Grade 7 Life Science Units
Scientific Inquiry
Classification of Living Things
Cells
Genetics
Evolution & Biodiversity
Ecology
Human Body Systems
MCAS Review Sequence
Use this power point along with the Grade 7 Life
Science Video links to review and complete the twentyfive (25) questions on the MCAS Packet you have been
provided.
Follow this power point in order along with the videos to
complete the questions.
Save the Scientific Inquiry videos for the end.
Good luck on your Grade 8 Science MCAS Exam!!
Standards 1-4
Classification and Cells
 Watch the Classification and Cell Video(s).
 Review the next set of slides.
 Answer questions 1 – 6 and the Open Response
Question in your MCAS Review Packet.
 Good luck!
Classification
Organisms are classified into specific groups (Kingdoms)
according to their common characteristics, such as:
Their ability to make food (Autotroph or Heterotroph)
Whether or not they have a nucleus (Eukaryote or
Prokaryote). IMPORTANT: Organisms with a nucleus are
Eukaryotes—Organisms without a nucleus are
Prokaryotes.
Whether they are unicellular or multicellular.
See next slide for examples and characteristics of
organisms in all Six Kingdoms of Life.
Classification
There are Six (6) Kingdoms of Life.
Animalia
Plantae
Fungi
Protista
Eubacteria
Archaebacteria
Classification
Cells and Living Things
Cell Theory:
All living things are composed of cells.
Cells are the basic units of structure and function
in living things.
New cells are produced from existing cells.
Cells and Living Things
Multicellular
Unicellular
Examples: Butterfly, Daisy,
Human
Examples: Ameoba,
Paramecium, Euglena
Composed of many cells
Single-celled
Kingdoms of Life:
Animalia Fungi
Plantae
Protista (some)
Kingdoms of Life:
Protista
Archaebacteria
Eubacteria
Composed of Levels:
Cells
Tissues
Organs
Organ Systems
Organism
--
Cells and Living Things
Within most cells there are membrane-enclosed
structures called organelles.
Can anyone list an organelle?
Cells and Living Things
Cell Wall
Cell Membrane
Nucleus
Mitochondria
Ribosome
Lysosome
Chloroplast
Endoplasmic Reticulum
Golgi Body/Apparatus Vacuole
Centriole
Cells
Organelle
Plant Cell, Animal Cell or Both
Nucleus
Both
Chloroplast
ONLY IN PLANT CELLS
Mitochondria
Both
Ribosome
Both
Vacuole
Both – larger in Plant Cells
Lysosome
Both
Cell Membrane
Both
Cell Wall
ONLY IN PLANT CELLS
Endoplasmic Reticulum
Both
Golgi Apparatus/Body
Both
Cells and Living Things
Cells and Living Things
Speaking of Cells, Organelles and
Glucose…let’s look at a very important cellular
process…one of the most important on the
biosphere…does anyone know which process
produces the oxygen and glucose that we need
to survive?
Did you say PHOTOSYNTHESIS??
Great work!!
Photosynthesis
Where?
In Plant Cells
What Organelle?
Chloroplast
Why?
1. To provide energy
In the form of glucose
to all living things.
2. To produce oxygen
for living things.
Cellular Respiration
Once the glucose and oxygen are produced by
photosynthesis, these molecules needs to be
broken down into energy for the cells to use and
waste material for the cells to get rid of.
Cellular Transport
Types of Cell Division
Meiosis what about Mitosis?
Meiosis produces gametes with ½ number of
chromosomes.
Mitosis is the process of cell division that
produces an identical replacement cell – such as
a skin cell, muscle cell, etc. It has the same
number of chromosomes as the original cell. It
has too!
Standards 7-10
Genetics and Heredity
Watch the Genetics Videos.
View the next series of slides.
Answer questions 11-15.
Good luck!
Genetics and Heredity
All living things contain cells.
All cells contain DNA—deoxyribonucleic acid—
whether contained in a nucleus (as in
eukaryotes) or not (as in prokaryotes).
