Welcome to Mrs.G's Web Site
Have fun learning science with a crazy teacher!
Web
page Directory
8th
grade curriculum
7th
grade curriculum
Student
Info page
Parent Signature pg
7th
grade parent page
8th
grade parent page
Science
Fair
Thoughts
to share
Helpful
Links
E-mail
Physics
PowerPts
For Little People
Introduction:
Study of Life
* First life forms arose on Earth more than 3.5 million years
ago
* Single-celled, microscopic organisms (living thing) appeared
first & floated alone in seas
* Over 40 million species (types of organisms) exist with only
about 2 million identified
* Many organisms are unidentified & new species are still discovered
* Biology is the study of all living things and how they interact
with each other & their environment
* Over long periods of time, species changed or evolved
so that new species arose from earlier organisms & came to inhabit
almost every part of the earth (bacteria living in thermal vents, parasites
living inside another organism, etc.)
* Organisms must adapt to their specific environment to survive
& reproduce
Unifying
Themes of Biology
The six unifying themes include:
1. Cell Structure & Function
2. Stability & Homeostasis
3. Reproduction & Inheritance
4. Evolution
5. Interdependence of Organisms
6. Matter, Energy, & Organization
Cell
Structure & Function
* Cell is the basic unit of structure & function
* All organisms are made of one or more cells; Unicellular (one
celled) or Multicellular (Composed of more than one cell)
UNICELLULAR
AMOEBA
*Cells are small but highly organized; they contain specialized
structures that carry out the jobs of a cell called organelles
|
CELLULAR
ORGANELLES * There are many different kinds of cells, but all cells have similarities * All cells are surrounded by a cell membrane, contain cytoplasm, and have DNA (the genetic information for making new cells or cell structures) * New cells made by unicellular organisms are identical (clones) to the parent cell that produced them – asexual reproduction * Multicellular organisms begin life as one fertilized cell (sexual reproduction), but the cells multiplied and underwent differentiation (changed structure & function) to become many different kinds of cells |
Stability & Homeostasis
*All organisms maintain stable internal conditions such as body temperature & water content
*Stable level of internal conditions called homeostasis
Reproduction & Inheritance
|
|
|
* All organisms reproduce new organisms like themselves by transmitting
hereditary material to their offspring
* DNA (Deoxyribonucleic acid) is a large molecule containing the
hereditary material of the cell
* In unicellular organisms like bacteria, DNA exists
as a single loop or chromosome in the cytoplasm
* In multicellular organisms, DNA is enclosed in a membrane known
as the nucleus
* Genes are short segments of DNA the carry the instructions
for a single trait of an organism
* DNA of a cell contains all of the genes (instructions) it will
ever need
* All body cells have a complete set of DNA (genome), but
different types of cells use certain genes from the set; example:
Muscle cells have the genes to make thyroxine, but they don’t use
these genes
* In sexual reproduction, an egg (ovum) is fertilized by
a sperm to form a zygote so the new organism is made of
cells with hereditary information from both parents
* In asexual reproduction, cells copy their DNA & split so
all new cells are identical
Evolution
* Populations of organisms change over time or evolve
(Theory of Evolution)
|
DARWIN - THEORY OF EVOLUTION * Natural selection or “survival of the fittest” is the process that drives evolution * Organisms with favorable traits are better able to survive & reproduce * The survival of organisms with favorable traits causes a gradual change in populations of organisms over many generations * Evolution by natural selection is driven by competition for resources such as food, habitat, mates |
Interdependence of Organisms
*Ecology is the study of the interaction of organisms with each other and their environment
 ENERGY FLOW IN A FOOD CHAIN |
*
Sunlight is the ultimate energy for all organisms * Energy from the sun is passed from one organism to another; producers (plants) to herbivore (plant eater) to carnivore (meat eater) to decomposers (break down dead organisms) * Abiotic (nonliving factors) such as air, water, energy, soil, temperature, & minerals are also needed for survival * Biotic factors include all living things on earth (plants, animals, fungi, microorganisms) * Biosphere supports life & includes the biotic (all organisms) & the abiotic (all nonliving factors) on earth |
* Organisms respond to their environment by:
* Fleeing * Adapting * Dying
* Most organisms can survive a temporary change, but permanent change can lead to extinction (dinosaurs)
* Thousands of species are listed endangered (population so small could become extinct)
* Human interference is the main cause for endangerment & extinction
* Pollution of land, air, and water
* Hunting for sport, food, and commercial products also threatens the survival of many organisms
* Clear-cutting rain forests
* Diverting rivers & lakes
* Draining wetlands (everglades)
*Global Warming
|
|
AMERICAN
BISON |
Matter, Energy, & Organization
*Organisms are highly organized, maintain internal order, & require a constant energy supply
|
*
Plants & unicellular organisms with chlorophyll capture
sunlight through photosynthesis & store it in food to be
used by other organisms * Autotrophs or producers use sunlight, water, & carbon dioxide to make glucose (energy rich sugar) & oxygen – photosynthesis * Heterotrophs (consumers) feed on producers or other consumers to get energy & release carbon dioxide |
Biology affects life in many ways
* Biotechnology uses organisms to make products needed by people (human insulin made by bacteria)
 OIL DRILLING |
* Fossils fuels (coal, oil, & natural gas) provide energy & materials such as nylon & polyester |
*Animal products such as wool, silk, and leather make clothing
* Wood provides energy & shelter for us, but endangers other animals (spotted owl) when forests are cut
* New medicines, better water treatment & garbage disposal improves our health