ________ later.

    Viviparous organisms, including almost all mammals (such as whales, kangaroos and humans) bear their young ____________.

  • Characteristics:
    1. _______ eggs
    2. terrestial environment
    3. nutrients come from _____________
    4. much parental care
    5. ___________ survival rate


Feynman on Beauty- stay curious

Bird's Courtship behavior



somatic cell
sex cell
egg cell
sperm cell
internal fertilization
external fertilization

Essential Questions:

1. In what ways do creatures that reproduce by internal fertilization different from those who practice external fertilization? Be sure to include number of eggs, location of fertilization, where the offspring is located and degree of parental care.


2. Which animals undergo internal fertilization and which fertilize externally? Give three examples of each.


3. Why is fertilization between two different individuals superior to having offspring from a single parent.



Female Reproductive System

Female Reproductive Structures

Gametes (in this case ________) are produced by ovaries.

Oviducts (___________ tubes) serve as passageways from ovaries to uterus. Fertilization occurs here but fetal development occurs in the uterus.

The uterus is a muscular sack that sits on top of the bladder. It is here that _________ develop. The lining is shed during menstruation.

The cervix is muscular _____________ between uterus and vagina.

The vagina is a muscular canal that functions as a _________ canal. It opens between urethra and anus.

The ___________ genitalia of females are called the vulva.

The clitoris is ________________ to the penis in males; it contains erectile tissue. The external genetalia of the female and male look identical up to about 8 weeks.

Labia are folds of skin near the opening of the vagina. Labia majora are fleshy and covered with pubic hair. They are homologous with the ___________ in the male.

Hormones and the menstrual cycle

Estrogen is a hormone created in the _____________. It causes the development of ___________ sex characteristics. ex.

The menstrual cycle is a hormone-controlled monthly cycle in the human female. It lasts ______ days. During the menstrual cycle, an egg is released from an _________ at midcycle and the uterine lining thickens in preparation for possible pregnancy.

It is divided into four stages:

  1. follicle stage: the egg is _____________
  2. ____________: when the egg is released from the ovary
  3. corpus luteum stage: the remains of the _________ after the egg left.
  4. ______________: the monthly shedding of the lining

Only humans and other primates have a menstrual cycle. Other mammals have an estrous cycle which is marked by periodic changes in the females's sex organs and in the desire to mate.

  • Reproductive cycles in many vertebrates and invertebrates are related to changes in day length. Female humans are NOT in this category!

If the egg is unfertilized, ____________ occurs and the uterine lining is shed.

If the released egg is ____________, no menstration occurs.


  • Around age 45-50, the ovaries gradually stop responding to pituitary hormones (FSH, LH).
  • As a result, follicle production stops and the menstrual cycle __________.



oviducts (fallopian tubes)
menstrual cycle
follicle stage
corpus luteum
secondary sex characteristics

Essential Questions:

1. What are the functions of the ovaries?


2. What is the function of estrogen?


3. Trace the path of the unfertilized egg as it leaves the ovary.


4. What are the stages of the menstrual cycle?


Male Reproductive System

Male Reproductive Structures

Sperm is produced in the ____________.

    • The testes are located in the _________ ; a sac outside the body. Sperm require a __________ body temperature than the body core.

Sperm travels from the testes through the ________ deferens tube into the urethra and finally out through the penis

  • The urethra is a tube that carries ________ from the bladder to outside the body.
  • In males, the urethra also carries ________.

Semen- fluid added to the sperm to nourish and _________ the sperm for the journey! Only 1% of the semen is sperm!

  • The prostate gland produces a secretion that is basic in pH which neutralizes the acidity of the vagina (which is normally a pH of ______ to 4.5).
  • The seminal vesicles add _________ to feed the sperm and make up 60% of the volume of semen.
  • The cowpers gland (bulbourethral gland) produces a high pH fluid that neutralizes the acidity of the vagina and the __________ residue in the urethra.

An average male produces approximately 1,000 sperm/second (30 billion/year).

Each ejaculation should contain 200-300 million sperm. Sperm counts below 10 to 20 million per milliliter usually present fertility problems.


Testosterone is the hormone responsible for the development and function of the male reproductive tract. It is created in the ___________.

  • The formation of ___________ is stimulated by testosterone.
  • Testosterone promotes growth.
  • It also stimulates the development of ______________ sexual characteristics such as beard growth, ____________ of the voice, etc.



vas deferens
prostate gland
seminal vesicle
Cowper's gland
secondary sex characteristics

Essential Questions:

1. What are the functions of the testes?

2. What is the function of testosterone?

3. Trace the path of sperm as it leaves the testes.


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