DNA contains the genetic information that is
passed from one generation to the next.
Genetics and Heredity
DNA is a molecule shaped like a twisted double
helix.
DNA structure: (1) Deoxyribose Sugar (2)
Nitrogenous base (Adenine, Thymine, Guanine
or Cytosine) (3) Phosphate Group.
These three (3) parts are referred to as a
nucleotide.
Genetics and Heredity
Base Pairing Rule
The “rungs” of a
DNA ladder are
made up of the
nitrogen bases.
The base pairing
rule establishes
the match up of
nitrogen bases.
Guanine will always
Match up with Cytosine.
C with G
Thymine will always
Match up with Adenine.
T with A
Genetics and Heredity
DNA Replication is the process in which one
original strand of DNA unwinds and becomes
two new identical strands of DNA.
The process of DNA replication is an important
part of Cell Division – Mitosis and Meiosis.
Genetics and Heredity
Sometimes a mutation in a sequence of DNA
occurs.
Mutations are not always harmful—in fact they
could help an organism survive.
Mutations acquired in an organism’s lifetime
cannot be passed on---only mutations on genes
or chromosomes can be passed on to future
generations.
Genetics and Heredity
Traits are passed on from parents to offspring on genes.
A gene is a section of a chromosome. Each chromosome
contains many genes – approximately 30,000 genes in
humans.
Humans have 23 pairs of chromosomes – 22 autosomes
(numbered 1-22) and a pair of sex chromosomes XX for girls
and XY for boys.
Each of these chromosomes contains the different genes that
code for your specific traits such as eye color and hair color.
Genetics and Heredity
The passing on of traits from parents to offspring
occurs during the cellular process of Meiosis.
Meiosis is the process in which the number of
chromosomes is divided in half to produce gametes.
The resulting gametes (egg and sperm cells) will
fertilize and produce a zygote.
The zygote (developing embryo) will again contain 23
pairs of chromosomes.
Genetics and Heredity
What’s a Punnett Square?
A Punnett square is a chart which
shows/predicts all possible gene combinations
in a cross of parents (whose genes are known).
Punnett squares are named for an English
geneticist, Reginald Punnett.
Genetics and Heredity
DNA is located on genes.
Genes are sections of chromosomes.
The different forms of genes are called alleles.
Each allele combination represents a person’s traits.
represent dominant or recessive traits.
Alleles can
A dominant trait is represented by a capital letter – example “A”. A
recessive trait is represented by a lower case letter “a”.
A genotype refers to a person’s genetic makeup. A phenotype refers
to an organism’s physical appearance.
Genetics and Herdity
A dominant trait is represented by a capital letter – example “A”. A recessive
trait is represented by a lower case letter “a”.
A genotype refers to a person’s genetic makeup.
For example, AA would represent a person’s genotype and that person would
have two (2) dominant alleles for that trait. This person would be homozygous
or a purebred for that particular trait.
Aa would represent a person who has one dominant allele and one recessive
allele. This person would be heterozygous or a hybrid for that trait.
If a person has the genotype “aa” this person would also be homozygous or a
purebred, however, they would have two (2) recessive alleles.
Genetics and Heredity
A pedigree is a chart that shows how traits have
been passed on through several generations.
A series of symbols is used to represent
dominant and recessive traits and males and
females. 
Genetics and Heredity
A karyotype is a “picture” of an individual’s
chromosomes.
A karyotype shows all 23 pairs of human
chromosomes and creates a “map” of all of the
person’s genes . 
Genetics and Heredity
Dominant vs. Recessive Traits.
A dominant trait will always be expressed in an
organism. Example: Say that the letter “T” represents
the dominant form of the allele for tallness. If an
organism has the genotype “TT” or “Tt”, then the
organism will be tall.
A recessive trait will only be expressed when there are
two alleles for that trait. The organisms genotype would
look like “tt” and the organism would be short.
