SOL Study Book
Fourth Grade
Living Systems
Table of Contents
Page 1: Behavioral and Structural Adaptations
Page 2: Organization of Communities
Page 3: Flow of Energy Through Food Webs
Page 4: Habits and Niches
Page 5: Life Cycles
Page 6: Influence of Human Activity on Ecosystems
Page 7: Natural Influences on Ecosystems
Page 8: Practice Questions
Behavioral and Structural Adaptations
Organisms have structural adaptations, or physical attributes that
help them meet a life need. For example: Fish have gills, birds
have beaks, and giraffes have long necks. Other examples:
-Some animals are camouflaged or blend in with their
surroundings to provide protection from predators
-Some have protective resemblance in which the animal
resembles something else also called mimicry.
-Thick coat of an artic fox helps it survive cold temperatures
Organisms also have behavioral adaptations, or certain types of
activities they perform, which help them meet a life need. Some
examples are:
-Spinning a web
-Migration
-Hibernating
-Moving in large groups
Page 1
Organization of Communities
The organization of communities is based on the
utilization of the energy from the sun within a given
ecosystem. The greatest amount of energy in a
community is in the producers.
Ecosystems include both living and nonliving things. The
living part is called a community which includes different
populations. Nonliving includes soil, water, and air.
Ecosystems can be found on land or in the water.
One ecosystem can differ from another by the amount of
water, the amount of sunlight, soil, and the types of plants
and animals.
Page 2
Flow of Energy Through Food Webs
Within a community, organisms are dependent on the
survival of other organisms. Energy is passed from one
organism to another through food chains.
Producers have the greatest amount of energy. They are
green plants that make their own food.
Consumers eat the producers or eat other consumers.
Example: A beetle eats a leaf then a bird eats the beetle.
Decomposers feed on dead producers, consumers, and
wastes. They help to also break it down into the soil.
In any ecosystem many food chains overlap. Different
food chains contain the same organisms. When this
happens, the food chains form a food web. They may be
connected to food webs in another community.
Page 3
Habits and Niches
Each organism’s home is called its habitat. A habitat is
the place or kind of place in which an animal or plants
naturally lives.
An organism’s habitat provides food, water, shelter, and
space.
The size of the habitat depends on the organism’s needs.
The organization of a community is defined by the
interrelated niches within it.
A niche is the function that an organism performs in the
food web of that community.
It includes everything else an organism does and needs in
its environment.
No two types of organisms occupy exactly the same niche
in a community.
Page 4
Life Cycles: Stages of Growth and Change
Flowering Plants
-Adult plant grows flowers.
-Bees pollinate the flowers.
-The plant is fertilized and grows a seed.
-The seed travels away from the parent plant.
-If the seed has enough light, water, nutrients, and air, it will germinate
and produce a seedling that will produce new seeds.
Metamorphosis is the change in body form. There are two
types, complete and incomplete.
Complete: Mealworms and Butterflies
1.
2.
3.
4.
Egg stage
Lava stage
Pupa stage
Adult stage
Incomplete: Mayflies and Grasshoppers
1. Egg stage
2. Nymph stage
3. Adult stage
All organisms follow the same general pattern of birth, growth,
reproduction, and death.
Human Life Cycle
Frog
1.
2.
3.
4.
5.
6.
Birth
Infancy
Childhood
Adolescence
Adulthood
Death
1. Egg
2. Tadpole
3. Froglet
4. Adult Frog
Death
Life span is how long an animal can be expected to live.
Page 5
Influence of Human Activity on Ecosystems
Humans can have a major impact on ecosystems. Impacts
can be positive or negative:
Negative Impacts:
-Pollution is when harmful substances are added to
Earth’s water, air, or land.
-Water pollution can be too dirty to use. It can make
living things sick which could end up killing the plants
and animals living in it.
-Air pollution can come from forest fires, cars, or
factories. They release acids that mix with water in the
air and can fall as acid rain. Smog hangs in the air like a
cloud and makes it hard to breathe.
-Land pollution is caused by trash being thrown to the
ground. This can harm plants and animals. It can make
the land ugly.
Positive Impacts
-Laws to control air and water pollution
-Use resources wisely
-Public parks and forests
-Laws to protect endangered species
Page 6
Natural Influences on Ecosystems
Drought is a long period of time with little or no
precipitation, such as rain. Plants will die and the
consumers that depend on them will also die.
Diseases such as Dutch Elm Disease can harm habitats
because the elm trees die.
Fire can affect an animal’s food supply and habitat.
Overpopulation is when an ecosystem has too many of
one kind of living thing. The animals run out of space,
food, and water.
Page 7
Practice Questions
Which of these is not considered ocean
pollution?
A
B
C
D
Dumping garbage
Artificial reefs
Oil Spills
Chemical runoff
The black widow spider is common to
Virginia’s ledges, rocks, and plants.
Why are these spiders important to
the balance in nature?
F
G
H
J
They poison other animals.
They are harmless to people.
They eat plants.
They help control some insects.
Page 8