Transcript Lecture 01, earth as a system

100A – Introductory Biology 1
Lecture: MW 9:50 – 11:05 AM, ASC-B 132
Lab classroom: ASC-B 344
Dr. Patrick Krug
[email protected]
Office hours: W, 1-2 PM
NOTE: 3- 4 PM, this Wed only
LaKretz Hall room 314, 3-2076
Course web page – http:// instructional1.calstatela.edu/pkrug/Bio100A
note: NO “www” in front!
skeletonized lectures missing some text will be posted before class
- download, print out, bring to class for note-taking
weekly study guides will be posted, with sample exam questions
100A – Introductory Biology 1
Lecture: MW 9:50 – 11:05 AM, ASC-B 132
Lab classroom: ASC-B 344
Dr. Patrick Krug
[email protected]
Office hours: W, 1-2 PM
NOTE: 3- 4 PM, this Wed only
LaKretz Hall room 314, 3-2076
Retaking class –
if satisfied with lab grade from a prior offering,
see me about re-taking the lecture portion only
as credit-by-exam
Adds will be done only if there is space in a given
recitation + lab section
Recitation + lab sections:
TA
02+03
M 11:15 am – 2:45 pm
LeBlanc, Mark
05+06
M 3:10 – 6:40 pm
Chau, Kevin
08+09
W 11:15 am – 2:45 pm
LeBlanc, Mark
11+12
W 3:10 – 6:40 pm
Santhanam, Ash
14+15
T 8:30 am – 12:00 pm
Barrett, Craig
17+18
T 12:10 – 3:40 pm
Meas, Diane
20+21
R 8:30 am – 12:00 pm
Johnson, Daisy
23+24
R 12:10 – 3:40 pm
Torres, Lisa
Structure of 100A
Required Textbook:
Principles of Biology, Nature Education e-text. Required
Purchase access to this class at the CSULA Bookstore
- this is an online text that will be used for the entire 100ABC series
Required Lab Manual:
Gamon JA, Krug P, Salmassi T (2005) Diversity of Life, 2nd edition
- available at campus bookstore, or at the Student Bookmart
(1725A N. Eastern Ave, Los Angeles, 323-262-5511)
Structure of 100A
Point assignment:
midterm
final exam
8 lab quizzes
8 recitation assignments
8 lab activities
writing assignment
Total
60
120
80 (10 pts each)
40 (5 pts each, all or nothing)
40 (5 pts each, all or nothing)
20_____________
360 points
Note: HALF your grade comes from the lab portion of class!
Take lab very seriously. You’re not leaving early.
Your TA is your new best friend.
“How am I doing?”
This class is graded on a curve, which means your grade
depends on how you do, relative to everyone else.
The mean (= average) score is roughly a low B
One standard deviation above the mean is where A’s start
One SD below the mean is the C-range
You need a C or better to advance to 100B
Flashcards
The #1 reason students don’t do well in 100A is they get
overwhelmed by the vocabulary
Required: You must make 10 flashcards per lecture
(20 per week) and show them to your lab TA
You will not get credit for the recitation activity if you do
not show your 20 cards from the previous week
Flashcards can be on 3 x 5 index cards, or pieces of paper,
but they must have a vocabulary word or phrase on the front
and the definition on the back
In my lectures, BOLDED terms in colored fonts are terms I expect
you to know for exams, so these would be good ones to use and
to learn – use the flashcards to study in your spare time
“Why didn’t I do better?”
To do well in this class, you MUST:
- review your vocabulary flashcards every week
- attend ALL lectures
- spend the full 2 ½ hr in every lab
- the lab manual is also your study guide
- do not expect to study for an exam in one week
- come to office hours regularly, to go over unclear material
- ask questions to stay awake and engaged
- DO THE STUDY GUIDES and go over your answers with
clever classmates, your TA, and me during office hours
Academic Honesty
ALL students are required to sign a pledge stating that they
understand the university academic honesty policy
A copy of the full policy is available in the lab to read, and a
link to the website is provided on the syllabus
You will FAIL the course for a SINGLE instance of plagiarism
- written assignment in lab will use proper citations
Excessive talking in lectures = I toss you out
Consideration of Others
Excessive talking in lectures = I toss you out
The people around you are paying money to learn,
not to be distracted by your conversation
God help you if I hear other students shushing you
because of your conversations
Likewise, stay off the web and use your laptop to
take notes in my lectures, nothing else
Main themes of 100A
(1) Ecology - how organisms interact with their living and
non-living (abiotic) environment
A) What controls the distribution and abundance of organisms?
B) What controls the biodiversity of an area – i.e., how many
different species are found there?
C) What ecosystem processes keep the species in a community
and their physical environment in balance?
D) What is the ecological niche of an organism: the living and
abiotic resources or requirements used to survive
Main themes of 100A
(2) Evolution - genetic change in a population over time
Understand:
A) How organisms that belong to biologically meaningful groups
are related by descent from a common ancestor
B) The adaptations of an organism that make it suited to its niche
are the product of natural selection
C) The forces that generated Earth’s biodiversity (the number
of different species in a place)
D) The form and function of key features in successful groups
what is it made of?
what does it do?
success = many species
in that group
What’s this “life” stuff, anyway?
