Download 7th Grade Science-Q4 Final Exam Study Guide CHAPTER 12

7th Grade Science-Q4 Final Exam Study Guide
CHAPTER 12
Infectious Disease and Pathogens
An infectious disease is a disease that is caused by pathogens. A pathogen is an organism or molecule that
causes disease. Louis Pasteur was a scientist that demonstrated that microorganisms can cause disease.
There are four major types of pathogens: bacteria, fungi, parasites, and viruses.
*Fungi are the type of pathogen that causes athlete’s foot.
*An example of pathogenic bacteria are E.coli
*Various types of the flu are caused by viruses.
*A tick is a parasite that can spread lyme disease.
The Spread of Disease
Colds and the flu are usually spread by direct or indirect contact with infected persons. Other diseases
can be transmitted through eating contaminated food, drinking contaminated water, or through a vector,
such as an insect.
Lines of Defense
1st line of defense:
-skin acts as a physical barrier and has destructive chemicals in oil and sweat that may destroy pathogens
-breathing passages have cilia and mucus that traps foreign particles and sneezing and coughing helps
remove foreign particles
-mouth and stomach has destructive chemical that may destroy pathogens
2nd line of defense - inflammatory response: is when fluids and white blood cells, called phagocytes, leak
from blood vessels into tissues and destroy pathogens. The inflammatory response is called a general
defense because it responds in the same way to any kind of pathogen.
3rd line of defense - specific immune response: (involves white blood cells called B cells and T cells) is
when cells of the immune system, called B cells and T cells, react to each kind of pathogen with a defense
targeted specifically at that pathogen. The immune response is called a specific defense because it
responds in a specific way to certain pathogens.
T cells in the immune system identify pathogens and distinguish one pathogen from another.
B-cells produce antibodies. Antibodies are proteins that destroy pathogens. Antibodies help destroy
pathogens by binding to antigens on the pathogens.
Antigens are the molecules on pathogens that enable the immune system to distinguish one kind of
pathogen from another.
Immunity
Immunity is the body’s ability to destroy pathogens before they can cause disease.
Active Immunity-is produced by person’s own body, is acquired by either getting the disease and fighting
it off or by getting a vaccine, and usually lasts a lifetime.
Passive Immunity-is not produced by a person’s own body, but is acquired by getting an injection of
antibodies or is given to a newborn from the mother, and usually only lasts a few months.
Examples of Infectious and Noninfectious Diseases
*Cancer is a disease where a person’s body cells multiply uncontrollably. Ways cancer can be treated are
surgery, chemotherapy drugs, and radiation. Substances that can cause cancer are called carcinogens.
*HIV damages the immune system by destroying T cells.
*Diabetes is a disease that occurs if a person’s pancreas does not produce enough insulin.
*Allergies occur because of a disorder in which the immune system is overly sensitive to a substance.
CHAPTER 13
Food Chains, Food Webs, and Energy Pyramids
The many overlapping food chains in an ecosystem make up a food web.
Consumers: Organisms that obtain energy by feeding on other organisms.
Consumers that eat only animals are called carnivores.
Consumers that feed on the bodies of dead organisms are called scavengers.
Consumers that eat both plants and animals are called omnivores .
Consumers that eat plants only are called herbivores. Herbivores eat producers.
Producers: Organisms that make their own food.
*The first organism in a food chain is always a producer
*Producers use carbon from carbon dioxide to produce other carbon-containing molecules, such
as glucose in a process called photosynthesis.
Be able to analyze food chain, food webs, and energy pyramids. Identify organisms as carnivore,
herbivore, omnivore, or decomposer in food chains and food webs. Identify organisms by their level of
consumption in an energy pyramid, food web, or food chain. Calculate how much energy is available in
the energy levels of an energy pyramid.
The Water Cycle
The three processes in the water cycle are evaporation, condensation, and precipitation. Know the water
cycle. See diagram on pg. 497
*Precipitation is any form of water that falls from clouds to Earth as rain, snow, sleet, or hail.
*The process where water change states from a gas to a liquid is called condensation.
*Evaporation is the process where water change states from a liquid to a gas.
The organisms responsible for the process of taking free nitrogen and converting it into a usable form are
called nitrogen-fixing bacteria.
Additional Material
Focus on these scientists for the exam:
-Gregor Mendel is known as the father of genetics. He is known for his study of heredity in pea plants.
-Charles Darwin developed the theory of evolution to explain biological change by natural selection.
-James Watson and Francis Crick are credited with co-discovering the double-helix structure of DNA.
-Carolus Linnaeus is known as the father of modern taxonomy. He established binomial nomenclature, a
system of naming organisms.
Jane Goodall contributed to biological science by studying Chimpanzees in their native environment for
many years.
From Genetics :*You must be able to perform a Punnett Square and answer questions about it.