chapter 6 organization of life
TRANSCRIPT
CHAPTER 6
ORGANIZATION OF LIFE
The smallest unit of an organism is a cell. Cells group together and form tissues; tissues and
then form organs, organs will form organ systems; and finally organism.
Living organisms can consist of only one cell called unicellular organism (examples;
Amoeba, Paramecium, and Euglena). Plants and animals are living organism consisting of more
than one cell and called multicellular organism.
A. Cell
1. Elements of cell
The main elements of a cell are the plasma membrane, protoplasm, and the nucleus.
The plasma membrane is the outer part of a cell. It controls the traffic of any material
in and out of the cell.
Protoplasm is the living contents of a cell. It is controls all the activities within the
cell. Protoplasm is composed of water, protein, carbohydrates, fats, mineral salts, and
enzymes. Protoplasm located inside the nucleus is called nucleoplasm. Protoplasm located
outside the nucleus is called cytoplasm. Cell organelles are located in the cytoplasm.
Inside the nucleus, there are chromosomes containing genes, which basic function is
to carry hereditary materials across generations.
2. The differences between animal cells and plant cells.
The differences between animal cells and plant cells are in the plasma membrane,
cytoplasm, and vacuole.
The plasma membrane in a plant cell is protected by a strong and tick cell wall, so a
plant cell constant shape.
Cytoplasm in plant cell contain plastids, which are granules carrying color
substances (chloroplast), containing chlorophyll which is used in the photosynthesis
process.
The vacuole is clearly visible in plant cell. It is produced as the result of cell wall
development which is faster than the growth of protoplasm.
B. Tissues
Group of cells with similar shape and function are called tissues.
Animal tissues
The animal body is composed of various tissues, for example, bone tissue functions to form
skeletons which further strengthen the body.
Nervous tissue function to transmit stimulus. The red blood tissue are carry oxygen from
respiratory organs. The muscle tissue play the role to generate motion.
Plant tissues
A plant is also formed of groups
of cells which may have different
shape and functions.
Epidermis tissues are covers and
protects the surface of a plant.
Vascular tissues are composed of
xylem and phloem tissues.
Xylem tissues allow water and
minerals to be transported from
the root to the leaves.
Phloem tissues allows the
photosynthetic nutrient to be transported from the leaves to the rest of the plant.
Vascular tissues may be found in every part of the plant (roots, stems, and leaves).
Palisade and spongy tissues are the primary location of photosynthesis because they contain
chlorophyll, especially the palisade tissues.
C. Organs
These groups of tissues are called organs.
1. Human body organs
Several important organ in the human body are the
heart, lungs, liver, kidneys, and stomach.
The heart function is responsible to pump blood
throughout the body.
The heart is composed nervous tissues, muscle
tissues, and blood vessels.
The lungs are responsible for performing respiratory
function.
The liver is responsible for controlling the
composition of nutrients and toxins within the blood.
Kidney are responsible for performing excretion,
such as removing residual substances containing nitrogen.
The stomach is responsible for the digestive function.
2. Plant organs
Plant are composed of the leaf, stem, and root.
a. Leaf
Plant leave are composed of epidermis tissues,
palisade tissues, spongy tissues, and vascular
tissues (xylem, and phloem).
Leaves are the location of photosynthesis and
also are responsible for respiratory functions.
b. Stem
The stem is composed of epidermis, cortex, and
stele which consist of parenchyma and vascular tissues (xylem and phloem).
The stem is responsible for transporting water and minerals from the roots to leaves
through the xylems, and transportation of nutrients from the leaves throughout the
whole parts of the plant through the phloem.
c. Roots
Roots are composed of epidermis tissues, the cortex, endodermis, pericambium, and
stele. They work together in tandem to absorb water and minerals from the ground.
Roots are also responsible for respiratory function.
D. Organ Systems
Several organs will work together to form an organ system.
Example organ system in humans are the digestive and respiratory system.
The digestive system is composed of several organs, such as the mouth, throat, stomach, liver,
and gall bladder, pancreas, small intestines, colon, and anus.
