Life Functions
Nutrition:
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Nutrition will include how an
organism obtains food for the
energy it will need to live as well
as how it will break down that
food in the process of digestion.
We can classify organisms into
two main groups based on how
they will obtain food:
 Autotrophes will make their
own food using the process of
photosynthesis or
chemosynthesis.
 Heterotrophes must bring in
food from their surroundings.
Obtaining Food: Autotrophes
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Photosynthesis is the process used by
organisms such as plants and some
protists where the energy from light is
converted into a usable form of energy that
is then used to put carbon dioxide together
and make sugar.
Chemosynthesis is the process used by
organisms that need to make their own
food but are not exposed to light (protists
that live in caves or at the bottom of the
ocean). This process follows the same
steps as photosynthesis except the original
source of energy is not light, it is inorganic
compounds from the environment.
Obtaining Food: Heterotrophes
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Endocytosis: each individual cell
will bring in food particles by
wrapping the cell membrane
around the food and engulfing it.
Absorption: food particles that
were digested outside of the cell
are then absorbed straight
through the cell membrane.
Filter Feeders: large amounts of
water are collected by the
organism who removes the food
floating in the water and releases
the water.
Carnivores: organisms that hunt
and kill animals.
Obtaining Food: Heterotrophes
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Omnivores: organisms that will
eat both meat and vegetation.
Herbivores: organisms that eat
only vegetation.
Detritivores: organisms that eat
decaying organic matter.
Scavengers: organisms that eat
meat that was killed by
carnivores.
Important: organisms have
specialized structures (teeth,
beaks, mouth parts) that allow
the organism to eat.
Digestion of Food: Autotrophes
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Plants and other
autotrophic organisms
are going to perform cell
respiration to break
down the sugars they
have created in order to
release energy. Any
minerals, vitamins, or
other nutrients needed
by the organism will be
absorbed from the
environment. Ex) plants
use roots to absorb
nitrogen from the soil.
Digestion of Food: Heterotrophes
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Heterotrophes will need to break down the food
they have obtained from the environment in
order to extract the usable particles from the
waste. This process is called digestion. After
this occurs each individual cell will perform cell
respiration or fermentation to obtain energy.
Digestion of Food: Heterotrophes
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Unicellular organisms such as
bacteria and protists as well
as sponges will perform
intracellular digestion. In this
process each cell will create
enzymes responsible for
breaking down the food within
the cell. The food is normally
held in a vacuole where the
enzymes are placed and
digestion occurs. After
digestion the “waste” is
eliminated from the cell using
exocytosis.
Digestion of Food: Heterotrophes
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In extracellular digestion the
food is broken down outside
of the cell, normally in a
digestive system, and then
the nutrients are absorbed.
Fungi and all kinds of
animals except sponges
use this method.
Fungi will secrete digestive
enzymes into the
environment and absorb
what is broken down around
them, they do not have a
digestive system.
Digestion of Food: Heterotrophes
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Gastrovascular cavity: this
digestive system consists of one
opening and a balloon shaped
organ. The food goes into the
cavity inside of the animal; the
cells at the edge of the cavity
secrete digestive enzymes and
absorb the nutrients. The “waste”
is release out the same opening
it entered through. The animals
that perform this type of
digestion include cnidarians,
platyhelminthes, and
echinoderms.
Digestion of Food: Heterotrophes
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Digestive tract: this system
moves in one direction with
two openings and
specialized organs to
perform different tasks.
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The length of the tract is
directly related to the food
that is eaten. It will take
longer to break down plant
cell walls than animal cells
that do not have cell walls
so herbivores have longer
digestive tracts than
carnivores.
Digestion of Food: Heterotrophes
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The organs of the digestive tract are also
related to the food eaten and how. The
tract will begin with specialized mouth parts
followed by a pharynx and esophagus. If
the food was swallowed whole the next
organ is a crop that will moisten and store
the food then a gizzard that will grind the
food. If the food was chewed and then
swallowed the next organ is a stomach that
will release digestive enzymes. Regardless
the next step is a series of intestines that
will absorb the nutrients and any excess
water before the “waste” is released
through the anus.
