Energy & Matter Cycles (7.L2U1.12)
Identify the original source of energy for a food chain: grass-> mouse-> hawk
Sunlight
What type of organism introduces new energy into a system?
Producer
Which structure acts as the boundary, controlling entry and exit?
Cell membrane
Which organelle contains the "blueprints" for all cell systems?
Nucleus
What is the smallest "basic unit" you must observe to prove an object is living?
The Cell
In photosynthesis, which TWO substances provide the physical atoms that are rearranged to become glucose?
Carbon dioxide and Water
A rabbit eats grass. Trace the energy in the rabbit back to its original source.
Sun Plant (photosynthesis makes glucose) Rabbit (digestion releases energy)
Name one structure that allows a plant to stay rigid and upright without a skeleton.
Cell Wall or Vacuole
How does the cell membrane maintain homeostasis when the environment changes?
Regulates molecules to keep internal conditions stable despite outside fluctuations
You see boxy, green structures on a slide. Is this a plant or animal cell?
Plant cell
A student claims: “An acorn produces its own energy independently once it falls.” Explain why this is incorrect.
Energy was made by the tree's leaves via photosynthesis and stored in the acorn
A plant in a sealed jar stops producing oxygen. Explain what is happening to the system.
Photosynthesis stopped (no light); oxygen is no longer being released
A cell has plenty of glucose but zero usable energy (ATP). Which organelle is failing?
Mitochondria
Explain the "Teamwork" between chloroplasts and mitochondria.
Chloroplasts make glucose/fuel (Photosynthesis); Mitochondria release energy from that fuel (Cellular Respiration)
You see a cell dividing. Which part of Cell Theory does this support?
Note: Cell Theory is a fundamental biology concept stating that all living things are made of cells, cells are the basic unit of structure and function in life, and all cells come from pre-existing cells.
All cells come from existing cells
Evaluate: “Sunlight is matter because it is an input that helps plants gain mass.”
Incorrect: Sunlight is energy; mass comes from the atoms in CO2 and Water
Oxygen levels are dropping in a sealed jar. Give TWO possible scientific explanations.
1. Lack of light; 2. Overpopulation of consumers using Oxygen (O2) faster than plants make it
Compare the structure of the cell membrane and cell wall. How does each maintain internal stability?
Membrane = flexible chemical control; Wall = rigid physical support
If a toxin destroys membrane proteins, explain TWO effects on other organelles.
1. Mitochondria cannot produce ATP (no nutrients enter); 2. Nucleus cannot maintain internal stability due to toxin buildup
Explain why a microscope is a necessary tool for supporting Cell Theory.
(We're going to the lab tomorrow to use microscopes)
Cells are too small for the naked eye; it provides the visual evidence required for the theory
The Atomic Shuffle: A plant doubles in mass over a year. Construct an explanation for where that new matter physically came from.
Carbon dioxide (CO2) from the atmosphere was taken in; atoms were rearranged into glucose and stored as mass
Evaluate: “Energy cycles through ecosystems the same way matter does.”
Incorrect: Matter cycles/is reused; Energy flows in one direction and leaves as heat
Compare wood from a desk to a leaf from a tree. Which provides better evidence of living cells and why?
The leaf; it shows active processes like photosynthesis, while wood is dead tissue
Why does a leaf cell have hundreds of chloroplasts while a root cell has zero?
Structure follows function; roots have no light, so chloroplasts are a waste of resources
Draw a model of energy moving from sunlight to usable energy (ATP) in a plant cell.
Must show Sun -> Chloroplast -> Glucose -> Mitochondria -> ATP