The respiratory system consist of several organs, such as the nose, trachea, bronchi, and lungs.
Digestive system Respiratory system
The human body also possesses some other organ system, example; the circulatory system,
excretory system, skeletal system, and the
nervous system.
Group of several organ systems are connected to
each other and work together to form organism.
The body of living organism is considered as an
organization of life that are consecutively
composed of:
cells tissues organs organ
systems organism
Disorder of one of the organ systems may affect
the performance of other organ systems.
Example: Kidney disorders may affect blood
circulation.
The description about the organization of life
can be explained using beside figure
CHAPTER 2
ECOSYSTEM
A. Environment
An environment is the totally of circumstances surrounding of living organisms which affect
their lives.
The suitable area for living organisms to perform their living activities is called a habitat.
B. Unit of Living Organisms in an Ecosystem
An ecosystem consist of living organisms (biotic) and non-living object (abiotic). Living
organism in an ecosystem consist of units such as, individual, population, and community.
1. Individual
A single, separate organism in an environment is called an individual. A fish, a turtle, or
alga is called an individual.
2. Population
The population is a group of individuals within the same species living in a certain area.
The number of individuals within the same species living in a certain unit area is called
the population density.
Example:
An area of 10 km2 is occupied by 50 deers.
The density of the deer population = 2km 10
deers 50 =
2km
deers5
3. Community
A community is composed of all the populations living organism inhibiting the same area
and interacting with one another.
A population goldfish, a population of mujair fish, a population of water lilies, and
population of Hydrilla in a lake are members of aquatic lake
community.
C. Ecosystem
Ecosystem are groups of communities and environments which
interact with each other.
Based on the formation process, an ecosystem is distinguished into a
natural ecosystem and an artificial ecosystem.
A natural ecosystem is an ecosystem which is naturally formed, for example lakes, swamps,
seas, forests, prairies, and rivers. Natural ecosystem can be broken down into land
ecosystems, freshwater, seawater, and beach ecosystems.
An artificial ecosystem is an ecosystem made by humans, for example, reservoirs, rice fields,
ponds, and aquariums.
D. Component of Ecosystems
Ecosystems consist of two main components, they are abiotic, and biotic component.
1. Abiotic components
Abiotic is all non-living objects found in an ecosystem.
Examples of abiotic components are water, soil, rocks, sand, air, light, temperature,
humidity, and gravity.
2. Biotic components
Based on the roles in an ecosystem, biotic components may be classified into three
groups; producers, consumers, and decomposers.
a. Producers
Producers are a group of living organisms which are able to produce their own food
(nutrients).
Green plants are called producers since they are able to produce their own food or
nutrient.
b. Consumers
Consumers include all animals and humans.
Animals which directly eat plants are considered as first level consumer (primary
consumer).
Animals which eat a first level consumer are considered as a second level consumer
(secondary level).
Animals which eat a second level consumer are considered as a third level consumer
(tertiary level).
c. Decomposers
Bacteria and saprophytic fungi are responsible for decomposing dead and decaying
organisms.
The producers are needed by the first level consumers; the first level consumers are
needed by the second level consumers; the second level consumers are needed by the
third level consumers (tertiary consumers); and so on.
Dead organisms, either from producers or consumers, will be decomposed by
decomposers.
E. Interdependence between Biotic and Abiotic Components
There is an interdependence between biotic components (human beings, animals, and plants)
and abiotic components (environment) within an ecosystem. Biotic components rely on
abiotic components. Biotic components may also affect abiotic components.
There are some abiotic components which cannot be affected by biotic factors, example; earth
gravity, sunlight, and air pressure.
F. Interdependence Among Biotic Components
There is an interdependence among biotic components. This interdependence forms a
continuous cycle.
In an ecosystem there is interdependence among its biotic components, which are producers,
consumers, and decomposers.
1. Food chain
The series of eating phenomena will form a food chain.
2. Energy flow in the food chain.
If plants are eaten by first level consumers, the energy stored within the plants is
transferred into the first level consumers. Furthermore, if first level consumers have been
eaten by second level consumers, energy from first level consumers is transferred into the
bodies of second level consumers, and so on. This phenomena is called a transfer of
energy.