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Why do organisms need to either eat or create food?
What are autotrophs? Include 3 examples.
What are heterotrophs? Include 3 examples.
What types of organisms perform photosynthesis?
What is the purpose of photosynthesis (what does it make)?
What materials are required in order for photosynthesis to occur?
What is the difference between photosynthesis and chemosynthesis?
What are some organisms that perform chemosynthesis?
What is endocytosis?
Identify what the following organisms eat and an example of an organism
that would fall into that category.
– Carnivore
– Omnivore
– Herbivore
– Scavenger
– Detritivore
• What is the relationship between and organisms mouth
structures and their source of food?
• How do plants obtain energy? How do they obtain materials to
build cell structures?
• What is intracellular digestion? What are some examples of
organisms that use intracellular digestion?
• What is extracellular digestion?
• What is a gastrovascular cavity? Identify if this is intracellular or
extracellular digestion. Identify some examples of organisms
that have this type of digestion.
• What is a digestive tract? Identify if this is intracellular or
extracellular digestion. Identify some examples of organisms
that have this type of digestion.
• How does the length of the digestive tract correspond to the
food being eaten?
• What is the function of a crop and gizzard? Do all organisms
have these organs? Why or Why not.
Respiration
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The process of bringing in
oxygen and getting rid of carbon
dioxide. Remember the
organisms that perform only
fermentation will not need to
perform this act. Also remember
that material moves easiest
across a thin moist membrane.
The simplest, smallest
organisms such as bacteria,
protists, fungi, sponges,
cnidarians, and all three types of
worms will use diffusion for each
individual cell to obtain oxygen
and get rid of CO2.
Respiration
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Plants have openings on
the undersides of leaves
called stomata that are
controlled by guard cells.
When the guard cells are
pulled apart and the
stomata open, oxygen and
carbon dioxide move freely
in and out of the plant.
However; this also causes
the plant to lose water
vapor in the process of
transpiration so the stomata
cannot stay open or the
plant would wilt.
Respiration
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Most aquatic animals that
do not use diffusion for
respiration will have gills.
Gills are respiratory
structures that will come
into direct contact with the
water in order to allow the
oxygen dissolved in the
water to diffuse through the
membrane and into the
blood stream. These
animals include fish,
juvenile amphibians, and
aquatic mollusks.
Respiration
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Animals that breathe air have
multiple types of respiratory
structures.
 Tracheal tubes: insects have a
series of tubes that span their
entire body that will allow air to
flow throughout and exchange
oxygen and carbon dioxide with
tissues.
 Book lungs: spiders have thin
membranes that are stacked
similar to the pages of a book
that will allow oxygen to be
passed into the blood stream.
Respiration
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Lungs: all mammals,
birds, reptiles, and
adult amphibians will
use lungs to bring air
into the body,
allowing oxygen to
go into the blood
stream and CO2 to
diffuse out.
Transport
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The process that moves oxygen, carbon dioxide,
nutrients, and wastes around the body.
The simplest organisms will use diffusion to move
materials from cell to cell until the material has
reached its destination. These organisms include
bacteria, protists, green algae, bryophytes, sponges,
cnidarians, platyhelminthes, and nematodes.
Transport
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Seedless vascular plants,
gymnosperms, and
angiosperms all have vascular
tissue (tubes to transport
materials). There are two
types of vascular tissue in
these plants. Xylem is a
vascular tissue that will
transport water from the roots
where it is absorbed through
the rest of the plant. Phloem
will transport the sugars made
in the leaves throughout the
rest of the plant.
Transport
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Open circulatory system: animals such
as insects and some (slower moving)
mollusks use a system where blood
carries the materials around the body,
but the blood does not stay in blood
vessels the entire time. The blood is
pumped by a heart or contracting
blood vessel through a series of tubes
until it comes to a system of spongy
cavities (sinuses) that allow the blood
to come into direct contact with the
individual cells. Eventually the blood
returns to the blood vessels to be
pumped again.
