Reproduction

What is reproduction?

Reproduction is the process by which biological organisms produce new individual offspring. It is also known as "breeding".

What are the two main types of reproduction?

The two main types are asexual and sexual reproduction.

What is asexual reproduction?

An organism can reproduce without the involvement of another organism. It involves only one parent. The offspring are genetically identical to the parent, or "clones".

What are some advantages of asexual reproduction?

It is quick and easy, even in harsh climates where sexual reproduction may not be possible.

What is a disadvantage of asexual reproduction?

It does not allow for genetic adaptation or evolution in response to the environment.

What are some methods of asexual reproduction in plants?

Methods include tubers, bulbs, rhizomes, runners, root suckers, plantlets, cloning, and cutting.

What is a tuber?

A tuber is a swollen part of a stem that can grow into a new plant. An example is a potato.

What is a runner?

A runner, or stolon, is a horizontal stem that roots and forms new plantlets.

What is sexual reproduction?

Sexual reproduction requires the sexual interaction of the specialized organs of an organism. It is advantageous because it permits for genetic variation.

What is a disadvantage of sexual reproduction?

It costs the plant a lot of time, energy, and resources. It also decreases the likelihood of a new plant being produced due to outside factors.

What are gametes?

Gametes are the specialized reproductive cells. They are also called sperm (male) and eggs (female).

What is fertilization?

Fertilization is when a sperm from a male enters and fertilizes an egg from a female.

What is a zygote?

A new cell created after fertilization that is the offspring of the two parent cells. The zygote is the first cell of a new organism.

What is an embryo?

The zygote is called an embryo from implantation to 8 weeks of development.

What is a fetus?

After 8 weeks of development, the embryo is known as a fetus.

What are some examples of hermaphrodites?

Snails and flatworms are hermaphrodites, meaning they have both male and female organs.

Human Reproductive System

What does the reproductive system consist of in both males and females?

The reproductive system consists of primary and secondary sex organs and sex glands.

What is the primary function of the reproductive systems?

The primary function is to perpetuate the species through sexual or germ cell fertilization and reproduction.

What is the female gamete (sex cell)?

The female gamete is the egg, or ovum.

What are the female reproductive organs?

The organs are the vagina, cervix, uterus, fallopian tubes, and ovaries.

What are ovaries?

They are small organs on the ends of the fallopian tubes that produce and release eggs. They are about the size of a large olive.

How many eggs are females born with?

Females are born with all of the eggs they will ever produce.

What are follicles?

Each ovary is filled with egg-containing sacs called follicles.

How often do ovaries release eggs?

Ovaries alternate the release of eggs each month.

What is ovulation?

Ovulation is the release of the ova.

What are fallopian tubes?

Also called oviducts, these are two tubes that connect the uterus with the ovaries. They carry egg cells toward the uterus and sperm cells toward the egg cell.

How big are the fallopian tubes?

They are about 10 cm long and 0.25 cm in diameter (the size of a cooked spaghetti noodle).

Where does fertilization take place?

Fertilization takes place in the upper third of the oviduct.

What is the uterus?

A hollow, fist-sized muscular organ located between the bladder and rectum. It is lined with endometrium, a blood lining.

What are the three functions of the uterus?

The three functions are: the endometrium sheds its lining every 21 to 40 days by menstruation; it provides protection and nourishment for the fetus during pregnancy; and it contracts during labor to expel the fetus.

What is the endometrium?

The mucous lining of the uterus.

How much can the uterus stretch?

The walls of the uterus have the ability to stretch to the size of a small watermelon.

What is the cervix?

The lower portion of the uterus, where the vagina and uterus meet. It is the neck or opening of the uterus. It is normally plugged with mucus and stays tightly closed during pregnancy, but thins and opens for delivery.

What is the vagina?

Also called the birth canal, a tube leading from the uterus to the outside of the body. It is an empty passageway that is about 8 cm long but can expand in length and width.

What is the male gamete?

The male gamete is the sperm.

What are the male reproductive organs?

The organs are the testes, scrotum, sperm duct (vas deferens), and penis.

What are testes (testicles)?

They are small organs that lie in the scrotum and produce sperm and the hormone testosterone. They are the male sex gland and the counterpart to the female ovary.

Why are the testes located outside the body?

The sperm manufactured in the testes need a cooler-than-body temperature for normal growth and development.

How many sperm cells are produced each month?

Four to five billion sperm cells are produced each month.

What is the scrotum?

A sac-like pouch located behind the penis that holds the testes and helps regulate their temperature for sperm production.

What is the sperm duct?

Also called the vas deferens, it transports sperm from the testes to the urethra during ejaculation. It also stores sperm before ejaculation and allows for them to mature.

What is the penis?

The penis releases semen containing sperm during ejaculation.

What is semen?

Semen is a fluid that helps sperm move through the urethra.

What are sperm?

The microscopic cells produced by the male's testicles that can fertilize the female's ovum. They are tiny, living cells that are 100 times smaller than a pencil dot.

What is the epididymis?

The structure that forms a mass over the back and upper part of each testes where sperm are stored for up to six weeks while they ripen to maturity.

Menstrual Cycle

How long does the menstrual cycle typically last?

The menstrual cycle typically lasts 28 days.

What marks the beginning of menstruation?

The beginning of a period is marked by the release of blood and lining from the inside of the uterus.

What is menstruation?

The flow of blood that typically lasts 3-7 days.

What happens after menstruation?

The ovaries release hormones that tell the uterus to grow a new lining and prepare to receive a new egg.

When does ovulation occur?

Ovulation occurs about halfway through a woman's cycle.

What happens if the egg is not fertilized?

If it is not fertilized, it breaks down and is released with the lining and blood of the uterus.

What happens on Day 26 of the cycle if there is no fertilization?

Estrogen and progesterone levels drop and the endometrium lining breaks down.

What happens on Day 28 of the cycle?

Menstruation begins again.

Plant Reproductive System

What are the male organs of a flower?

The male organs are the stamen, which consists of the anther and the filament.

What is the anther?

The anther produces sperm nuclei, which are enclosed by pollen grains.

What is the filament?

The filament holds the anther up.

What are the female organs of a flower?

The female organs are the pistil, which consists of the stigma, style, and ovary.

What is the stigma?

The stigma is the sticky surface at the top of the pistil where pollen sticks.

What is the ovary?

The ovary contains the ovules (eggs).

What does the ovule form after fertilization?

The ovule forms the seed.

What does the ovary form after fertilization?

The ovary forms the fruit.