7th Grade 2nd Six Weeks Test Topics
Everything and anything we covered since the first day of school could be the topic of a question on this
exam. This exam is intended to be cumulative of all topics we have addressed this school year in
science.
Week 1- Safety

Safety gear-goggles, apron, gloves

Safety equipment-fire extinguisher, emergency eyewash, fire blanket

P.A.S.S. –pull, aim, squeeze, sweep

Safety drills-Shelter in place, fire,tornado

Tetrahedron of Fire-heat, oxygen, fuel, and uninterrupted chain reaction

3 Stages of Fire- ignition, smoke, flame

Safety procedures for conducting labs-Wear safety gear. Tell teacher first if anything is wrong!!
Wash hands last. Follow all instructions. Wait for instructions. Clean up after yourself. Never
use damaged lab ware. Ask questions. No horseplay!
Weeks 2-12: Photosynthesis, Cycles of Matter, Energy Flow Through Living Systems, Organic
Substances, Digestion, Molecules
Photosynthesis

Autotrophs are self-feeders. They make their own food by conducting the process of
photosynthesis. Examples of autotrophs are plants, some bacteria, and algae.

The energy source for autotrophs is radiant energy, or light energy. For most autotrophs, Sun is
the source of radiant energy.

Autotrophs transform radiant energy into chemical energy in the form of glucose (C6H12O6)

The reactants are the substances the autotroph uses for photosynthesis. The reactants are
water (which the plant absorbs through its roots)and carbon dioxide (which enters the leaves
through stomata of plants).

Radiant energy and chlorophyll must be present for photosynthesis to occur.

The products are what is formed during photosynthesis. The products are glucose and oxygen.

Glucose is used by the plant for energy to grow, repair, and replace plant parts. Glucose is
converted by the plant into starch and cellulose and other essential compounds to make stems,
leaves, roots, etc.
Cycling of Matter

Matter cycles and energy flows through the environment.

Biosphere-living part of Earth

Hydrosphere- water part of Earth

Atmosphere- air around Earth

Lithosphere- solid part of Earth (crust)

Water cycle processes:
o
evaporation- liquid water changes into water vapor, a gas
o
condensation-water vapor changes into water droplets to form clouds
o
precipitation- water falls back to Earth in the form of rain, snow, hail, etc.
o
runoff- some water that lands on Earth flows into streams, rivers, lakes, and eventually
the oceans
o
percolation or filtration- water that sinks into the ground to form groundwater and fill in
pore spaces between the soil particles and rock pore spaces.
o
transpiration- plants give off water vapor through stomata to regulate amount of water
in the plant
o
accumulation- water collects in lakes and oceans

Be sure to understand a model of the water cycle.

Carbon cycle processes:
o
respiration- organisms release energy from food and carbon dioxide is a waste product
exhaled
o
weathering- limestone rocks break down into smaller pieces and release carbon dioxide
o
combustion- burning of biomass and fossil fuels releases carbon dioxide
o
decomposition- de composers release carbon dioxide while absorbing energy from dead
things

Long-term storage places for carbon:
o
forests
o
seashells

o
ocean water
o
limestone and other rocks formed in marine environments (reefs, etc)
o
fossil fuels buried deep underground
The carbon dioxide/oxygen cycle is a part of the carbon cycle in which plants give off oxygen and
use carbon dioxide while animals breathe in oxygen and exhale carbon dioxide.
Nitrogen Cycle

nitrogen travels from the atmosphere to the lithosphere, biosphere, and hydrosphere of Earth
and then back to the atmosphere

atmosphere is 78% nitrogen

plants and animals require nitrogen

plants get their nitrogen from the soil

animals get their nitrogen from their food

animal wastes and dead plant and animal matter decays and is broken down by bacteria that
release nitrogen back into the atmosphere

legumes are plants that have bacteria in root nodes that are able to change nitrogen into a
usable form of nitrogen for plants to use
Energy Flow Through Living Systems

Food chains and food webs show the flow of energy from Sun to producers, to primary
consumers, to secondary consumers, to tertiary consumers

The arrows in food chains and food webs mean “gives energy to” and point to the direction the
energy flows.

The original source of energy is Sun

herbivores eat only plants

carnivores eat only other consumers

the energy pyramid shows the amount of energy available at each trophic level

10% rule shows how much is available to pass to the next trophic level. 90% is used up for life
processes and thermal energy that is released.

Most energy is available at the producer level at the bottom of the pyramid. Least amount of
energy is available at the top of the pyramid. That is why we see more plants and fewer hawks,
for example.
Organic Substances

come from living or once-living things

contain carbon

carbon, hydrogen, and oxygen are found in carbohydrates

carbon, hydrogen, oxygen, and nitrogen are found in proteins

carbon, hydrogen, oxygen are found in lipids

carbohydrates are starches and sugars

proteins are found in meats and eggs

lipids are fats and waxes found in butter, fats, meats, nuts, oils

carbohydrates are the main source of energy for people

carbon can combine with other elements in rings, long chains, and branched chains

inorganic substances do not come from living things: example carbon dioxide, water
Molecules

lipids break down to form fatty acids

proteins break down to form amino acids

carbohydrates break down to form simple sugars
Digestion

large molecules are broken down into smaller molecules that can be absorbed into the
bloodstream

mechanical digestion includes chewing, grinding, and churning

chemical digestion includes the addition of enzymes and acids to the food

digestion in mouth is both mechanical and chemical: chopping, grinding by teeth is mechanical
and adding saliva with the enzyme amylase is chemical.

digestion continues in the stomach and small intestine

liver and pancreas add enzymes to the small intestine to help digest foods

bile produced by liver breaks down fats into fatty acids

small intestine has villi that increase surface area and help absorb small molecules into
bloodstream

large intestine collects the undigested part of food and prepares it for elimination from body

nutrients include: water, fiber, fats, carbs, proteins, vitamins, and minerals

fiber is indigestible by humans but is important for bowels to move regularly

peristalsis is the rhythmic contraction of muscles of the digestive tract that push the food
through the tract from esophagus, to stomach, to small intestine, to large intestine, to rectum,
to anus

salivary glands around mouth add moisture and enzymes to food
https://pawneeisd.stemscopes.com
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