Transport
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Closed circulatory systems are far
more efficient because the blood
stays in blood vessels the entire
time. However there are several
types.
 Annelid worms have a closed
system where five blood vessels
called the aortic arches are
going to contract to pump the
blood where it needs to go.
 Echinoderms have a closed
system but the liquid in their
system is water not blood. This
is called a water vascular
system.
Transport
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Fish have a closed system
where the blood moves in one
continuous circle through the
animal and a two chambered
heart is responsible for
pumping the blood. In this case
the blood enters the atrium
from the body and then goes to
the ventricle where it is pumped
to the gills to pick up oxygen.
Then the blood travels through
the rest of the body before
returning to the atrium.
Transport
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Amphibians, reptiles,
birds, and mammals
have a closed system
where the blood
makes two trips to the
heart as it moves
throughout the body
allowing it to move
faster. But there are
two types of hearts for
this two loop system:
Transport
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Amphibians and most retiles
have a three chambered heart
where the blood enters the right
atrium from the body, is passed
into the only ventricle, is
pumped to the lungs, returns to
the left atrium, flows again to
the same ventricle, and is
pumped to the body. Since the
ventricle is suppose to be
sending blood to two different
destinations, the blood in the
ventricle mixes slightly and
some ends up going to the
wrong destination making this
slightly inefficient.
Transport
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The crocodilian family,
birds, and mammals
have a four chambered
heart. The ventricle has
split into a left and right
ventricle ensuring that
there is no mixing of
blood. The steps are the
same as the three
chambered heart except
now there are two
different ventricles.
• What is respiration?
• When moving materials from one side of a membrane to
another what does then membrane need to be?
• What is diffusion? Does it require energy? What types of
organisms use diffusion to bring in oxygen and remove
CO2?
• What are stomata? What types of organisms have stomata?
What are they used for?
• What is transpiration? What types of organisms experience
transpiration? Why is transpiration a negative thing?
• What are gills and how do they function? What are some
examples of organisms that have gills?
• What are tracheal tubes and what types of organisms use
them?
• What are book lungs and what types of organisms use
them?
• What are lungs and what types of organisms use them?
• What is the function of transport?
• What types of organisms use diffusion for transport?
• What is xylem and phloem? What are their functions?
What types of organisms have these structures?
• Explain the process of an open circulatory system.
What types of organisms use this system? Is this more
or less efficient than a closed system? Explain why.
• Explain a closed circulatory system.
• What is special about the circulatory system of an
annelid worm? Of a starfish?
• Explain the circulation of blood in fish. In amphibians
and reptiles. In birds and mammals.
• List the types of closed systems in order of increasing
efficiency.
Excretion
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The process that eliminates waste created by each individual cell
as they break down proteins and controls the amount of water in
the organism. The waste created is a nitrogen based molecule
called ammonia and is extremely toxic to living tissues. This is
not the same as the leftover food that was not used in digestion.
The elimination of that waste was part of the digestive system.
Simple organisms such as bacteria, protists, plants, sponges,
cnidarians, and nematodes are capable of diffusing this toxic
substance out of the body.
The rest of the organisms turn ammonia into a less harmful
substance (either uric acid or urea), collect it all in one place, and
then release it from the body.
Excretion
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In aquatic animals most of the waste is eliminated using the same
surface used for respiration (gills or skin). The excretory systems in
these animals are more related to maintaining the proper water
balance. In flatworms flame cells collect excess water and pump it
out of the body. In fresh water fish and amphibians kidneys collect
excess water and eliminate it. In salt water fish excess salt is also
passed through the respiratory surface and the urine created by the
kidneys is very concentrated.
Excretion
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Terrestrial animals must eliminate waste but they must also
conserve water. All of these organisms will pump body fluid that
has collected the waste from around the body through a structure
that will remove and concentrate this waste. Worms and mollusks
use a structure called nephridia. Insects and spiders use a structure
called malpighian tubes. Birds, reptiles, amphibians, and mammals
use kidneys. Once the waste is removed from the blood it is
released from the body.