1. Life Science Review
7th grade

2. Cell
The smallest unit that can perform all the processes necessary for life.

3. Why are cells so small?
There volume is limited by how much material can to get into the cell to keep it alive.
This is referred to as the “surface area to volume ratio”.

4. Cell Division
Cells make more cells using Cell Division.

5. The Cell Theory All organisms are made of one or more cells.
The cell is the basic unit of all living things.
All cells come from existing cells.

6. The Organization of (multi-cellular) Living Things
Cells – The smallest unit that can perform all life processes. (The building blocks of life)
Tissue – A group of similar cells that can perform a common function.
Organ – a collection of tissues that carry out a specialized function of the body.
Organ System – A group of organs that work together to perform body functions

7. The Organization of living things

11. Organism A complete living thing
All organisms take in raw materials and energy
All organisms get rid of wastes

12. Larger organisms Larger organisms are made of
more cells, not larger cells.

13. Unicellular organism – A complete living thing made of only one cell
Unicellular organism – A complete living thing made of only one cell. It’s lifespan is limited to the life of it’s one cell.
Multi-cellular organism – A complete living thing made of more than one cell. It’s lifespan is not limited to the life of one cell.

14. Larger organisms
Larger organisms get more cells through the process of “cell division”.

15. Benefits of being Multicellular
Larger Size – Large organisms are prey for fewer predators
Longer Life – Life span is not limited to the life span of a single cell
Specialization – Each type of cell has a particular job so the organism is more efficient.

16. Specialized Cells
Even simple multicellular organisms are made of specialized cells that perform many different functions for the organism.
Red blood cells carry oxygen
Nerve cells carry messages

17. Specialized Cells Leaf cells carry out photosynthesis
Root cells collect water

18. Photosynthesis
The process by which plants, algae, and some bacteria use sunlight, carbon dioxide, and water to make food.
CO H2O + (light energy)  C6H12O6 + O2
Carbon dioxide water sunlight  glucose oxygen
Reactants  products

19. Cellular Respiration
The process by which cells use oxygen to produce energy from food.
C6H12O6 + O2  CO2 + H2O + ATP energy
glucose oxygen  carbon dioxide water energy for life
Reactants  products

20. Photosynthesis Cellular Respiration How are they related?
CO H2O + (light energy)  C6H12O O2
Carbon dioxide water sunlight  glucose oxygen
Cellular Respiration
C6H12O6 + O2  CO2 + H2O + ATP energy
glucose oxygen carbon dioxide water energy for life

21. How are they related? They are pretty much identical, only reversed.
The reactants of Photosynthesis are the products of Respiration.
The reactants of Respiration are the products of Photosynthesis.
Except they use a different type of energy.

22. Organelles
Small bodies in a cell’s cytoplasm that are specialized to perform specific functions.

23. Mitochondria
The organelle that breaks down food molecules to make ATP (energy) needed to power the various processes in the cell.
This is where cellular respiration occurs

24. Chloroplast
The organelle that uses the energy of sunlight to make food in a process called photosynthesis.
The food is called glucose.
Found in plant cells.

25. Exchange with the Environment
The exchange of materials between a cell and it’s environment takes place at the cell’s membrane.

26. Exchange with the Environment
The exchange of materials between a cell and it’s environment takes place at the cell’s membrane.

27. The movement of particles from regions of higher density to regions of lower density.

29. Osmosis
The diffusion of water
through a semi-permeable membrane.

30. Semipermeable means… …Only certain materials can pass through.
It is also called selectively permeable

32. Passive Transport
The movement of substances across a cell membrane without the use of energy by the cell.

33. Active Transport
The movement of substances across a cell membrane that requires the cell to use energy.

34. Exocytosis
The process in which a cell releases a particle by enclosing the particle in a vesicle that then moves to the cell surface and fuses with the cell membrane

35. Exocytosis

36. Endocytosis
The process by which a cell membrane surrounds a particle and encloses the particle in a vesicle to bring the particle into the cell.

37. Endocytosis