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THE SCIENCE OF LIFE
Unit 1: Ch 1
300
WHAT IS BIOLOGY???
(living & once living things)
What do biologists study???• Do they all study the same thing?
– yes & no…
What is an organism?• a complete
living thing that carries out all life processes
• Organisms have 1 or more cells.
http://www.bigelow.org/bacteria/kingdom_2.jpg
Living vs. Non-living• How do we know?
–All living things must exhibit each of the “characteristics of life”.
http://www.animationlibrary.com/animation/25626/Fire_burns/http://www.animationlibrary.com/animation/18709/Dolphin_in_frame/
Characteristics of Life
• 1. Living things are organized.– What is the smallest
(basic) unit of life?• the cell
– What is the largest unit of organization?• the biosphere
– the portion of earth that supports life (all life on earth) complete living
thing carrying out all life processes
• 2. Living things respond to stimuli.
– What is a stimulus?
• a change in an organism’s (internal or external) environment
– Why is responding to stimuli so important?
• can help an organism survive, stay safe, get what need, etc.
Plants Responding to Light
Characteristics of Life
• 3. Living things maintain homeostasis.–What is homeostasis?
• ability of an organism/cell to maintain a constant internal environment (balance / equilibrium)– examples:
» body temperature: too hot sweat, too cold shiver
» CO2 level in blood: too high breathe faster
Characteristics of Life
• 4. Living things grow & develop.–What is the difference?
• growth = increase in size of organism due to increase in size or # of cells
• development = changes in form– ex. from zygote (fertilized egg) to adult stage of life– ex. from tadpole to frog
Characteristics of Life
• 5. Living things reproduce.– What is the “goal” of reproduction?
• make more organisms & pass on genetic information
– What is the difference between asexual & sexual reproduction?• asexual
– 1 parent
– offspring genetically the same as parent & each other
• sexual– 2 parents
– offspring are genetically different from parents & each other (combined DNA)
Characteristics of Life
• What is the theory of biogenesis?– all life comes from life
• explains the unity of life
• “Like produces like…” – What does this mean?
• An organism will reproduce an offspring of it’s own type.
• How is reproduction unique as a life function?– Not every organism NEEDS to reproduce
• But, every organism needs to carry out other life functions.
Characteristics of Life
• 6. Living things have adaptations & evolve.– What is an adaptation?
• characteristic that makes an individual organism better able to survive in its environment
– Over time, beneficial adaptations are “selected for” & the population or species evolves.
» Individual organisms do NOT evolve!!!
Characteristics of Life
Pepper Moth “Game” http://www.techapps.net/interactives/pepperMoths.swf
Principles of Natural Selection "Interactive"
Explains the diversity of life…
• 7. Living things need energy.– How do organisms get energy?
• nutrition (make own food or eat)
– Why is (chemical) energy needed?• metabolism
– all physical & chemical processes in the body that convert or use energy
» ex. respiration, circulation, homeostasis, growth, reproduction, movement, digestion, excretion, nervous system function, etc.
Characteristics of Life
Where do organisms get energy?• Almost all the energy
organisms use comes from the sun!!!– What type of organisms make
their own food using the sun?• producers (autotrophs)
– examples:» plants, phytoplankton
– What process do they use to make food (sugars)?• photosynthesis
• What is the equation for photosynthesis?
• Where is the energy stored?– in the chemical bonds between the atoms
Where do organisms get energy?
• Some organisms can make their own food without sunlight by chemosynthesis.
– examples:• bacteria at
hydrothermal vents
Where do organisms get energy?
• What if an organism can’t make its own food? How would it get energy/nutrition?– It has to eat (ingest) food.
• What do we call organisms that have to eat to get energy?– consumers/heterotrophs
• What do we call consumers that eat:– plants?
» herbivores– other animals?
» carnivores– both plants & animals?
» omnivores
Where do organisms get energy?
• In most organisms, what process releases the energy stored in the chemical bonds of food (glucose)?– What materials are needed?
– What is given off?• & some “waste” heat
Where do organisms get energy?
• cellular respiration…– What is the equation?
– What other equation does it look like?
• photosynthesis
• What do organisms use the energy for?– life functions (metabolism)
Where do organisms get energy?
ATP & heat
Where do organisms get energy?
cellular
• Can energy be recycled (in the same form)?– NO!!!! It can only be transferred & transformed…
• usually given off as heat
Energy & Nutrients
• Can nutrients be recycled?– yes
• Why must nutrients be recycled?– so that they can be put back into the soil & used
again by other organisms (usually autotrophs)
Energy & Nutrients
• What type of organisms recycle nutrients (back into the soil)?– special types of heterotrophs
• detritivores– eat dead organisms
» ex. crabs, worms, snails
• decomposers– break down organic waste (poop)
» ex. fungi & bacteria
Where do organisms get energy?
Energy Flow: Food Chains
• Does energy only flow through individual organisms?
– No… energy also flows through communities.
• shown by food chains
***Arrow always points toward organism taking in the energy & away from the organism “giving up” the energy.***
Where do almost all communities
get their energy?
http://www.cnr.vt.edu/forsite/owlpellet/josh/PICTS/foodchain.jpg
1st trophic level
2nd trophic level
4th trophic level
3rd trophic level
5th trophic level
Energy Flow: Food Chains
Trophic level = step in the food chain
Toxins & Food Chains• What is bioaccumulation?
– Contaminants accumulate in individual over its lifetime.
• What is biomagnification?– Contaminants build up as go
up food chain b/c larger organism is eating MANY smaller, tainted organisms.
• Ex. of toxins that accumulate & magnify in food chains:– DDT– mercury– PCBs
Food Chains & Food Webs
•food chain just one path of energy
•food web most/all possible paths of energy
Food Web Interactive
Energy Flow: Food Webs
What occurs as energy is passed to each trophic level?
• there is less energy available to be passed on
Amount of energy passed on to the next level.
Lost Energy
Lost Energy
20 J
80
• The 10% Rule of Ecological Efficiency– ~10% energy is passed to next level
• ~90% “lost”– some “lost” b/c used by original organism for its life
processes– most “lost” as heat
» Energy can NOT be recycled, only transferred or transformed.
Energy Flow: Energy Pyramids
What chain is most efficient? Why?