Parents:
Offspring:
Aa and Aa
A is dominant
= freckles.
A is recessive
= no freckles.
Which ones
will have
freckles?
Standard 6
Watch the Human Body Systems Video.
View the next set of slides.
Answer questions 7-10 in your MCAS packet.
Good luck!
Human Body Systems
Let’s review how multicellular organisms (like
humans) are organized:
Cells, tissues, organs, organ systems, ORGANISM.
There are eleven (11) human body systems.
They all work together to maintain
homeostasis. What’s that??
Can anyone name a few systems??
Human Body Systems
System
Structures
Circulatory
Heart, blood, blood vessels
Digestive
Stomach, large/small intestines
Endocrine
Endocrine gland, hormones
Excretory
Kidneys
Immune
White blood cells, thymus
Integumentary
Skin, hair and nails
Nervous
Brain, spinal cord, nerves
Muscular
Smooth, cardiac and striated
Reproductive
Reproductive organs
Respiratory
Nose, Lungs, Bronchi
Skeletal
Bones, bone marrow
Standards 10 and 11
Evolution and Biodiversity
Watch the Evolution and Biodiversity Videos.
View the next set of slides.
Answer questions 16-18 in your MCAS Review
Packet.
Good luck!
Evolution and Biodiversity
Everything has evolved including humans.
Evolution has occurred over millions of years.
Evolution is a change in species over time.
There is specific evidence of evolution:
Fossils, Vestigial Structures, Embryology, DNA/
Chemical Evidence & Homologous Structures
Evolution and Biodiversity
All of these types of evidence demonstrate that
organisms have shared a common ancestor.
Fossil evidence can be found in sedimentary
rock.
Two ways to date fossils:
Relative Dating – Uses law of superposition
Absolute Dating - Uses radioactive dating
Evolution and Biodiversity
Which layer contains the oldest fossil?
Evolution and Biodiversity
Those organisms that have been best suited to their
environments have survived over time.
Some organisms have specific “adaptations” or physical
traits that allow them to survive and reproduce offspring
over other organisms.
This is referred to as “natural selection” or survival of the
fittest.
Natural selection results in evolution. The organisms with
the best traits will pass on these traits to their offspring.
Standards 12 – 18
Ecology and Evolution
Watch the two (2) Ecology Videos, and, if you
have to, watch the Evolution video again!
View the next set of slides.
Answer questions 19-25 in your MCAS Review
Packet.
Good Luck!
Ecology
All living organisms interact with each other and
their environment.
Just like there are levels of organization in the
human body, there are ecological levels of
organization.
From the smallest to largest: organism,
population, community, ecosystem and
biosphere.
Ecology
The biotic factors are the living organisms in an
environment, such as plants, animals, humans.
The abiotic factors are the non-living things in
the environment, such as rocks, streams, air and
temperature.
The way that living organisms can interact with
each other varies. There are several different
scenarios.
Ecology
There is symbiosis – when at least one organism
benefits.
There are three (3) types of symbiosis:
Commensalism – One organism benefits and the
other doesn’t benefit or get harmed.
Mutualism – Both organisms benefit. WIN WIN
Parasitism – One organism benefits and the other
gets harmed.
Ecology
There are also classic predator – prey
relationships – such as a Hawk and a mouse.
Finally, there is competition – when organisms
compete with each other for limited resources,
such as: food, water or living space.
Ecology
Every organism has its role in the environment:
Decomposers – these break down old living
organisms. These include: bacteria and fungi.
Producers – these are autotrophs, such as plants,
which make food for themselves and others.
Consumers – there are many levels – first, second
and third – these eat the producers and other living
organisms.
Ecology
Decomposers
Ecology
Food Chain – A food chain shows the one-way (arrows in
only one direction—the direction in which the energy is
transferred)transfer of energy (food) within an ecosystem.

Food Web – A food web is a series of interconnected food
chains. 
Scientific Inquiry
Watch the Scientific Inquiry Videos.