3. Food webs
Food webs is a group of several food chains which are interconnected to one another.
This food web show a series of eating and being eaten within an ecosystem.
4. Pyramid of food
A pyramid of food is a composition of food chains which the higher the level position the
lesser the quantity.
CHAPTER 3
ENVIRONMENT POLLUTION
A. Air Pollution
A pollutant is a substance that contaminates the environment. Air pollutants include
soot, smoke, ash, and gases such as carbon dioxide (CO2), carbon monoxide (CO), nitrogen
oxides (NO), and sulfur oxides (SO).
Wherever cars, trucks, airplanes, factories, homes, or power plants are found, air pollution is
likely.
Air pollution can be caused by volcanic eruptions, wind-blown dust and sand, forest fires, and
the evaporation of paint and other chemical.
Smog is a form of air pollution created when sunlight reacts with pollutants produced by
burning fuels. It can irritate the eyes and make breathing difficult for people with asthma or
other lung diseases.
Smog can be reduce if people take buses or trains instead of driving or if they use
vehicles, such as electric cars, that produce fewer pollutants than gasoline-powered vehicles.
B. Water Pollution
Wastewater from factories and sewage-treatment plants often is released into
waterways. In the United States and many other countries, laws require that wastewater be
treated to remove pollutants before it is released. But, in many parts of world, wastewater
treatment is not always possible. Pollution also enters water when people dump litter or waste
materials into rivers, lakes, and oceans.
Some water pollutants poison fish and other wildlife, and can be harmful to people who
swim in or drink the water. For, example, chemical pesticides sprayed on farmland can wash
into lakes and streams. These chemicals can harm the insects that fish, turtles, or frogs rely on
for food. Shortages of food can lead to deaths among water-dwelling animals.
Some pollutants, especially those containing mercury and other metals, can build up in
the tissues of fish. Eating contaminated fish and shell-fish can transfer these metals to people,
birds, and other animals. In some areas, people are advised not to eat fish or shellfish taken
from polluted waterways.
Algae blooms are another water pollution problem. Raw sewage and excess fertilizer
contain large amounts of nitrogen. If they are washed into a lake or pond, they can cause the
rapid growth of algae. When the algae die, they are decomposed by huge numbers of bacteria
that use up much of the oxygen in the water. Fish and other organisms can die from a lack of
oxygen in the water.
Rivers and streams eventually flow into oceans, bringing their pollutants along. Also,
polluted water can enter the ocean in coastal areas where factories, sewage-treatment plants,
or shipping activities are located. Oil spills are a well-known ocean pollution problem. Much
of that oil comes from ships that use ocean water to wash out their full tanks.
C. Soil Pollution
Soil can become polluted when air pollutants drift to the ground or when water leaves
pollutants behind as it flows through the soil. Soil also can be polluted when people toss litter
on the ground or dispose of trash in landfills.
Most of solid waste is dumped in landfills, for example old refrigerator, old TVs, and
toys. Most landfills are designed to seal out air and water. This helps prevent pollutants from
seeping into surrounding soil, but it slows normal decay processes.
Even food scraps and
paper, which usually
break down quickly, can
last for decades in a
landfill. In populated
areas, landfills up
quickly. Reducing the
amount of trash people
generate can reduce the
need for new landfills.
Waste materials that are harmful to human health or poisonous to living organisms are
hazardous wastes. They include dangerous chemicals, such as pesticides, oil, and petroleum-
based solvents used in industry. They also include radioactive wastes from nuclear power
plants, from hospitals that use radioactive materials to treat disease, and from nuclear
weapons production.
Many household items also are considered hazardous. If these materials are dumped into
landfills, they could seep into the soil, surface water, or groundwater over time. Hazardous
wastes usually are handled separately from other types of trash. They are sealed in steel drums
or treated in other ways to prevent them from polluting the environment.
References:
Sumarwan, Sumartini, and Kusmayadi. 2011. Bilingual Science Biology for Junior High School
1. Jakarta: Erlangga.