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. w.org/bacteria/kin gdom_2.jpg

Living vs. Non-living How do we know? –All living things must exhibit each of the “characteristics of life”.

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 »CO 2 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” 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?

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: –DDTDDT –mercurymercury –PCBsPCBs

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 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?