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?