Download 7th Grade Science Notes Chapter 2

7th Grade Science - Chapter 2 Notes
Photosynthesis - is a series of chemical reactions that convert light energy, water, and
carbon dioxide into the food-energy molecule glucose and give off oxygen.
chlorophyll
Carbon Dioxide + Water ------------------------ Sugar + Oxygen
sunlight
Cellular Respiration - is a series of chemical reactions that convert the energy in food
molecules into a usable form of energy called ATP.
mitochondria
Sugar + Oxygen ------------------------------- Carbon Dioxide + Water
Xylem - tiny tubes in plants that carry water
Phloem - tiny tubes in plants that carry food
Stomata - small openings on the undersides of leaves. Where oxygen and carbon dioxide
pass through.
Chloroplasts - the organelle where photosynthesis occurs
Chlorophyll - a plant pigment found in chloroplasts that traps and stores sunlight
Glucose - a liquid sugar (food) made by plants; usually made in the leaves
Mitochondria - the ‘powerhouses’ of the cell. Where energy is released from food.
Water covers 70% of the Earth’s surface. 97% of water is found in the oceans.
Water Cycle - a natural process where water moves from the Earth’s surface into the
atmosphere and back again by evaporation, condensation, and precipitation.
Evaporation - the process during which liquid water changes into a gas called water vapor.
Condensation - the process during which water vapor changes into liquid water.
Precipitation - any water that falls from clouds to the Earth’s surface.
Transpiration - the release of water vapor from leaves and stems of plants.
Nitrogen - necessary for life. It is an essential part of proteins and DNA. The most abundant
gas in the atmosphere.
Nitrogen Fixation - the process that changes atmospheric nitrogen into nitrogen
compounds that are usable by living things. This can be done by: lightning, bacteria in the
soil, or animal wastes like manure.
Bacteria - a group of microscopic unicellular organisms without a membrane-bound
nucleus.
Oxygen - 2nd most abundant gas in the atmosphere. Needed for cellular processes that
release energy. Essential to life! Needed to make water!
Carbon - all organisms contain carbon. Animals and humans get it from food. Plants get it
from the atmosphere.
Greenhouse Effect - the atmosphere contains water vapor and CO2 which help to both
reflect and hold in some of the heat energy from the sun. This keeps the Earth from
becoming too hot or too cold.
Ecosystem - a community of living and non-living things that work together.
Organism - any whole and complete living thing.
Producers - living organisms that make their own food. Green plants.
Consumers - living organisms that do NOT produce their own food, but get their energy by
consuming other organisms.
Herbivores - consumers that eat plants.
Carnivores - consumers that eat other animals.
Omnivores - consumers that eat both plants and animals.
Detritivores - consumers that eat dead plants and/or animals.
Food Chains - a model that shows how energy flows in an ecosystem through feeding
relationships.
Food Web - a model that shows how food chains in an ecosystem are interconnected.
Energy Pyramid - a model to show the amount of energy available in each step of a food
chain.
Trophic Levels - what the steps in a food pyramid are called. Less energy is available as
you go up the steps.
Chemosynthesis - the process during which producers use chemical energy rather than
light energy to make food.