BIOLOGY
NATURE OF SCIENCE NOTES
Biology is the study of living organisms. “Bio”- meaning life, and “ology”-meaning the study of.
We study: the origins and history of life, and the structure and function of living things.
Biologists:
1. Study the diversity of life.
Jane Goodall studied the behavior of chimpanzees in the wild in 1960. She discovered that
chimps make and use tools, as humans do.
2. Research disease:
Mary Claire King studied the link between genes and disease in the 1970s. In 1990, she
discovered the BRCA1 gene which is linked to breast and ovarian cancers. Scientists also
developed vaccines for smallpox, polio, chickenpox and diphtheria. Research into AIDS and
Alzheimer’s is ongoing.
3. Develop technologies:
Technology is application of scientific knowledge to address human needs and increase
human capabilities.
Charles Drew developed a technology to separate blood cells from blood plasma. He also
developed technology for storing blood and blood products. He is accredited to being the
“Father of the Blood Bank.”
4. Improve agriculture:
Help develop plants that grow in poor soil and drought conditions. Help develop plants that
are mildew and frost resistant, as well.
Joann Chory studied growth hormones in plants, and use of light in plants.
5. Preserve the environment:
Dr. Lee Anne Martinez developed outdoor composting toilets for areas of rural Africa. These
toilets use no water, and return materials back to the soil.
Characteristics of Life:
1. Must be made of one or more cells. Streptococcus pyogenes is a single celled bacterium
that causes strep throat.
2. Must display organization. Living things have some body plan.
Cellstissuesorganssystemsorganism
3. Grows and develops. One cell becomes many cells, small infant to grown adult.
4. Reproduces: either sexually (2 organisms) or asexually (1 organism) Reproduction is not
essential for a lifespan. For example, cats and dogs are often spayed or neutered to prevent
reproduction. Reproduction is only essential to preserve a species. Reproduction among
members of the same species insures fertile offspring.
5. Responds to stimuli: External environment includes all aspects of Earth and weather.
Internal environments are kept stable by homeostasis.
6. Requires energy: living things require energy to survive, either from the sun or from other
organisms.
7. Maintains homeostasis: must have a way to regulate internal conditions. Reptiles need heat
from environment to digest food. Mammals have a controlled internal environment. Lack of
regulation = death. Human blood pH can only wary a sight amount over 7.4 or under 7.4.
Any other blood pH causes all enzyme reactions to stop, thus causing death of the human.
8. Adapts over time: Adaptation is a inheritable change in a species due to change over time.
Some trees have adapted leaves that drain water away. This prevents fungal infection of the
leaves.
Principles of Ecology:
Abiotic and biotic factors interact in complex ways. Abiotic factors are the non-living elements
in an environment, like the soil, water and air. Biotic factors are the living elements of an environment.
Ecology: the study of the relationships between the environment and the living organisms in the
environment.
The biosphere is the portion of the Earth that can support life.
Thin layer- several km above the Earth’s surface to several km below the ocean.
Includes land masses, bodies of fresh and salt water, and material below earth’s surface.
Levels of Organization:
Organism- lowest level
Population- members of the same species that share the same location at the same time;
competition for resources can limit populations.
Community-group of interacting populations that share the same place at the same time.
Ecosystem- biological community and all its abiotic factors
Biome- large group of ecosystems with the same climate and similar communities
Biosphere- largest category, highest level of organization that supports life.
Ecosystem interactions: communities of organisms increase the survival of all.
Habitat- area where organisms live
Niche- role or position of organism has in environment, ideal conditions for food, shelter and
reproduction.
Community Interactions:
Competition- more than one organism uses resources at a time.
Resource- food , water, shelter, light, mates
Example: Drought conditions- scarce water may force weaker organisms out and the stronger
are favored to survive, or some may leave to find water elsewhere.
Predation- act of pursuing and consuming another organism.
Predator- hunter
Prey- eaten
Ex: cat and mouse
Ex: Ladybugs and praying mantisesBeneficial insects used by farmers to kill harmful insects.
Used in organic farming.
Venus flytrap- carnivorous plant
Symbiotic Relationships: Close relationships between 2 species.
Mutualism: both species benefit
Ex: Plant roots and fungi, human intestines and bacteria,
Fungi help fix nitrogen for plant’s use, bacteria help break down
molecules for absorption by human
Commensalism: One benefits, one is neither helped nor harmed
Ex: orchids in trees- get more light, do not help nor harm the tree
Parasitism: One benefits and the other is harmed
Ex. Tapeworms, mosquitos, ticks, fleas
Brood parasitism- Brown- headed cowbirds use nests of other birds, and the
other bird mothers to hatch their young. Also, when BHC birds hatch, they push native birds out
of nest. This behavior damages the population of songbirds.
Trophic Levels: Producers always at the bottom, most biomass, most energy content.
Producers- plants, photosynthetic, autotrophic
Consumers- heterotrophic
Omnivore- eats meat (insects) and plants
Herbivore- eats plants only
Carnivore- eats meat only
Autotroph- makes own food, energy comes from the sun
Heterotroph- gets food by consuming another organism.
Food Chains- simple, usually one producer, one primary consumer, one secondary
consumer.
Food Webs- more complex, interwoven pattern where there are a number of food
sources.
Detritovores- eat fragments of dead matter and return it to the soil, ex: earthworms
Decomposers- absorb nutrients by secreting digestive enzymes into the material, ex:
bacteria and fungi
All heterotrophs perform some decomposition during digestion
Ecological pyramids:
Pyramid of Energy, pyramid of Biomass, Pyramid of Organisms.
Energy- 10% transferred, rest lost as heat
Biomass- producers are largest.
Organisms- producers are largest.