Reproduction - make more of your own kind
Energy transfer, metabolism
Membranes, cells
Respond to the environment (regulation)
Organization - there is an order to living things
Information content (DNA, RNA)
Common features of all cellular life
Information stored in DNA; genes expressed through RNA
Same 20 amino acids used to make proteins, which then
catalyze chemical reactions in the cell
Same genetic code used to direct the synthesis of proteins
Membranes separate inside from outside
Generation of ATP (stored energy) by electron transport
systems, made up of proteins embedded in membranes
Levels of Biological Organization
molecules
- proteins, DNA, sugar, water
100B
cells
- smallest unit of life (perhaps)
tissues
- 2 or more cell types,
working together (muscles, nerves)
organs
- 2 or more tissues form a structure
performing a function for the
organism (leaf, heart)
100C
Levels of Biological Organization
molecules
Organisms
cells
Communities
100A
tissues
Ecosystems
organs
Biosphere
Levels of Biological Organization
molecules
Organisms
 individual living things
cells
Communities
 all species in an area
tissues
Ecosystems
 species + abiotic things they
interact with, in an area
(forests, deserts, coral reefs)
organs
Biosphere
 all the ecosystems of the earth,
combined into one planet-wide
system
Earth as a System
Aug 1992,
NASA
a complex system has
its own properties that
are more than the sum
of its parts
the earth functions
as a system, with
different biomes
connected through
global processes
like climate and the
carbon cycle
Earth has changed over 4.6 billion years
Early conditions (first 800 MY): hostile to “life as we know it”
bombardment from outer space
extremely hot
volcanic activity – release of SO2 (acidic)
no atmosphere
Later conditions
early atmosphere: lots of CO2, no O2 (oxygen gas) or O3 (ozone)
Our oxygen-rich atmosphere was eventually created by microbes
(cyanobacteria) producing O2 as a by-product of photosynthesis
-- a fairly recent development in our plant’s hsitory
Evidence for early life
3.8 BYA – Evidence from molecular (DNA) studies
(early life was hot, lived on chemical energy)
– Geological evidence
(organic deposits in earliest sedimentary rocks)
3.5 BYA – Possible fossil bacteria with organic inclusions
3.2 BYA – Filamentous microfossils
3.0 – 2.7 BYA – Developed bacterial communities
(photosynthesizers that built stromatolites)
BYA = billion years ago
A “clock” view of life’s history
bacteria appear
very early on
Raven & Johnson 1992
A “clock” view of life’s history
bacteria appear
very early on
life began changing
the atmosphere
Raven & Johnson 1992
A “clock” view of life’s history
bacteria appear
very early on
cells got
more complex
(eukaryotes)
life began changing
the atmosphere
Raven & Johnson 1992
A “clock” view of life’s history
multi-cellular
life appears
bacteria appear
very early on
cells got
more complex
(eukaryotes)
life began changing
the atmosphere
Raven & Johnson 1992
Stromatolites, modern “rock”
formations built as sediment
sticks to mats of bacteria
(Australia, ~3,000 yr old)
Fossil stromatolite,
~ 3.5 billion yr old
The age of fossil stromatolites suggest bacteria may have appeared
almost as soon as the planet was cool enough to permit life,
~3.9 billion years ago (MY)
Evolution of the Earth’s atmosphere
% of today’s oxygen
100%
10%
1%
0.1%
millions of years ago
life created our oxygen-rich atmosphere
Graedel & Crutzen 1995
Aug 1992,
NASA
Earth as a System
Biomes are big terrestrial
ecosystems, defined by a
dominant vegetation type,
and distinctive abiotic
environmental conditions
Examples:
- Arctic tundra
- tropical rainforest
- temperate dry forest
14 terrestrial biomes
The biome that develops in an area is mainly determined by
(1) average temperature and rainfall, (2) variation in temp, rain
These factors regulate how much photosynthesis occurs, and when
Global Carbon Cycle
Photosynthesis
& respiration
drive the exchange
of carbon (as CO2)
between the
biosphere & the
atmosphere
Biological
processes
are affected
by the
environment,
but also alter
the environment.
Stan Houston
Primary Production
All biomes are connected by the global carbon cycle, the
uptake and release of CO2 by living things
Photosynthesis “fixes” CO2, = removes it from the atmosphere
and traps it in solid form (plant + animal bodies  oil)
Productivity = amount of CO2 fixed as organic (solid) carbon,
“producing” energy for an ecosystem by trapping sunlight
CO2 is produced by respiration, burning (woods, fossil fuels)
Net primary production = how much carbon is fixed and not
burned off by respiration ... i.e., stays trapped in plant tissue
Seasonal patterns of net primary production
Satellites and computer
models provide new tools
for studying the Earth as a
system
Global photosynthesis
during our summer (top)
and winter (bottom)
 note shift in net primary
production with season
http://earthobservatory.nasa.gov/Newsroom/NasaNews/2003/2003042214379.html
Global Carbon Cycle
human activity puts ~8 gigatons of carbon into the atmosphere a year
(= 2 trillion pounds)
- net 4.5 gigatons fixed by photsynthesis on land & in the ocean
- so, we add 3.5 extra gigatons per year to our atmosphere
Increasing atmospheric [CO2] and average global temperatures
Long predicted
that increased
CO2 would trap
sunlight, leading
to greenhouse
effect
There is scientific
consensus that
this temperature
increase is mainly
caused by human
activity
Campbell &
Reece, 2005
Kerr (2005) Science 309: 1807
Take-home messages
1) Living things adapt to their environment -- both the living and
non-living parts of their environment
2) Organisms also change their environment
- our oxygen-rich atmosphere is entirely a product of life
- the increasing CO2 levels in our atmosphere can only be
explained as a product of human activity
- primary production (photosynthesis by plants, algae and
ocean-dwelling bacteria) only removes half what we make
3) If the environment changes faster than living things can adapt...
extinctions usually follow; we will come back to this at the end
of the course