1. Life’s Structure and Classification
Section 3: Cell Structure

2. "My work, which I've done for a long time, was not pursued in order to gain the praise I now enjoy, but chiefly from a craving after knowledge, which I notice resides in me more than in most other men. And therewithal, whenever I found out anything remarkable, I have thought it my duty to put down my discovery on paper, so that all ingenious people might be informed thereof."
- Anton Van Leeuwenhoek
Letter, June 12, 1716

3. A. Cells were first seen 400 years ago, when van Leeuwenhoek invented the first microscope.

4. Unfortunately, none of Anton Van Leeuwenhoek's microscopes exist today
Unfortunately, none of Anton Van Leeuwenhoek's microscopes exist today. His instruments were made of gold and silver and were sold by his family after he died, none have been recovered.

5. B. Improvements to the microscope and more observations led to the cell theory

6. It states: All organisms are made up of one or more cells.
2. The cell is the basic unit of organization in organisms.
All cells come from cells Human epithelial cells

7. C. Cells are either prokaryotic or eukaryotic.
Prokaryotic cells lack membrane-bound structures

8. 1. cell wall – tough, rigid outer coverings that protect cells
and give them their shape

10. 2. cell membrane – regulates interactions between the cell and its environment.

11. 3. cytoplasm – gelatinlike substance that constantly flows inside the cell membrane of all cells

12. 4. ribosomes – structures that
make proteins

13. 5. organelles -
structures within the cytoplasm of eukaryotic cells. Most organelles are surrounded by a membrane

14. 6. nucleus – directs all cellular activities; contains long, threadlike, hereditary material made of DNA

15. 7. Chloroplasts – green organelles in the cytoplasm of plant cells; use light energy to make a sugar
called glucose ( C 6 H 12 O 6 )

16. 8. mitochondrion – where energy is released when food is broken down into carbon dioxide and water

17. 9. endoplasmic reticulum, also called ER – is a series of folded membranes in which materials can be processed and moved around inside the cell. Rough ER contains ribosomes

18. 10. Golgi bodies -
stacked, flattened membranes that sort and package materials and move them to the outside of the cell

19. 11. vacuole - membrane-bound space that can store water,
waste products, food, and other materials

20. 12. lysosomes – help break down and recycle food molecules, cell wastes, and worn-out cell parts

21. C. In a many-celled organism, each cell depends on other cells in the organism

22. 1. tissue – group of similar cells that work together to do one job
organ – structures made up of two or more tissues that work together

23. 3. Organ system – group of organs working together to perform a certain function 4. Organ systems work together to make up an organism