Living Environment Final Exam Review - Unit 5

Unit 5 Review

types of reproduction

• asexual reproduction and sexual reproduction

• species transcend individual life spans through reproduction

asexual reproduction

• # parents: 1

• genetic comparison w/ parents: genetically identical

• amount of genetic variation in the offspring: no variation

• advantages: fast, offspring are clones

• disadvantages: everyone is the same - a change in the environment can wipe out an entire population

sexual reproduction

• # parents: 2

• genetic comparison w/ parents: not genetically identical

• amount of genetic variation in the offspring: lots of variation

• advantages: increased chances of species survival due to increased variation in the population

• disadvantages: none

types of cell division

• mitosis

• meiosis

mitosis

• uses: growth, repair/replace damaged tissue, asexual reproduction

• type of starting cell: diploid (2n)

• # of divisions: 1

• # of ending cells: 2

• # of human chromosomes: 46

• type of ending cells: diploid (2n)

• amount of genetic variation in ending cells: none - cells are identical

• other: aka cloning

meiosis

• uses: making the egg and sperm (gametes)

• type of starting cell: diploid (2n)

• # of divisions: 2

• # of ending cells: 4

• # of human chromosomes: 23

• type of ending cells: haploid (n)

• amount of genetic variation in ending cells: lots - due to sorting of chromosomes & crossing over, chromosome # cut in half

• other: crossing over occurs, creating genetic variation in the gametes (male gamete = sperm, female gamete = egg)

embryo development

1. meiosis results in the production of eggs (female gametes) and sperm (male gametes)

2. the sex cell contains half of the genetic information from each parent and are haploid cells (n)

3. during fertilization, gametes join together to form a zygote which contains a complete set of genetic information for the offspring - the fertilized egg is diploid (2n) - all cells that descend from the zygote receive the same set of chromosomes as this cell

4. once fertilization occurs, then mitosis occurs as the embryo begins to grow and develop

5. differentiation occurs - stem cells in the embryo (cells with no specific function) begin to specialize and take on specific functions (ex. become muscle cells, skin cells, etc.)

6. once the cells begin to take on their specific roles and functions, tissues will form and organs will begin to develop (development is influence by factors such as combinations of genes, which genes are turned on and off, cell location, and environmental factors both internal and external)

human reproduction

• the human female reproductive system is responsible for producing gametes in the ovaries, allowing for internal fertilization, supporting the development of the embryo and the fetus in the uterus, and providing essential materials through the placenta and nutrition through milk for the newborn

• the human male reproductive system is responsible for producing gametes in testes and making possible the delivery of these gametes for fertilization

parts of the female reproductive system

• fallopian tube

• ovary

• uterus

• vagina

parts of the male reproductive system

• seminal vesicles

• prostate gland

• testicle

• vas deferens

testicles

• produce sperm and testosterone

vas deferens

• transport system from testes to urethra

prostate gland

• produces fluid for semen

penis

• adaptation for internal fertilization

scrotum

• keeps the testes cooler for proper sperm production

ovaries

• produce eggs, estrogen, and progesterone

oviducts (fallopian tubes)

• where fertilization takes places

uterus

• where the fetus develops

vagina

• adaptation for internal fertilization

placenta

• exchange (diffusion) of nutrients, gases, and wastes

umbilical cord

• transport system of nutrients, gases, and wastes between mother and embryo

amniotic fluid

• cushions the embryo