Transcript Semester 1 Final Review Biology

Semester 1 Final Review
Biology
Part 3:
Carbohydrates to Sustainability
Carbohydrates are:
Sugars and starches
 Sugars end with suffix “-ose”
 Produced by photosynthesis
 Contain the elements: C,H,O or C(H2O)
Monosaccharides:
 Monomer (1 sugar)
 Simple sugars
 Ex. Glucose
C6H12O6
* very, very important!
 It is from this molecule that
animals get their energy
 Ex. Fructose
C6H12O6
“1”
All C6H12O6:
Notice that glucose and fructose and galactose have identical formulas
but their structures are different.
These are examples of ISOMERS!
Disaccharides
•
•
•
•
“2”
Polymer (more than 1)
Glucose + glucose
= maltose
glucose + fructose
= sucrose (table sugar)
glucose + galactose
= lactose (milk sugar)
Polysaccharides “many sugars”
• Complex carbohydrates
Long chains of monosaccharides
• Also joined through dehydration synthesis
• Two basic types and purposes of
Polysaccharides:
– Storage, used to store energy
– Structural, for support and composition
Storage Carbohydrates
• Starch: complex, stores energy in plants
“pearl necklace, each pearl = glucose”
broken down into monosaccharides
glu-glu-glu-glu-glu-glu-glu-glu
Storage Carbohydrates
• Glycogen – a branched chain of as many as
2000 glucose units. Storage form of glucose in
animals.
Structural Carbohydrates
• Cellulose:
– Structural compound in plant cell walls
• found in wood and paper
– uses a modified form of glucose
– still a “string of pearls”
– cannot be broken down by the body
Cellulose
Structural Carbohydrates
• Chitin:
– Structural carbohydrate in insect exoskeletons and fungal
cell walls
– uses a highly modified form of glucose
– still a “string of pearls”
Nutrient Cycles
• Energy transfer through an ecosystem is
ONE WAY
– Most energy is lost as heat
• Matter such as nitrogen, water and
carbon are able to cycle through an
ecosystem and be reused
Nutrient Cycles
• Matter changes form, but it does not
disappear, therefore the total amount of
matter remains the same. This is known as
The Law of Conservation of Matter.
– Matter can change from a solid to liquid to gas
and back again.
– Example: Water
THE CARBON CYCLE
Link between Atmosphere and Terrestrial:
Plants acquire CO2 thru stomata in their leaves and
incorporate it in to organic molecules of their own
biomass  photosynthesis
Link between Atmosphere and Terrestrial:
• All organisms return CO2 to the atmosphere thru
respiration
• Decomposition recycles carbon to the soil and back
to atmosphere
• Fires oxidize
organic material
to CO2 (burning)
Link to animation
The Nitrogen Cycle
Since animals cannot get
nitrogen directly from the
atmosphere they must eat
it through plants.
Plants get their nitrogen
through nitrogen-fixing
bacteria that live in the soil
The Nitrogen Cycle
• What is the source of nitrogen for animal?
– Plant matter
• What is the source of nitrogen for plants?
– Decomposers, bacteria
• What is the source of nitrogen for decomposers?
– Once-living matter
• Which organisms act as a bridge between the nitrogen in
the atmosphere and the organisms of the biosphere?
– bacteria
• How does fixed nitrogen (nitrate) get back into the
atmosphere (nitrogen gas)?
– Denitrifying bacteria
Human Population Growth and Natural
Resources
Why does the human population keep growing?
(Sanitation, Agriculture, Medicine)
According to this chart,
when will humans reach
carrying capacity?
When the slope of the line = 0
and remains that wayl
This is completely
hypothetical. Carrying
capacity could be 10, 20,
or even 50 billion. In fact
maybe we already passed
it!
What decreases Biodiversity?
The two big ones are:
 Habitat Loss
 Introduction of new species
Loss of Habitat
As humans take up more
and more land, there is
less wilderness available
for organisms and many
risk going extinct.
Habitat fragmentation
occurs when a barrier
forms that prevents an
organism from
accessing its home
range.
Wildlife crossing to prevent fragmentation.
Introduced Species
An introduced species is any organism that was brought to an
ecosystem as a result of human actions.
If an environment has a niche that the introduced species can
exploit, or if the introduced species is a better competitor,
original species may be pushed out or die. This particularly
happens when there are no predators for the introduced
species.
When an introduced species has established itself in a new
ecosystem, it is called an invasive species.
Nile Perch
Kudzu
Burmese Python
Conservation
Sustainable development is a practice in which natural resources are used and managed in a
way that meets current needs without hurting future generations.
Example: Global Fisheries:
Overfishing has depleted fish populations worldwide. Fish stocks are not as hardy as they once
were. One reason for this is that the fish that are caught represent the healthy,
reproducing age groups of the fish population.
Researchers found that 29
percent of species had been
fished so heavily or were so
affected by pollution or
habitat loss that they were
down to 10 percent of
previous levels, their
definition of “collapse.”
To continue fishing at our
current rate, the year we see
a collapse in 100% of
species is quite surprisingly
within our lifetimes: 2048
The Atlantic cod
has, for many
centuries, sustained
major fisheries on
both sides of the
Atlantic. However,
the North American
fisheries have now
largely collapsed.
Making Fisheries Sustainable
Bottom-Trawling
1)
Rotation: rotating catches between
different species gives the “off” species
time to recover their numbers.
2)
Fishing Gear Review: choosing gear that
doesn’t hurt the sea floor or
unintentionally catch other species.
3)
Harvest Reduction: Slowing the harvests
of deep-water species that grow very
slowly allows more time for them to
recover.
4)
Fishing Bans: Creating and enforcing
bans in certain areas and on certain
species helps to replenish numerous
populations in the area.
Bottom-Trawling catch
Which species do we save?
Conservationists try
to focus efforts on
umbrella species,
which are species
whose being
protected leads to
the preservation
of its habitat and
all the other
organisms in its
community.
Manatee
Bay Checkerspot
Butterfly